MCCT SKADS Mixed Workshop

Towards third generation calibration in radio astronomy

SKADS Set of Standard Challenges

Participants of the workshop, which will be held in Nançay (France) from 27 Sept to 10 Oct 2009, will be selected and notified not later than Sept 1st.

To qualify, we would like you to work through your own selection of the Open Challenges of the “SKADS Set of Standard Challenges” (SSSC), which you can find at:

NB: These instructions are also available on this website, together with lots of other supporting information, and a list of answers to Frequently Asked Questions about what we are trying to do. Your friendly contact for all matters pertaining to this site is Ian Heywood:

Each item in the list of Open Challenges is based on a data-set (MS) with simulated uv-data. These are generated for an existing instrument (e.g. the WSRT), using a particular Local Source Model (e.g. a point source), and corrupted with a specific set of instrumental errors (e.g. antenna phases that vary sinusoidally with time).

The “difficulty” of an item is indicated with a rating (one or more stars). You will notice that the first ones are variations on the theme of a single point source in the centre of the field. Since we are working hard to stay just ahead of you, more interesting items will appear by the time you are ready for them.

The PURR log in the first item will guide you trough the various steps: Looking at the uv-data, trying to subtract the LSM from it, and solving for the corrupting instrumental errors. In principle, you can use any 2nd generation data reduction package of your choice to do all this. But in view of the 3GC Challenges to come, we really recommend that you invest the time to master MeqTrees.

Whatever tools you use, we ask you to report your findings in the form of PURR logs (see below), marked with your name, email address and other useful information. Please send your PURR logs to Jan Noordam:

While we will give points for zeal (e.g. if you work through all the available Challenges), we are more interested in other traits (see also below). We will be particularly impressed with people who go one step further, and generate new Open Challenges of their own. For instance by making interesting variations on the ones that are already there. Instructions for doing so are in another PURR log in the first Challenge. With your consent, we will put your new items on the SSSC page, for others to play with, and to make their own variations on.

If you get carried away, and want to use your special skills to contribute something to our tools, we will be pleased to offer you some suggestions.

Somewhere in August, we will introduce some special Challenges that deal with the two main themes of our workshop, i.e. station beamshapes (EJones) and ionosphere (ZJones and FJones). For some of you, this might be the moment to specialize a bit.

This is all you need to know to start. We hope that you will enjoy this exercise, and feel that it opens new ways of doing things, and particularly of doing them together. We very much look forward to getting to know you, and to see what you can do.

(One more thing: If you know anyone else who would enjoy participating in this, just pass on this information, and tell him or her to start sending in PURR logs. Registration is not necessary.)

Jan Noordam

Ian Heywood