Catalogue of Dark Nebulae
Lynds B.T.
<Astrophys. J. Suppl. Ser. 7, 1 (updated version) (1962)>
Description:
This catalog is an updated version from the published version. The catalog was based on the red and blue prints of the National Geographic - Palomar Observatory Sky Atlas. The catalog contains positions, both equatorial and galactic for the centers of dark nebulae. Values for the cloud sizes are given in square degrees, and estimates of their opacity are given. The updated catalog is ordered by galactic longitude and includes cross references to the published catalog and Barnard Object numbers associated with the clouds.
File Summary:
| FileName | Lrecl | Size | Records | Explanations |
| ReadMe | 80 | 7KB | This file | |
| ldn.dat | 92 | 37KB | 1791 | The LDN Catalogue |
See also:
VII/191 : Catalogue of Southern Dark Clouds (Hartley+ 1986)
J/A+AS/113/325 : Distance measurements of some Lynds nebulae (Hilton+ 1995)
Byte-by-byte Description of file: ldn.dat
| Bytes | Format | Units | Label | Explanations |
| 1-4 | I4 | LDN | *[1/1802]?+ Catalogue number from original published version (ApJS 7, 1) | |
| 6-7 | I2 | h | RAh | Right Ascension 1950 (hours) of Cloud Center |
| 9-12 | F4.1 | min | RAm | Right Ascension 1950 (minutes) |
| 16 | A1 | DE- | Declination 1950 (sign) of Cloud Center | |
| 17-18 | I2 | deg | DEd | Declination 1950 (degrees) |
| 20-21 | I2 | arcmin | DEm | Declination 1950 (minutes) |
| 23-28 | F6.2 | deg | GLON | [0/360[ Galactic longitude of Cloud Center |
| 30-35 | F6.2 | deg | GLAT | Galactic latitude of Cloud Center |
| 37-43 | F7.3 | deg2 | Area | Area, in square degrees, of the Cloud |
| 45 | I1 | Opacity | *[1/6]?=0 Opacity class | |
| 47-49 | I3 | ID | *[0/416] Identification Number. | |
| 51-54 | I4 | Seq | [1/1791] Running Number in this version of the Catalogue (ordered by GLON) | |
| 56-59 | I4 | Lynds2 | *Number that B. Lynds assigned when the updated catalogue was created. | |
| 61-92 | A32 | Barn | *Cross-identifications with Barnard Objects. (up to 8 Barnard numbers in format 8A4) |
Note on LDN:
Compared to the printed edition:
=> 15 "duplicated" LDN numbers were removed: 184, 366, 457, 465, 924, 1025, 1318, 1342, 1344, 1413, 1575, 1592, 1593, 1603, 1792
=> there are 4 nebulae without a LDN number at the end of the table
Note on Opacity:
The opacity is on a scale of 1 (lightest) to 6 (darkest). in cases where small dark clouds are within large, lighter clouds, both or all clouds have been listed separately. But they will be identified with the same ID (bytes 48-50) number.
Note on ID:
Entries with null identification number are objects lying in the general obscuration of the Milky Way.
Note on Barn:
Barnard designations are made by a number followed by a letter; see Barnard E.E., 1927, Carnegie Inst. Washington, "A photographic Atlas of selected regions of the Milky Way"
Note on Lynds2:
Number that B. Lynds assigned when the updated catalogue was created. The significance of this number is unknown. Also, it is not a unique number throughout this version of the catalogue.
Historical Notes:
* July 1979, by Theresa A. Nagy, from NASA document R-SAW-7/79-13, "Documentation for the machine-readable version of Lynds' Catalogue of Dark Nebula":
The initial version of the machine-readable version of the Lynds' Catalogue of Dark Nebulae was received from the University of Maryland. This version was obtained from the author and represents an updated version of the original published catalogue (1962 Astrophysical Journal Supplement #64). The major differences between these two versions are as follows:
- The galactic coordinates have been revised.
- Some of the original observations of "clouds" have been deleted.
- There are 1791 objects in the updated version and there were 1802 objects in the original published catalogue.
The original version, as such, does not exist in machine-readable form except in the cases where we have added the Barnard identification(s) to the appropriate objects. Since a correlation had to be made from the original catalogue numbers to obtain the Barnard cross-identifications (data obtained from a table in the original publication), these original numbers were retained.
The version of the catalogue as received from the University of Maryland was updated as follows:
- The catalogue was sorted by galactic longitude.
- A running number (Seq) was added after the sort.
- A cross-reference table between the old Lynds numbers and the Barnard numbers was made so that this information could be added to the machine-readable version. Therefore, the Barnard numbers and the original Lynds numbers were added (one record had as many as eight Barnard numbers).
* October 1991: the catalogue is prepared for the ADC CD-ROM "Selected Astronomical Catalogs" Vol. 1 (NASA), in directory /nonstell/nebulae/ldn
* 25-Sep-1995: Description added by Gail L. Schneider [SSDOO/ADC]
* 22-Feb-1996: James Marcout and Francois Ochsenbein, CDS) The previous version only contained a fraction of LDN numbers (about 1500 were missing). A new version 'A' of the catalogue was created, incorporating all original LDN numbers, with the exception of nebulae originally duplicated (see Note on LDN above); the columns were re-ordered to follow more closely the original publication.
(End) James Marcout, Francois Ochsenbein [CDS] 22-Feb-1996