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GSoC 2014 Application Brigitta Sipocz:Work on the photometry package

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Brigitta Sipocz edited this page Mar 20, 2014 · 10 revisions

Project proposal aims:

  • I propose to work on the photutils package, which is used to measure the brightness of stars. The backbone of my proposal is the implementation of astropy.wcs, astropy.coordinates, and astropy.table integration in photutils. Currently photometry is carried out using a (x,y) - image pixel-based - coordinate pairs. My implementation would allow the package to work with non-pixel based coordinates, Angle objects (part of astropy.coordinates), and to use the wcs information of the images in order to make the necessary transformations to pixel space. This is clearly a very much needed feature, as it is very common to use external catalogue coordinates or a (single) master image source catalogue to perform photometry.

Programing experience:

  • I use python as my primary working environment in the last 2-3 years (numpy, pyfits, matplotlib, pp). Before that I mainly used bash/awk and gnuplot scripting for my work. I'm familiar with version tracking systems (though new to git).
  • This would be my first contribution to a real open source project. In the past I contributed to smaller scale projects, like our group's data processing and analysing pipeline (that mainly is in python, but uses instrument optimized C/fortran code wraps) and occasional bug reports to purpose build astro codes with a singe developer.
  • I casually started using Astropy a few month ago.

Photometry experience:

  • As an astronomer I am very experienced with photometry and photometric data reduction. I mainly work with optical and NIR data (mainly imaging) and photometric data products.

Timeline with proposed project plan:

First part: Implementing coordinate/WCS (non-pixel) based, list driven photometry

Community bonding period and Week 1

  • Familiarizing with the current aperture and PSF photometry features of photutils.

Week 2

  • Begin to implement astropy.wcs and astropy.coordinates integration into aperture photometry

Week 3

  • Work on aperture photometry documentation, and work on wcs integration

Week 4

  • Begin to implement wcs integration into psf photometry

Week 5

  • Work on psf photometry documentation, and work on wcs integration

Week 6

  • Debugging and testing the wcs integration

Mid-term

Second part: Improvements on photutils input and output: implementing astropy.table and astropy.nddata integration

Week 7

  • Implementing astropy.table integration in photutils, enabling to write results in different table formats.

Week 8

  • Implement photometry wrapper that inputs tables (e.g. an astrometry table), does photometry using specified columns from input, and returns the photometry result in an updated table containing the input information from the input (e.g. source classification, any quality flags, metadata from original image headers). Having such an output will be very handy for e.g. light curve generation.

Week 9 & Week 10

  • Integration of NDData objects (astropy.nddata) in photutils.

Week 11

  • Implementing custom statistics for aperture photometry.

Week 12

  • Debugging and final documentation

Optional if time allows:

  • Work on other, smaller scale unfinished tasks from the API wishlist.

After GSoC

  • Keep being involved in astropy development

Patch samples

PRs to astropy:

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