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2.2.5 Check Stars and Other Options

It is an advantage to have a check star that is bright enough to see on the TV acquisition system included on the plate. When the final setup is made on the program field, it will be very nice to be able to see the check star coming through a slitlet to give confidence that the alignment and offset were done properly. A check star need not be brighter than V~15 or problems could occur with saturation on the acquisition TV. The program has a special option for ensuring that check stars always are drilled and always appear on each solution if more than one solution is requested (i.e. NPLATE>1). To use this option, the OBJNAME must be listed as CHECK STAR (upper case only). This will automatically set the object weight to 9999. and produce a 3.0 arc-second long slitlet.

One useful option, that is also available, covers the need for the field center to be a position, i.e. not a target object. This is useful for making minor manual tweaks to the field center to include more objects in the solution, especially in crowded fields. To envoke this feature, call the field center name 'BLANK CENTER' in the coordinate list. The "object weight" is ignored, here.

Another option available is one where no setup stars are used. Users are cautioned that before using this option, they should have had at least one successful multi-slit run on the telescope. If all of your astrometry seems to be working correctly, then the chances are good that the no setup star option could work for you. To invoke this option, enter -99 as the object NUM for the setups. No position or other information is needed by the program. You must have one check star to use as a field locator.
Updated 18Apr1996