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Published October 2008 | Published
Journal Article Open

Calibrated griz magnitudes of Tycho stars: All-sky photometric calibration using bright stars

Abstract

Photometric calibration to ~5% level is frequently needed at arbitrary celestial location. However, existing all-sky astronomical catalogs do not reach this accuracy, and time consuming photometric calibration procedures are required. I fitted the Hipparcos B-T and V-T magnitudes, along with the 2MASS J, H, and K magnitudes of Tycho-2-catalog stars with stellar spectral templates. From the best-fit spectral template derived for each star, I calculated its synthetic SDSS griz magnitudes and constructed an all-sky catalog of griz magnitudes of bright stars (V ≾ 12). Testing this method on SDSS photometric-telescope observations, I find that the photometric accuracy, for a single star, is usually about 0.12, 0.12, 0.10, and 0.08 mag (1 σ), for the g, r, i, and z-bands, respectively. However, by using ~10 such stars, the typical errors per calibrated field (systematic + statistical) can be reduced to about 0.04, 0.03, 0.02, and 0.02 mag, in the g, r, i, and z-bands, respectively. Therefore, in cases for which several calibration stars can be observed in the field of view of an instrument, accurate photometric calibration is possible.

Additional Information

© 2008 Astronomical Society of the Pacific. Received 2008 June 06; accepted 2008 August 13; published 2008 October 2. I would like to thank the referee for constructive comments. I thank Shri Kulkarni for expressing the need for an all-sky catalog of standard stars, and to Avishay Gal-Yam, Dovi Poznanski, Orly Gnat, and Andrew Pickles for valuable discussions. This work is supported in part by grants from NSF and NASA.

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Additional details

Created:
August 22, 2023
Modified:
October 18, 2023