Comets in Art - Panel from Bayeux Tapestry, 11th century (Wikimedia Commons)
THE COMET’S TALE Comet Section – British Astronomical Association Journal–Number352016May
britastro.org/comet
Comet 252P LINEAR: conjunction with M14: Alan Tough 2016 April 05
1
TableofContents
1
2
3
4
5
6
7
8
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11
12
13
14
Contents
Director’s
Welcome
Comet
Predictions
Author
NickJames
SectionDirector
JonathanShanklin
VisualObservations
andAnalysis
CometsReaching JonathanShanklin
Perihelion
VisualObservations
andAnalysis
BAAComet
DenisBuczynski
Image–an
Secretary
appeal
Discovering
MichaelMattiazzo
Cometsusing
SWAN
BirthofComet
NeilNorman
Watch
OutburstComets RogerDymock
Outreachand
Mentoring
CometImagingin PeterCarson
aPollutedSite
CCDImagingAdvisor
Tarbatness
DenisBuczynski
Observatory
Secretary
VEM
NickJames
SectionDirector
WilliamTempel DenisBuczynski
Secretary
Editor’sWhimsy JaniceMcClean
Editor
Contacts
Pleasenotethatcopyrightofallimages
PictureGallery
belongswiththeObserver
2
Page
3
5
7
10
12
15
17
20
23
26
31
36
37
38
1
FromtheDirector–NickJames
Welcometothefirstissueofthenew‐style
Comet’sTale.InthefutureIhopeto
publishtheJournaltwiceayear;asnearto
theequinoxesaspossible,althoughthat
mightchange.Ilookforwardtoreceiving
allyourcontributionsandaspecialthank
youtothosewhomadetheirsubmissions
forthisfirstedition.Pleaseletmeknowif
youhaveanysuggestionsforfuture
material.
Comet’sTalewehavehadtwobright
comets:C/2014Q2(Lovejoy)andC/2013
US10(Catalina)andplentyofinteresting
faintcomets.Inparticular,theamazing
imagesof67PfromRosettahaveshownus
howmuchwedon’tknowaboutthe
physicsofcometsandhowimportant
amateurobservationscanbe.I’vetriedto
observeasmanycometsaspossibleusing
the0.28mSCTatthebottomofmygarden
(picturedhere)andremotelyusing
iTelescopeandSierraStars.
ThisissueismyfirstasDirectorofthe
CometSection.ItookoverfromJonathan
ShanklinattheBAAAGMlastOctoberand
becamethe12thDirectoroftheBAAComet
Sectioncontinuinganunbrokenlinegoing
backtoW.F.Denning,whowasthefirst
Director,appointedin1891.
BecomingtheDirectorofaBAASection
carriesagreatresponsibility.IknowthatI
haveaveryhardacttofollowanditwill
takemeawhiletogetusedtothenewrole.
IwouldliketothankJonathanforthe
dedicationhehasshowntotheSectionas
Director.Hisdirectorshiplasted25years
sohecertainlydeservesabreak!This
durationissecondonlytoCrommelin's
seconddirectorship,amonumental32year
stintbetween1907and1939.Jonathan's
knowledgeofmattersrelatedtocometsis
moreextensivethananyoneelseIknow
andIamverypleasedthathehasagreedto
stayonthesectioncommitteeasvisual
observationsandanalysiscoordinator.
Althoughastronomycanbeasolitary
hobbyIstronglyfeelthatwegetthemost
outofitthroughdiscussionand
cooperationwithothers.TheBAAComet
Sectioncanbeasignificantpartofthisbut
therearealsomajorhubsofcomet
observinggoingonelsewhere,particularly
onlineinsocialnetworks,seethenotefrom
NeilNormanlaterinthisissue.Ifeel
stronglythatcooperationbetween
observersandorganisationswillimprove
thingsforeveryone.
Weallknowthatcometsarewonderfully
unpredictableobjects.Thisiswhatmakes
themsomuchfuntoobserve.Younever
quiteknowwhatyouaregoingtoseewhen
yougoouttoobserve.Sincethelast
LastsummerJakubČernýorganiseda
conferenceoncometobservingatthe
famousOndřejovObservatoryintheCzech
Republic.IattendedonbehalfoftheComet
3
SectionandRichardMileswasalsothere.
Thiswasaveryenjoyableandproductive
weekendandIcamebackwithlotsof
thoughtsabouthowtoimprovethe
efficiencyofourcometobserving
programmeandhowtoincreaseco‐
operationwithotherEuropeangroups.
Thereisalotthatwecanlearnfromeach
other.
observationsof370differentcometsmade
by170observershavebeenimportedso
far.PleaseconsidersigninguptoCOBSto
submityourdata.YoucanfindtheCOBS
databasehere:
http://www.cobs.si/
IfyouregisterasaBAAmemberwecanget
amonthlyreportonobservationsmadeby
ourmembers.Complementingthedata
heldbyCOBStheBAAmaintainsahuge
archiveofcometimagesonourwebsite
here:
http://www.britastro.org/cometobs/
ThisismaintainedbyDenisBuczynskiand
itisupdatedalmostdaily.Itnowcontains
thousandsofimagesofhundredsof
differentcometsandisoneofthemost
extensivecometimagearchivesinthe
world.Wearekeentoreceiveyourimages
butifyouhavenotsubmittedanybefore
pleasecontactDenisfirstforinformation
onhowtosubmityourobservations.
MymainfocussinceIreturnedhasbeen
howtoimprovetheCCDcometVisual
EquivalentMagnitudeworkflowby
implementingsomesoftwaretodomostof
theworkautomatically.I'mstillworking
onthisandyouwillfindasummaryofthe
currentstatusinthiseditionoftheTale.
Finally,Iwouldliketowelcomeandto
thankMsJaniceMcCleanforvolunteering
totakeontheroleofEditor,andforher
workinpreparingthisfirstedition.Let’s
hopeforgoodweatherthroughthe
northernsummerandforplentyofcomet
observingpossibilities.TheCometSection
officerslookforwardtoreceivingyour
observations.
Anotherimportantaspectdiscussedatthe
Conferencewasthearchivingofcomet
observations.Oneofthekeymotivations
forpeoplewhentheysubmittheir
observationsistheknowledgethatthedata
willbeavailableforusebyresearchers.
Thisfunctionusedtobeperformedbythe
ICQbutthatarchivenowappearstobe
effectivelydefunct.Ourconclusionwas
thattheCOBSdatabasewasthebestoption
andthatthiswouldhavealong‐termfuture.
TheBAAhasaconsiderablearchiveofICQ
formatobservationscuratedbyJonathan
Shanklinand,throughthehardworkof
JureZakrajsek,manyofthesehavenow
beenimportedintoCOBS.Over30,000
NickJames–SectionDirector
4
2
CometPredictionsfor2016MaytoDecember–JonathanShanklin
IntheSouthernHemisphere2013X1
(PanSTARRS)couldbevisibleinbinoculars
duringtheirwinter.45P/Honda‐Mrkos‐
Pajdusakovaisthebrightestoftheperiodic
comets,andmaybevisibleinbinocularsat
theendoftheyear,thoughitisrelatively
closetotheSun.
observersareencouragedtoreport
electronicvisualequivalentmagnitude
estimatesviaCOBS.Whenpossibleusea
wavebandapproximatingtoVisualorV
magnitudes.Theseestimatescanbeused
toextendthevisuallightcurves,andhence
derivemoreaccurateabsolutemagnitudes.
Thesepredictionsfocusoncometsthatare
likelytobewithinrangeofvisual
observers,thoughcometsoftendonot
behaveasexpectedandcanspring
surprises.Theyhavebeenrevisedfrom
theversionthatappearedintheJournalfor
theComet’sTale.Acompleteupdateisalso
availableonthevisualco‐ordinator’sweb
page.
InadditiontotheinformationintheBAA
HandbookandontheSectionwebpages,
ephemeridesforthebrighterobservable
cometsarepublishedintheCirculars,and
ephemeridesfornewandcurrently
observablecometsareontheJPL,CBAT
andSeiichiYoshida'swebpages.TheBAA
ObservingGuidetoCometsisavailable
fromtheBAAOffice.
Membersareencouragedtomakevisual
magnitudeestimates,particularlyof
periodiccomets,aslongtermmonitoring
overmanyreturnshelpsunderstandtheir
evolution.Guidanceonvisualobservation
andhowtosubmitestimatesisgiveninthe
BAAObservingGuidetoComets.Pleasee‐
mailyourestimatesusingtheICQformat
orsubmitthemtoCOBS,anddorefertothe
datafilesonthevisualco‐ordinator’sweb
pageforcorrectlyformattedexamples.
Drawingsarealsouseful,asthehumaneye
cansometimesdiscernfeaturesthat
initiallyeludeelectronicdevices.
9P/Tempelwasfirstobservedin1867,
butwaslostbetween1879and1967
followinganencounterwithJupiterin
1881,whichincreasedtheperihelion
distancefrom1.8to2.1au.Further
encountersin1941and1953putqbackto
1.5auandcalculationsbyBrianMarsden
allowedElizabethRoemertorecoveritin
1967.Alternatereturnsarefavourable,but
anencounterwithJupiterin2024willonce
againincreasetheperiheliondistanceto
1.8au.ItwasthetargetfortheDeep
Impactmission,withtheStardust
spacecraftsubsequentlypassingbythe
comet.Thecometcameintovisualrange
inMarch,andremainsvisibleforUK
observersuntilJune.Itcouldbeatits
brightestaround11thmagnitudeinearly
July,whenitpassessouthofthecelestial
equator,andSouthernHemisphere
observerswillbeabletofollowitasit
fades.
Theoriesonthestructureofcomets
suggestthatanycometcouldfragmentat
anytime,soitisworthkeepinganeyeon
someofthefaintercomets,whichareoften
ignored.Theywouldmakeusefultargets
forthosemakingelectronicobservations,
especiallythosewithtimeoninstruments
suchastheFaulkestelescopes.Such
5
226P/Pigott‐LINEAR‐Kowalskihasa
rathercomplicatedhistory.Itwas
discoveredbyEdwardPigottfromYork
andwasobservedbyHerschel,Mechain
andMessieramongstothers.Aparabolic
orbitwascomputed,buttherewere
suspicionsthatitmightbeofshortperiod.
Itwasthenlostuntilacometwasfoundby
LINEARin2003January,whichwas
thoughttoprobablybethelonglostcomet.
Thecometthenpassed0.056aufrom
Jupiteron2006September10inan
encounterthatconsiderablychangedthe
orbit.FinallyRichKowalskidiscovereda
verydiffusecometduringtheCatalinaSky
Surveyon2009September10,whichwas
thenlinkedtothePigottandLINEAR
comets.Thisisafavourablereturnfor
northernobservers,withthecometpassing
thecelestialequatorheadingnorthinearly
August.Itwillbebrightestatperhaps10th
magnitudeintheautumnwhenitnears
opposition.
29P/Schwassmann‐Wachmannisan
annualcometthathasoutbursts,which
overthelastdecadeseemtohavebecome
morefrequent.Thecomethadoneofits
strongestoutburstsyetrecordedinearly
2010.RichardMileshasdevelopeda
theorythatsuggeststhattheseoutbursts
areinfactperiodic,andarisefromatleast
fourindependentactiveareasonthe
slowlyrotatingnucleus.Theactivityofthe
activeareasevolveswithtime.Thecomet
isanidealtargetforthoseequippedwith
CCDsanditshouldbeobservedatevery
opportunity.Thecometisatasouthern
declination,reachingoppositionin
ScorpiusinJuneandpassingthroughsolar
conjunctionattheendofDecember.
45P/Honda‐Mrkos‐Pajdusakovahashad
severalcloseencounterswithJupiter,the
mostrecentin1983whichmadedramatic
changestoand.Theperihelion
distancehassteadilydecreasedandisclose
tothesmallestithasbeenforthelast200
years,thoughisnowincreasingagain.It
canapproachquitecloselytotheEarthand
didsoatthelastreturnin2011(0.06au)
andisonitswaytoanothercloseapproach
postperihelion,in2017(0.08au).At
presenttheMPConlylistseight
approachescloserthan0.06auoutof20
passescloserthan0.1au,andnineofthese
arebyfiveperiodiccomets.Itcanalsopass
closetoVenusandpassedat0.085auin
2006,gettingevencloserin2092.The
cometbrightensrapidlyinNovember,but
itiswellsouthofthecelestialequator.For
northernobserverstheremaybeashort
periodwhenitmightbevisibleattheclose
oftheyear,whenitisatperihelionand
perhaps7thmagnitude.
2013X1(PanSTARRS)was9thmagnitude
atthebeginningoftheyearandwellplaced
intheeveningskyfornorthernhemisphere
observers.Itisrapidlymovingsouth
however,andaftermidFebruarywillbe
losttoview.Aftersolarconjunction
SouthernHemisphereobserverswillbe
abletoobserveitfromaroundApriluntil
September,withthecometbrightestat
around6thmagnitudeinJune.
Theotherperiodicandparaboliccomets
thatareatperihelionduring2016are
unlikelytobecomebrighterthan12th
magnitudeorarepoorlyplaced.
Ephemeridesforthesecanbefoundonthe
CBATwebsite.SeveralD/cometshave
predictionsforareturn,thoughsearchesat
favourablereturnsintheintervening
periodhavefailedtorevealthecometsand
theorbitswillhavebeenperturbedby
6
Jupiter.Thereishoweveralwaysachance
thattheywillberediscoveredaccidentally
byoneoftheSkySurveypatrols.SixSOHO
cometsarepredictedtoreturn,however
thesewillonlybevisiblefromtheSOHOor
STEREOsatellites.
lostinthetwilight.Februaryislikelytobe
abusyperiodforthenewDirector,as
41P/Tuttle‐Giacobini‐Kresakisalso
likelytobeabinocularobjectonitswayto
a0.14auapproachtotheEarthonMarch
30.Itcouldbeabinocularobjectfrom
FebruaryuntilJuneandperhapsanaked
eyeobjectwhenbrightest.
Lookingaheadto2017,therearesome
goodprospectsforonce.45P/Honda‐
Mrkos‐Pajdusakovaemergesfromsolar
conjunctiononitswaytopassing0.08au
fromtheEarthonFebruary11.Itcouldbe
abinocularobjectasitmovesrapidly
acrosstheskyduringFebruary.2P/Encke
shouldalsobeseenduringFebruary,when
itisvisibleintheearlyevening,perhaps
reachingbinocularbrightnessbeforeitis
JonathanShanklin–VisualObservationsandanalysis
coordinator
3
Cometsreachingperihelionin2016
Comet
T
q
P
N
H1
K1
Peakmag
302P/Lemmon‐PanSTARRS
May1.4 3.30
8.85
2
12.5 10.0
20
PanSTARRS(2015B2)
May6.4 3.37
9.5
10.0
17
77P/Longmore
May13.6 2.34
6.88
6
7.0
20.0
15
LINEAR(2015Y1)
May15.9 2.50
12.0 10.0
17
Gibbs(2015W1)
May17.2 2.23
12.5 10.0
18
224P/LINEAR‐NEAT
May24.4 1.99
6.31
2
15.5 10.0
21
Spacewatch(2011KP36)
May26.9 4.88
238
4.5
10.0
14
Gibbs(2007R3)
May27.4 2.52
8.92
1
13.5 10.0
19
136P/Mueller
May31.2 2.98
8.62
3
11.0 10.0
17
216P/LINEAR
May31.2 2.15
7.63
2
12.4 10.0
17
157P/Tritton
Jun10.4 1.36
6.29
3
14.0 10.0
17
202P/Scotti
Jun10.6 2.52
7.33
3
13.5 10.0
20
7
P/Scotti(2011A2)
Jun14.0 1.55
5.47
1
16.5 10.0
20
118P/Shoemaker‐Levy
Jun17.0 1.98
6.44
4
9.3
9.6
15
PanSTARRS(2015T4)
Jun18.9 2.30
800
1
11.0 10.0
16
146P/Shoemaker‐LINEAR
Jun30.0 1.43
8.11
3
15.0 10.0
18
16.0 10.0
17
207P/NEAT
Jul1.1
0.94
7.64
2
P/SOHO(1999N5=2005E4)
Jul1.5
0.05
5.67
2
P/SOHO(2000O3)
Jul1.9
0.05
5.31
3
208P/McMillan
Jul2.1
2.54
8.15
2
12.5 10.0
18
P/WISE(2010N1)
Jul8.0
1.63
5.95
1
17.0 10.0
18
279P/LaSagra
Jul14.5
2.16
6.78
2
14.0 10.0
18
56P/Slaughter‐Burnham
Jul18.4
2.51
11.5
5
8.5
15.0
16
81P/Wild
Jul20.3
1.59
6.41
6
8.7
6.9
12
P/Gibbs(2009K1)
Jul24.7
1.34
7.09
1
17.0 10.0
20
150P/LONEOS
Jul25.0
1.76
7.66
4
13.5 10.0
18
9P/Tempel
Aug2.6
1.54
5.58
11
6.6
19.7
11
ATLAS(2015X7)
Aug3.5
3.75
9.0
10.0
18
PanSTARRS(2014R3)
Aug7.9
7.28
6.5
10.0
19
P/Barnard(1884O1)
Aug10.8
1.31
5.41
1
225P/LINEAR
Aug16.8
1.32
6.98
2
18.0 10.0
19
43P/Wolf‐Harrington
Aug19.7
1.36
6.13
11
8.9
10.0
12
33P/Daniel
Aug22.5
2.16
8.07
10
10.5 20.0
19
PanSTARRS(2015V4)
Aug25.8
5.47
80
1
8.5
10.0
19
LINEAR(TQ209)
Aug27.5
1.41
10.5 10.0
14
330P/Catalina
Aug30.0
2.96
16.9
2
10.0 10.0
17
LINEAR(2016A8)
Aug30.5
1.89
220
12.0 10.0
15
144P/Kushida
Aug31.0
1.43
7.57
3
4.3
11
8
32.1
Sheppard‐Tholen(2015T5)
Sep2.2
9.18
180
1
7.5
10.0
22
226P/Pigott‐LINEAR‐Kowalski
Sep5.1
1.78
7.32
4
6.0
15.0
10
212P/NEAT
Sep10.2 1.65
7.76
2
17.0
5.0
20
PanSTARRS(2015H2)
Sep13.3 4.97
7.5
10.0
18
314P/Montani
Oct7.1
4.24
19.6
2
9.0
10.0
18
237P/LINEAR
Oct11.7 1.98
6.57
2
14.5
5.0
17
P/SOHO(1999N5=2005G2)
Oct11.7 0.05
5.76
2
238P/Read
Oct22.8 2.36
5.63
2
14.5 10.0
19
94P/Russell
Oct27.7 2.23
6.58
5
9.0
15.0
16
Read(2005S3)
Nov1.5 2.82
10.8
1
12.0 10.0
18
LINEAR(2010A2)
Nov8.5 2.01
3.47
1
15.5 10.0
19
288P/Spacewatch=(300163)
Nov8.9 2.43
5.32
3
16.0
5.0
19
D/Haneda‐Campos(1978R1)
Nov11.2
1.29
6.44
1
P/Boattini(2008T1)
Nov18.2
3.06
8.76
1
11.0 10.0
18
P/McNaught(2008J3)
Nov23.0
2.30
7.71
1
12.0 10.0
16
323P/SOHO
Nov23.8
0.04
4.15
3
NEOWISE(2016B1)
Dec4.7
3.23
9.5
10.0
18
316P/LONEOS
Dec6.8
2.42
11.2
1
10.0 10.0
15
PanSTARRS(2014OE4)
Dec10.7 6.24
11.0
5.0
19
89P/Russell
Dec15.2 2.24
7.32
5
11.5 15.0
19
45P/Honda‐Mrkos‐Pajdusakova Dec31.2 0.53 5.26 11 12.6 19.1
7
Thedateofperihelion(T),periheliondistance(q),period(P),thenumberofpreviously
observedreturns(N),themagnitudeparametersH1andK1andthebrightestmagnitude
(whichmustberegardedasuncertain)aregivenforeachcomet.Themagnitudes,orbits,and
inparticularthetimeofperihelionofthesingleapparitionD/comets,areuncertain.
MagnitudeinformationisnotgivenfortheSOHOcomets;thesearenowbeingnumberedby
theIAUonceobservedoversufficientreturns.
Note:m1=H1+5.0*log(d)+K1*log(r)
9
Referencesandsources
Belyaev,N.A.,Kresak,L.,Pittich,E.M.andPushkarev,A.N.,CatalogueofshortPeriodComets,Bratislava(1986).
CometObservationsDatabase(COBS)http://www.cobs.si/(Accessed2016March)
CometOrbitHomePage(KazuaKinoshita)athttp://jcometobs.web.fc2.com/index.html(Accessed2015October)
Jenniskens,P.MeteorShowersandtheirParentComets.CambridgeUniversityPress(2006).
JPLSmall‐BodyDatabaseBrowserhttp://ssd.jpl.nasa.gov/sbdb.cgi#top(Accessed2016March)
Kozlov,E.A.,Medvedev,Y.D.,Pittichova,J.,andPittich,E.M.CatalogueofshortPeriodComets,2ndedition,
(http://astro.savba.sk/cat/)(2003).
Kronk,G.W.,Cometographia,CambridgeUniversityPress,(1999,2004,2007,2009,2010)and
http://www.cometography.com(Accessed2015October).
Marsden,B.G.andWilliams,G.V.CatalogueofCometaryOrbits,17thedition,IAUMPC/CBAT,(2008).
MinorPlanetElectronicCirculars
NakanoNotesathttp://www.oaa.gr.jp/~oaacs/nk/(Accessed2015October)
Shanklin,J.D.,ObservingGuidetoComets,3rdedition(2013)
4
TheBAACometImageArchive:AnAppeal–DenisBuczynski
InthepasttwoyearstheSectionhas
establishedanextensivearchiveof
thousandsofimagesofcometsthathave
appearedinourskies.Thevastmajorityof
thesehavebeenimagesindigitalformthat
havebeensubmittedtotheSectionfrom
BAAmembersandsubscriberstoThe
AstronomerMagazine.Thisarchivecanbe
accessedatthefollowinglink:
http://www.britastro.org/cometobs/
Howevertheremustbemanymembers
whostillhaveimagesofcomets,either
printedasphotographsorrecordedon
slides.Therewillbesomewhohave
sketchesanddrawingsmadeatthe
telescope.Wewouldliketoincludeallof
theseinourarchiveandIinvitemembers
tosubmittheseolderobservations.Many
peoplewillhaveaccesstoascannerso
printsandsketchescaneasilybecopied.
Slidescanbemoredifficult,butagainmany
10
peoplemayhaveslidescanners.Ifyouhave
anyolderobservationsandwanttosubmit
themthensendthemto:
[email protected]
4. date=UTCdateintheformat
YYYYMMDD
5. time=UTCtimeintheformat
HHMMorHHMMSS.
6. obscode=Yourobservercode
"xxxx"(Letmeknowifyouwould
preferadifferentcode).Youcan
havemultipledifferentobserver
codesifyouneedthem.
Ihopetoreceiveafloodofobservations!
Wehaveveryfewimagesofcometssuchas
1PHalleyorofgreatcometsC/1995O1
Hale‐BoppandC/1995Y1Hyakutake.I
knowtheremustbemanyobserverswho
tookpicturesandmadesketchesofthese
andothercomets.Soplease,consider
searchingthroughyourownrecordsandif
youfindanyrelevantimagesthensubmit
them.Nomatterhowoldtheobservation
maybe.
So,forexample,animageof2014q2taken
on2014‐12‐29at23:45UTCwouldbe:
2014q2_20141229_2345_xxxx.jpg
Youshouldincludedetailsinacaptionon
theimage.Ifyouwouldliketoinclude
otherdescriptivetextinthearchiveyou
candothisbysubmittingatextfilewith
thesamenameastheimagebutwith.txt
appended,i.e.
SubmissiondetailsfortheBAA/TAcomet
imagearchive.
Ourstandardimage‐namingrulesshould
befollowedasweneedtoarchiveeach
imageunderastrictprotocol.Please
submityourimagesto
[email protected].
2014q2_20141229_2345_xxxx.jpg.txt
Ifyouneedanyhelpincopyingany
observationsthencontactmeat
[email protected]
Theimagearchivepagesaregenerated
automaticallybasedonthefilenameofthe
imagesoitwouldhelpusgreatlyifyou
couldconformtothefollowingformat:
1. object_date_time_obscode.jpg
2. wherethefieldsareseparatedbya
singleunderscorecharacter'_'.The
fieldsare:
3. object=objectname.Forperiodic
cometsthiswouldbe,forexample,
303p.Forlong‐periodobjectsitis
"2014q2".
DenisBuczynski‐SecretaryCometSection
11
5
DiscoveringcometsusingtheSWANinstrumentonSOHO–Michael
Mattiazzo
IwasborninAdelaide,SouthAustralia,and
Ifirstbecameinterestedinastronomyat
theageof16in1986.Thatwasatthetime
ofcometHalley’sreappearance.Myfirst
viewofitwasinearlyMarchthroughapair
of7x50mmbinocularsanditdisplayeda
beautifulstar‐likenucleus,embedded
withinacoma,withadusttail5degrees
longlookingdirectlyoverthecityof
Adelaide.Itmadeaverystrongimpression
onmeandgavebirthtoalifelonginterest
inobservingandimagingcomets.
startedobservingandhuntingforcomets.
Usingan8”telescopeatthetime,I
narrowlymissedoutonfindingcometsLee
andLynn.
InJuly2000,Ipurchasedapairof
25x100mmbinoculars.Onthenightof
November24,2000,Isweptupabright7th
magnitudeobjectinArawhichwasnota
knowncomet.Ireportedthistothe
CentralBureauAstronomicalTelegrams,
basedinHarvardUniversityintheUSA,but
subsequentlydiscoveredIhadbeenpiped
atthepostbyAlbertJonesinNewZealand,
whohadpickeditup24hoursearlier.The
cometwasannouncedasC/2000W1
Utsunomiya‐Jones.
Todaythesamefeatwouldbeimpossible
becauseoftheAdelaidelightpollution
blockingmostthingsfromview.Iknow
thatIwasveryfortunatetoobservethe
cometfromadarkskysitethatfirsttime,
andwhenitwasatclosestapproachback
in1986April11.NotonlycouldIseethe
cometand5degreetaileasilywiththe
nakedeye,buttheMilkyWayalsostood
outinallitsglory.Thescenehadme
hookedandIwasdeterminedtofinda
cometofmyown.
Iwasdisappointed.Thenin2002,thefirst
SWANcometwasannounced.SWAN
standsforSolarWindAnisotropies(i.e.
windsdirectionallydependent),an
experimentonboardtheSOHO(Solarand
HeliosphericObservatory)spacecraft,
developedincollaborationwiththeFinnish
MeteorologicalInstitute.TheSWANcomet
discoveredwasC/2002O6andwas
discoveredbyM.Suzuki,Utsunomiya,
Tochigi,Japan.TheSWANcameracanpick
upcometsquiteeasilyviatheultraviolet
emissionofHydrogeninthecoma.Atthe
sametimetheSWANprojectteamstarted
tooffertheirdatain“comettrackermap”
formtothepublic.
Becomingacomethunter
IjoinedtheAstronomicalSocietyofSouth
Australiain1990andhadtheprivilegeto
knowoneofthegreatestvisualcomet
huntersofalltime.BillBradfield,anoted
discovererof18comets,wasmymentor
andgavememuchsupport.Theonly
problemIhadwasdealingwithAdelaide’s
increasinglightpollution.Ihadthechance
in1997whenItookupapositionas
pathologylaboratorymanagerinWallaroo,
asmalltowninSouthAustralia.Thedark
skieswereperfectandthatiswhenI
Asaresultofthis,Igaveupvisualcomet
huntinginfavourofconfirmingSWAN
comets.SWANwascapableofdetecting
cometsasfaintas12thmagnitude.The
firstobjectIpickedupwasinApril2003,
12
notedasuspiciousobjectlocatedonthe
Leo/ComaBerenicesborderonimages
datedAug3and4.Imeasuredvery
approximatepositionsonthesedates,as
wellasapossibleearlierdetectiononJuly
28.Positionaccuracyisgenerallyinthe
orderof1to2degreesofsky.Alsosince
thecomettrackermapsarepostedwitha
timedelayofnearlyaweek,Ihadto
predictwherethecometmayhavemoved
to,inthesky.
butnoonewasabletoconfirmitonthe
grounduntilamonthlaterwhenEric
ChristensenoftheCatalinaSkysurvey
discoveredit.Thisshortperiodobjectis
nowcalled210PChristensenbut,inmy
opinion,itshouldhavebeenlabelledas
SWAN‐Christensen.
Eventually,myfirstsuccesscameinMay
2004withthedetectionofC/2004H6
SWAN.Itwasagreatsensationtobethe
firstpersonintheworldtovisually
observethiscomet,justafewdegrees
abovetheeveninghorizon,using
25x100mmbinoculars.Unfortunatelythe
cometwasapproachingsolarconjunction
andIhadtowaitafurtherweek,before
reconfirmingitinthemorningsky.Then
thenextissuewastotryandconvince
CBATthatthecometwasreal,sincethey
areconstantlyreceivingnumerousreports
ofSWANcomets.Ihadtosendtheman
imageofthecometwithitstail,asproof.
Isearcheda10degreesquarepatchofsky
inVirgo,situatedaroundRhoVirginisthat
evening,at09:11UT,andconfirmedthe
cometphotographicallyafterthethird
sweepusingaCanon60Da+Sigma200mm
F/2.8lens,trackingonaVixenpolariestar
tracker.Thecometappearedslightly
condensed,ofphotometricmagnitude11.8,
withacomadiameterof2arcminutes.The
bluegreencolourofthecometstoodout
fromthewhiteappearanceoftheVirgo
superclusterofgalaxies.
CurrentlyIhavebeencreditedwiththe
discoveryofsevenfurtherSWANcomets,
namelyC/2004V13,C/2005P3,P/2005
T4,C/2006M4(thebrightestonereaching
4thmagnitude),C/2015C2andC/2015P3.
Therearecurrently15cometscarryingthe
SWANname,withfiercecompetition
amongstSWANcomethunters.Ihaveto
saythatitbecomesaddictiveandIenjoy
thecompetitiveelementtoo!My
competitorsareothersuccessfulSWAN
hunterssuchasRobertMatsonand
VladimirBezugly.
RapidmotionwasevidentasIimagedthe
cometforthehourfollowingdiscovery.I
thenmeasureditsvariouspositionsusing
AstrometricaandsentitthroughtoCBAT
forpostingonthePossibleComet
Confirmationpage.Thediscoverywas
announcedonCBET4136andthecomet
designatedC/2015P3SWAN.The
preliminaryorbitindicatedthatperihelion
hadalreadyoccurredon2015July27at
0.71AU.Thecometwasnotexpectedto
becomemuchbrighterthanmagnitude11.
Itwasveryfaintintrinsically(mag14)and
I'msurpriseditevensurvivedperihelion.
Aclueliesinitsrevisedorbit‐itisa
dynamicallyevolvedobject,orbitingthe
Sunevery3,000years.
Mymostrecentdiscovery‐C/2015P3SWAN
On2015Aug9at03UT,Idownloadedthe
latestSWANcomettrackermapsat
http://swan.projet.latmos.ipsl.fr/and
13
SouthernCometsWebsite
http://members.westnet.com.au/mmatti/s
c.htm
Theideaofsettingupthiswebpagecame
aboutin2002,afterIhadobservedthe
spectacularoutburstofC/2000WM1
LINEAR,eruptingfrommagnitude6to2.
Through25x100mmbinoculars,the
starlikenucleushad2jets"horns"
emanatingatoppositepolesofthenucleus.
Theviewwasveryreminiscentofclassical
drawingsofthepast.
MyTelescopeSetup


Sincethen,Ihavebeendocumentingevery
brightcometthatIhavehadthefortuneto
observefrommyperspectiveinthe
SouthernHemisphereincludingthegreat
cometsC/2006P1McNaughtandC/2011
W3Lovejoy.IalsosimulateKreutz
sungrazingcometsinmysoftwareasI
searchalongtheKreutzline(as
recommendedbyBillBradfield).




Ihadasimulatedsungrazeralready
programmedin,withaperiheliondateof
December15,anddiscoveredthatTerry
Lovejoy’spositionsexactlymatched,to
withinafewdegreesofthesimulation,
showingthesamespeedanddirectionas
theKreutzcomet.Itwasaeurekamoment
forme,knowingthathisfindwasa
memberoftheKreutzgroupafterjusttwo
setsofobservations.
IcurrentlyobservefromSwanHill,Victoria,
Australia.Ifyouhaveasparehourand
wouldliketolistentome(andothers)talk
aboutcometsforApril,http://afm‐
originals.s3.amazonaws.com/AFM_Comet
Watch/AFM_CometWatch_160402‐
013_JupiterFamilyOfComets_DevID_6930.
mp3
MichaelMattiazzo
Telescope:CelestronNexstar11GPS
Camera:StarlightExpressMX7c
CCD,oneshotcolour752x582pixels,
resolutionof1.9"perpixelatf/3.3
withC11setup.
DigitalCamera:Canon60Da+Sigma
70‐200mmf/2.8lens.
Telescopecontrol:Guide9software
ImageProcessing:MaximDL6
Observatorycodesused:E00
Castlemaine,D87BrooklynPark,
D82Wallaroo,427Stockport.
14
6
TheBirthofCometWatch–NeilNorman
viewing,theremainderwereregular
contributorsofobservationsandimages.
Thesitenowhasanarchiveofover5,000
imagesfromcontributorsalloverthe
world.Althoughthequalitymayvary
dependingontheexperienceofthe
observer,eventhenewestobserver’s
imagesmaybeausefulcontributionto
scientificknowledge.Imagesmayhelpto
identifyorcharacterisedisconnection
eventsintailsaspeoplesubmitimages
minutesorhoursapart.InearlyNovember
2013TonyAngelpostedanimageof
C/2012S1(ISON)showingatotally
differentshapeofthecomettoother
observerstakenonlythepreviousday.
ThisprovedtobethefirstimagesofISON’s
outburstatpre‐perihelion.Arealcatchfor
thenewFacebooksite.
C/2014Q2LovejoySimonWhite
Inthe80’sMonthlymagazinesandTV
showssuchastheSkyatNightwerethe
sourcesIusedtoaccessthelatestnewson
mypassion–Comets.Butofcoursethe
Webhascompletelychangedthatnow.
InformationisatmyfingertipsandIcan
communicatewithfellowenthusiastsin
secondsnotdays.TheadventofSocial
MediasuchasFacebookandTwitterwere
seenasanintrusionforsomebuttome
theyseemedlikeagreatopportunityto
bringinformationtogetherinoneplace.
InAugust2013IcreatedaFacebookGroup
aheadofthearrivalofCometC/2012S1
(ISON)Itwasdueatperihelionthat
November.Toutedasthe‘Cometofthe
Century’,Iknewtherewouldbemuch
interestinfollowingitandinsharing
informationandobservations.Icalledthe
Facebookgroup‘CometWatch’andfrom
aninitial15peopleitgrewtoover1,500
membersbytheendof2013.Theaimof
CometWatchistoshareinformationonall
Cometsvisibleinthesky,notjustthe
brightones.
CometWatchattractscontributorsofall
skillsandnationalities.Weareproudto
countnamessuchasRodneyAustin,
ThomasBopp,DonnaBurton,Leonid
Elenin,SvetlanaGerasimenko,AlexGibbs,
AlanHale,CristovaoJacques,Richard
Kowalski,DavidHLevy,TerryLovejoy,
CometWatch,continuedtogrowstrongly
andbymid20143,000memberswerein
thegroup.Whilstabout50%wereonly
15
ArtyomNovichonok,JimScotti,Justin
Tilbrook,andTomasVorobjovamongstour
contributors.Allgreatnames,wellknown
inthefieldofCometobserving.
sharetheannouncementofnew
discoveries.Thesecontributions
contributetoourunderstandingofthese
icyghosts,objectswhichhaveengrossed
humanityforcenturies.
OneofthefirstmemorabledaysforComet
WatchwaswhenCristavaoJacques
submittedamessageintheearlymorning
ofAugust20th2014.HestatedthatTerry
LovejoyhadpossiblyfoundanotherComet
(afterhispreviousyear’sC/2013R1).The
entiredaywasaflurryofconstantupdates
ontheprogressofthisnewobjectonthe
JPLpage(PCCP).AndresChapmanof
ArgentinaconfirmeditasaCometon
imageshehadtaken,butitwasalongwait
untilfinallytheannouncementwasmade
ataround21:30UTAugust20ththatthe
newCometwasdesignatedC/2014Q2
(Lovejoy).Orbitsweresubmittedtothe
siteduringthedayandmagnitude
predictionsgaveitM1=10atbest,buthow
theywerewrong!TheCometwasa
fantasticspectacle,brieflyreachingnaked
eyevisibilityandImyselftookover150
observationsofitover6monthsfromDec
2014‐June2015.
InadditiontoCometWatchIshallcontinue
withthemonthlyradioshow,Astronomy
FM.Thisisco‐hostedwithNickEvettsand
MarySpicerthatwerecordmonthlyfor
AstronomyFM.Eachmonthwegivearun‐
downonthelatestnewsandhavegueststo
chatwithus.Regularcontributorsare
RodneyAustin,DavidEicher,AlanHale,
TerryLovejoy,MichaelMattiazzo,Jim
Scotti,andJustinTilbrook.Soeventhough
cometactivitymaybelowthereisstilllots
todiscussuntilthenextbrightcomet
arrives.Idohopeyouwilltunein,the
websiteis‐http://astronomy.fm/.Just
searchfor‘astronomyFM’anditcanbe
found.Ifyouhavethesmartphoneappfor
Tune‐inradioyoucanfindittheretoo‐
http://tunein.com/radio/Astronomy‐
FM‐s122373/.AsanhistorianofComets,
whenquieterobservingperiodscome,I
liketoconcentrateonthegreatsofyears
past.AnexampleofthisisthearticleI
havejustcompletedonCometD/1770L1
(Lexell).Thereissomethingveryspecial
abouttheseobjects,notjustthefactthat
theywerebrightorpassedclosetoEarth
orthattheywerevisibleindaylightor
possessed100degreelongtails.Forme,
it'saboutfindingoldimages,oldsketches
Ofcoursesandwichedbetweenallthiswe
hadacloseapproachofC/2013A1(Siding
Spring)toMarsandthehugelysuccessful
encounterofESA’sRosettawith67P.
CometWatchhasalsohadsubmissionson
brightCometssuchasC/2014E2,C/2012
K1,C/2015M1,C/2014Q1,C/2015V5,
2p/,C/2014us10,254Brewingtonand
others.
TheInternetmayhaveitsdetractorsbutI
stronglyfeelthat,usedintherightway,an
enthusiasticandtalentedgroupof
observersandimagers,broughttogether
bytheinternet,canhelptodocumentand
sharethepassingofknownCometsand
16
andresearchingthecircumstances
surroundingthecomet’sdiscovery.Ifind
thestoryofthemenandwomenwho
discoveredthem,whethertheywerewell
knownestablishedprofessionalobservers,
ortheywerejusthobbyingastronomers
whohappenedtobelookingintheright
placeattherighttime,fascinatingtoo.
IhopethatyoutakealookatCometWatch.
IfyouhaveaFacebookaccountyoucan
jointhegroupandcontribute.
NeilNorman
ofcometdatasopleaserememberthatif
yousubmitimagestoaFacebooksiteyou
shouldalsosubmitthemtotheBAAarchive
andmakesurethatanymeasurements
(astrometry,photometryetc.)issubmitted
totheappropriatedatabase(COBSorMPC)
sothatwe(andothers)canaccessitfor
analysis.
Director’scomment–Neil’sFacebookgroup
isveryactiveand,ifyouareaFacebookuser,
itisagreatwaytokeepintouchwithmany
cometobserversaroundtheworld.Itis
complementarytotheworkthattheBAA
CometSectiondoesinmoredetailedanalysis
7
DetectingCometOutbursts‐RogerDymock
InthisprojectIplaythepartofthemonkey
toRichardMiles’sorgangrinder.Rather
thancollectingdonations,othersand
myself,collectobservationsofthese
unusualcomets.Observationof
outburstingcometsisinterestingand
usefulsciencenotleastbecauseofthe
differentwaysinwhichtheoutbursts
occur:themeasurementoftheperiodsof
activity,thevaryingexpansioncoma
speeds,observationsofthespectral
emissionsofthegas,lightscatteringand
spectralreflectance,variationsinshape
andformofthecomaandmore.The
reasonwhycometsmayperiodically
behaveinthiswayhasbeendescribedby
Dr.RichardMilesandothersatvarious
conferences,meetingsandinjournals,as
listedinthefootnote.1Insimpleterms
cometsincludedinthisprojectaresubject
toperiodicoutburstswhicharenotdueto
fragmentation.Allhaveslowrotationsand
thecometaryicesbeneaththecrustcanbe
observedtostarttomeltandsubsequently
tooutgas.
AcometwhichRichardMileshas
investigatedinsomedepthisComet
29P/Schwassmann‐Wachmannandits
regularoutburstsarewellshowninFigure
1takenfromtheSpanishCometGroup’s
17
difficulttomeasureitsbrightnessonthat
date.
websiteat
http://www.astrosurf.com/cometas‐obs/
Figure1.Variationofnuclearmagnitude(m2)ofcomet
29PFigure2belowshowshowthetotalmagnitude(m1)
similarlyvaries.ThislightcurvewastakenfromtheComet
ObservationDatabase(COBS)athttp://www.cobs.si/.
Figure3.Comet29PlurkingintheMilkyWay
Figure2.Variationoftotalmagnitude(m1)ofcomet29P
Ihavebecomeasomewhatlazy
astronomerandmuchprefermaking
observationsusingtheSSONand
WarrumbungleRoboticTelescopes‐
http://sierrastars.com/.Theformeris
locatedintheUSAandthelatterin
Australiaandtogethergiveaccesstoboth
northernandsouthernskies.Useofthese
telescopesisdescribedinatutorialat
http://www.britastro.org/projectalcock/U
sing%20the%20SSON%20robotic%20teles
cope.htm
Cometsectionmembersarestrongly
recommendedtosubmittheirobservations
toCOBSasithasbecometheworld‐wide
repositoryforcometobservations.Howto
generatetotalorVisualEquivalent
MagnitudesfromCCDimagesisdescribed
at
http://www.britastro.org/projectalcock/C
CD%20Astrometry%20and%20Photometr
y.htm
IamgratefultotheBAAforhelpingto
financethisparticularexerciseviathe
RoboticTelescopeProject‐
http://www.britastro.org/robotscope/.
Anyonewishingtosubmitprojectsshould
beawarethatacceptedprojectsreceive
50%ofthecostofusingtheSSONtelescope
fromtheBAA.
Althoughitcouldbeimagedusingthe
WarrumbungleRoboticTelescope,Comet
29PwashidingintheMilkyWaythrough
mostof2015andwasthusdifficultto
measure.Figure3showsthisandits
variationinbrightness.Itwasapprox
magnitude12(m1)onMay14th–
obviouslymuchbrighterthanonApril29th
butthepackedstarfieldmadeitvery
UsingtheSSONtelescopeiseasyoncean
accounthasbeensetupandafterlogging
in.Scheduleajobby:


18
Choosingthecometfromalist
Inputtingtitleandobservername


TheMooncanbeaproblemandacomet–
Moonseparationofatleast30degreesis
recommendedwhenusingthe
aforementionedrobotictelescopes.Over
exposureandtrailingmustbeavoidedand
calculationstoavoidsuchproblemsare
describedinthetutorial.Referencedabove.
Selectingtelescope,filter,duration,
numberofexposures(5),delay
betweeneach(15mins)
Aconfirmationemailis
subsequentlyreceivedandthen
anotheronewhenthejobhasrun.
Ihavefounditextremelyhelpfultouse
planispheresfortheUSAandAustraliato
judgewhichcometsareavailablefor
imagingtogetherwithMegastar,a
planetariumprogramme,which
incorporatesthelatestorbitalelements
downloadedfromtheMinorPlanetCenter.
Recommendedtargetsfor2016arelisted
inTable1.Ifyouareinterestedinimaging
thesemostinterestingcometsplease
contactRichardMiles(ARPSSection
Director
Observationalperiod,comments
Comet
17P/Holmes
Approachingperihelion2017September–very
faint
29P/Schwassmann‐
Wachmann
Allyear
41P/Tuttle‐Giacobini‐
Kresak
From2016November.Perihelion2017April
174P/Echeclus
2016Jun–2017Feb
186P/Garradd
2016Feb–2016Jun
P/2010V1(Ikeya‐
Murakami)
2016Feb–2016Aug
C/2013C2(Tenagra)
2016Feb–2016Aug
Table1.Observingopportunitiesforoutburstcomets
RogerDymock‐OutreachandMentoring
19
TheEuropeanCometConferenceon2015June6.https://drive.google.com/file/d/0B8OVnW0WLB3EdVNDQmV4V3M3dHc
BAAOrdinaryMeeting2013Dec14‐https://britastro.org/video/99/3654
BAAOrdinaryMeeting2014January29‐https://britastro.org/video/5367
OnLiquidphasesincometarynuclei,RichardMilesandGeorgeFaillace,IcarusVol219,pp567‐595(2012).
AnatomyofoutburstsandquiescentactivityofComet29P/Schwassmann‐Wachmann,RichardMiles,GAFaillace,SMottola,
HRaab,PRoche,J‐FSoulier,andAWatkins.IcarusVol272,pp327‐355(2016).
DiscretesourcesofcryovolcanismonthenucleusofComet29P/Schwassmann‐Wachmannandtheirorigin,RichardMiles.
IcarusVol.272,pp387‐413(2016).
Heatofsolution:anewsourceofthermalenergyinthesubsurfaceofcometarynucleiandthegas‐exsolutionmechanism
drivingoutburstsofComet29P/Schwassmann‐Wachmannandothercomets,RichardMiles.IcarusVol.272,pp356‐386
(2016).
Thechemistryofcomets,RichardMiles,JBAAVol.126,No.2,2016April
8
CometImaginginaLightPollutedSite–PeterCarson
Background
fact,ontherecentcomet67PRosettaPro
Amcollaborationsocialmediasite,atfirst
glanceitwasquitedifficulttotellapart
imagestakenunderapristineskyata
mountaintopsitefromimagestakeninthe
backgardensofamateurslivingintowns
with4thmagnitudevisuallimiting
magnitudeskies.
Mostobserversandimagersoperatefrom
theirhomelocationswhichgenerallytend
tobeinanurbanarea.Theseurbanareas,
whilstconvenientfornon‐astronomical
activities,areusuallylightpollutedmaking
themchallengingforsuccessfulcomet
imaging.Toalleviatetheseproblemsyou
couldmovehousetoaruralenvironment,
moveyourobservatoryandoperateit
remotelyorgiveup.Alltheseoptionsare
usuallynotacceptabletoeitheryour
partner,bankbalanceoryourenjoyment.
Frommylightpollutedurbansitewith18.5
to19.5magnitudepersquarearcsecond
SQMzenithskiesIcan,withcare,record
cometsfainterthanmagnitude18.I’m
usinga315mmreflectorandexposuresof
120secondswithanSbigST8300fromthe
budgetendoftheCCDcamerarange.
Cometsaretransientobjectsofan
unpredictablenaturewhichiswhatmakes
themrewardingtoobserve.Theydemand
attentionatshortnoticeandonaregular
basissoideallyyourequipmentneedstobe
whereyouare…..inthelightpollution.By
adoptingsomespecifictechniques,alittle
advancedplanning,andtakingsomebasic
precautions,goodqualitycometimaging
canbedonefromalightpollutedsite.In
Sohowshouldyougoaboutimaging
cometsfromalightpollutedlocation?The
considerationsfallintofourcategories:
1)Sitepreparations
2)Imageacquisitionconsiderations
3)Postacquisitioncalibrationtechniques
4)Imagecleanuptechniques
20
1)
Sitepreparations
achieveanacceptablesignaltonoiseratio.
Theresultantimagemustnotbesaturated.
ThefullwelldepthcapacityoftheCCD,
especiallythepixelscoveringthecomet,
shouldnotbeexceeded.Ideallythere
shouldbeagoodspreadofbrightness
levelsacrossthecamera’sdynamicrange,
withoutbrightnesslevelsbeingbunched
upateitherthebackorwhiteendsofthe
histogram.MostDSLRcamerasand
softwarepackageswillenableyoutoview
ahistogramofthecamerabrightnesslevels.
Chooseanexposurelengththatcreatesthe
largestbrightnesscount(whichwillbethe
backgroundlightpollution)nohigherthan
25%to33%ofthemaximumlevel,
providingthisdoesnottrailorsaturatethe
cometnucleusorsaturatetoomany
backgroundstars.
Thesearequiteobviousandapplytoall
branchesofastronomicalobservingand
imaging.
Reduceyourlocalsourcesoflightpollution.
Persuadeyourneighbourstoadjustor
reducetheirlightingtoavoidlightspilling
ontoyourobservingsite.Tacklemajor
sourcesoflocallightpollution.I’vefound
themajorityoflargecommercial
organisations,carparkmanagers,pubsetc.
canbeencouragedtomakeimprovements.
Reduce,asfaraspractical,theeffectsof
streetlighting.Localauthoritiesusuallyco‐
operatewithrequeststoshieldoffending
lightingcolumns.
Screenyourobservingareafromstraylight
orhouseyourequipmentinanobservatory.
2)
Theexposurelengthsneedtobechecked
andre‐adjusteddependingonthealtitude
ofthecomet,thetransparencyofthesky
onaparticularnight,thebrightnessofthe
cometanditsspeedofmotioninthesky.It
isveryeasytooverexposeandrisk
saturatingthecamerawhenimagingalow
altitudeareaofskyatalightpollutedsite.
Imageacquisitionconsiderations
Wherepracticaltakeyourimageswhenthe
comethasculminatedreachingthehighest
pointintheskysoyouimagethroughthe
leastthicknessofatmosphere.
Oftenartificiallightinglevelsreduceafter
midnightsolightpollutionlevelstendto
reduceintheearlyhoursofthemorning.
Myskiesimprovedramaticallybetween
22.30hrsand23.30hrs,i.e.theyimprove
fromdiabolicaltoawful!!
Takelotsofexposures,atleast7,
preferablyafewtensandstackthem
together.Lightpollutionwillcausethe
imagebackgroundtoappearnoisy.
Stackingmanyimagesubexposureswill
averageoutthenoisemakingtheimage
muchsmoother.
Endeavourtoimagethecometintheleast
lightpollutedpartofyourlocalsky.ASky
qualitymeterisusefultodeterminethe
factsregardingwhatcanotherwisebea
subjectiveassessment.
ALightpollutionfiltercouldbeusedifthe
imageisintendedtocreateanaesthetic
recordonly.Howeverbecausetheimage
wouldbelackingvariouspartsofthevisual
spectrumcausedbytheblockingnatureof
thefilteritwouldnotbeatruerecordof
thecometsvisualappearance.LPRfilters
Exposurelengthsneedtobeshortenough
tofreezethemotionofthecometagainst
thebackgroundstarsbutlongenoughto
21
spoilthescientificvalueoftherawdataso
filteredexposuresarenotsuitablefor
subsequentphotometrymeasurements.
equalnumberofflatframestakenofthe
samelightsourcerotatedthrough90
degrees.Theresultingimage,ifheavily
contraststretched,willrevealanynon‐
uniformityinthelightsource.Checkthe
pixelinformationofthe“flattedflat”in
softwaresuchasMaxImDLandaimto
achieveallpixelbrightnesseswithin1%of
eachother.
3)
Postacquisitioncalibration
techniques
Probablythemostimportantthingtodoto
anyimagetakenunderalightpollutedsky
istoproperlycalibrateitusingagood
masterflatframe.Flatframesareimages
takenofauniformlyevenlightsourceand
representameasureoftheinherent
sensitivityvariationsofthecamerapixels,
theunevenlightdistributionoftheoptical
systemandshadowsofdustparticlesinthe
lightpath.Theflatframes,togetherwith
darkframesandbiasframes,areusedto
correcttherawlightimagestoremove
unevenilluminationandotherelectronic
artefacts.Thisprocess,calledcalibration,
canbecarriedoutusingmostimage
acquisitionsoftwarepackages.
4)
Someofthetechniquesusedbythe“deep
skypicture”imagerscanbeemployedhere
providingtheydonotintroduceimage
artefactsorspoilthebasicimagedata.I
wouldsuggestthatunsharpmasksorother
filters,techniquesinvolvingworkingon
partsoftheimageusingalayerstechnique,
oranysimilarimagemanipulation,are
stepsintotheworldofartandnotscience.
Howevertheuseofsimplegradient
removal,thecloningoutofobviousimage
defectsandmildnoisefilteringis
acceptableinproducinganimagethat
extractsthemaximumtrueinformation
fromtheimageandfaithfullyrepresents
whatispresentintheoriginaldata.
Becauseacomet,especiallyitstail,willbe
onlyjustbrighterthanthelightpolluted
skybackgrounditisveryimportantthata
cleanundilutedimageissecuredpriorto
contraststretchingorsubsequent
photometricmeasurement.Thiswill
enableonlytheweaktenuoussignalfrom
thecomettoremainintheimagewhich
whencontractstretchedcanbe
successfullydisplayed.
Gradientremovaltoolsareusefulfor
removinganyremainingeffectsoflight
pollutionpresentinthecalibratedimage.
Lightpollutionisgenerallybrighternearer
thehorizonthanatthezenith.Thiscauses
abrightnessgradientacrossanimagethat
isnotremovedbyimageflatfield
calibration.Myfavouritegradientremoval
toolisGradientXterminatoraPhotoshop
plug‐inwrittenbyRusselCrowman.
MaximDLandotherimageprocessing
packagescontainsimilartools.IRIS
softwareisfreeandcontainsasimpleto
usegradientremovaltoolsimilarto
GradientXterminator.Caremustbetaken
Agoodmasterflatframeshouldconsistof
anaverageofatleast50subexposures,
preferablymore.
Flatframescanbegeneratedbyimaginga
cleartwilightskyormoreeasilyusinga
purposemadelightboxorilluminatedflat
panel.Theuniformityofthelightsource
shouldbecheckedbycreatingastackof
flatframesandcalibratingthemwithan
Imagecleanuptechniques
22
whenusingtheseremovaltoolstoavoidan
unintentionalchangetothecomettail
brightnessbyapplyingittoostrongly.
yourtelescopeequipmentsetupandclose
athandwillenableyoucatchthatexciting
taildisconnectionevent,witnessanucleus
fragmentationorbefirsttorecordthe
appearanceofanewlydiscovered
comet....andhavethereassurancethatyour
warmbedisonlystepsaway!
Lowlevellightpollutionmanifestsitselfas
abackgroundnoiseinyourimage,someof
whichisremovedbycalibrationand
gradientremoval.Theremainingnoisecan
betemperedbyusingasoftwarenoise
filter.Thesefiltersgenerallyhavea
detrimentaleffectonthefinedetailofan
imagebutifusedsparinglycanbeusefulin
creatingamorepleasingvisualappearance
ofafinishedimage.IprefertouseNoel
Carboni’sactionforPhotoshop,butmany
othersoftwarepackagesareavailable.
Myobservatoryislocatedintheback
gardenofmyhomeunderlightpolluted
skiesonemilefromLondonSouthend
InternationalairportinEssex.It’swithin
theurbanareaofSouthendonseawhich
partoftheLondonGatewaybusinessarea,
notanareamostpeopleassociatewith
cometimagingandphotometry.Whilst
perhapsmoredifficulttoachievethanfrom
adarksite,myimagesdostandfavourable
comparisonwithimagersbasedatmuch
betterplacedsitessodon’tletlight
pollutionputyouofffromtakingand
submittingimagestotheSection.
Conclusion
Certainlythereislittlereasontobeputoff
fromimagingcometsfromanurbanlight
pollutedsite.Greatimagesandgood
sciencecanbecarriedoutattheselessthan
ideallocations.Theconvenienceofhaving
PeterCarson
[email protected]
23
9
MyObservatory‐TarbatnessMPCCodeI81‐DenisBuczynski
TarbatnessDomes
6”f8Newtonianand30cmf4Newtonian
Ifirstbecameinterestedincometsin1974.
SirPatrickMooreappearedonTVtelling
theworldthattherewasgoingtobeavery
brightcometvisibleinthewesternevening
skyaroundChristmasandNewYear.He
said,“ThisiswillprobablybetheCometof
theCentury”.SoIwentoutinthefreezing
cold,everyclearevening,butIneverdid
seethatComet.ItwasC/1973E1
Kohoutek.Butitsparkedafascinationfor
observingcometsthatIhaveneverlost.
Myinterestincometsandobservingthem
wasfurtherenhancedwiththeprospectof
the1986returnofPeriodiccomet
1P/Halley.MyfriendsandIhadbuilta
large55cmF/5reflectorinmy‘Conder
BrowObservatory’inmyhometownof
Lancaster.Thistelescopewasequippedfor
cometphotographyandIwasdetermined
toobservecometHalleyandmakesome
scientificobservationsofitasitpassed
throughourskies.Iwasfocussedon
methodsofphotographiccometary
astrometry.Thisisthedeterminationof
precisepositionsforthepurposeofcomet
orbitcalculation.
EventuallyIdidseemyfirstcomet‐
PeriodicComet6P/d’Arrestin1976.Iwas
determinedtoseethisreturningcomet
afterreadingaCometDigestarticleinSky
andTelescope(July1976)byJohnBortle
andBrianMarsden.Thearticleoutlined
theprospectsforitsnextupcoming
apparition.A6inchf/8Alt‐Azimuth
reflectorwasmyonlyinstrumentatthat
time.Iusedacarefulstar‐hoppingmethod
withthattelescopeuntilIreachedthefield
containingmyfirstcomet.Thatsimpler
ageislonggoneandmyroutinenow,
duringanobservingrun,istoimagemore
thanadozencomets,manysofaintthat
visualobservationofthemwouldbe
impossible.
Iwasveryfortunatetobetaughthowto
makemeasurementsofthecometimages
onmyphotographsbyanexpertinthe
subject,ProfessorVinicioBarocasatthe
UniversityofCentralLancashire.
Subsequentlyhissuccessor,ProfessorIan
Robson,loanedtomeUCLAN’sHilgertwin
axismeasuringmachine.Thisallowedme
tomakethemeasurementsatmyhome.
Thereductionsofthemeasurementsto
celestialpositionsweremadeonaBBC
Microusingsoftwarewrittenformeby
KeithRobinsonattheJeremiahHorrocks
ObservatoryinPreston.Numbersfromthe
24
sky,(i.e.positionsandmagnitudes),that
wasmyaim.
wasprobablythelastcomettobewidely
observedusingphotographicmeans.
AspartoftheBAACometSection/IAU
HalleyWatchProgrammeIwasprivileged
toworkalongsideDrReggieWaterfield,
HaroldRidley,BrianManningandPeter
BirtwhistleallablydirectedbyMike
Hendrie.ManypositionsofHalleyand
othercometsweresubmittedtotheMPC
overthenext10yearsandallwere
painstakinglyobtainedbymeansof
photographyandplatemeasurements.
In2010Iretiredfromworkandmovedto
HighlandScotland.NowIhadthe
opportunitytoestablishamodernand
dedicatedobservatoryfromwhichto
observecomets.Mymaininterestisstill
cometaryastrometryandnowthatIam
freedfromtheconstraintsofearninga
livingIamabletopursuethiswitha
renewedvigourandinamorerelaxedway.
Anights’observingnowmeansstopping
onlywhentheobservingconditions
deteriorateordawnarrives.Allthecomets
abovethehorizon,brightorfaint,arenow
availabletomeandmytelescopesareset
upandequippedforcometimaging
withoutmanualinterference.The
computers,CCDsandtheGOTOsystemsgo
abouttheirbusiness,onlypromptedbyme
tomovetothenexttarget.Iamnow
producingmorecometaryastrometryina
monththanIdidover10yearsof
photographicastrometry.
Howevertherewasmassivechangeonthe
horizonwiththeintroductionand
availabilityoftheCCDtotheamateur
community.Irememberwalkingintoa
BAAExhibitionMeetinginLondoninthe
early1990’sandMartinMobberleystating,
“photographyisdead”.RonArbourwas
demonstratinghisnewTerryPlatt
designedStarlightXpressFramestoreCCD
camera.Objectsthathadneededtensof
minutesofphotographicexposurecould
nowbecapturedinsecondsonthe
sensitiveCCDchips.Weunderstoodthen
thatournewfoundabilitytorecordfaint
lightsources,likecomets,whichhad
eludedusupuntilthenshowedthatMartin
wasrightandfilmphotography’sdays
werenumbered.CometHale‐Boppin1996
Ihaveinstalledtwoobservatorydomesat
myhomeatPortmahomackonthe
stunningTarbatnessPeninsula.Itlies
betweentheFirthsofMorayandDornoch,
juttingoutintotheNorthSeaabout40
milesnorthofInverness.Bothdomesare
2.7metresindiameterandhavemoreor
lessunobstructedhorizons.Inoneofthe
domesisaCelestron0.35m,f/10Schmidt
Cassandawidefield80mmApoona
ParamountME.TheCCDcamerasusedat
presentonthisinstrumentareanSBIG
ST9XEandaStarlightXpressSXVH9.The
otherdomecontainsa30cmf/4Newtonian
withaBaaderMulti‐Purposecoma
corrector(MPCC)andaBAAloanCCD,a
SBIGST10XE.Inadditiontothesecomet
imagingtelescopesIhavetwovisual
55cmf5Newtonian1
25
instruments‐a23cmf/4Newtoniananda
Victorianbuilt100mmRossApochromatic
refractor(TheGeorgeAlcocktelescope).
Myobservatoryisalsoequippedwithtwo
automaticmeteordetectioncameras
operatingfortheBAANEMETODE
Network.
Iamlookingforwardtotakingpartinthis
programme,possiblyusingthetechnique
describedbytheDirectorelsewhereinthis
issue.
Inafurtherstep,Iamjoiningthecomet
observingprogrammerunbyCARA(the
Italianteam)whoseaimistoimagecomets
inredlightinordertomeasureand
calculatecometdustproductionvalues
definedthroughtheparameter(Afρ).The
prolificBelgiancometobserver(andBAA
CometSectionmember)ErikBryssinckis
oneofthementorsforthisprogrammeand
Ihopetoenlisthisassistancewithmy
participationinthisjointeffort.
Thisismycometarylifetodate.Ifyoufind
yourselfinmybelovedHighlands,please
letmeknowandarrangeavisit.Iwillbe
veryhappytoseeyouandshowyoumy
observatoriesandtelescopes.Ifitisdark
andclearwemayevenseeacometortwo.
Icontinuetoproducecometaryastrometry
andwillalsoparticipateintheprogramme
toobtainvisualequivalentcometary
photometryfromtheCCDimagesItake.
Thiswillbenewterritoryforme.However
Denis Buczynski – Secretary Comet Section 10 MethodforthecalculationofVisualEquivalentMagnitudes–anda
pleaforhelp–NickJames
Formanyyearsamateurcometimagers
havebeenproducingqualityastrometry
usinghighlyautomatedprogramssuchas
Astrometrica.Theastrometryissubmitted
totheMinorPlanetCenterand,despitethe
largeamountofprofessionalsurvey
astrometry,itisstillanimportant
contributortothecomputationofaccurate
cometorbits.Astrometricaalsocalculates
amagnitudeasaby‐productofcomputing
theastrometrybut,forcomets,thisisoften
muchfainterthantheactualmagnitude
sincethephotometricapertureissmall
comparedtothecomet’sapparent
diameter.
CurrentMethods
FromtheinceptionoftheBAAComet
Sectionvisualobservershavebeen
contributingestimatesofthetotal
magnitudesofcometsusingseveral
methods.The‘visualtotalmagnitude’is
definedasthetotalamountoflightcoming
fromthecomet’scoma.Brightercomets
aregenerallyestimatedusingsmaller
opticalaidsothatthefulldimensionsofthe
26
comaareseen.Thesemagnitudeestimates
aresubmittedalongwithotherinformation
intheICQ(InternationalCometQuarterly)
formatandcanbeusedtogenerate
lightcurvesandtoestimatethemagnitude
parametersofaparticularcomet.The
COBS(CometsOBservationDatabase‐
http://www.cobs.si/)databaseisthe
currentrecommendedrepositoryforthis
information.
Visualobserverssomehowmanagetodo
thisverywellbyinstinctandexperience.
Anysoftwareprogramdesignedtodothis
reductionmustdothesamebysomekind
ofobjective,repeatablealgorithm.
OneapproachtoproducingaVEMisthe
methodthatiscurrentlyadoptedbythe
CometSection.Thisusesacombinationof
threeprograms:Astrometrica,Focasand
kphot.Inthismethodthemagnitudeofthe
comaismeasuredinsixconcentric
photometricaperturesofradii5.6–33.6
arcsec.Asthephotometricaperture
increases,theestimatedmagnitudewill
alsoincreasesincemoreofthecomais
included.Themeasurementsin
consecutiveaperturesallows
determinationofagrowthcurvewhich
definestheincreaseincountsasthe
aperturesizeincreases.Ifthecomais
smallerthanthemaximumradiusaperture
(andtheskyhasbeenestimatedcorrectly)
thegrowthcurveshouldflattenoutatlarge
radius.Ifnot,thegrowthtrendwillstillbe
brighteningevenatthelargestaperture.
ThesixmeasurementsfromFocasarethen
usedbykphot.Thisprogramassumesa
particularphysicalmodelwhichpredicts
howbrightnesschangeswithradius,andit
fitsthemeasuredgrowthcurvetoan
examplecoma.Usingthecurvefit
parametersitcanextrapolatethetotal
magnitude.Thisworkswellaslongasthe
comaisreasonablysmallandthecamera
fieldofviewisconsiderablylargerthanthe
comadiametersothattheskyestimateis
accurate.Themethodfailsifthecomais
largecomparedtotheFoVorthe
photometricaperturesorifanybrightstars
areincludedintheconcentricapertures
sincetheywilldisturbthegrowthcurve
andleadtoanincorrectextrapolation.
Giventhattherearenowmanymore
imagersthanvisualobserversweinthe
CometSectionwouldliketofindaneasy
wayforimagerstoextractVisual
EquivalentMagnitudes(VEM)fromtheir
imagedata.Inprinciplethisisrelatively
straightforward.Adeterminationofthe
VEMrequiresthatacountallofthelight
arrivingfromthecomatoobtainan
instrumentalmagnitude.Thiscanthenbe
convertedintoarealmagnitudeby
determiningthemagnitudezeropointof
theimageusingacataloguecontaining
photometricreferencestars.Ideally,to
correspondtoavisualmagnitude,the
overallresponseoftheimagingsystem
shouldbeapproximatetothatofthe
humaneye.
Countingallofthelightinthecomais
complicatedfortworeasons:
1. Weneedtomakeaveryaccurate
estimateoftheskybackground
fromtheimagesothatthecount
contributionfromtheskycanbe
removedfromthemeasurement.
Theskybackgroundestimateisalso
importanttogetanaccurate
determinationofthecomadiameter.
2. Weneedtoignorethecontribution
fromstarswithinthephotometric
aperturesincethiscouldotherwise
significantlyskewtheestimate.
27
Analternativeapproachistomeasurethe
lightinthecomausingaphotometric
aperturewhichislargeenoughsothatit
includestheentirecoma.Forthistobe
effectiveitisnecessarytoaccurately
estimatetheskybackgroundlevelandto
removethelightcontributedbythe
backgroundstarsinthephotometric
aperture.Toobtainagoodskyestimate
theimagefieldofviewmustbe
considerablylargerthantheactual
apparentcomadiameterso,forlargebright
cometsashortfocallengthandaDSLRare
ideal.Themainproblemwiththismethod
isthatitinvolvestheremovalofthestars
beforethemagnitudeestimateis
performed.Therearesomewaysofdoing
thisbuttheyareoftendifficulttouse.
butthecomet’smotionwillbe
frozensothatthephotometric
countinthecomaaperturecanbe
determined.
Theprogramfirstmakesanestimateofthe
skybackgroundusingamedianestimator.
Thisrequiresthatthecomaoccupyonlya
relativelysmallpartofthefieldofview.To
automatethisapproachitisnecessaryto
haveaveryrobustmethodforestimating
theskybackground.Aspartofthisitis
importantthattheskybackgroundinthe
measuredimageisflatsoaccurateflat
fieldingandgradientremovalisnecessary
priortoperformingthemeasurement.
Oncetheskybackgroundhasbeen
determinedtheprogramestimatesthe
noiseintheimageasthefirststagein
settingathresholdfordetectionofthe
limitsofthecoma.Theestimateddiameter
ofthecomaisthenusedtosetthe
photometricaperturesize.
Proposal–newapproach
ForsometimeIhavebeenworkingonan
alternativeapproachwhichIhopewill
simplifytheextractionofVEMstothepoint
thattheeffortrequiredissimilartothat
currentlyneededtoextractastrometry
usingAstrometrica.Myobjectiveisto
comeupwithasoftwareapproachwhichis
robustoverawiderangeofcircumstances:
fromfaintcometsinlargetelescopesto
brightcometsinwide‐fieldsystemsand
whichrequiresminimaluserinteraction.
Sincethephotometricaperturemay
containstarsinadditiontothecometwe
needtoremovethem.Asimplewayof
removingthestarsistouseastatistical
approachwhichassumesthatthecomais
essentiallyrotationallysymmetricabout
thephotocentre.Idividethephotometric
apertureintoasetofconcentricannuli
centredonthephotocentre.Ineach
annulusIdeterminethemediancount.The
medianisastatisticalaveragewhich
correspondstothemiddlevalueinasorted
listofvaluesfromthesmallesttolargest.It
hastheadvantagethatitisnotbiasedby
occasionaloutlierssuchasthestarswhich
appearintheannulus.Effectivelythestars
areignoredinthemedianestimation.The
totalcomacountisthenthesumofallof
themediancountsinthedifferentannuli.
Thisappearstobeaneffectiveapproach
Theapproachisbasedonmeasuringthe
totalcountsinanaperturewhichmatches
thecomadiameter.Thesoftwarerequires
twostacksforeachcomet:
1. Astackwhichisalignedonthestars
andwhichisusedtodeterminethe
magnitudezeropointusinga
definedcatalogue.
2. Astackwhichisalignedonthe
comet’smotion.Thiswillhavethe
samezeropointasthefirststack
28
sincethecomaeofmostcometsare
symmetricalaroundthephotocentre.
IcurrentlyhavesomeLinuxsoftwarethatI
havewrittentodemonstratethisapproach
andIhavebeenusingitonanumberof
imagestakenbyothersandmyself.Iam
pleasedthatinmostcasesthemagnitude
estimateisinlinewithvisualobserversbut
thereareanumberofcaseswhereIhave
obtainedresultswhicharesignificantly
differenttootherestimatesonCOBS.This
isstillworkinprogressandIamlookingat
waystomakethealgorithmmorerobust.
Theimagesbelowgiveexamplesofthe
processforabrightcomet(C/2014Q2
Lovejoy)andafainterone(C/2014W2
PanSTARRS).Inbothcasesthesame
softwarewasusedandallparameterswere
extractedautomatically.
Thesamestackalignedonthecomet.Thisisthefullframe
usedforVEMmeasurement.
Detailofthestackedframe.Thesoftwarehasestimated
andremovedtheskybackgroundandhasestimatedthe
comaradius(andhencephotometricaperturesize)at790
arcsec.Thisisacolourcodedlogstretchwithpixelsbelow
thenoisethresholdsettozero.Thephotometricaperture
sizeisshownastheinnerredcircle.Notethattherearea
largenumberoftrailedstarsintheaperture.The
estimatedmagnitudeinthisapertureis4.18.Themeanof
the23COBSvisualestimatesonthisdateis4.20withan
RMSscatterof0.41.
Examplestackalignedonstars.C/2014Q2.2015January
15,20:53.18x120s.FoV143’x108’.Estimatedzeropointof
thisframeusingUCAC‐4,Rmags=23.01.
29
basicapproach.Mostofthemethodisin
placebutmoretestingisrequiredand
sometweaksarenecessarytomakethe
processmorerobust.Ifanyonewouldlike
totakeoverthispartofthedevelopmentI
wouldbemorethanhappytohearfrom
you!Pleasecontactmeviaemailatthe
addressonthefrontpage
NickJames–SectionDirector
http://www.britastro.org/projectalcock/CCD
%20Astrometry%20and%20Photometry.htm Exampleresultforamuchfaintercometina
narrowfield.ThisisanimageofC/2014W2
obtainedbyDenisBuczynski.Thisshowsthe
outputofthesoftwarewhichincludesa
Focas‐likesetofmulti‐boxmagnitude
measurements.Notethatthemedian
approachleadstoa60x60estimatewhichis
around0.15magfainterthanthenormal
approach.Thisisbecausethemedian
ignoresfaintstarsintheaperture.The
meanofthe7visualobservationsinCOBS
aroundthisdateis12.4withanRMSscatter
of0.9.
Unfortunately,duetoothercommitments,I
havenotbeenabletoprogresswiththis
projectasfastasIwouldlike.Ihaveone
volunteerwhohasofferedtoturnthe
algorithmsintoauser‐friendlyWindows
programbutthisisbeingheldupdueto
myownlackofprogressindevelopingthe
For a description of the various methods currently in use see: 30
Comet Observers of the Past – Histories Contributions and Achievements Director’sNote‐Thisisanewsectionintroducinghistoricalperspectivesoncomet
discoveries,theirroleingeneralsocietyandinpolitics.Ihopeyouenjoyitandalsofeelfree
tocontribute.
11
WilhelmTempel’sPeriodicComets‐DenisBuczynski
toproveessentialtoTempelthroughout
hislife.
Tempelworkedfirstasalithographerin
Copenhagenandthensearchedforand
foundworkasanassistantastronomerat
variousEuropeanObservatories,mainly
Marseilles,BolognaandVenice.Itwas
duringworkattheseobservatories,but
predominantlyinhisownpersonaltime,
thathediscoveredthecomets,asteroids
andnebulaethatbroughthimfamebutnot
fortune.Hewasaprolificobserverand
couldhavebeendescribedassomewhat
obsessivelysingle‐mindedinhisdevotion
toastronomicalobserving.
TempelandhisdiscoverytelescopeJournalofAstronomical
HistoryandHeritage,13(1),43‐58(2010).43.WILHELM
TEMPELANDHIS10.8‐cmSTEINHEILTELESCOPE.Simone
Bianchinietal
Observableinourskiesduringthepastfew
monthshavebeentwoofWilhelm
Tempel’speriodiccomets,9Pand10P.So
nowisagoodtimetorememberhislife
andworkandtoconsiderhisimportant
periodiccomets.
Itmayseemsurprisingthatthelarge
telescopessituatedattheformal
observatorieswerenot,ingeneral,the
telescopesthatTempelusedtomakehis
discoveries.Formostofhislifehe
employedasmall4inch/10.8cmSteinheil
refractorof5feet/1.62mfocallength
whichhehadpurchaseddirectlyfromthe
manufacturerin1858.Thissmall
telescopewasmountedinanunusualAlt‐
Azimuthformandremainedunaltered
duringhislonguseofituntilhisdeathin
ErnstWilhelmLiebrechtTempel(1821‐
1889)wasborninGermanyinthe
KingdomofSaxony.Hisparentswere
farmersandTempel’sonlyformal
educationwasatthevillageschool.Hewas
mentoredbyhisteacherJohanKiesewalter
whointroducedhimtothenightskyand
alsotaughthimtheskillsneededto
becomealithographer.Bothofthesewere
31
1889.Heusedverylowpowereyepieces
(x24witha2degreefield)forobserving
cometsandheattributedmanyofhis
discoveriestotheexcellentqualityofthe
Steinheiltelescope.
Tempel'sdiscoveries.JournalofAstronomicalHistoryand
Heritage,13(1),43‐58(2010).43.WILHELMTEMPELAND
HIS10.8‐cmSTEINHEILTELESCOPE.SimoneBianchiniet
al
Thesecometsreturntoperihelion
regularlyandthisallowsustoobserve
thematmultipleapparitions.Someofhis
periodiccometsareimportantcometsand
areassociatedwithmajormeteorshowers
andanotherwasmorerecentlyassociated
withaspacecraftmission.Thediscovery
detailsfollowingaremostlyderivedfrom
theexcellentCometographySeriesbyGary
Kronk.
Tempelaccomplishedanimpressivelistof
28discoveriesofvariousclassesof
astronomicalobjects(19comets,6
asteroids,1reflectionnebula,1galaxyand
1planetarynebula).Thereflectionnebula
discoveredwasthenowfamousMerope
nebulainthePleiades.Thesediscoveries
weremadebetween1859and1874.The
observingsitesweremainlyinVenice,
MarseillesandMilan.Howeverthemore
preciselocationswerelistedas“home
garden”“homewindow”,“homebalcony”.
Onlyafewinstancesofdiscoverylocations
arelistedas“Observatory”.Someofthe
cometswereindependentdiscoveriesand
otherswerejointlydiscoveredwithother
observers,butwereunknowntoTempelat
thetime.Hereceivedmanyawards,
medalsandprizesduringhislifeandwas
regardedbymanyofhiscontemporariesas
anexceptionalandkeen‐eyedobserver.
Todaywemainlyrememberhisname
becauseoftheperiodiccometshe
discovered:7P,9P,10P,11P,38Pand55P.
http://cometography.com/index.html
AlsosomedetailsaretakenfromJon
Shanklin’sPeriodicCometSectiononhis
webpage‐
http://www.ast.cam.ac.uk/~jds/per0010.h
tm
Lastlythemostcomprehensivepaperon
Tempel’slifeistobefoundatthislink‐
http://www.narit.or.th/en/files/2010JAH
Hvol13/2010JAHH...13...43B.pdf.Ihave
reliedheavilyonthispaperinwritingthis
article.
Periodiccomet7P(periodin1996was6.37
years)
Thiscometwasoriginallydiscoveredby
JeanLouisPonsatMarseilleson1819June
12.Itwasaccidentallyrediscoveredby
32
FriedrichAugustTheodorWinnecke(Bonn,
Germany)on1858March8.Winnecke
recoverediton1869April10anditwas
independentlyfoundbyTempelon1869
June29.Thiscometisassociatedwiththe
JuneBootidsmeteorshower.
Periodiccomet10P(periodin1873was5.1
years)
Periodiccomet9P(periodin1972was5.5
years)
Tempeldiscoveredthiscometon1873July
4attheBreraObservatory,Milan.He
probablyusedhis4inchSteinheilrefractor
whichheconsideredtobeahigherquality
telescopethanthemountedtelescopesat
theObservatory.Thecomet’sorbitis
stable.Thisisoneofthereasonswhyitisa
favouredtargetforpossiblespacecraft
missions.In1983theIRASsatellite
detectedanextensivedusttrailbehindthe
comet.Witha5.5yearperiodalternate
returnsarefavourable.Thecurrent
apparitionisongoing.
ThiswasdiscoveredbyTempelon1867
April3atMarseilles.Itwasfirst
recognisedasbeingperiodicearlyinMay
whenK.C.Bruhns,Leipzig,Germany,
determinedtheorbitalperiodas5.74years.
Bythetimeofthefinalobservations,the
orbitalperiodhadbeenrevisedto5.68
years.Tempelhimselfmadetherecovery
observationatthe1879returnonApril25.
PerturbationsbyJupiterhaveresultedin
observationallyfavourableand
unfavourableapparitionsbutsince1972all
apparitionshavebeenobserved.This
cometwaschosenforthespacecraftDeep
ImpactMissionin2005andthespacecraft
impactorcrashedintothecomet.Itwasre‐
visitedbytheStardustspacecrafton2011
February15.Thecurrentapparitionof
2016isafavourableone.
Periodiccomet11P(periodin1881was5.5years)
ThisimagewasobtainedbyJ.‐F.Soulieron2014
September1,usinga30‐cmreflectorandanSBIGST8XME
CCDcamera.Thenuclearmagnitudewasdeterminedas
20.5‐20.7,whilethecometwasabout9"across.Notailwas
visible.
ThiscometwasdiscoveredbyTempelon
1869November27inMarseillesbutwas
33
onlyobservedfor39daysthusmakingthe
determinationofaperioduncertain.The
cometwasindependentlydiscoveredby
LewisSwiftoftheWarnerObservatory,
NewYork,asadiffuse,circularcometin
Pegasuson1880October11.Bymid‐
November,astronomersrealizedSwift's
cometwasareturnofTempel's1869
comet.After1908itwaslostuntil
observationson2001December7bythe
LincolnNearEarthAsteroidResearch
(LINEAR)programmefoundanobject
usinga1.0‐mreflectorandaCCDcamera.
CarlHergenrotheroftheLunarand
PlanetaryLaboratoryandKenjiMuraokain
Kochi,Japan,independentlysuggestedto
BrianMarsdenthattheLINEARcomet
mightbeareturnofcometTempel‐Swift.
Thelinkwasalmostimmediately
confirmedbyMarsdenandSyuichiNakano,
inSumoto,Japan.Thecurrentdesignation
is11PTempel‐Swift‐LINEAR.
Stephan'sdiscovery,henotedadistinct
differenceinthedescriptionfromhisand
assumedwronglythathehadfounda
differentcomet.Tempeldescribedthe
cometasveryfaintandabout3arc
minutesacross.Thecometwaslostuntilit
wasaccidentallyfoundbyLiisiOtermain
1942.Itnowhasthedesignation38P
Stephan‐Oterma.In2018itshouldcome
withinvisualrangeinSeptemberasit
brightensrapidlyonitswaytothe
Novemberperihelion.Itwillbeatits
brightestinNovember,whenitisinthe
lateeveningskyandremainswellplaced
into2019.
Periodiccomet55P(periodin1866was33
years)
Tempeldiscoveredthiscometfrom
Marseilleson1865December19.Horace
ParnellTuttle(HarvardCollege
Observatory,Cambridge,Massachusetts)
independentlydiscoveredthiscometon
1866January6.Todayithasthe
designationof55PTempel‐Tuttle.Afew
yearsafterthediscovery,JohnRussellHind
madethesuggestionthatthecometmight
havepreviouslybeenseenin868and1366.
Noformalanalysiswasconducteduntil
1933,whenShigeruKandatookupthe
challenge.Heconcludedthatthecometof
1366wasmostlikelytohavebeenTempel‐
Tuttle,butthecometof868wasnot
related.In1965JoachimSchubarttookthe
comet's1866orbitandusedacomputerto
examinethecomet'smotionthroughthe
solarsystemfor500yearsintothepast,
applyingthegravitationaleffectsofthe
planetsthroughoutthatentireperiod.He
confirmedKanda'sproofthatthecometof
1366wasTempel‐Tuttleandalsofound
thatasingleobservationofacometby
GottfriedKirchon1699October26was
Periodiccomet38P(periodin1942was38.3
years)
JérômeEugèneCoggia(Marseilles,France)
foundwhathethoughtwasan
uncataloguednebulaon1867January22.9.
Theskycloudedupalmostimmediately
andremainedcompletelycloudyuntilthe
nightofJanuary24,whenÉdouardJean‐
MarieStephaninMarseilles,France,
checkedonthenebulathroughabrief
breakinthecloudsandsawthatithad
moved.Stephanwasabletoconfirmthis
wasacometonJanuary25.86andsaidthat
itwasratherbrilliant,round,andwitha
verymarkednucleus.Theinitial
announcementsdidnotmentionCoggia's
nameandsothecometwasnamedafter
Stephan.Tempel,theninMarseilles,
independentlydiscoveredthiscometon
January28.86.Althoughheknewof
34
alsoTempel‐Tuttle.Withthreeapparitions
nowavailable,theorbitwasimprovedand
Schubartprovidedapredictionforthe
1965return.Thecometwasrecoveredby
MichaelBesterinSouthAfricaon1965
June30andthepositionindicatedthat
Schubart'spredictionhadbeenonly5days
tooearly.GiovanniVirginioSchiaparelli
(Italy)wrotealettertotheAstronomische
Nachrichtenon1867February2which
showedthatthiscometwasprobably
relatedtotheLeonidmeteorstormthat
wasobservedduringNovemberof1833
and1866.Acomparisonofthecomet's
orbitwiththatoftheNovember1866
Leonidstreamshowedanalmostperfect
match.Thelastperihelionwason1998
February28andthenextison2031May
20.
Tempelwasasignificantfigureinthefield
ofvisualastronomicaldiscovery.Hewas
recognisedbythemajorastronomical
institutionsandnationalbodiesasan
exceptionalobserverbutthisdidnotresult
inanypersonalwealthandatonepointin
1865hecontemplatedsellinghisSteinheil
telescopetoraisesomemoneyuponwhich
tolive.Howeverhepulledbackfromthis
option,unabletopartwithhisbeloved
telescope.Duringhislifeheandhiswife
MariannaGambinisharedameagreand
frugallife,andshefoundherselfinastate
ofpovertyuponthedeathofherhusband,
afterwhichshedidsellhistelescopeand
paperstoArcetriObservatorywherethey
remaintoday.Hislifewasdevotedto
visualastronomicalobservingevenwhen
hewasillandclosetodeath.Hiswifesaid,
“Tempelworkedtothelast…thepoor
suffererobserved,illashewas,fromthe
topofhishousewithasmalltelescope.”
Anotherinstanceofscientificdistinctionis
reservedforoneofTempel’scomets,in
thathiscometC/1864N1wasthefirst
comettohaveitsspectrumobserved.This
wasaccomplishedbyGiovanniBattista
Donatiin1864.
Byobservinghiscometstodayweare
payingtributetoagreatobserverand
discoverer.
DenisBuczynski‐SecretaryCometSection
35
12
Editor’sWhimsy–JaniceMcClean
“Mr.Babinetalertedbyhishousekeeperofthearrivalofthe
comet..”,
ByM.HonoréDaumier,illustrationfor“LeCharivari”,a
FrenchsatiricalmagazinesimilartoPunch.This
lithographappearedon22ndSeptember1858.With
thankstotheDaumierRegisterDigitalWorkCatalogue
Thislithographisfromaseriescalled
ACTUALITÉS(NewsoftheDay).
AlargesectionofDaumier’sworkcarriesa
heavysocio‐politicalmessageandmustbe
interpretedascaricaturesofprotest
againsttheFrenchestablishment.Almosta
fourthofhislithographsdealswith
politicaltopicsandwaspublishedinthe
seriesACTUALITÉSoftheCharivari.The
appearanceofthisserieswasdirectly
linkedtothefreespaceleftbycensorship
laws.OnceaGovernmentdecidedthatthe
liberalpresswasgettingtooobnoxious,the
lawsimmediatelyforcedjournalistsaswell
ascaricaturiststomovetowardsless
aggressivetopics.
MostoftheACTUALITÉSseriescanbe
foundin1850and1851,beforeNapoléon
IIIbecameemperor,reinstatingthe
controllingsystemofthepress.Between
1854and1856duringtheCrimeanwar,
thesupportofthepresswasagainneeded
bytheGovernmentandACTUALITÉS
appeareduncensoredforashortperiod.
After1856,oncethewarwasover,
publicationoftheserieswasstoppedagain
andDaumierwasforcedtoconcentrateon
themoreharmlesstopicsofeverydaylife.
Occasionally,aprintwaspublishedunder
theoldseriesname,howeveritnever
coveredanycrucialthemesquestioningthe’
Emperor’s2decisions.
Onlyin1865,underpressureofthe
populationwhowantedtoseeandread
moreaboutFrance’sinvolvementinher
variousmilitaryengagementsunder
NapoléonIII,theACTUALITÉSstartedto
appearagain(DR3480)showingit’sbite
andbittersarcasmtowardsmilitaryre‐
armamentasaguaranteeforpeace.Later,
between1870and1871,Daumier’sprints
becameratherbiasedwhenFrance
declaredwaragainstPrussia.Still,one
shouldnotforgetthatinallofhisworkhe
vehementlyopposedmilitaryforceagainst
France’sneighbours.
2LouisNapoleonoriginallystyledhimself,“hisImperial
andRoyalHighnessprinceLouisNapoleonofFrance,
PrinceofHolland”.Ultimatelyhisfulltitlewas,“His
ImperialMajestyNapoleontheThird,bytheGraceofGod
andthewilloftheNation,EmperoroftheFrench”.
36
Thelastprintofthisseries(DR3936)
appearedinDecember1875,25yearsafter
thefirstprintofACTUALITÉShadbeen
published.
"WiththankstotheDaumierRegisterDigitalWork
Catalogue.Formoreexamplesonastronomy&caricature,
goto:
http://www.daumier‐
register.org/werklist.php?themen=76&esok_themasrch=on JaniceMcClean‐Editor,Comet’sTale
13
CometSectionContacts
NickJames,11TavistockRoad,Chelmsford,Essex, CM16JL,England.
Phone:(+44)(0)1245354366
E‐mail:[email protected]
JonathanShanklin,11CityRoad,Cambridge,CB11DP,England.
Phone:(+44)(0)1223571250(H)or(+44)(0)1223221482(W)
Fax:(+44)(0)1223221279(W)
E‐Mail:[email protected]@bas.ac.uk
DenisBuczynski,Templecroft,TarbatnessRoad,Portmahomack,,Ross‐Shire,IV20
1RD,Scotland
Phone:(+44)(0)1862871187
E‐mail:[email protected]
GuyHurst,16WestminsterClose,Basingstoke,Hampshire,RG224PP,England.
Phone&Fax:(+44)(0)1256471074
E‐Mail:[email protected]@ast.star.rl.ac.uk
PeterCarson.85Whitehouseroad,Leighonsea,Essex,SS95ST,England.
Phone(+44)01702525539
Email:[email protected]
RogerDymock,67HaslarCrescent,Waterlooville,Hampshire,PO76DD,England.
Phone:(+44)(0)23‐926‐47986
E‐mail:[email protected]
JaniceMcClean
E‐mail:[email protected]
Director
VisualObservationsandAnalysis
Secretary
TALiaison,alsoEditorofThe
Astronomermagazine
CCDImagingAdvisor
OutreachandMentoring
NewsletterEditor
37
14 Picture Gallery The Copyright for all images remains with the observer Comet67PChuryumov‐Gerasimenko:
ByChrisSchur,ArizonaUSA2016April14Lens:10"f/3.9OrionAstrographwithBaaderMPCCcomacorrectorPlatform:
AstrophysicsAP1200Camera:SBIGST10XMEExposure:LRGB=16:3:3:3mLocation:Payson,ArizonaElevation:5150ft.Sky:
Seeing7/10,Transparency8/10OutsideTemperature:30FProcessingTools:MaximDL6,PhotoshopCS2
Comet2014W2panSTARRS
38
LowandHigherresolutionCometarySpectratakenbyamateurs.
39
CometaryactivityobservedbyJuanJoseGonzálezinthisunusualobject.Thiscomet
maybeassociatedwithComet252P.
CometaryactivityimagedbyMikeOlason
40
Comet252PimagestakenbyMichealJägerandPeterCarson.
ByMichaelJaeger:colorimagetakenwithEsprit80/400andMoravianG3‐11002April5UT3.30Green3x540secBlue,Green
1x540
41
CometC/2013US10
ByAdrianoValvasoriimage2016March11:ImageofC/2013US10:FSQ105f/5SBIGSTL‐11000Ml2x60sbin1RGB1X120S
bin2
42
CometC/2013US10continued
ByDamianPeach
2016January18:ImageofC/2013US10.Theiontailshowssomefinestreamers.FSQ106withSTL11k.LRGB.20/2/2/2min.
43
CometC/2014Q2Lovejoy
IanSharp
M.Jäger
44
CometC/2014Q2Lovejoycontinued
byGeraldRhemannCometC/2014Q2Lovejoy2015January1Mosaicof3panelsDate:21012015UT18h17mLocation:
Turmkogel,LowerAustriaTelescope:ASAH8f2.9Camera:FLIPL16803Mount:ASADDM60Exposuretime:LRGB
400/250/250/250secondseachframe
byJ.Tipping.2015January24.
45
CometC/2014Q2Lovejoycontinued
byMartinMobberley.2015January24.
byDenisBuczynski.2015February1.
46
CometC/2014Q2Lovejoycontinued
ChrisSchurArizonaUSA
Lens:80mmf/4.6Platform:AstrophysicsAP1200Exposure:L=200m,RGB=6mCamera:ST10xmeLocation:Payson,Arizona
Elevation:5150ft.Sky:Seeing4/10,Transparency9/10OutsideTemperature:25FProcessingTools:MaximDL,PhotoshopCS2
47