taskGNU Astronomy Utilities - Tasks: task #14116, MakeProfiles option to set...


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task #14116: MakeProfiles option to set non-masked pixels in background image to zero

Submitter:  Mohammad Akhlaghi <makhlaghi>
Submitted:  Thu 11 Aug 2016 09:55:39 PM UTC
Should Start On:  Thu 11 Aug 2016 03:00:00 PM UTC Should be Finished on:  Thu 11 Aug 2016 03:00:00 PM UTC
Category:  MakeProfiles Priority:  5 - Normal
Item Group:  Enhancement Status:  Done
Privacy:  Public Assigned to:  makhlaghi
Percent Complete:  100% Open/Closed:  Closed
Effort:  0.00

Sat 13 Aug 2016 12:56:12 AM UTC, comment #1: 

The input image can now be used as a canvas to build mock profiles, please see the commit message for more details.

Mohammad Akhlaghi <makhlaghi>
Group administrator
Thu 11 Aug 2016 09:55:39 PM UTC, original submission:  

The motivation for this task is related to task #14115 and the aperture photometry process explained there. As explained there, for aperture photometry (when you already have the positions and elliptical properties of objects you want to do photometry on) with Gnuastro, you will need to take the following steps:

  • Run NoiseChisel on the data image (to get an estimate of the Sky and its standard deviation).

  • Use MakeProfiles to generate elliptical/circular apertures with given ID values on the positions you want.

  • Use MakeCatalog on NoiseChisel's output, but replace the object HDU with the image you created with MakeProfiles.

In order to be sure you do the aperture photometry accurately it is very important that all the header information (including the image size, WCS and everything else) of NoiseChisel and MakeCatalog's outputs match exactly. This can be done currently with MakeProfiles, but you have to set them all by hand and make sure you set the image size properties correctly. Making sure of all these issues can be very bothering.

So with this task, we will add an option to MakeProfiles which essentially sets all the non-NaN (or non-masked) pixels of the background image (the optional FITS argument to MakeProfiles) to zero. In this way the default addition process will finally result in the object IDs. This feature can be used for other cases too. For example building mock profiles over the same region of sky as a real image.

Mohammad Akhlaghi <makhlaghi>
Group administrator


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