WHITE GUIDER DESCRIPTION

A picture of the White GuiderClick to zoom in on either image. Another picture of the White Guider

Description: (#24)
There is one guider head available for imaging CCDs, the "WHT" guider. It can use the TK4 CCDs. The guider accepts the usual optical-band filters. The imaging system can also be used in a "high-speed" mode, meaning integration times as short as 20 seconds. The high-speed imager can be operated in a remote guiding mode.
Contact person: (#24)
Scientist: Mr. David Doss, 915/426-3263, doss@astro.as.utexas.edu
Available telescope positions: (#24)
2.7-m (f/17.7, f/8.8)
2.1-m (f/13.7)
0.9-m (f/13.5)
Available CCD's: (#24)
TK4
Filter Wheels: (#07)
The standard filter wheel holds 8 each, one inch square filters up to several millimeters thick. There are two optional wheels available. These identical wheels have two 2" square filter positions and two 1" square filter positions.
Filters: (#07)
The standard White Guider filter set is mounted in the standard filter wheel. This set consists of:
  1. B: CUSO4(#3) + BG12(1mm) + GG385(2mm)
  2. V: BG18(2mm) + GG495(3mm)
  3. R: OG550(2mm) + KG3(2mm)
  4. I: BG3(1mm) + RG610(2mm)
  5. BVR: GG2425(1mm)
  6. (blank)
  7. (blank)
  8. (Pinhole)
Filter Wheel Repeatability: (#17)
The Filter Wheel's stepper motor driver can start up in a different phase each time it is powered up. (End of night, power glitches, etc). To insure that the stepper is in the same phase every time YOU start up, the following must be done:

 

 
 
 

Turn off the stepper driver power (labelled "Stepper Motors") on the on the right side of the instrument. Manually turn the knob on the Filter Wheel stepper motor to position #1. The wheel is detented by a spring forced lever. You will feel a definate detent 'stop'. While carefully observing the knob on the stepper motor, turn on the power switch. On rare occasion, the knob will rotate slightly. This indicates that the driver came up out of phase. Turn the stepper off and back on again until the knob does not rotate. This is the correct phase and should be repeated for every power-on situation. The stepper motor driver is then completely repeatable so long as AC power does not fail.

The filters are held in place by internal snap rings. The rings will allow some movement of the filter. A piece of tape accurately positioned can replace the snap ring and hold the filter firmly in place, or a shim of paper or tape can push the filter firmly against the holder and minimize any movement.

By the way: Make sure the hex bolt that locks the filter wheel in to the drive is tight.