BAIT: manual operation

INTRODUCTION

The Berkeley Automated Imaging Telescope (BAIT) is an automated telescope with a CCD camera. Although it is designed to operate unattended, the telescope can be controlled manually. Note: The software is not particularly user friendly and contains many bugs.

STARTING

In order to get a better picture of what is going on we recommend that you open a terminal window and type: show log . This will show the low level commands that are sent to the telescope controller.

To open up the observatory, move the mouse to an open terminal window and type: openup This procedure opens the observatory slit, sets the tracking rate etc. You can see the details in the log window.

You may then send the telescope commands using the tx command. For details see the tserver manual.

MOVING THE TELESCOPE

To point the telescope you must type in a command of the following form:

tx point ra=hh:mm:ss.s dec=dd:mm:ss.s epoch=yyyy

where hh:mm:ss.s is the Right Ascension in Babylonian (hour-minute-second) notation, the declination is in Babylonian degrees, and the epoch of the coordinates is in years. (If it is not specified, the present epoch is used). For example to point the telescope to alpha lyra (Vega) type in:

tx point ra=18:36:39.1 dec=38:46:32 epoch=1991.5

Note: be careful that no spaces are present in the keyword=value parts of the string. Also once the telescope starts to move there is no way to stop it.

To find out what the local sidereal time is you can type: lst . To find out where the telescope is currently pointing type: tx where . You can offset the telescope from its present position by an angular amount using the command: 


tx offset [ra=x.xxx] [dec=y.yyy] [cos]
where xxx.x and yyy.y are in decimal degrees (sorry). The [] mean that the string is optional... do not type in brackets since UNIX will interpret them oddly. The optional keyword `cos' means that the angular motion in Right ascension is to be divided by the cosine of the declination. For example to move the telescope .02 degrees as seen on the chip in Right Ascension type:


tx offset ra=.02 cos

TAKING PICTURES

The filter wheel is positioned by typing: pfilter name where name is either `clear', `U','B', `V', `R', or `I'. If you do not specify a name, the command will print out the present filter position.

To take a picture with an 5 second exposure time type: image time=5 This writes a file `image.fts' in the current directory.

To display the image type the command: tv image

The `image' command writes the default file name `image.fts' which you can rename by typing: 

mv image.fts xxx.fts
where xxx.fts is the new name.

HOMING THE TELESCOPE

The telescope motor controllers only move incrementally, they do not know the absolute location of the telescope. The telescope has Hall effect sensors mounted on it to provide fixed reference points. To get the telescope to move to the index type the following: 
tx point tense
tx point home
tx encoder home
If the telescope is really lost and the Renishaw encoders are mis calibrated, the home procedure will fail. If this occurs it can be re-calibrated by moving the telescope to the North and West limits and resetting the Renishaw encoders. 

tx point home_limit
tx encoder home_limit
tx point home
tx encoder home

USING THE FINDER

There is a small tv camera with a 180 mm lens attached to the side of the telescope. To take a picture with it type the command: fimage Then display it by tv fimage. If you want to center the star on the main ccd.

USING THE GUIDER

There is a small CCD camera that can be used to guide the telescope during long CCD exposures. The camera is mounted on a 2x2 inch translation stage that must be positioned to a nearby guide star to work. I have written a program `setstage' which reads the current telescope coordinates, finds best guide star and positions the guider table. Once the stage is positioned, turn on the small tv to the right of the sun and type:

acquire

This program takes a 10 second guider image and looks for the brightest target and then moves the telescope to center it in the guider field. If nothing is found you must either try offsetting the telescope manually or zeroing in on a nearby star.

If a star is found, then you can turn on the guider by moving the mouse into an unused terminal window and typing: guide <cr> There are other parameters (type guide help) which you may want to adjust. The guider will then take pictures and offset the telescope as needed. To stop the guider, move the mouse into the active terminal window and type Cntrl^C.

ZEROING THE TELESCOPE

The telescope pointing is not as good as it should be, particularly at startup. For this reason you should `zero' the telescope on known bright stars frequently. Run the following procedure which points the telescope to a bright star and automatically centers it. Type:

zero meridian

FOCUSING

To focus the telescope run the procedure:

focus.csh

CLOSING DOWN

To close down the telescope, type the following command:

closedown

Last Updated January 13, 1998