Share Email Print
cover

Proceedings Paper

More flexibility in representing geometric distortion in astronomical images
Author(s): David L. Shupe; Russ R. Laher; Lisa Storrie-Lombardi; Jason Surace; Carl Grillmair; David Levitan; Branimir Sesar
Format Member Price Non-Member Price
PDF $14.40 $18.00

Paper Abstract

A number of popular software tools in the public domain are used by astronomers, professional and amateur alike, but some of the tools that have similar purposes cannot be easily interchanged, owing to the lack of a common standard. For the case of image distortion, SCAMP and SExtractor, available from Astromatic.net, perform astrometric calibration and source-object extraction on image data, and image-data geometric distortion is computed in celestial coordinates with polynomial coefficients stored in the FITS header with the PV i_j keywords. Another widely-used astrometric-calibration service, Astrometry.net, solves for distortion in pixel coordinates using the SIP convention that was introduced by the Spitzer Science Center. Up until now, due to the complexity of these distortion representations, it was very difficult to use the output of one of these packages as input to the other. New Python software, along with faster-computing C-language translations, have been developed at the Infrared Processing and Analysis Center (IPAC) to convert FITS-image headers from PV to SIP and vice versa. It is now possible to straightforwardly use Astrometry.net for astrometric calibration and then SExtractor for source-object extraction. The new software also enables astrometric calibration by SCAMP followed by image visualization with tools that support SIP distortion, but not PV . The software has been incorporated into the image-processing pipelines of the Palomar Transient Factory (PTF), which generate FITS images with headers containing both distortion representations. The software permits the conversion of archived images, such as from the Spitzer Heritage Archive and NASA/IPAC Infrared Science Archive, from SIP to PV or vice versa. This new capability renders unnecessary any new representation, such as the proposed TPV distortion convention.

Paper Details

Date Published: 24 September 2012
PDF: 13 pages
Proc. SPIE 8451, Software and Cyberinfrastructure for Astronomy II, 84511M (24 September 2012); doi: 10.1117/12.925460
Show Author Affiliations
David L. Shupe, NASA Herschel Science Ctr., California Institute of Technology (United States)
Russ R. Laher, Spitzer Science Ctr., California Institute of Technology (United States)
Lisa Storrie-Lombardi, Spitzer Science Ctr., California Institute of Technology (United States)
Jason Surace, Spitzer Science Ctr., California Institute of Technology (United States)
Carl Grillmair, Spitzer Science Ctr., California Institute of Technology (United States)
David Levitan, California Institute of Technology (United States)
Branimir Sesar, California Institute of Technology (United States)


Published in SPIE Proceedings Vol. 8451:
Software and Cyberinfrastructure for Astronomy II
Nicole M. Radziwill; Gianluca Chiozzi, Editor(s)

© SPIE. Terms of Use
Back to Top