143 GHz brightness measurements of Uranus, Neptune, and other secondary calibrators with Bolocam between 2003 and 2010

TL;DR

This study analyzes 143 GHz brightness measurements of Uranus, Neptune, and other calibrators from 2003-2010, finding consistent brightness ratios and providing absolute flux density values, aiding calibration accuracy.

Contribution

It provides a comprehensive analysis of planetary brightness ratios at 143 GHz over decades, establishing their stability and refining flux calibration standards.

Findings

Brightness ratio of Uranus to Neptune is 1.027 ± 0.006 with no variability.

No evidence of time variability in brightness ratios over 1983-2010.

Absolute 143 GHz flux densities for calibrators are determined with ~3% accuracy.

Abstract

Bolocam began collecting science data in 2003 as the long-wavelength imaging camera at the Caltech Submillimeter Observatory. The planets, along with a handful of secondary calibrators, have been used to determine the flux calibration for all of the data collected with Bolocam. Uranus and Neptune stand out as the only two planets that are bright enough to be seen with high signal-to-noise in short integrations without saturating the standard Bolocam readout electronics. By analyzing all of the 143 GHz observations made with Bolocam between 2003 and 2010, we find that the brightness ratio of Uranus to Neptune is 1.027 +- 0.006, with no evidence for any variations over that period. Including previously published results at \simeq 150 GHz, we find a brightness ratio of 1.029 +- 0.006 with no evidence for time variability over the period 1983-2010. Additionally, we find no evidence for time-variability in the brightness ratio of either Uranus or Neptune to the ultracompact HII region G34.3 or the protostellar source NGC 2071IR. Using recently published WMAP results we constrain the absolute 143 GHz brightness of both Uranus and Neptune to ~3%. Finally, we present ~3% absolute 143 GHz peak flux density values for the ultracompact HII regions G34.3 and K3-50A and the protostellar source NGC 2071IR.