Piff 0.2.4

PSFs in the Full FOV

Piff is a Python software package for modeling the point-spread function (PSF) across multiple detectors in the full field of view (FOV).

Features: (Some are aspirational. We’re still working on the code!)

• Has multiple basis sets for the underlying PSF model, including pixel-based, shapelets, Gaussian mixture, maybe also Moffat and/or Kolmogorov.

• Can build the models in either chip or sky coordinates, properly accounting for the WCS of the image.

• Can interpolate across the full field-of-view, or across each chip separately, or a combination of both.

• Can do the fitting in either real or Fourier space.

• Has multiple interpolation functions including polynomials, gaussian processes, and others.

• Can take knowledge of the optical aberrations as input to convolve the model of the atmospheric PSF.

• Performs outlier rejection to detect and remove stars that are not good exemplars of the PSF. Outputs the list of stars that were actually used to build the final model.

• Allows the centroid to be fixed or floating.

• In general, allow any value to be fixed rather than fit for.

• Uses highly readable YAML configuration files to set the various options.

• Includes Python code to read in the PSF files and use it to draw an image of the PSF at an arbitrary location.

• Currently, the lead developers are: - Mike Jarvis (mikejarvis17 at gmail) - Josh Meyers (jmeyers314 at gmail) - Pierre-Francois Leget (leget at stanford) - Chris Davis (chris.pa.davis at gmail) If you’d like to join the development effort, or if you have any other questions or comments about the code, feel free to contact us at the above email addresses.

Installation

The current stable version, v0.2.4, is installable with pip:

pip install Piff

If you need the bleeding edge version on master, you can download or clone the repo and install with:

python setup.py install

Depending on your setup, you might prefer/need one of these variants:

sudo python setup.py install
python setup.py install --user
python setup.py install --prefix=PREFIX

Running Tests

After installing Piff, you can run the unit tests by doing:

cd tests
nosetests

Reporting bugs

If you have any trouble installing or using the code, or if you find a bug, please report it at:

https://github.com/rmjarvis/Piff/issues

Click “New Issue”, which will open up a form for you to fill in with the details of the problem you are having.

Requesting features

If you would like to request a new feature, do the same thing. Open a new issue and fill in the details of the feature you would like added to Piff. Or if there is already an issue for your desired feature, please add to the discussion, describing your use case. The more people who say they want a feature, the more likely we are to get around to it sooner than later.