LYNDS_DN (N0): Lynds' Catalog of Dark Nebulae (19921223)
FILE: lynds_bn.n0 (1791 objects)
CONTENTS: Lynds' Catalog of Dark Nebulae
DATASET: This file comes in HyperSky dataset N-1.2, version 19921223 Availability on HyperSky CD-ROM: Vol. 1 (1993)
DESCRIPTION: This datafile contains a total of 1791 dark nebulae from the machine-readable version of Lynds' Catalog of Dark Nebulae, as provided on the NASA/GSFC Astronomical Data Center cd-rom "Selected Astronomical Catalogs", Volume 1. The original catalog source reference is: Lynds, B. T. 1962, ApJS, 7, 1.
Lynd's catalog covers the sky from the north pole south to about -30 degrees declination, and most of his cataloged dark nebulae lie along the Milky Way.
DATA: The HyperSky datafile contains the following data from the catalog:
COORDINATES: Equatorial coordinates are stored in the datafile at equinox 2000, having been precessed from equinox 1950 coordinates in the Lynds catalog.
MAG: no magnitudes are provided in the Lynds catalog, such values are meaningless for dark nebulae. Instead, the catalog provides an opacity value, as discussed below.
IDENTIFICATION: The Lynds dark nebula (LDN) running catalog number.
COMMENTS: The comment lines contain the following information, provided if available for each nebula:
* An optional line listing one or more of Barnard's nebula numbers which correspond to Lynds' entry. In most cases, only one Barnard number is associated with a Lynds dark nebula. However, in some cases there are up to 8 associated Barnard numbers.
* A line starting with "Area=", giving the approximate area of the dark nebula in square degrees. Approximate nebula diameters have been derived for HyperSky by taking the square root of these areas, thereby assuming approximately square shapes. Keep in mind that this assumption will not be correct for all dark nebulae, and thus the sizes shown in HyperSky fields may not always be proper.
Note that some of the Lynds nebulae are very large, and all nebulae are represented by boxes even though many are long and thin. Thus, regions with many dark nebulae appear confusing, with overlapping boxes, when this datafile is used.
* A line starting with "opacity=", giving the nebula opacity based on the scale of 1(lightest) to 6(darkest).