Deep advanced camera for surveys imaging in the globular cluster NGC 6397: reduction methods

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Hansen, Brad M. S.

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Deep advanced camera for surveys imaging in the globular cluster NGC 6397: reduction methods

Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/47563

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Title: Deep advanced camera for surveys imaging in the globular cluster NGC 6397: reduction methods
Author(s): Anderson, Jay; King, Ivan R.; Richer, Harvey B.; Fahlman, Gregory G.; Hansen, Brad M. S.; Hurley, Jarrod; Kalirai, Jasonjot S.; Rich, R. Michael; Stetson, Peter B.
Abstract: We describe here the reduction methods that we developed to study the faintest red dwarfs and white dwarfs in an outer field of NGC 6397, which was observed by HST for 126 orbits in 2005. The particular challenge of this data set is that the faintest stars are not readily visible in individual exposures, so special care must be taken to combine the information in all the exposures in order to identify and measure them. Unfortunately, it is hard to find the faintest stars without also finding a large number of faint galaxies, so we developed specialized tools to distinguish between the point-like stars and the barely resolved galaxies. We found that artificial-star tests, while obviously necessary for completeness determination, can also play an important role in helping us optimize our finding and measuring algorithms. Although this paper focuses on this data set specifically, many of the techniques are new and might find application in other work, particularly when a large number of images are available for a single field.
Publication type: Journal article
Research centre: Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Astrophysics and Supercomputing
Source: Astronomical Journal, Vol. 135, no. 6 (Jun 2008), pp. 2114-2128
Publication year: 2008
FOR Code(s): 0201 Astronomical and Space Sciences; 020103 Cosmology and Extragalactic Astronomy
Keyword(s): Astrometry; Globular clusters; Image processing; Low-mass, brown dwarfs; NGC 6397; Photometric techniques; Stars; White dwarfs
Publisher: University of Chicago Press
ISSN: 0004-6256
Publisher URL: http://dx.doi.org/10.1088/0004-6256/135/6/2114
Peer reviewed