A special version of JSkyCalc is available at the MDM 2.4m; this version interfaces with the telescope and guide probe in a way that many observers may find convenient and helpful.

The version is called JSkyCalc24mGS -- for "JSkyCalc 2.4-meter GuideStar".

This document tells you a little about JSkyCalc24mGS, describes how to invoke it, and warns about some odd behaviors. The program includes a lengthy help text, which is not repeated here.

In addition to the JSkyCalc features, JSkyCalc24mGS also lets you do the following:

• Select guide stars on a map of the MIS field of view, and move the guide probe to your selected star with the click of a mouse.
• Select targets by clicking them on a map of the sky, and send the target coordinates directly to the telescope, again with just a mouse click. (You do still have to hit GO in the xmis window to move the telescope).

Those are the major new capabilities. It also supplies the following niceties:

• You can load several different observing lists and switch between them conveniently. This makes it easy to see the targets for different programs, or targets appropriate to different conditions, or standards versus program objects, etc., without overcrowding the display.
• The program reads the telescope coordinates from time to time and paints a little red circle on the sky map showing where you're pointing.
• Little "warning lights" tell of proximity to the moon, twilight, and high airmass.
• A list of "how long until" and "how long since" quantities are computed and displayed.

Documentation.

To start the program,

• On the workstation, click Applications>Telescope Control>JSkyCalc24mGS

• The Help button brings up a complete help text on how to use the program -- but read on for an important list of quirky behaviors.

Quirky Behaviors:

• It's Important to note that When you reset the encoders, the coordinates to which the encoders will be set are those displayed in the xmis window, and that these are not updated when you send coordinates from JSkyCalc24mGS. If you're updating coordinates, be certain to load the right coordinates into the xmis window. If you reset to the wrong coordinates and then go off-target before realizing your error, you are doomed to a complete coordinate reset (with a slew to the zenith, tilt meters, and all that).
• For some reason, the little red circle in the guide star selector window does not get updated reliably. In principle this represents the current guide probe coordinates. The numbers reported in the xmis window are reliable; just make sure they match the star you're looking for. (This appears to be a fault in xmis, which sometimes flat-out lies when asked where the guide probe is.)
• The program is on a thread that wakes up every 15 seconds and reloads the display. This makes it difficult to load any values by hand into JSkyCalc, because you're forever being interrupted and overwritten. To enter something by hand, just hit the Stop Update button; don't forget to Resume Update when you're done.
• The program queries the telescope and guide probe coordinates every 10 seconds or so. This causes the message "Executing remote command..." to appear in the status lines in xtcs and xmis. This is completely normal, and hopefully not too distracting.
• There's a bug in the list handling software, which requires that no two targets can have the same name. The symptom of this problem is that the last target(s) on the list do not appear. If all the targets have distinct names, it works fine.
• The terminal window from which you launch JSkyCalc24mGS will have a never-ending stream of stuff printing in it. This is harmless and could even be useful at times.