Aperture Photometry Tool Versus SExtractor for Noncrowded Fields

ABSTRACT Outputs from new software program Aperture Photometry Tool (APT) are compared with similar outputs from SExtractor for sources extracted from R-band optical images acquired by the Palomar Transient Factory (PTF), infrared mosaics constructed from Spitzer Space Telescope images, and a proces...

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Published in:	Publications of the Astronomical Society of the Pacific Vol. 124; no. 917; pp. 764 - 781
Main Authors:	Laher, Russ R., Rebull, Luisa M., Gorjian, Varoujan, Masci, Frank J., Fowler, John W., Grillmair, Carl, Surace, Jason, Mattingly, Sean, Jackson, Ed, Hacopeans, Eugean, Hamam, Nouhad, Groom, Steve, Teplitz, Harry, Mi, Wei, Helou, George, van Eyken, Julian C., Law, Nicholas M., Dekany, Richard G., Rahmer, Gustavo, Hale, David, Smith, Roger, Quimby, Robert M., Ofek, Eran O., Kasliwal, Mansi M., Zolkower, Jeff, Velur, Viswa, Walters, Richard, Henning, John, Bui, Khahn, McKenna, Dan, Kulkarni, Shrinivas R.
Format:	Journal Article
Language:	English
Published:	Chicago, IL University of Chicago Press 01-07-2012
Subjects:	Astronomy Earth, ocean, space Exact sciences and technology Statistical analysis Telescopes Photometry
Online Access:	Get full text
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Summary:	ABSTRACT Outputs from new software program Aperture Photometry Tool (APT) are compared with similar outputs from SExtractor for sources extracted from R-band optical images acquired by the Palomar Transient Factory (PTF), infrared mosaics constructed from Spitzer Space Telescope images, and a processed visible/near-infrared image from the Hubble Legacy Archive (HLA). Two large samples from the PTF images are studied, each containing around 3 × 103 sources from noncrowded fields. The median values of source-intensity relative percentage differences between the two software programs, computed separately for two PTF samples, are +0.13% and +0.17%, with corresponding statistical dispersions of 1.43% and 1.84%, respectively. For the Spitzer mosaics, a similar large sample of extracted sources for each of channels 1-4 of Spitzer's Infrared Array Camera (IRAC) are analyzed with two different sky annulus sizes, and we find that the median and modal values of source-intensity relative percentage differences between the two software programs are between -0.5% and +2.0%, and the corresponding statistical dispersions range from 1.4 to 6.7%, depending on the Spitzer IRAC channel and sky annulus. The results for the HLA image are mixed, as might be expected for a moderately crowded field. The comparisons for the three different kinds of images show that there is generally excellent agreement between APT and SExtractor. Differences in source-intensity uncertainty estimates for the PTF images amount to less than 3% for the PTF sources, and these are potentially caused by SExtractor's omission of the sky background uncertainty term in the formula for source-intensity uncertainty, as well as differing methods of sky background estimation.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23
ISSN:	0004-6280 1538-3873
DOI:	10.1086/666507