PA is a program that calculates the mean atmospheric dispersion for a given exposure time and position of the telescope. PA is started from the user account on gouda, karnak, or shanepc computers by typing pa at an xterm prompt.

You will then be prompted for the following information:

Enter starting HA (hh.hh, hh:mm, or hh mm):
Enter starting Dec (dd.dd, dd:mm, or dd mm):
Length of Exposure (sec):

The average position angle and nixie readout will be displayed. This information can then be given to the Telescope Operator so that he/she can rotate the TUB to the proper position.

Example:

Enter starting HA (hh.hh, hh:mm, or  hh mm): 2:34
Enter starting Dec (dd.dd, dd:mm, or  dd mm): 15:37
Length of Exposure (sec): 1200

Starting HA = 2.57      Dec = 15.62     Time = 1200 seconds

PA (average) = 231 (or 51)      Airmass (average) = 1.35
Nixie readout = 201.0 (or 44.4)

NixiPA is a program that converts the nixie tube readout to a position angle in degrees East of North, and vice versa. NixiPA is started from the user account on either gouda or karnak by typing nixipa. To convert from position angle to nixie reading, enter the position angle and click "PA to NIXIE" or hit the Enter key. The corresponding nixie reading will be both displayed in the NIXIE Reading entry box and on the simulated nixie tubes. To convert from nixie reading to position angle, enter the nixie reading in its entry box and click "NIXIE to PA" or hit the Enter key. The corresponding position angle (in degrees East of North) will be displayed in the Position Angle entry box. Nixie readout limits to the rotation of the TUB are also displayed for reference. The "Quit" button exits NixiPA.

NixiPA User Interface