Telescope Control System User's Guide

Created 09/01/94 by TG
Updated 09/26/19 by EF

This document describes the TCS program, which controls the 1.5m telescope from the flwo60 Linux PC. The system provides controls via a Graphical User Interface (GUI) labeled ntcs, see below. The system also runs a command xterm window labeled Telshell, which allows the observer to enter telescope and instrument commands and to run observing scripts.


The purpose of TCS is to control the new TCSGalil program running on tcs60 from flwo60 and move the telescope and control FAST and TRES. It also manages catalogs, and inserts information from the telescope and catalogs in FITS headers. Another major function is to control the Autoguiding functions. See guide for more info. Lastly it controls the motors and lamps for the FAST instrument.


The only way users should start TCS is by starting the Realtime system. TCS is an integral part of the Realtime system; it is started when you type either gofast or gotres. If you attempt to start TCS independently, bad things will happen!


The TCS window will display a series of buttons and a list of information. The information area will update every few seconds, and will accept no input. This display will not contain the profiles and rotator widget (see below) if you are running TRES. Some of the listed information varies according to instrument, for example TRES shows other options related to calibrations and fibers. To select any button place the cursor on the button and depress the left mouse button. The Buttons, starting at top left, have the following functions:

These functions are supported only by the FAST version of TCS:


Some of these buttons when selected will cause a window with further choices to appear. This section will explore these windows, and their usage. In most cases these windows were designed to pop-up, be used, and disappear. For these windows, other windows will not work until the current pop-up has been dismissed.


When you click on NEW COORDS this window appears for selection of the next telescope position desired, either manually or via catalog management commands. The single white line can be used to display the last coordinates entered from this menu by using the up-arrow key.

If you wish to manually type in coordinates, simply put the cursor anywhere inside the white line, and type coordinates, for example :

  12:12:12 32:00:01 1950.0 or   12 12 12 32 00 01 1950.0

Spaces or colons are used to separate the fields RA, DEC, and EPOCH. A control-K entered on this line will delete from the cursor to the end of the line, and the delete key will delete the character prior to the cursor. The epoch field is optional, but Ra and Dec MUST BOTH be entered!

This window also allows the management of catalogs. When typing into the white line, three catalog commands are recognized:


Please note that a catalog MUST be loaded before you can retrieve objects. After manually entering coordinates, or selecting an entry from a catalog, click on the "OK" button to transmit coordinates to PC-TCS . In a few seconds, the "Slew Enabled" message will appear on the PC. at this point you can click on the "Slew Enabled" button, and the telescope will slew to the coordinates. See the catalog section below for specification of catalog layout, location, names, etc...

Under this area is a window which displays the loaded catalog, and you may select an object from this window by right clicking on that line.

 If you select Load Catalogs, this window pops up, and  will allow selection of catalog directory, and your choice  of catalogs to load from that directory.


All catalog files must have the extension .mct, e.g. mytargets.mct.
All catalogs must be stored in the directory /Realtime/lib/catalogs.


Object catalogs have the following format:
!P.I.: Furesz
!Program: 140 Pulsators
AUPeg        21:24:00.2 +18:16:43. 2000.0  0.00 -1.3
V411Lac      22:28:58.3 +50:57:47. 2000.0 -0.02 -0.3

The first two lines specify the P.I. and Program for the catalog. If these lines are in the file, the information therein will be placed in the headers of all objects selected from this catalog. Subsequent lines have 4 fields (6 if proper motion is needed). The first field is the object name, the second field is RA, the third field is DEC, and the fourth is the epoch. Two additional, optional fields are for proper motion (PM) in RA and DEC in that order. The DEC PM is in arcsec/century and RA PM in (sec of time)/century. To convert the change in RA to arcsec per century, multiply by 15*cos(DEC). After the 4 or 6 fields, never pad with spaces.

Object names must have fewer than 20 characters (fewer is better) and cannot contain blanks, as the program uses blanks as delimiters. Valid object names comprise letters, numbers and characters from the set "+-_." ONLY. Object names must not contain blanks, as the parser uses blanks as delimiters.

Observers are able to write in the catalog directory; please avoid clobbering existing catalogs! All catalogs must be in /Realtime/lib/catalogs. If you change a catalog, please make sure that it is group writable when you are done, i.e. "chmod g+w mymunged.mct".


As of 5/2010, all catalogs are checked for consistency prior to being loaded into TCS. There are several categories of errors trapped. If the catalog fails any of the tests, it WILL NOT LOAD, and an error window will pop up for a short time. A description of the error and the line number of the first error found is printed to the error output window.

The catalogs are tested using the standalone program testcats. If a catalog fails to load, use testcats to test and then correct the catalog. For example:
testcats /Realtime/lib/catalogs/brightstars.mct
A common error is using a file created on a Windows machine, which will contain DOS-style new-line carriage-return combos at the end of lines. In this case testcats will complain about a special character 13. A program to easily fix this error is convert_dos, which may be run like this:
convert_dos /Realtime/lib/catalogs/brightstars.mct

When you click on the Rates Menu button, this window appears :

Misc Menu

When you click on the Misc Menu button, this window appears :

Selecting HA MOVES is no longer available.

GuideTrim is the time span between guide moves, in milliseconds.
Entering a value and clicking Change Thresh sends that value to the guider as the threshold.
Not for casual use.

Tele Tasks

When you click on the Tele Tasks button, this window appears :
Clicking on Set TelePos will produce this window:
It will show the last coordinates that you used for a slew. After centering your target with the guider, hit OK, and it will set your coordinates to where you centered the target.

Clicking Cosdec, Track, and Dome widgets will toggle that value. Track and Dome need to be on for Dome to follow telescope. Cosdec should stay on.

Stow Dome will turn off Dome, and send the dome to its stow position.

Selecting Dome to Az will produce this window where you can enter a dome azimuth. The dome will move to that azimuth when you click OK.

Selecting Stow Tele will turn off telescope tracking and stow it. Note that this command DOES NOT stop dome tracking. The rationale is that to rotate FAST, one needs to either stow the telescope or have it near zenith, but the dome need not be stowed or stopped. To return to the object after rotating, turn tracking back on and then click "Slew Enable," assuming you have not entered new coordinates with "New Coords" or with tele coords. At the end of the night, you should stow both telescope (Stow Tele) and dome (Stow Dome) or just use Stow All.


The autoguider is a Linux-based system. Note that the autoguider works best when the TV background is low. Thus, if the sky background is high (e.g., when observing near the moon), turn the TV gain down to minimize this background.

The TV image is grabbed via a frame grabber in the guide PC. The pixel size is about 0.33 arcsec along both the EW and NS directions. The format of 640x480 pixels gives a full field of about 211x158 arcsec (EW x NS).

Begin Guide and Stop Guide

These buttons allow you to start and stop guiding. Clicking start guide will produce a frame from the guide computer in a window on flwo60. Left click on a star in this window to start guiding on this star. If the frame seems empty or if you change your mind, hit Stop Guide, and then Begin Guide until you see the star.


Following the Focus Move widget is a label that displays GUIDER - OFF or GUIDE - ON depending on the guiding state.


When you click on the Focus Move button, this window appears :
The focusing mechanism uses a stepper motor controlled from flwo60 (Linux PC) via the TCS window to change spectrograph focus. The size of the movement can be changed with the Focus Set button. The default movements are steps of 20. The current spectrograph focus position is displayed in the main TCS info window.


There follows two chart widgets that display the RA and DEC combined signal profiles when guiding. If these have a flat top, drop the guide camera gain!


Following the Profiles is a gray widget that displays the current rotator position in a label at the top, and an input box in black. If you type the deisred rotator angle in this input box and hit return, the rotator will move to that position. Moves are limited to positions between -70 degrees and 110 degrees, and no move can be longer than 70 degrees at once. CHECK THE CABLES PRIOR TO ROTATING !


The rest of the main window contains the info window, which shows the current values of telscope position, time, focus setting, airmass, ADC PA, sidereal time, etc. This window updates about once a second :