THE 182 CM TELESCOPE

AFOSC: Observing modes -IMAGING
Imaging with AFOSC is obtained by putting an open hole both in the slit and grism wheels and selecting the desired filter in the filter wheel. Refer to on-line documentation for AFOSC setup operations. Due to its optical configuration AFOSC permits a large field of view (8.1 arcmin) with the drawback of sky concentration being typical of focal reducers.

Up to seven filters can be mounted on AFOSC. Filters currently available are:

 

Band
Mean wavelength
width peak transmission
  (nm)  (nm)  
U 365.9 34.5 0.53
B 420.0 72.8 0.71
V 547.44 89.9 0.94
R 647.6 157.0 0.86
I 871.0 236.3 0.97

 
Johnson U, B, V, R, I transmission curves
I Gunn transmission curve
Flat field

Currently exposure times for dome flat fields only are available. Two lamps (0.3 and 1.0 kW) can be selected which illuminate the white screen in the dome. The telescope must be positioned at zero degree declination, zero hours HA and azimuth dome position at 311 degrees. In this condition, using R and i filters, saturation is achieved in 1 sec exposure time even for the 0.3 kW lamp. 
It is possible to position the lamps to the opposite part of the screen to obtain a diffuse, lower level, illumination. There are no significant differences between sky and dome flats  (less than 2% peak to peak in the V band).

 

filter lamp (kW) exp time (s) counts remarks
U 1.0 20   dome screen
B 1.0 1   dome screen
V 0.3 1   dome screen
R 0.3     lamp opposite to the screen
I 0.3     lamp opposite to the screen

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IMAGING | SPECTROSCOPY | POLARIMETRY | SPECTROPOLARIMETRY