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D. Barnaby, E. Fernandez, E. Spillar, I. DeLarue, A. L. Wells (AFRL/DES)
The primary mission of the Starfire Optical Range (SOR), located on Kirtland Air Force Base, New Mexico, is to develop methods for atmospheric compensation using adaptive optics and laser guide stars. The SOR has hosted many astronomers who have used our facilities for astronomical imaging observations in both optical and near-infrared bands. Anticipating more collaborations in the future, we undertook to measure the sky brightness in the Johnson R and I bands during the early morning of 19 November 2000 UT. To do this, we imaged Landolt star fields SA93, SA95, SA96, and SA100 using a Photometrics CCD camera attached to a C-8 telescope at the SOR's beam director. That night the moon was 7 days from new and 42% illuminated. We began with star field SA93, when it had a lunar separation angle of 131 degrees and when the moon was < 6 degrees above the horizon. We then observed the fields in order of decreasing lunar separation. From 42 measurements of standard star magnitudes in the first 2 fields, we derived sky brightness values of R=19.7 ±0.1 and I=18.5 ±0.1 per square arcsecond. In both bands the sky was brighter by 0.15 mag per square arcsecond for the star fields with lunar separation < 90 degrees. We also measured the sky brightness at elevation angle 20 degrees over the nearby city of Albuquerque, deriving values of R=18.5 ±0.1 and I=17.5 ±0.03 per square arcsecond. We will present our data and compare SOR values to those at Kitt Peak and CTIO.
We thank the Air Force Research Laboratory Directed Energy Directorate and the Air Force Reserve for funding this research.