A new version of the telescope control program for the 1.5-m telescope was installed in mid June. The functionality and performance of the telescope have changed very little, so that this upgrade will be largely invisible from the point of view of the user. However, the VME hardware and software at the heart of the system are significantly different. In particular the code has been ported to the VxWorks operating system in order to restore commonality between the 1.5-m software and that in use at the 4-m. Although the control systems at the two telescopes were originally very similar, the 1.5-m system got left behind when the 4-m was converted to VxWorks several years ago. Furthermore, due to a bug in the compiler for the development system used previously, we have been unable to modify the 1.5-m code for a considerable time. The CPU for the VME bus computer was also upgraded making it identical with that in use at the 4m. These changes will greatly simplify the task of maintaining and improving the two systems.
In mid-August the 1.5-m TCS will be replaced by a Graphical User Interface modeled on that in use at KPNO. A similar GUI will be installed at the CTIO 4m telescope shortly thereafter. This GUI includes two tools that may be of interest to observers.
Firstly, there is the Xgstar program that can be used by the telescope operator or the observer to select guide stars from the HST Guide Star Catalog. This has been customized so that it knows the correct size and shape of the region accessible with the guide probe at the various foci of each telescope. The new version of the program also accesses a copy of the GSC stored on hard disk, rather than reading the CDRoms, resulting in improved speed and reliability. The telescope operator can use Xgstar to select guide stars on the fly. However, it can also be run from any of the CTIO visitor accounts, allowing users to pre-select guide stars for each object. This is the recommended procedure for working in sparsely populated fields, especially with the f/14 secondary at the 4-m telescope where the field accessible to the guider is rather small.
Secondly the Xobject package is available to help selection of coordinates from several standard catalogs (including the SAO, Yale Bright stars, IR and optical photometric and spectrophotmetric standards, etc.), as well as from user coordinates files. The format of the user files is the same as that previously in use at both telescopes. The entry for each object consists of a label, three numbers for RA (hours, minutes and seconds), three numbers for DEC (degree, minutes and seconds), the epoch in years, proper motion in RA and DEC (both in arcsec/year), and finally an arbitrary comment. Each entry is one line of text, containing a maximum of 80 characters, in free format, with the fields delimited by spaces. For example:
The label field must contain printable characters only, with no commas, semicolons, spaces or tabs. There is no limit on the number of entries, although for speed of access no more than about 1000 objects should be recorded in a single file. The TCS control computer can access coordinate lists stored on any computer in the CTIO network. Users who have prepared coordinate lists in advance need only copy them to their visitor account in Chile via ftp or e-mail.
Steve Heathcote, German Schumacher,
Rolando Cantarutti, Pedro Gigoux