J/ApJ/639/227 MSX IRDC candidate catalog (Simon+, 2006)
A catalog of Midcourse Space Experiment infrared dark cloud candidates. Simon R., Jackson J.M., Rathborne J.M., Chambers E.T. <Astrophys. J., 639, 227-236 (2006)> =2006ApJ...639..227S
ADC_Keywords: Molecular clouds ; Interstellar medium ; Infrared sources Keywords: catalogs - dust, extinction - Galaxy: general - infrared: ISM - ISM: clouds - ISM: structure Abstract: We use 8.3µm mid-infrared images acquired with the Midcourse Space Experiment satellite to identify and catalog infrared dark clouds (IRDCs) in the first and fourth quadrants of the Galactic plane. Because IRDCs are seen as dark extinction features against the diffuse Galactic infrared background, we identify them by first determining a model background from the 8.3µm images and then searching for regions of high decremental contrast with respect to this background. IRDC candidates in our catalog are defined by contiguous regions bounded by closed contours of a 2σ decremental contrast threshold. We identify 10,931 candidate IRDCs. For each IRDC, we also catalog cores. These cores, defined as localized regions with at least 40% higher extinction than the cloud's average extinction, are found by iteratively fitting two-dimensional elliptical Gaussian functions to the contrast peaks. We identify 12,774 cores. The catalog contains the position, angular size, orientation, area, peak contrast, peak contrast signal-to-noise, and integrated contrast of the candidate IRDCs and their cores. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file catalog.dat 72 23705 MSX IR dark cloud candidate catalog
See also: V/114 : MSX6C Infrared Point Source Catalog (Egan+ 2003) J/AJ/126/1423 : MSX 8.3um fluxes of star-forming regions (Kraemer+, 2003) J/ApJ/641/389 : Properties of IRDC cores (Rathborne+, 2006) Byte-by-byte Description of file: catalog.dat
Bytes Format Units Label Explanations
1- 5 A5 --- --- [MSXDC] 7- 19 A13 --- MSXDC Cloud name (MSXDC GLLL.ll+BB.bb) 21 A1 --- m_MSXDC Indicates a cloud (0) or core (a,b,c,...) 23- 29 F7.3 deg GLON [-0.005,360[ Galactic longitude 31- 36 F6.3 deg GLAT Galactic latitude 38- 41 F4.1 arcmin MajAxis Major axis of the cloud (1) 43- 46 F4.1 arcmin MinAxis Minor axis of the cloud (2) 48- 50 I3 deg PA Position angle of ellipse (3) 52- 56 F5.2 arcmin2 Area Total area of the cloud (4) 58- 61 F4.2 --- PC Peak Contrast 63- 66 F4.1 --- c/Dc ? Ratio of the core's peak contrast to its uncertainty (c/Δc) 68- 72 F5.2 arcmin2 Int Integrated contrast (5)
Note (1): Defined as twice the distance between the cloud's contrast centroid and the most distant pixel from the centroid. Note (2): Defined as twice the distance between the cloud's contrast centroid and the most distant pixel from the centroid along the axis perpendicular to the major axis. Note (3): The position angle East of North of the major axis, defined as the line connecting the cloud's contrast centroid and the cloud's most distant pixel from the centroid. Note (4): Area of the pixels above 2σ. Note (5): Defined as the sum of the contrast over all pixels above 2σ.
History: From http://www.bu.edu/galacticring/msxirdc.
(End) Marianne Brouty [CDS] 08-Jun-2006
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