Calibration of the MACHO Photometry Database

Journal Article · Wed Dec 01 04:00:00 EST 1999 · Publications of the Astronomical Society of the Pacific

DOI:https://doi.org/10.1086/316469· OSTI ID:20215821

Alcock, C; Allsman, R A; Alves, D R; Axelrod, T S; Becker, A C; Bennett, D P; Cook, K H; Drake, A J; Freeman, K C; Geha, M ^[1]

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1. and others

The MACHO Project is a microlensing survey that monitors the brightnesses of {approx}60 million stars in the Large Magellanic Cloud (LMC), Small Magellanic Cloud, and Galactic bulge. Our database presently contains about 80 billion photometric measurements, a significant fraction of all astronomical photometry. We describe the calibration of MACHO two-color photometry and transformation to the standard Kron-Cousins V and R system. Calibrated MACHO photometry may be properly compared with all other observations on the Kron-Cousins standard system, enhancing the astrophysical value of these data. For {approx}9 million stars in the LMC bar, independent photometric measurements of {approx}20,000 stars with V(less-or-similar sign)18 mag in field-overlap regions demonstrate an internal precision {sigma}{sub V} =0.021, {sigma}{sub R} =0.019, {sigma}{sub V-R} =0.028 mag. The accuracy of the zero point in this calibration is estimated to be {+-}0.035 mag for stars with colors in the range -0.1 mag<V-R<1.2 mag. A comparison of calibrated MACHO photometry with published photometric sequences and new Hubble Space Telescope observations shows agreement. The current calibration zero-point uncertainty for the remainder of the MACHO photometry database is estimated to be {+-}0.10 mag in V or R and {+-}0.04 mag in V-R. We describe the first application of calibrated MACHO data: the construction of a color-magnitude diagram used to calculate our experimental sensitivity for detecting microlensing in the LMC. (c) (c) 1999. The Astronomical Society of the Pacific.

• OSTI ID: 20215821
• Journal Information: Publications of the Astronomical Society of the Pacific, Journal Name: Publications of the Astronomical Society of the Pacific Journal Issue: 766 Vol. 111; ISSN 0004-6280; ISSN PASPAU
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CALIBRATION
COLOR
DATA ANALYSIS
DATA BASE MANAGEMENT
DATA COMPILATION
EXPERIMENTAL DATA
GALAXIES
GRAVITATIONAL LENSES
NONLUMINOUS MATTER
PHOTOMETRY
SENSITIVITY