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 <Enter>. 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.

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