13. Telescope and CCD camera control

Fitsblink has some ability to control a computer controlled telescope. This option was included specifically for the use with the robotic telescope operated at the Crni Vrh observatory. Therefore, there may not be enough flexibility to control some other telescopes. Also, only very basic functions are supported. The program assumes that all of the functions that access both the telescope and the camera are accessed through a program called tx. As you probably don't have a program with such a name for telescope and camera control, you will need to make a script or a small program named tx which will convert the commands run by fitsblink into a your specific telescope driving program.

  

Figure 20: Telescope and camera control window.

13.1 Telescope commands

At the moment, fitsblink knows the following telescope commands:

• Start (point start). Starts the telescope sidereal motion.
• Park (point park). Go to the park position.
• Zero (zero ra=RA dec=DEC). Tell the telescope server that the current coordinates are RA and DEC.
• Go! (point ra=RA dec=DEC). Go to the desired position. RA (hh:mm:ss.s) and DEC (+dd:mm:ss.s) are templates which are replaced by the actual values from the input fields in the Telescope and camera control window.
• Read (where) Reads out the telescope position.

Also, there are some commands for CCD camera control.

• Read (ccd temp) camera temperature.
• Set (ccd temp=TEMP) camera temperature. TEMP is a template which is replaced by a value from the temperature field.
• Expose (ccd file=FILE time=TIME [dark]) Make an exposition for TIME seconds and FILE is the output file name.
• Dark image can be taken if the appropriate button is pressed.
• Center (center time=TIME) Take a exposition for TIME seconds, find the brightest star and move the telescope so that the star is centered in the middle of the image.

The provided commands should be enough for using the essential commands of most telescopes and CCD cameras. The problem is with the readout of telescope position and camera temperature which is quite specific and hard coded in the telescope.c source file. For readout of the telescope position, fitsblink assumes response in form where done ra=RA dec=DEC, followed by two empty lines, where RA and DEC have to be replaced by the actual values expressed in the same units as described above. Similarly, for CCD camera temperature readout, the response from the camera server should be ccd done temp=TEMP followed by two empty lines, where TEMP is a real number. So, the basic framework for any other telescope is here and you only need to modify the telescope.c and settings.c files to adapt fitsblink if you have your own ideas of how to implement communication between fitsblink and outside world.

13.2 Access to catalogs

It is possible to access object catalogs from the telescope control form and to transfer the coordinates from a catalog entry to the RA and DEC fields in order to use the Zero and Go! functions. Catalog entries should be ordered in some way. To be useful, they must have a right ascension in HH:MM:SS.ss format in the column 4 and a declination in +DD:MM:SS.s format in the column 5. To transfer object coordinates to RA and DEC fields, just click on the chosen entry. Few entries from our catalog of very bright stars follow here:

alf And    2000   0:08:23.2  +29:05:26   2.06 -0.11
bet Cas    2000   0:09:10.6  +59:08:59   2.27  0.34
gam Peg    2000   0:13:14.1  +15:11:01   2.83 -0.23

Note that it doesn't matter what is in other columnns nor have many columns exist in each line. It is only important to have correct coordinates in columns 4 and 5. Columns are white space separated.