Pierre Laporte Oct 8 4:15 PM
I use the Fv software to read the ldn.fit file in GUIDE 9.0 and use two examples (LDN 2 and LDN 4) to check.
Here is what I found
Original Catalog (Lynd 1962)
L(II) B(II) RA B1950 DEC AREA OPACITY ID
LDN 2 0.2 -5.13 18h 4.0m -31° 30' 1.240 2 0
LDN 4 0.04 12.00 16h 59.5m -22° 8' 0.004 5 27
Lynd Catalog in GUIDE 9.0
L(II) B(II) RA B1950 (J2000) DEC B1950 (J2000) AREA OPACITY ID Cat No in original versionr Lynds Number
LDN 2 0.02 -1.15 17 47.0 -29 30(17h 50m 18,75s; -29° 30' 23'') 2.770 2 0 747
LDN 4 0.13 -5.32 18 4.0 31 30 (18h 07m 21,77s; -31° 29' 09'') 1.240 2 0 837
In the header of ldn.fit, there is information about the catalog Here is the transcrip
Lynds' Catalogue of Dark Nebula
This version of the catalog was obtained fron the author and represents an updated version of the original published catalogue.
Source Catalogue Reference: Lynds, B. T. 1962, ApJS, 7, 1
Documentation Reference: Nagy, T. A. 1979, R-SAW-7/79-13
A copy of the documentation should accompany any computer-readable version of the catalog. The FITS Table header(s) in this file only give the basic format of the catalog. Please refer to the documentation or source reference for a more detailed discussion of the data.
So my understanding is that Lynd made a revised version of his original catalog and change the order in the revised version.
Also, as the Guide use the "revised version" in fit format, the RA and Dec refer both to B1950 and use it to plot the objet but with J2000 epoch....
Any other comments ??
Centre d'Observation Astronomique des Monts-Notre-Dame
Envoyé : 8 octobre 2014 15:01
À : email@example.com
Objet : RE: [guide-user] Lynd Dark Nebula used in GUIDE 9.0
I’ve just installed the newest version of Fv, but it sure doesn’t like to play well with Windows! It deleted my copy of ldn.fit (twice), made a duplicate copy of my ‘Program Files (x86)’ folder with the parentheses changed to underscores, and (mostly) refuses to open the file. I did get it open and saw the data stream 1 time out of 6. I was going to check the individual entries and make a corrected file for folks here that were interested, but perhaps this would be better suited to being done by someone with a Linux machine.
On 08/10/2014 2:23 AM, 'Anthony J. Kroes' akroes@... [guide-user] wrote:
I can verify that problem, Pierre. The original Lynd’s Catalog from 1962 shows LDN 2 at coordinates RA 18 4 Dec -31 30 which, once converted to epoch 2000 coordinates, gives RA 18h 07m 14.6s, Dec -31° 29m 35s, almost exactly what you got when plate-solving your image.
This is indeed where Guide shows LDN 4, which has the size of LDN 2 (1.24 sq. deg) listed for it as well. Guide shows nothing at all in the spot where LDN 4 should be according to the epoch-corrected coordinates from the Lynd catalog (RA 17h 2m 30.1s Dec -22° 12m 15.2s)
I searched through the Guide folders and subfolders doing various text searches and cannot find where the LDN data is either.
There are lbn and ldn folders under nebulae. Guide uses these catalogs in FITS format which aren't human readable. If you have a copy of "fv" you can read them. http://heasarc.gsfc.nasa.gov/ftools/fv/
--There's no point in being grown up if you can't be childish sometimes.-- Dr. Who