ACT
The 1m Austro-Croatian Telescope
at the Hvar Observatory
Monika Rode-Paunzen, Martin Netopil
The 1m ACT
the location
on the croatian island
Hvar „the sunny island“
reachable using the
ferry from Split
The 1m ACT
Island of Hvar
Napoleon: View from Hvar
view from ACT
The 1m ACT
weather
temperature
hours of sunshine: 7,5 h/day,
yearly average value: more than 2.700 h
The 1m ACT
the Hvar observatory
The observatory hosts three instruments:
double solar telescope 13 cm
65 cm (equipped with photomultiplier)
1m ACT
The 1m ACT
Fort Napoleon
built 1811
•solar observatory
•Accommodation:4 bungalows
•kitchen, living room and office
The 1m ACT
accommodation
The 1m ACT
solar double telescope
refractor:
1 chromospheric
1 photospheric
diam.:130 mm
The 1m ACT
astronomical telescopes
The 1m ACT
65 cm
Cassegrain
Primary mirror 65 cm
Secondary mirror 19 cm
built: 1977
The 1m ACT
ACT building
geogr. lon.:+16 26.9 ; geogr. lat.:+43 10.7 ;
238 meters above the mean sea level
The 1m ACT
the telescope
Primary mirror 100 cm
Secondary mirror 26,6 cm
Cassegrain-Focus f/15
Mounting english
Field of View (without vignetting) 8'
Field of View (currently) 3'
Filters (currently) : Bessell UBVRI
CCD: Apogee Alta U47 (currently)
The 1m ACT
dome office
The 1m ACT
First Light
NGC 869
3.Sep.2001, 23:30 UT
Filter: Stömgren y
t= 90 sec
field of view
5,7
x
5,7 arcmin.
The 1m ACT
instrumentation
CCD‘s
2001 – 2008
2008 – 2010
2010 – ?
available filters
Bessell UBVRI
Strömgren uvby
Delta-a
CCD provided by Werner Weiss (1024x1024px; FOV 5.7‘)
Pixis 2048B by Princenton Inst. (2048x2048px; FOV 6.3‘)
Apogee Alta U47 by Gerald Handler (1024x1024px; FOV 3‘)
The 1m ACT
observing …
due to wrong polar alignment there is a restriction in exposure times
typically 100-200sec possible (depending on position)
currently, manual adjustment in RA speed is
possible only; DEC hopefully soon …
together with automatic correction.
typical pointing accuracy: ~3‘, but is going
to be improved during the night by „zeroing“
the coordinates.
However, doing a good and efficient job
there is possible anyway …
open cluster NGC 6830, 150s exposure
The 1m ACT
observing …
still, one is in direct contact to the
instrument there during observations …
controlling of CCD and telescope is separated
The 1m ACT
some recent results
open cluster survey
coverage of 26 open clusters in standard BVRI (mostly poorly investigated ones)
could have been many more, but damage of CCD stopped that successful run
NGC 7062: logt = 8.8, d=1.8kpc, [Fe/H]~-0.30
method by Pöhnl & Paunzen (2010)
The 1m ACT
some recent results
NGC 6830:
logt = 8.35, d=2.2kpc, [Fe/H]~0.20
some CP candidates were detected
via Delta-a photometry (Netopil et al. 2007)
only 1 star seems to be a very probable member
The 1m ACT
some recent results
comparison of B,V photometry for 5 clusters (=1 night) to photoelectric measurements
(mostly Hoag et al. 1961)
The 1m ACT
some recent results
comparison of R and I photometry …
The survey IPHAS (INT/WFC Photometric Hα Survey of the Northern Galactic Plane)
provides r‘,i‘,Hα photometry using 34‘ fields (total coverage >1600 degrees^2)
still not homogeneously calibrated (only on nightly basis; often considerable offsets
between fields are present)
fortunately one of our clusters (NGC 7788) is covered by IPHAS together with
NGC 7790 (a standard field by Stetson 2000) on one frame, allowing a direct comparison
several calibrations for ugrizÙUBVRI are available (e.g. Ivezic et al. 2007) …
∆R [mag]
∆I [mag]
NGC 7790 (Iphas - standard)
0.016(2)
0.034(2)
NGC 7788 (Iphas – own)
0.036(3)
0.043(3)
=> ~2% accuracy of standard BVRI photometry
The 1m ACT
some recent results
just to show that providing standard photometry is not that easy …
only some examples taken from WEBDA (different clusters, different studies)
unfortunately, there are many, many more …
The 1m ACT
further programmes
variable stars in open clusters
some open clusters are already covered with high and lower time resolution to
detect both, short periods as well as e.g. eclipsing binaries …
among these also clusters with detected CP stars (NGC 6830, NGC 7296)
reduction still in progress …
The 1m ACT
further programmes
Follow ups …
Zeljko Ivezic (co-head of SDSS) initiated a programme to investigate
variable stars found in the LINEAR survey (Lincoln Near-Earth Asteroid
Research) – several hundred observations down to V~18mag (single, broad bandpass).
Follow up observations in multiple colours are carried out for a better classification.
e.g. to separate RR Lyrae c and contact eclipsing binaries, which have a similiar behaviour in a
single passband, but not in colours …
The 1m ACT
further programmes
pulsating white dwarfs
some white dwarfs were selected by Gerald Handler for test purposes.
observations were carried out by Ernst and Monika in August 2010.
PG 2246+121 (y ~16.7mag)
~700 15sec exposures (without filter)
=> 3.3h
main period by Handler 2001
329 sec.
Preliminary analysis => 328 sec
The 1m ACT
how to get there?
rather cheap observing run
… flight to Split ~200 Euro, accommodation for free
plenty of time available
… Austria has at least 50% per year (which is by far not covered, in addition
„croatian“ time is also under-utilized)
beside sommer months it should not be a problem at all …
Just contact one of us (Ernst, Monika, Martin), we are in regular contact with the
croatian side …