II/247 Variable Stars in the Large Magellanic Clouds (MACHO, 2001)
Variable Stars in the Magellanic Clouds from the MACHO Project Alcock C., Allsman R., Alves D., Axelrod T., Bennett D., Cook K., Freeman K., Lehner M., Griest K., Marshall S., Minniti D., Peterson B., Pratt M., Quinn P., Rodgers A., Stubbs C., Sutherland W., Welch D. <MACHO Project (2001)>
ADC_Keywords: Stars, variable ; Photometry, CCD; Magellanic Clouds Description: The MACHO Project is a collaboration between scientists at the Mt. Stromlo & Siding Spring Observatories, the Center for Particle Astrophysics at the Santa Barbara, San Diego, & Berkeley campuses of the University of California, and the Lawrence Livermore National Laboratory. The primary aim of the project is a search for dark matter in the halo of the Milky Way in the form of objects like brown dwarfs or planets also named MACHOs, for MAssive Compact Halo Objects. The signature of these MACHOs is the occasional amplification of the light from extragalactic stars by the gravitational lens effect. The amplification can be large, but events are extremely rare: it is necessary to monitor photometrically several million stars for a period of years in order to obtain a useful detection rate. The MACHO project is described by Alcock et al. (1992, in "Robotic Telescopes in the 1990s", A.V. Fillippenko Ed., ASP Conf. Series 34, p.193). A dedicated 1.27-m telescope at Mount Stromlo, Australia is used to obtain observations of the LMC year-round, using a camera imaging a field of view of 0.5 square degrees at prime focus. Photometric observations of the LMC fields are obtained in two bandpasses simultaneously, using a dichroic beamsplitter to direct the blue (440-590nm) and red (590-780nm) light onto 2x2 mosaics of 2048x2048 Loral CCDs; the 15um pixels map to 0.63arcsec on the sky. The photometric reduction methods are detailed in Alcock et al. (1996ApJ...461...84A). Acknowledging: Please acknowledge the MACHO Project data with: "This paper utilizes public domain data originally obtained by the MACHO Project, whose work was performed under the joint auspices of the U.S. Department of Energy, National Nuclear Security Administration by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48, the National Science Foundation through the Center for Particle Astrophysics of the University of California under cooperative agreement AST-8809616, and the Mount Stromlo and Siding Spring Observatory, part of the Australian National University." File Summary: File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file machovar.dat 168 21474 Variable Stars in the Magellanic Clouds
See also: http://wwwmacho.anu.edu.au/ : the MACHO Project Home Page http://wwwmacho.mcmaster.ca/ : MACHO Project Home Page J/A+A/313/841 : MACHO LMC No.1 microlensing event (Dominik+, 1996) J/ApJ/562/337 : High proper-motion stars from MACHO astrometry (Alcock+, 2001) J/AJ/124/2039 : LMC Blue variable stars from MACHO (Keller+, 2002) Byte-by-byte Description of file: machovar.dat
Bytes Format Units Label Explanations
2- 3 I2 --- Field Macho Identification (Field) (1) 5- 9 I5 --- Tile Macho Identification (Tile) (1) 11- 14 I4 --- Seqn Macho Identification (Sequence) (1) 16- 17 I2 h RAh Right Ascension J2000 (hours) 18 A1 --- --- [:] 19- 20 I2 min RAm Right Ascension J2000 (minutes) 21 A1 --- --- [:] 22- 27 F6.3 s RAs [0,60] Right Ascension J2000 (seconds) 28 A1 --- DE- Declination J2000 (sign) 29- 30 I2 deg DEd Declination J2000 (degrees) 31 A1 --- --- [:] 32- 33 I2 arcmin DEm Declination J2000 (minutes) 34 A1 --- --- [:] 35- 39 F5.2 arcsec DEs [0,60] Declination J2000 (seconds) 41- 50 F10.5 d rPer Period for "red" light (590-780nm) 52- 61 F10.5 d bPer Period for "blue" light (440-590nm) 63- 68 F6.3 mag Vmag Averaged Kron-Cousins V magnitude 70- 75 F6.3 mag Rmag Averaged Kron-Cousins R magnitude 77- 82 F6.3 mag rAmp Amplitude in "red" light (590-780nm) 84- 89 F6.3 mag bAmp Amplitude in "blue" light (440-590nm) 91- 96 F6.3 mag cAmp Amplitude in b-r index 98-102 F5.2 --- rSupRSA Deviation from fitted light curve in red (2) 104-108 F5.2 --- bSupRSA Deviation from fitted light curve in blue (2) 110-116 F7.2 --- rchi2 Chi-2 fit of light curve in red 118-124 F7.2 --- bchi2 Chi-2 fit of light curve in blue 126-131 F6.3 mag rsig Standard deviation of focal plane's red mag. 133-138 F6.3 mag bsig Standard deviation of focal plane's blue mag. 140-145 F6.2 --- Var Pierce's Variability index (Pierce et al., 1994Natur.371..385P) 147-148 I2 --- Class Variable star classification (3) 150-153 I4 --- Points Number of observations 155-158 I4 --- cPoints Number of concurrent points (4) 160-163 I4 --- rPoints Number of points for red light curve 165-168 I4 --- bPoints Number of points for blue light curve.
Note (1): The Macho Project identifier for the star consists of Field.Tile.Seqn made of the Macho Field, Tile, and Sequence identifiers for an individual star. Note (2): Sup RSA is the weighted mean absolute deviation of the data from the fit to the light curve. The weighting is such that good fits typically have values less than 1.0. Note (3): Classification of variable star based on statistical analysis of its photometry over time; note that the current classifications are preliminary and have been made in an automated manner. Most light curves displayed when selecting a particular classification will belong to that class, but there will be contamination by non-members (primarily binaries). The classes are: 0 = unknown : undefined classification 1 = RRL AB : RRLyrae ab 2 = RRL C : RRLyrae c 3 = RRL E : RRLyrae e 4 = Ceph Fund : Cepheid fundamental 5 = Ceph 1st : Cepheid first overtone 6 = LPV WoodA : Long Period Variable Wood-A (see 2000PASA...17...18W) 7 = LPV WoodB : Long Period Variable Wood-B (see 2000PASA...17...18W) 8 = LPV WoodC : Long Period Variable Wood-C (Mira) 9 = LPV WoodD : Long Period Variable Wood-D (see 2000PASA...17...18W) 10 = EB : Eclipsing Binary (all kinds including Wood-E) -- default 11 = RRL + GB : RR Lyrae and GB blends (supersedes Cepheid first overtone in overlap region) Note (4): Number of observations where the star was observed simultaneously in both blue and red focal planes.
History: Originally prepared by Robyn Allsman for CDS in September 2001.
(End) Francois Ochsenbein [CDS] 28-Jun-2003
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