Check list to confirm the discovery of a
Alain Klotz - 28 Aug 2012
Emmanuel Conseil - 08 Sep 2020 (update)
What to do if a new object is detected ? This page is dedicaded to
people that are using the SN_TAROT tool to discover supernovae.
However, the main lines can be used by any discovery program.
Follow the steps of this check list :
At time T+0h, one must confirm that the candidate is not an
artifact, not a known star neither
for image artifacts
: Comparison with an atlas image
: Check known solar system objects
: Check variable stellar objects
: Verify if the candidate has been already
: First measurements of the candidate
Between T > +1h and T < +24h, the goal is to confirm the candidate is really a star.
additional images of the candidate, by the same telescope or any other telescope, at least separated by 1 hour or more from the first detection image.
At this step you must decide if the candidate is true or not.
Don't hesitate to ask the Tarot team for help, especially if it's your first detection.
: Post a new candidate on the Transient Name Server (TNS)
: Post an Astronomer TELegram (if possible)
To include additional observations
Follow-up of the discovery
Detailed check list procedures
Step 1 : Searching for image artifacts
Some rare cosmic traces appear to be star like. In this case, if the
image is a stacked frame the only way to discriminated a cosmic from a
real celestial object is to vizualize the individual frames.
If you don't have access to the individual frames, feel free to ask to the team through the Tarot_sn mailing-list to check for yourself.
- Hot pixels
- Bad group of pixels
- Cosmic trace
- Satellite trace
- Airplane trace with flash lights
Step 2 : Comparison with an atlas image
You must compare your recent image with another one taken few years
ago. Sometimes your candidate is only an active region (HII) of
the galaxy that seems apparently brighter and could be erronenously
attributed to a candidate when the seeing is better.
The Digital Sky Survey allows to download an old image.
The Sloan Digital Sky Survey provide more recent deeper images.
Don't hesitate to look at the images from all available wavelengths. And always compare your image with an archive of better quality, at least.
Step 3 : Check for known solar system objects
There is statistically about 90% of stellar candidates that are in fact
close approaches of asteroids
Step 4 : Check variable stellar objects
Cataclysmic variable stars of our galaxy can lie foreground of the
galaxy. In particullar dwarf novae (U Gem type). Crisis phase of such a
star spend about 2 to 20 days and the brightness increases by 2 to 5
magnitudes. Long periods are observed during two crisis. A dwarf nova
is red and its spectrum is completly different than a supernova (not
easy to diagnotic with only images).
Strong erratic brightness rising of a background quasar can provide the
apparence of a supernova. Check if your candidate coincide with a known
Classical variable stars must be check using the GCVS database or the
International Variable Star Index (VSX) of the AAVSO :
Step 5 : Verify if the candidate has been
already recently found
Concerning the most recent informations, the CBAT "Transient Objects
Confirmation Page" provides non officialized recent discovered sources
that have been declared to the IAU. The ATEL telegrams can also provide
non official candidates:
Step 6 : First measurements of the candidate
The declaration of a new supernova candidate needs to indicate :
You can use any astronomical tool to measure the brightness of the candidate. Don't forget the estimated error of your measure.
- The date of the middle of the image (Ex: 2012 Jan. 23.567 UT)
- The name of the discover
- The telescope characteristics
- The celestial coordinates (Ex: R.A. = 17h48m48s.70, Decl. =
-60o42'19".3 equinox J2000)
- The magnitude of the candidate
- The associated bandwidth (Clear, V, R, ...)
- The last time you saw nothing at this location, or the date of an archive image
- Search the nearest archive image on database where the candidate does
Step 7 : Obtain additional images of the
Before its declaration, the supernova candidate needs to have been observed at
least two nights or many times a night, and if possible by more than one telescope.
- Wait for the next automatic images because it not not sure your
galaxy will be reobserved. For example, galaxies observed by TAROT in
the supernovae search programme are coming back every three days.
- Contact your collaborators
- Contact the members of the TAROT mailing-list
Step 8 : Post a new candidate on the Transient Name Server (TNS)
The TNS is the place where the IAU gathers all the supernovae candidates, and the confirmed ones.
You will need :
Don't forget to fill the "Reporting group" with the value "TAROT".
- A personal account on this server (You can apply here - this may take some time) associated with the TAROT TNS Group
- A minimum list of characteristics for your candidate :
- The J2000 coordinates of the candidate (format : HH MM SS.SS dd mm ss.s)
- The discovery magnitude (+ associated error magnitude)
- The filter used
- The telescope characteristics (location, name, diameter, focal length)
- The exposure time
- The limiting magnitude of the image
- The date of last non detection (or the date of a known archive image)
- OPTIONAL, but useful : the image itself, with a mark showing the candidate
- OPTIONAL : All the known magnitudes measures so far (from you or the people who healped you confirm the object)
Step 9 : Post an Astronomer TELegram (if possible)
The ATELs are posted on various hot subjects. It is the same objective
The ATEL text will be on-line instantaneously.
WARNING : You need to be a professional astronomer, or associated with a professional team of scientists to get an account on this website and post ATELs. Or you need to known someone who has got such credentials and ask him to post the telegram for you.
Authors(Affiliation): A. Klotz (Institut de Recherche en Astrophysique
et Planetologie, France)
E-Mail Address: email@example.com
Telegram Title: PSN J19065165-6142163 a supernova candidate by TAROT in
Objects : Supernovae
From images taken on 2012 June 20.36
with the TAROT La Silla telescope
A. Klotz report the discovery of a
supernova candidate located at R.A. = 19h06m51.65s,
Decl. = -61o42'16.3" (equinox 2000.0),
which is offset of 6" E and 12" S from the
nucleus of IC 4815. The image was R filtered
and magnitude was R~19.
The presence of the candidate is confirmed
on two images taken on 2012 June 26.34 with the
same telescope. R=17.6.
The candidate is not detected in images
taken by TAROT on 2012 June 08.34 (limiting
Step 10 : Follow-up of the discovery
To include additional observations you can post comments on the TNS page of your candidate : https://wis-tns.weizmann.ac.il/object/
You must be loggued in on the TNS server to post comments. Your comments can include text or images.