University of Surrey

Test tubes in the lab Research in the ATI Dance Research

Accurate photometry of extended spherically symmetric sources

Anders, P, Gieles, M and Grijs, RD (2006) Accurate photometry of extended spherically symmetric sources A, 451.

Full text not available from this repository.

Abstract

We present a new method to derive reliable photometry of extended spherically symmetric sources from {\it HST} images (WFPC2, ACS/WFC and NICMOS/NIC2 cameras), extending existing studies of point sources and marginally resolved sources. We develop a new approach to accurately determine intrinsic sizes of extended spherically symmetric sources, such as star clusters in galaxies beyond the Local Group (at distances <~ 20 Mpc), and provide a detailed cookbook to perform aperture photometry on such sources, by determining size-dependent aperture corrections (ACs) and taking sky oversubtraction as a function of source size into account. In an extensive Appendix, we provide the parameters of polynomial relations between the FWHM of various input profiles and those obtained by fitting a Gaussian profile (which we have used for reasons of computational robustness, although the exact model profile used is irrelevant), and between the intrinsic and measured FWHM of the cluster and the derived AC. Both relations are given for a number of physically relevant cluster light profiles, intrinsic and observational parameters. AC relations are provided for a wide range of apertures. Depending on the size of the source and the annuli used for the photometry, the absolute magnitude of such extended objects can be underestimated by up to 3 mag, corresponding to an error in mass of a factor of 15. We carefully compare our results to those from the more widely used DeltaMag method, and find an improvement of a factor of 3--40 in both the size determination and the AC.

Item Type: Article
Authors :
NameEmailORCID
Anders, PUNSPECIFIEDUNSPECIFIED
Gieles, Mm.gieles@surrey.ac.ukUNSPECIFIED
Grijs, RDUNSPECIFIEDUNSPECIFIED
Date : 3 February 2006
Identification Number : https://doi.org/10.1051/0004-6361:20054175
Uncontrolled Keywords : astro-ph, astro-ph
Related URLs :
Depositing User : Symplectic Elements
Date Deposited : 17 May 2017 12:40
Last Modified : 17 May 2017 15:05
URI: http://epubs.surrey.ac.uk/id/eprint/836263

Actions (login required)

View Item View Item

Downloads

Downloads per month over past year


Information about this web site

© The University of Surrey, Guildford, Surrey, GU2 7XH, United Kingdom.
+44 (0)1483 300800