For those who really understand astronomy and astrometry…
Wow this is DEEP stuff.
The question is: what “position format” to use (1 or 2)? I put photos into nova.astrometry.net and get RA and Dec, I have taken the output FITS files and put them into SAO Image DS 9 to get RA and Dec. Could they just be reasonable and agree? NO! I am using the “FK5” numbers.
In nova.astrometry.net - if you use the World Wide Telescope you apparently get numbers in HH MM SSs but the values for Dec do not show units.
In SAO Image DS 9 there are no units shown for RA or Dec.
Now we should get a lot of hints from the displayed digits.
On two of my recent images, I see:
Begin (observation 1):
Astrometry: RA 06 19 53 Dec +60 32 29
SAO Image: RA 06 19 20.9036 Dec +60 28 20.283
End (observation 2):
Astrometry: RA 05 48 50 Dec +56 35 09
SAO Image: RA 05 50 05.7637 Dec +56 45 14.211
I do try to keep very careful records since I have mixed up the begin and end, I have mixed up numbers (there are a bunch of them), etc. I really need to automate this to eliminate errors!
So, for anyone using a digital camera or who understands how those two sources work, what values of RA and Dec should I use, and what position format should they go into?
I think that I should use position format 1 and get the RA and Dec from Astrometry, the World Wide Telescope option.
I have read up on the Fifth Fundamental Catalog and what FK4 and FK5 are - have looked for help and FAQs on the two sources. I have not found the answers I need.
Can anyone help?