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Data reduction

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Flamingos 2

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FLAMINGOS-2 Data Format

All Flamingos-2 images are stored in multi-extension FITS format (MEF), following the Gemini standard data format. The primary header unit (PHU) includes the generic  information, and the actual data are stored in the first extension with a separate extension header.

Note that the number of the ADUs depend on the number or reads. The data always consist of the difference between the counts at the beginning and the end of the observation:

  • CDS (one read) = First Read - Last read
  • MDS (multiple reads) = Sum of the first reads  -  Sum of the last reads. Here, MDS counts ~ Nreads * CDS counts 

Current and historic issues

  • In 2015 , there was a discrepancy between the UTEND keyword and the actual time of exposure completion.  Only UTSTART and EXPTIME provided reliable timeing information. The problem was fixed in December 2015, and all archival data have been corrected.

  • Data taken before April 2015 had a discrepancy between the NREADS (number of initial and final non-destructive read pairs) and LNRS keywords. All archival data have been corrected. In archival data retrieved before April 2015, the reported values depend on the used readmode as follows:
    ▪          LNRS=1, NREADS=1  for Bright Object mode
    ▪      LNRS=2, NREADS=4  for Medium Object mode
    ▪      LNRS=6, NREADS=8  for Faint Object mode
    For these data, the header has to be corrected before using the F2 Gemini IRAF Package; otherwise the data will not be reduced correctly. A script to fix this error is available here, or you just download the data again. 

Data Reduction

The Gemini IRAF package currently supports imaging and long-slit reduction of FLAMINGOS-2 data. It is sufficient for initial assessment of the data, but a full science grade reduction might require a different effort. The IRAF package contains a "f2examples.cl" script for reducing  example imaging and example spectroscopy datasets.

A FLAMINGOS-2 Data Reduction Cookbook provides instructions and PyRAF scripts for reducing both imaging and longslit spectroscopic data using the Gemini IRAF package.  The latest version will always be availalbe from http://gemini-iraf-flamingos-2-cookbook.readthedocs.io.  A pdf version is also availalbe there as well (click on the version tab in the bottom right corner).  Comments, notification of errors, and any other issues are welcomed and should be submitted via the Gemini HelpDesk in the FLAMINGOS-2 category.

The stand-alone THELI reduction pipeline has full built-in support for FLAMINGOS-2 images.

Further advice about reduction of FLAMINGOS-2 data has been posted on the Gemini DR forum.