CAT User's Guide


The Field Acquisition Telescope for the Coude Auxiliary Telescope, FAT-CAT, is a wide field CCD camera mounted at the top of the focusing mechanism for the CAT secondary mirror and is used as a finder for the CAT. In its current configuration it consists of an Opticstar DS-335C CCD camera coupled to a 180 mm f/2.8 Nikkor lens with a plate scale of 3.95 arcsec/pixel and an effective field of view of 135 arcmin x 101 arcmin. The camera is connected to a computer named fatcatpc that resides on a shelf near the MOS via a USB cable. The camera software is run remotely using a VNC environment. To use FAT-CAT follow these instructions: At the start of the night center a star on the slit and start guiding then capture an image making a note of the (row,column) coordinates of the star. Move the cursor to the location of the star on the image and right click the mouse to mark this position. To use FAT-CAT to find your way when you are lost follow these instructions:

Known USB issues: When you first start up the Nebulosity program and select the camera if you are greeted with a popup window saying "Cannot Init Camera" then close the program and go upstairs and unplug the USB cable coming from the camera from the USB extension cable and then reconnect the two cables. Do not unplug the USB cable from the computer!

If you have any other questions or need further instructions please contact Thomas Lowe at