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VISIR Quality Control:
Imaging Standard Star frames

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QUALITY CONTROL
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VISIR QC
Trending & QC1
   std imaging
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QC links:
sensitivity | conv. factor | background
 
QC PLOTS
  CURRENT HISTORY
sensitivity in N band
sensitivity in Q band
conv. factor N
conv. factor Q conv factor Q conv factor Q histo
QC1 database (advanced users): browse | plot
   Click on CURRENT to see the current trending (Health Check).
   Click on HISTORY to see the historical evolution of the trending.


VISIR imaging standard stars are observed during night in order to monitor changes of the MIR observing conditions and to provide photometric flux calibration. The calibration plan requires the imaging standard stars to be taken within 3 hrs (+/- 3 hrs) from the science imaging frames.

img_std_new Imaging Standard Star frame. An example observation of an imaging standard star with the post-upgrade detector. The integrated frame of all half-cycle frames at the first nodding position is shown. Note that the actual field of view is smaller than the detector size.

 

img_std_old Imaging Standard Star frame (pre-upgrade). This is an example pipeline product from an imaging standard star observation. Note persistent horizontal stripes characteristic for the pre-upgrade detector.


top sensitivity

QC1 parameters
parameter QC1 database: table, name procedure
sensitivity visir_zp_img, sensit Sensitivity is the estimated limiting flux expected in an 1 hour on-source integration of a point source detected with S/N of 10. Units: mJy at 10 sigma in 1hr.

Trending

Sensitivity is trended for a number of N band and Q band filters.

History

until May 2012: pre-upgrade sensitivities were trended for both small-field (SF) and intermediate-field (IF) pixel field of view.
April 2015: start of operations after upgrade; new detectors, only SF pixel field of view is offered.

top conversion factor

QC1 parameters

parameter QC1 database: table, name procedure
conversion factor visir_zp_img, conver Conversion between ADU and Jy: F(total oberved) / F(model) [ADU/Jy], where F(total observed) is the measured and F(model) is the predicted flux for the standard star from a catalog.

Trending

The conversion factor is trended for a number of N band and Q band filters.

History

until May 2012: pre-upgrade conversion factor is trended for both small-field (SF) and intermediate-field (IF) pixel field of view.
April 2015: start of operations after upgrade; new detectors, only SF pixel field of view is offered.

top background

QC1 parameters
parameter QC1 database: table, name procedure
background visir_zp_img, backgd_mean The mean background level is measured from the half-cycle frames (in ADU).

Trending

The background level is currently not trended because the half-cycle frames are not saved in the standard observing mode for imaging.

History

until May 2012: pre-upgrade background levels were trended for both small-field (SF) and intermediate-field (IF) pixel field of view.
April 2015: start of operations after upgrade; background level not determined and trended.


 
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