Adopt a supernova

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This programme is not yet open to everybody!

Adopt a Supernova

Gaia now detects 1-4 new transients every day. In this (pilot) programme you can pick one (or more!) transients detected by Gaia (supernova or any other) and treat it is a your "pet". This involves simply taking care your object is classified and has enough observations so it can be useful for further studies of supernovae. In particular, supernovae Type Ia, once they have their redshift measured and their light curve sampled enough, can be then modelled and be used for cosmological studies of the expansion of the Universe.

Picking a target

Gaia transients are listed on couple of pages. Note: Some pages require authorisation. Please contact us if need the passwords stating who you are and why would like to join this programme.

The main selection criterion is that the target is still on-going (ok, you can also pick one which is now gone, but then not much apart from modelling and studying the target is possible). This Online Julian Date converter can be helpful to understand the Julian Dates plotted on the light curves. Note various offsets on different plots, e.g. JD-2456000 on Gaia light curves.

Taking care of your target

Your task is to make sure your supernova gets enough follow-up data to be useful for studies of supernovae and cosmology. It means that apart from spectral classification (which for a while is out of this programme), it has a nice light curve in multiple bands. If a SN is young (around max) you probably want it to be observed every 3-5 days, but once it is a bit older, say ~10 days afer max, it is enough to observe it once every 7-10 days. Remember, supernovae get fainter so you have to balance your sampling with available telescopes, e.g. you can not wait with collecting next point when it is reaching ~20 mag, as it will be very hard to observe with most instruments we currently have.

Requesting observing

First, check the visibility of your target using this tool (be careful: when entering coords in degrees remember to add "d" before right-ascension). If you want your supernova to have a new data point:

  • observe it yourself or ask your colleagues to have it observed (Ostrowik, Loiano)
  • request observations with the LCOGT network (primarily south) - currently request via LW
  • request observations via Gaia Science Alerts WG10 for Photometric Follow-up via LW (Gaia-FUN-TO: network of European telescopes, so north only)

Reducing the data

You want to know what is going on with your supernova and taking an image is not enough, of course. You need your data to be reduced as soon as possible. We are currently establishing an automated or semi-automated data reduction pipeline, but many of you know the procedures already! But careful, supernovae are tricky! Especially those very close to their host galaxy and embedded in the diffuse galaxy light. Ultimately, a difference imaging pipeline would be the best for such purpose, but as a first approximation, a SExtractor or similar tool is good enough. Before executing SExtractor, you usually will need to obtain astrometric solution for your image, I suggest using astrometry.net.

Submitting the observations to the Calibration Server

Once you have obtained magnitudes of all stars from your image in a given filter, then the data needs to be submitted to the [gsaweb.ast.cam.ac.uk/followup/ Calibration Server] (see manual there). This is designed to provide calibrated magnitudes of your supernova as well as to store all follow-up observations. The procedure of submission can be fully automatised and we hope it will be part of the data reduction pipeline.

Final steps

Once your supernova is gone you should make sure that all available data has been reduced and collected at the Calibration Server. You should be able to extract all the data from the Calib Server (authorisation required) and you should then have a critical look at all the measurements. Some will need to be removed due to their errors or large scatter. The remaining light curve should be analysed with an attempt of modelling it. We will later include the details on how to do it.

Enjoy! And clear skies!