SADT: The Survey Areas Definition Tool
What is SADT?
The Survey Area Definition Tool (SADT) is a tool that generates the pointing positions for each tile within a survey. In addition it searches the guide star catalogues and selects the suitable sets of guide and active optics stars necessary to observe the individual pawprints of each survey tile. In the case it does not find a sufficient number of guide stars or active optics stars, the tile position is slightly re-adjusted and the tool searches automatically again for suitable AG/AO stars. The output of the SADT (survey area file in XML format) must be used together with the P2PP version 3 (P2PP3) to generate the Observing Blocks (OBs) for observing runs scheduled on the VISTA or VST telescope.
Important note concerning releases
The current public release of SADT is version 5.04 of the software for VIRCAM observations, or version 5.06 to prepare OBs for OmegaCAM.
NEW in the SADT v5.04 (for VIRCAM/VISTA observations) is the extension of the 2MASS catalog to the visible wavelength. A synthesised I-band magnitude, which corresponds to the response of autoguider and wavefront sensor CCDs, is calculated from the 2MASS JHKs colours. The new magnitude limits in the sadt.cfg file correspond to this I-band magnitude and were tested on sky. It is now recommended to use the extended 2MASS catalog for the search of guide and wavefront sensor (aO) stars, in particular at high Galactic latitude fields and around extended targets. At low Galactic latitude, GSC-2 or UCAC3 should be preferred because the 2MASS transformation suffers from high Galactic extinction. After the re-coating of the mirror, the magnitude limits of the guide and aO stars remain the same as in the last period (P87). Thus, some fields at high Galactic latitudes still may suffer from frequent backtracking or even failures of aO star searches. Solutions are to try and make a small shift in DEC, since backtracking is only done in one direction, or to try using another catalog.
NEW in version 5.06: this is the latest version of SADT for observations with OmegaCAM at VST. It is tailored for the preparation of survey areas for early science observations of the Public Surveys. Some specifics of this SADT release for VST are:
- the position angles of the detectors on the sky can now be set to any value;
- a definition of an area as geodesic rectangle is not offered, coordinate ranges or circles should be used;
- the positions of guide and active optics stars are not propagated to the OBs. Thus, please use SADT for VST without the option 'Find Guide/aO Stars'!
The latest version of the Survey Area Definition Tool (SADT) is available for Scientific Linux running Java 1.6. It is known to work also under other Linux flavours, but not all have been tested. As a Java application it should also run under Unix, Mac OS X, or MS Windows operating systems running Java 1.6, but no support is guaranteed on other systems. Please note that running P2PP3 also requires Java 1.6.
The SADT can be retrieved via anonymous FTP:
How to use SADT
- The SADT Cookbook provides step-by-step instructions on how to use SADT with some examples:
- For a quick overview of the main SADT functionalities (for the VIRCAM/VISTA case) there is a 5 min long movie tutorial.
- Users should familiarize themselves with VIRCAM or OmegaCAM and its templates before using SADT. This information can be found in the VIRCAM/VISTA User Manual and the OmegaCAM/VST User and Template Manual.
This page is specific to Public Surveys on the VST and VISTA telescopes.