Improved Photometric Calibrations for Red Stars Observed with the SDSS Photometric Telescope

TL;DR

This paper develops new photometric transformation equations for red stars observed with SDSS, enabling accurate calibration between the Photometric Telescope and the main SDSS telescope for low-mass stars.

Contribution

It introduces extended calibration relations for red stars, specifically low-mass stars with certain color ranges, improving photometric consistency between two SDSS instruments.

Findings

Extended calibration relations to include low-mass stars.

Achieved accurate transformations for stars with 0.6 ≤ r-i ≤ 1.7.

Facilitated better photometry for bright, low-mass stars in SDSS data.

Abstract

We present a new set of photometric transformations for red stars observed with the Sloan Digital Sky Survey (SDSS) 0.5-m Photometric Telescope (PT) and the SDSS 2.5-m telescope at the Apache Point Observatory in New Mexico. Nightly PT observations of US Naval Observatory standards are used to determine extinction corrections and calibration terms for SDSS 2.5-m photometry. Systematic differences between the PT and native SDSS 2.5-m {\it ugriz} photometry require conversions between the two systems which have previously been undefined for the reddest stars. By matching $\sim 43,000$ stars observed with both the PT and SDSS 2.5-m, we extend the present relations to include low-mass stars with colors $0.6 \le r-i \le 1.7$. These corrections will allow us to place photometry of bright, low-mass trigonometric parallax stars previously observed with the PT on the 2.5-m system. We present new transformation equations and discuss applications of these data to future low-mass star studies using the SDSS.