Calibration of the MACHO photometry database

C. Alcock; R. A. Allsman; D. R. Alves; T. S. Axelrod; A. C. Becker; D. P. Bennett; K. H. Cook; A. J. Drake; K. C. Freeman; M. Geha; K. Griest; M. J. Lehner; S. L. Marshall; D. Minniti; B. A. Peterson; P. Popowski; M. R. Pratt; C. A. Nelson; P. J. Quinn; C. W. Stubbs; W. Sutherland; A. B. Tomaney; T. Vandehei; D. L. Welch

doi:10.1086/316469

Calibration of the MACHO photometry database

C. Alcock^*, R. A. Allsman, D. R. Alves, T. S. Axelrod, A. C. Becker, D. P. Bennett, K. H. Cook, A. J. Drake, K. C. Freeman, M. Geha, K. Griest, M. J. Lehner, S. L. Marshall, D. Minniti, B. A. Peterson, P. Popowski, M. R. Pratt, C. A. Nelson, P. J. Quinn, C. W. StubbsW. Sutherland, A. B. Tomaney, T. Vandehei, D. L. Welch

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

125 Citations (Scopus)

Abstract

The MACHO Project is a microlensing survey that monitors the brightnesses of ∼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 ∼9 million stars in the LMC bar, independent photometric measurements of ∼20,000 stars with V ≲ 18 mag in field-overlap regions demonstrate an internal precision σ_V = 0.021, σ_R = 0.019, σ_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.

Original language	English
Pages (from-to)	1539-1558
Number of pages	20
Journal	Publications of the Astronomical Society of the Pacific
Volume	111
Issue number	766
DOIs	https://doi.org/10.1086/316469
Publication status	Published - Dec 1999

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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., Griest, K., Lehner, M. J., Marshall, S. L., Minniti, D., Peterson, B. A., Popowski, P., Pratt, M. R., Nelson, C. A., Quinn, P. J., ... Welch, D. L. (1999). Calibration of the MACHO photometry database. Publications of the Astronomical Society of the Pacific, 111(766), 1539-1558. https://doi.org/10.1086/316469

@article{88c0a7460f3849c1846e288b954d17c3,

title = "Calibration of the MACHO photometry database",

abstract = "The MACHO Project is a microlensing survey that monitors the brightnesses of ∼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 ∼9 million stars in the LMC bar, independent photometric measurements of ∼20,000 stars with V ≲ 18 mag in field-overlap regions demonstrate an internal precision σV = 0.021, σR = 0.019, σV-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.",

author = "C. Alcock and Allsman, {R. A.} and Alves, {D. R.} and Axelrod, {T. S.} and Becker, {A. C.} and Bennett, {D. P.} and Cook, {K. H.} and Drake, {A. J.} and Freeman, {K. C.} and M. Geha and K. Griest and Lehner, {M. J.} and Marshall, {S. L.} and D. Minniti and Peterson, {B. A.} and P. Popowski and Pratt, {M. R.} and Nelson, {C. A.} and Quinn, {P. J.} and Stubbs, {C. W.} and W. Sutherland and Tomaney, {A. B.} and T. Vandehei and Welch, {D. L.}",

year = "1999",

month = dec,

doi = "10.1086/316469",

language = "English",

volume = "111",

pages = "1539--1558",

journal = "Publications of the Astronomical Society of the Pacific",

issn = "0004-6280",

publisher = "Institute of Physics Publishing",

number = "766",

}

Alcock, C, Allsman, RA, Alves, DR, Axelrod, TS, Becker, AC, Bennett, DP, Cook, KH, Drake, AJ, Freeman, KC, Geha, M, Griest, K, Lehner, MJ, Marshall, SL, Minniti, D, Peterson, BA, Popowski, P, Pratt, MR, Nelson, CA, Quinn, PJ, Stubbs, CW, Sutherland, W, Tomaney, AB, Vandehei, T & Welch, DL 1999, 'Calibration of the MACHO photometry database', Publications of the Astronomical Society of the Pacific, vol. 111, no. 766, pp. 1539-1558. https://doi.org/10.1086/316469

TY - JOUR

T1 - Calibration of the MACHO photometry database

AU - Alcock, C.

AU - Allsman, R. A.

AU - Alves, D. R.

AU - Axelrod, T. S.

AU - Becker, A. C.

AU - Bennett, D. P.

AU - Cook, K. H.

AU - Drake, A. J.

AU - Freeman, K. C.

AU - Geha, M.

AU - Griest, K.

AU - Lehner, M. J.

AU - Marshall, S. L.

AU - Minniti, D.

AU - Peterson, B. A.

AU - Popowski, P.

AU - Pratt, M. R.

AU - Nelson, C. A.

AU - Quinn, P. J.

AU - Stubbs, C. W.

AU - Sutherland, W.

AU - Tomaney, A. B.

AU - Vandehei, T.

AU - Welch, D. L.

PY - 1999/12

Y1 - 1999/12

N2 - The MACHO Project is a microlensing survey that monitors the brightnesses of ∼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 ∼9 million stars in the LMC bar, independent photometric measurements of ∼20,000 stars with V ≲ 18 mag in field-overlap regions demonstrate an internal precision σV = 0.021, σR = 0.019, σV-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.

AB - The MACHO Project is a microlensing survey that monitors the brightnesses of ∼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 ∼9 million stars in the LMC bar, independent photometric measurements of ∼20,000 stars with V ≲ 18 mag in field-overlap regions demonstrate an internal precision σV = 0.021, σR = 0.019, σV-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.

UR - http://www.scopus.com/inward/record.url?scp=0033268053&partnerID=8YFLogxK

U2 - 10.1086/316469

DO - 10.1086/316469

M3 - Article

SN - 0004-6280

VL - 111

SP - 1539

EP - 1558

JO - Publications of the Astronomical Society of the Pacific

JF - Publications of the Astronomical Society of the Pacific

IS - 766

ER -

Calibration of the MACHO photometry database

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