SHERA: SHEar Reconvolution Analysis

This webpage is the official site for the SHERA (SHEar Reconvolution Analysis) software package, which can be used to generate realistic, optionally sheared galaxy images as they would appear from a ground-based telescope, using HST (ACS COSMOS) galaxy images to represent realistic galaxies, and user-supplied PSFs for the ground-based data to be simulated. The COSMOS galaxy data is available at IRSA, here.

References and basic release information

The paper describing the code is available on arXiv and has been submitted for publication in MNRAS. The software developer, Rachel Mandelbaum, can be found here. While this code is distributed freely, we ask that any scientific work making use of the software cite the paper.

Optionally, those who wish to receive e-mail notifications of updated releases of the SHERA software or associated data should e-mail Rachel to be included on the mailing list.


To download the associated galaxy postage stamp images, please go to the page at IRSA. The files on this website only include the code, manual, and catalogs:

File name (click to download) Associated SHERA version Content description
shera_v1.tar.gz v1 SHERA v1 release: the code (; a wrapper script demonstrating its use (; an image of a blank ACS field needed for the image processing; several example images that can be used with the wrapper script; and the manual (shera_manual_v1.pdf)
shera_manual_v1.pdf v1 SHERA manual
cosmos_acs_shera_may2011.fits.gz all FITS catalog of COSMOS galaxies that form the parent sample from which galaxy postage stamps were generated.
cosmos_acs_shera_may2011.README all File description for the catalog above.
postage_stamp_info_shera.fits.gz all FITS catalog containing other useful information about the COSMOS galaxies with postage stamps, including failure flags and weighting factors, plus information about the galaxy detection in SDSS data.
postage_stamp_info_shera.README all File description for the catalog above.

Fits catalogs can be read in IDL as:
IDL> cat=mrdfits('cosmos_acs_shera_may2011.fits.gz',1)

The contents of the catalog can be seen via:
IDL> help,cat,/str


The SHERA code uses several functions that are part of the standard astronomy libraries for IDL: mrdfits, getrot, hrot, rot, sxaddpar, sxpar, array_indices, polywarp, hcongrid, congrid, mwrfits, sxaddhist, sshift2d.

What's next?

There are several features that should be included in upcoming releases, including

Anyone who updates the code to provide additional functionality that they think others would find useful is encouraged to contact me to discuss including it in the release of the subsequent version. Suggestions for updates that need to be done collaboratively (i.e., you think of something generally useful, but are not sure how to implement it, and would like to collaborate) are also welcome. However, my recent work on image simulation development has been done in the context of the GalSim software package, which is also public, and which includes a lot more functionality besides what is in Shera. As a bonus, it is not in IDL. Users who want to do what is in Shera but wish for additional functionality or updates are encouraged to check out GalSim.