https://pfspipe.ipmu.jp/jira This file is an XML representation of an issue en-us 8.3.4 803005 13-09-2019 https://pfspipe.ipmu.jp/jira/browse/PIPE2D-389 DRP 2-D Pipeline <p>The coarse 10x10 covariance matrix, COVAR2, of the 1-D spectrum output from the 2D DRP is defined in <a href="https://github.com/Subaru-PFS/datamodel/blob/master/datamodel.txt" class="external-link" rel="nofollow">https://github.com/Subaru-PFS/datamodel/blob/master/datamodel.txt</a> and is used to model the spectrophotometric errors. </p> <p>As part of the flux calibration activities, generate COVAR2 and populate the corresponding pfsObject HDU with that information.</p> PIPE2D-389

Populate COVAR2 coarse covariance matrix

Story Normal Open Unresolved Masayuki Tanaka hassan flux-calibration Fri, 8 Mar 2019 17:23:02 +0000 Mon, 3 Jul 2023 00:43:47 +0000 0 5 <p>Could you please elaborate on this?  Covariance from what process/procedure?</p> <p>The datamodel specifies a non-sparse covariance matrix COVAR2 which is supposed to capture the large-scale behaviour of the spectrophotometry (there's also a banded covariance matrix COVAR that captures the pixel-to-pixel errors and covariances).   If we had an optical spectrograph covering grizy, then I'd think of this as a 5x5 matrix with components that roughly correspond to the e.g. <tt>&lt;(g - &lt;g)&gt;)(z - &lt;z&gt;)&gt;</tt> – i.e. the large scale errors in the spectrophotometry. These could come from the uncertainty in the spectrophotometric standards, from the corrections due to guiding/fibre centring errors, the mismatch between the extended object and resolve object PSFs (and thus extraction errors), and other things that I don't yet understand! </p> <p>I don't have a concrete proposal for how to measure these, e.g. what is the rôle of the fibre magnitudes, but the flux calibration work seems to be the place to put this.</p> <p> The COVAR2 matrix is currently 10x10 because we have c. 5 optical photometric bands and sometimes some NIR information (J) and a factor of c. 2 oversampling seemed wise.</p> Duplicate PIPE2D-74 Development Epic Link PIPE2D-303 Rank 0|02qpt6:508yl0chzzy1 Story Points 8.0