and are also available via FTP at
To access Obscat, which is updated continuously, click on the link on the right side of the CXC homepage or the ``proposer'' icon at the top of the CXC page and follow the links to Obscat. This Java interface will take 1-2 minutes to load. If you are a first-time user you will have to download a 7 Mbyte ``plugin''(with Netscape 4). Instructions will appear which should enable you to install the plugin successfully.
You may search for a particular target or group of targets, or by name, position, Date, Exposure, Type, or Observation Number. The filters are additive, and combinations of all the above can be used to generate output lists. Once the parameters are input, click on ``submit" (bottom of the page) to start the search. Targets found are listed on a new page and detailed target information can be displayed by highlighting the target of interest and clicking the ``Detail'' button at the bottom of the listing. To start a new search, click the ``New Search'' button. Do not click Netscape ``Back''; this will reinitiate Obscat.
The Chandra science page (http://asc.harvard.edu) also contains the non-Java tool which performs searches and displays plots useful for observation planning.
To use, click on ``Detailed target info'' which brings up a search form similar to that displayed by Obscat . Targets may be listed for a given PI, science catagory, instrument, or status; or, a cone search may be done to list targets close to any particular location. The result of the search is displayed on a new screen and, for detail, the user can then click on the sequence number of any of the targets listed. A new page will then appear with basic information for that target and with four buttons. Click on ``parameter file'' for a listing of instrument settings. Click on ``DSS'' for an overlay of the instrument FOV on a picture from the Digital Sky Survey. Click on ``ROSAT'' for an overlay on a ROSAT X-ray image (if one exists for this location). Click on ``Roll/Visibility'' for a plot of nominal roll and target visibility as a function of date. This tool uses an information base which is updated daily. It does not calculate overlays (as does Obsvis) but displays overlays generated by the mission planning process after an observation date has been assigned for each target.
- Fred Seward