Calibrating the acm

The Acquisition Camera on the HET is used to image the sky for the purpose of pointing the telescope so that various instruments are positioned for observing a position on the sky.

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The bias level must be measured

A script to take acm bias frames: acm_bias_run

Take a set of 5 ACM bias images:

• In the run below we use a script to take 5 acm bias images and this will take about 75 seconds to complete. The script needs to know the UT date for which the data are being collected. This is the date string gnerated by the 'cwd' script on mcs (as astronomer). Enter the UT date string when you are queried by the script at run time.

  [astronomer@mcs ~]$ cd ~astronomer/acm_bias
  [astronomer@mcs ~]$ acm_bias_run 5 
  1375.5416 0.0451 29.3489 25 20190220T182024.6_acm_sci
  1375.5341 0.0450 29.3068 25 20190220T182039.6_acm_sci
  1375.5309 0.0450 29.3163 25 20190220T182048.8_acm_sci
  1375.6678 0.0451 29.3683 25 20190220T182058.0_acm_sci
  1375.6355 0.0454 29.5571 25 20190220T182107.2_acm_sci
  Number in first subset file = 5
  

• Some other output is generated, but is not very important for the user. In the case above we see some simple statistics generated for each acm bias image. The first number is the mean bias level in the raw frames. This is usually in the range 1374 < Mean_BIAS < 1386 (adu units). If the values depart from this range by (for instance) tens of adu, then it s likely that some camera (like PV) has been left on and is creating scattered light in the pfip.