New guider for 1.5-m echelle ---------------------------- A.Tokovinin October 3, 2008 On October 2, 2008, the guiding camera in the Front-End Module of the 1.5-m fiber echelle spectrometer has been replaced. Instead of the old (analogue) CCD camera, a new digital camera (GC650 from Prosilica) is installed. The camera is powered in the same way, from the main electronics box, and is turned on/off when the box is powered. The signal is transmitted via Ethernet cable to the dedicated PC computer installed in the rack in the computer room of 1.5m. Camera parameters: model GC650, 659x493 pixels. Pixel size 7.4 micron (0.38 arcsec on the sky), field of view 3 arcmin. diameter. The signal depth is 14 bits (4096 counts). Minimum exposure time 0.000001s (10 microseconds). Computer parameters: Linux PC, rack-mounted. IP: 139.229.12.62, name ctioxb, user name bme2. The standard PCguider program runs on this computer. Some additional information on the guide system can be found in http://www.ctio.noao.edu/~atokovin/echelle/guider.pdf User instructions ----------------- 1. After powering on the system (hence the camera), enter the guiding program by VNC connection from suitable terminal: > vncviewer 139.229.12.62:1 2. In the VNC screen, open the PCguider from a menu activated by the left mouse button. 3. In order to see better star images, use automatic intensity scaling (this is a new program feature added yesterday). To do so, use menu in PCguider: Options --> Parameters --> olut = "off" (the default is "sigma"). 4. The position of the guide box corresponding to the fiber hole is fixed: X=289, Y=255. You may want to shift the box by +-1 pixel to achieve better centering on the hole. The normal box size is 29 pixels. The North-South direction coincides with Y. 5. Adjust camera exposure to avoid saturation (max. counts < 4096). To do this, in PCguider menu: Windows --> Camera control --> set new exposure time, press . The effect is immediate. 6. For better viewing the image, adjust the display using its control panel (display menu: Options --> Control panel). It is helpful to adjust contrast and brightness and to use zoom for larger view of the image in the hole. 7. For focusing the telescope, move the star away from the hole, make sure that the image is not saturated in the camera (max. count < 4096) and in the display (with bad settings of brightness/contrast, the central part of the image looks "flat", with right settings it is peaked). 8. The position of the guider arm must be checked because the GAM control software systematically goes wrong, so the coordinates of the guide arm do not match its actual position. The correct position should be X=-268, Y=+259, Z=-41. Put a bright star away from the hole, defocus the telescope, and verify that the image is ring-like, not cut on one side. If this is not the case, re-initialize the GAM control program and set the GAM probe again where it should be. ---------------------------