J/AJ/109/709 K survey of Ori A molecular cloud (Ali+ 1995)
A 2.2um imaging survey of the Orion A molecular cloud
Ali B., Depoy D.L.
<Astron. J. 109, 709 (1995)>
=1995AJ....109..709A 1995AJ....109..709A (SIMBAD/NED BibCode)
ADC_Keywords: Infrared sources; Positional data; Photometry, infrared
Description:
We present results from a 2.2µm (limiting K about 14.5mag) survey
of the northern portion of the Orion A molecular cloud. A total of
3548 sources were detected in the 1472arcmin2 area surveyed. We
detect clustering of 2.2µm sources at the locations of the
Trapezium and OMC-2. No strict boundaries for these clusters could be
drawn from our data because we find that the entire region surveyed
shows an overabundance of sources when compared with background field
levels. We find that the form of the observed K luminosity function
(KLF) of stars near the Trapezium is consistent with that predicted
from a Miller and Scalo (ApJS 41, 513 (1979) IMF, if the age of the
cluster is about 1Myr. Away from the Trapezium and the OMC-2, the KLF
of stars suggests that either this population contains more low mass
stars or that it is older than the Trapezium stars.
The survey was carried out using the Ohio State InfraRed Imaging
System (OSIRIS) 256x256 HgCdTe array on the Perkins 1.8m telescope in
November 1992. In survey mode OSIRIS provides a spatial resolution of
1.50arcsec/pixel; the total field of view of the camera is 6.4arcmin.
The telescope was rastered on 4.2arcmin steps to produce a mosaic
approximately 39x39arcmin, centered near the Trapezium. A total of 81
K-band images were obtained, each with an exposure time about 3s.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 40 3548 *List of the 3548 sources
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Note on table2.dat: the published Table 2 contains only the 100 brightest
non-saturated stars.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq [1/3548]+ Designation [AD95]
6- 7 I2 h RAh Right Ascension 1950 (hours)
9- 10 I2 min RAm Right Ascension 1950 (minutes)
12- 16 F5.2 s RAs Right Ascension 1950 (seconds)
17 A1 --- DE- Declination 1950 (sign)
18- 19 I2 deg DEd Declination 1950 (degrees)
21- 22 I2 arcmin DEm Declination 1950 (minutes)
24- 28 F5.2 arcsec DEs Declination 1950 (seconds)
31- 35 F5.2 mag Kmag K magnitude (2.2um)
37- 40 F4.2 mag e_Kmag Mean error on Kmag
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Courtesy: Babar Ali
(End) Francois Ochsenbein [CDS] 02-Oct-1995