Finding charts may be used for locating suitable guide stars for a particular telescope, for transparent overlays to find objects on Schmidt survey plates, and for visualization purposes when cross-correlating catalogs. The largest catalog of stars currently available for this purpose is the STScI Guide Star Catalog (GSC), which is available on CD-ROM from the ASP. It contains positions which are precise to between 0and 0. Note, however, that this catalog is not magnitude-limited, but that the selection of stars has been carried out so as to provide a homogeneous density of guide stars over the sky. The EXOSAT and SIMBAD databases (see §3.2.9.) and others (e.g., the GASP package in IRAF/STSDAS, or STELLA, which is described below) allow guide stars to be selected from user-defined areas of the sky. A ``pocket version'' (300 MB) of the GSC has been produced by Preite-Martinez and Ochsenbein (1994).
SKYMAP is a computer program which produces maps of arbitrary portions of the sky in a variety of projections and coordinate systems. Over the past 10 years it has been used to produce finding charts for very different purposes. It can display multiple source catalogs, including the HST Guide Star Catalog, as well as solar system objects with astrometric accuracy. SKYMAP can be tuned to a specific task using an ASCII parameter file which controls how information is displayed on any Tektronix-compatible graphics display or hardcopy device. The program contains a variety of interactive graphic and image processing features and has been ported to a variety of computer systems. The program is available by anonymous FTP from cfa0.harvard.edu (128.103.40.1) in the pub/gsc directory. Contact D. Mink mink@cfa.harvard.edu for an illustrated manual of the program. [Reference: Mink (1993).]
Other packages to produce finding charts from the GSC have been developed, e.g., by Megevand (1992), Smirnov and Malkov (1993), and Malkov and Smirnov (1994). Finding charts based on the SAO star catalog can be produced with the CHART option within the Starlink software package (Allan 1989). SAO star charts as well as images of the surroundings of 58,000 galaxies (from POSS-I) can also be generated using LEDA (see §3.2.7.). ``Preview'' images of galaxies from the Surface Photometry Catalogue of the ESO-Uppsala Galaxies (Lauberts and Valentijn, 1989), are available through the STARCAT interface (see §3.3.7.).
SkyView is a facility available over the net which allows users to retrieve data from public all-sky surveys conveniently. The user enters the position and size of the region desired and the catalogs desired, and the data is extracted and formatted for the user. SkyView handles coordinate conversions and provides the user with data in the desired coordinate system. A description of SkyView is in the SkyView User's Guide and SkyView Design document, both available via anonymous FTP in skview.gsfc.nasa.gov:pub/doc. SkyView also has extensive internal help available. Access to SkyView is via telnet to legacy.gsfc.nasa.gov, login as user xray. No password is required, but when you first log in you will be asked for information to set up your own user file area. To start SkyView, type skyview and you will start up the SkyView GUI user interface. An article on SkyView will be appearing in the next issue of Legacy, the Journal of the High Energy Astrophysics Archive Research Center (HEASARC). A scaled down WWW version is available as the URL http://skview.gsfc.nasa.gov/skyview.html. For questions or problems with SkyView contact K. Scollick (scollick@skview.gsfc.nasa.gov) or T. McGlynn (mcglynn@grossc.gsfc.nasa.gov). [Reference: McGlynn, White, and Scollick (1994).]
STELLA is a chart generator supporting access to the GSC, SAO, PPM, IRAS, and other catalogs. These are accessed through STARCAT (see §3.3.7.). STELLA is available to users at ESO (contact B. Pirenne at bpirenne@eso.org).