Characterisation of Sloan Digital Sky Survey Stellar Photometry

TL;DR

This study thoroughly characterizes the photometric properties of SDSS stellar data, confirming calibration accuracy, analyzing stellar classifications, and establishing reliable temperature estimations from colour indices.

Contribution

It provides a detailed analysis of SDSS stellar photometry, validating calibration, characterizing stellar colours, and linking colour indices to stellar parameters.

Findings

Photometric calibration is tightly aligned with SDSS standards.

Broad band fluxes from spectrophotometry agree within 0.04 mag.

The g-r - inverse temperature relation is a reliable temperature estimator.

Abstract

We study the photometric properties of stars in the data archive of the Sloan Digital Sky Survey (SDSS), the prime aim being to understand the photometric calibration over the entire data set. It is confirmed that the photometric calibration for point sources has been made overall tightly against the SDSS standard stars. We have also confirmed that photometric synthesis of the SDSS spectrophotometric data gives broad band fluxes that agree with broad band photometry with errors no more than 0.04 mag and little tilt along the wide range of colours, verifying that the response functions of the SDSS 2.5 m telescope system are well characterised. We locate stars in the SDSS photometric system, so that stars can roughly be classified into spectral classes from the colour information. We show how metallicity and surface gravity affect colours, and that stars contained in the SDSS general catalogue, plotted in colour space, show the distribution that matches well with what is anticipated from the variations of metallicity and surface gravity. The colour-colour plots are perfectly consistent among the three samples, stars in the SDSS general catalogue, SDSS standard stars and spectrophotometric stars of Gunn & Stryker, especially when some considerations are taken into account of the differences (primarily metallicity) of the samples. We show that the g-r - inverse temperature relation is tight and can be used as a good estimator of the effective temperature of stars over a fairly wide range of effective temperatures. We also confirm that the colours of G2V stars in the SDSS photometric system match well with the Sun.