A Transient Astronomy
“Free for All” at
The Astronomer’s Telegram
Derek B. Fox, Caltech
Robert E. Rutledge, McGill
VO Events Meeting
Pasadena – 13 April 2005
A Transient Astronomy Free-for-All
• ATEL in Context
– What need does it serve?
– How does it work?
• ATEL in Action
– How has it been used?
– What have we learned?
• From ATEL to VO Events
– Minimal standards for VOE
– ATEL-like components
– New/Novel components
The Astronomer’s Telegram
in Context
The Astronomer’s Telegram
• Online December 17, 1997
• Founder: Bob Rutledge
• Application of the Web to
transient astronomy
• All Perl CGI
• Daily emails + Instant
Notices
On the same day:
• GCNs #9 to #13 on
GRB971214
• IAUC 6791, also on
GRB971214
ATEL Approach
Philosophy:
• Universal access
• Vet authors on registration
• Trust them thereafter . . .
(can revoke if necessary)
• Complete automation
• Instant distribution
– On web in seconds
– Email in minutes (instants)
– A must for transient
astronomy
• Free for all
Universal Access  Collaboration
•
•
•
•
Observers expect others to
be aware of ATEL
Watch ATEL for transient
events
Respond by initiating
observations
Post results to ATEL
Extremely rich phenomena are
intensively observed, without
prior agreement, between major
observers at the largest facilities
ATEL Usage
In the 7 1/2 years since:
• ATEL #457 – all freely
available via ADS query
• GCN 3255
• IAUC 8509 (+1718) –
approx. 5000 notices
• CBET 137 – New since
Jan 25, 2005
• Multiple project-specific
mailing lists
ATEL Users
• Authors self-describe
telegrams by bandpass
and subject matter
• Multiple selections are
allowed & encouraged
• 107 “Requests for
Observations”
• 18 “Comments”
323
162
109
103
80
10
10
7
7
6
X-ray
Optical
Radio
Gamma-ray
Infrared
Far-Infrared
> GeV
Ultraviolet
Millimeter
Submillimeter
ATEL Subjects
327
263
170
146
104
33
24
22
20
15
Transients
Binaries
Black Holes
Neutron Stars
Pulsars
Variables
SGRs
Supernovae*
GRBs
Stars
12
AGN
9
6
6
5
Novae*
CVs
SN Remnants
Glob’r Clusters
5
3
1
Microlensing
Quasars
Comets
1
Meteors
The Astronomer’s Telegram
in Action
ATEL Lessons
• Personal registration of
users
• HTTP User + Password
sufficient to verify (cookie)
• Cryptographic signatures still
rare
• Content verification via the
website
• Authors have “pushed the
envelope” for instant notices
• Theory telegrams didn’t work
• Observers encouraged to
interpret results
Registration of Users
Necessity of vetting users
• Verify identity by personal
contact
• Professional astronomers
and graduate students
Considerations:
• Several requests per year
from non-astronomers
• Amateur astronomers would
like to post
• Usually users attempt to post
prior to registration
Instant Email Notices
Exception to daily emails
intended for:
• Discovery with new
coordinates
• New outburst of known
transient
• Typing of supernova
• Request for observations
From Astronomer’s Telegram
to Virtual Observatory
(Events)
Elements of VO Events
• XML Schema
– Event Coordinates
– Event Properties
– Descriptive elements
• Distribution channels
– Vetted in advance
– Providing event verification
– Cafeteria style selection (not
all or nothing)
• Registration service
– Identity
– Qualifications
Elements of VO Events
ATEL:
•
Schema
–
–
–
–
–
•
Author names + affiliations
First author email address
Telegram Title (string)
Wavebands + Object types
Text description
Distribution channels
– Website, Email, RSS
– Event verification by visiting the
website
•
Registration service
– Personal contact by Editors
The Information Registry
•
•
VO Events may enable machine-intiated observations on subsecond
timescales.
To work in this fashion they must have registry metadata enabling identity
and content verification
If these are not included in the VO event schema then events will be
distributed only between previously known & trusted sources, and the
utility of a universal schema will be lost.
From ATEL to VO Events
VO-Events:
• XML Schema
– Ongoing process
• Distribution channels
– Website, Email, RSS, SOAP
– Identity verification
– Content verification
• Registration service
– ?
The VO Event Free-for-All
•
•
•
•
ATEL has been up for 7.5 years
Instant access enabling
progress in transient astronomy
Registration of users has
allowed us to trust them
Increasing usage + diversity of
subject matter
VO Events as a free-for all:
•
•
•
•
Flexibility of subscriptions
Flexibility of subject matter
Freedom of access
Verification of author and
content provided