Variability-selected quasars in MACHO project Magellanic Cloud fields

M. Geha; 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; K. Griest; S.C. Keller; M.J. Lehner; S.L. Marshall; D. Minniti; C.A. Nelson; B.A. Peterson; P. Popowski; M.R. Pratt; Peter Quinn; C.W. Stubbs; W. Sutherland; A.B. Tomaney; T. Vandehei; D.L. Welch

doi:10.1086/344947

Variability-selected quasars in MACHO project Magellanic Cloud fields

M. Geha, 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, K. Griest, S.C. Keller, M.J. Lehner, S.L. Marshall, D. Minniti, C.A. Nelson, B.A. Peterson, P. Popowski, M.R. Pratt, Peter QuinnC.W. Stubbs, W. Sutherland, A.B. Tomaney, T. Vandehei, D.L. Welch

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Abstract

We present 47 spectroscopically confirmed quasars discovered behind the Magellanic Clouds identified via photometric variability in the MACHO database. Thirty-eight quasars lie behind the Large Magellanic Cloud and nine behind the Small Magellanic Cloud, more than tripling the number of quasars previously known in this region. The quasars cover the redshift interval 0.2 < z < 2.8 and have apparent mean magnitudes 16.6 less than or equal to (V) over bar less than or equal to 20.1. We discuss the details of quasar candidate selection based on time variability in the MACHO database and present results of spectroscopic follow-up observations. Our follow-up detection efficiency was 20%; the primary contaminants were emission-line Be stars in Magellanic Clouds. For the 47 quasars discovered behind the Magellanic Clouds, plus an additional 12 objects previously identified in this region, we present 7.5 yr MACHO V- and R-band light curves with average sampling times of 2 10 days.

Original language	English
Pages (from-to)	1-12
Journal	Astronomical Journal
Volume	125
Issue number	1
DOIs	https://doi.org/10.1086/344947
Publication status	Published - 2003

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Geha, M., 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., Griest, K., Keller, S. C., Lehner, M. J., Marshall, S. L., Minniti, D., Nelson, C. A., Peterson, B. A., Popowski, P., Pratt, M. R., ... Welch, D. L. (2003). Variability-selected quasars in MACHO project Magellanic Cloud fields. Astronomical Journal, 125(1), 1-12. https://doi.org/10.1086/344947

@article{34a960aff6584567b20df9536fa890ee,

title = "Variability-selected quasars in MACHO project Magellanic Cloud fields",

abstract = "We present 47 spectroscopically confirmed quasars discovered behind the Magellanic Clouds identified via photometric variability in the MACHO database. Thirty-eight quasars lie behind the Large Magellanic Cloud and nine behind the Small Magellanic Cloud, more than tripling the number of quasars previously known in this region. The quasars cover the redshift interval 0.2 < z < 2.8 and have apparent mean magnitudes 16.6 less than or equal to (V) over bar less than or equal to 20.1. We discuss the details of quasar candidate selection based on time variability in the MACHO database and present results of spectroscopic follow-up observations. Our follow-up detection efficiency was 20%; the primary contaminants were emission-line Be stars in Magellanic Clouds. For the 47 quasars discovered behind the Magellanic Clouds, plus an additional 12 objects previously identified in this region, we present 7.5 yr MACHO V- and R-band light curves with average sampling times of 2 10 days.",

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

year = "2003",

doi = "10.1086/344947",

language = "English",

volume = "125",

pages = "1--12",

journal = "The Astronomical Journal",

issn = "0004-6256",

publisher = "IOP Publishing",

number = "1",

}

Geha, M, Alcock, C, Allsman, RA, Alves, DR, Axelrod, TS, Becker, AC, Bennett, DP, Cook, KH, Drake, AJ, Freeman, KC, Griest, K, Keller, SC, Lehner, MJ, Marshall, SL, Minniti, D, Nelson, CA, Peterson, BA, Popowski, P, Pratt, MR, Quinn, P, Stubbs, CW, Sutherland, W, Tomaney, AB, Vandehei, T & Welch, DL 2003, 'Variability-selected quasars in MACHO project Magellanic Cloud fields', Astronomical Journal, vol. 125, no. 1, pp. 1-12. https://doi.org/10.1086/344947

TY - JOUR

T1 - Variability-selected quasars in MACHO project Magellanic Cloud fields

AU - Geha, M.

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 - Griest, K.

AU - Keller, S.C.

AU - Lehner, M.J.

AU - Marshall, S.L.

AU - Minniti, D.

AU - Nelson, C.A.

AU - Peterson, B.A.

AU - Popowski, P.

AU - Pratt, M.R.

AU - Quinn, Peter

AU - Stubbs, C.W.

AU - Sutherland, W.

AU - Tomaney, A.B.

AU - Vandehei, T.

AU - Welch, D.L.

PY - 2003

Y1 - 2003

N2 - We present 47 spectroscopically confirmed quasars discovered behind the Magellanic Clouds identified via photometric variability in the MACHO database. Thirty-eight quasars lie behind the Large Magellanic Cloud and nine behind the Small Magellanic Cloud, more than tripling the number of quasars previously known in this region. The quasars cover the redshift interval 0.2 < z < 2.8 and have apparent mean magnitudes 16.6 less than or equal to (V) over bar less than or equal to 20.1. We discuss the details of quasar candidate selection based on time variability in the MACHO database and present results of spectroscopic follow-up observations. Our follow-up detection efficiency was 20%; the primary contaminants were emission-line Be stars in Magellanic Clouds. For the 47 quasars discovered behind the Magellanic Clouds, plus an additional 12 objects previously identified in this region, we present 7.5 yr MACHO V- and R-band light curves with average sampling times of 2 10 days.

AB - We present 47 spectroscopically confirmed quasars discovered behind the Magellanic Clouds identified via photometric variability in the MACHO database. Thirty-eight quasars lie behind the Large Magellanic Cloud and nine behind the Small Magellanic Cloud, more than tripling the number of quasars previously known in this region. The quasars cover the redshift interval 0.2 < z < 2.8 and have apparent mean magnitudes 16.6 less than or equal to (V) over bar less than or equal to 20.1. We discuss the details of quasar candidate selection based on time variability in the MACHO database and present results of spectroscopic follow-up observations. Our follow-up detection efficiency was 20%; the primary contaminants were emission-line Be stars in Magellanic Clouds. For the 47 quasars discovered behind the Magellanic Clouds, plus an additional 12 objects previously identified in this region, we present 7.5 yr MACHO V- and R-band light curves with average sampling times of 2 10 days.

U2 - 10.1086/344947

DO - 10.1086/344947

M3 - Article

VL - 125

SP - 1

EP - 12

JO - The Astronomical Journal

JF - The Astronomical Journal

SN - 0004-6256

IS - 1

ER -

Variability-selected quasars in MACHO project Magellanic Cloud fields

Abstract

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