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IMACS Calibrations

Note: numbers for spectroscopy below correspond to the previous configuration - they need to be updated


Imaging (updated) 

 

In the table below we provide some reference numbers of imaging flat counts obtained in the various filters and suggested lamp intensities (Ql and Qh refer to the Quartz lamps in the DCU). These frames were obtained with the dome closed at night. 


Note: During daytime the dome is not completely light tight and the exposure times should be kept <10sec in order to minimise fluctuations due to stray light:


Camera f/2 :


Filter Counts (Fast bin1x1) Exposure time (sec)  Voltage (V)
  Bessel - B         28000           6      Ql
  Bessel - V         27000           8      3.0
  Bessel - R         28000           3      2.5
  CTIO - I          30000           5      2.0
  sloan - g         25000           7      3.5
  sloan - r         26000           5      2.5
  sloan - i         27000           5      2.0
  sloan - z          26000           3      2.0

 


Camera f/4 :


Filter Counts (Fast bin1x1) Exposure time (sec)  Voltage (V)
  Bessel - B         28000           3      Qh
  Bessel - V         30000           4      4.0
  Bessel - R         24000           2      3.0
  CTIO - I          25000           2      2.5
  sloan - g         29000           4      Ql 
  sloan - r         30000           4      3.0
  sloan - i         30000           3      2.5
  sloan - z          26000           2      2.5

 
Flats of the sloan-u are not possible with current lamps (120sec with Ql+Qh give ~4500counts with f2 and ~2500counts with f4). For this filter twilight flats should be obtained. 

 

 

Spectroscopy

 

Camera f/2 :

The following exposure times will give between 20000-25000 counts using the Qh lamp in the DCU and the Spectroscopic2 filter 

Grism/Slit 0.7" 0.9" 1.2" 1.5" 2.5"
 150_10.8  5sec  4sec   3sec  2sec  1sec
 200_15.0  7sec  5sec  4sec  3sec  2sec
 300_17.5  15sec 11sec  9sec  7sec  4sec
 300_26.7  11sec  8sec  6sec  5sec  3sec
 
 

 

Camera f/4 (old configuration - to be updated) :

The following exposure times will give between 13000-17000 counts using the Qh + Ql lamps in the DCU 

 
Grating (tilt) /Slit 0.7" 0.9" 1.2" 1.5" 2.5"
 150-3.4 (3.4)   11sec  9sec  7sec  5sec  3sec
 300-4.3 (6.0)   40sec  30sec  20sec  16sec  12sec
 600-6.54(8.0)   sec  sec  sec  sec  sec
 600-8.6 (9.3)  80sec  60sec  50sec  40sec  25sec
 600-13.0 (14.0)  50sec  35sec  25sec  20sec  15sec
 1200-17.5 (19.0)   300sec  250sec  150sec  125sec  90sec
 1200-26.7 (27.32)   100sec  85sec  60sec  50sec  35sec
 1200-26.7 (33.5)  120sec  100sec  70sec  55sec  40sec
 1200-32.0 (32.2)   sec  sec  sec  sec  sec
 
 
 

 

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