RA and Dec of the Sun at J2000

I'm in the somewhat awkward position of asking something that, despite me thinking there should be hundreds and hundreds of web pages and datasets showing this particular value, I've been unable to find anything about it.

What, indeed, are the Right Ascension and Declination angles of the Sun for J2000 ? Wikipedia shows some values (RA = 286.13, Dec = 63.87), but it is not clear whether they are J2000 or not...

• What Wikipedia article gave those coordinates? The Sun's declination on Jan 1 should be more like -23°. Apr 9, 2020 at 22:32
• I think the coordinates you mention are the RA and Dec. of the direction of the North Pole of the Sun. If you're looking for the RA/Dec. of the position of the Sun in the sky, then they need to be computed based on the date and time, since they change throughout the year. You may be interested in this Wikipedia article : Position of the Sun. Also, several web services, software and programming libraries can compute them for you (Ex: Pyephem, Skyfield, Stellarium, JPL Horizons, etc.) Apr 9, 2020 at 23:46
• @FSimardGIS I'm pretty sure that Izhido is asking for the RA & Dec of the Sun at the exact instant of the J2000 epoch, i.e., on the 1st of January 1, 2000, at 12:00 Terrestrial Time. Apr 10, 2020 at 3:14
• @PM2Ring You're right, he says "at J2000", I guess I misread earlier. Then we need to compute RA/Dec. for January 1, 2000 12:00 TT. Apr 10, 2020 at 3:31
• @MikeG, check en.wikipedia.org/wiki/Sun, in the table at the right side of the page, under "Rotation Characteristics" Apr 10, 2020 at 23:30

1 Answer

At noon on 1 Jan 2000 (UT) the sun's RA & dec were (J2000):

18hrs 45min 9.36s

-23deg, 2 m, 8.2s

This is per Guide9 software.

• This answer would be better if you use 11:58:55.816 UTC, see en.wikipedia.org/wiki/Epoch_(astronomy)#Julian_Dates_and_J2000 Apr 10, 2020 at 11:39
• Thanks, I wasn't aware of that. To the nearest second, both RA and Dec, it makes no difference. Apr 10, 2020 at 12:03
• No worries. I didn't expect it to make a significant difference. But since the OP wants the values right at the instant of the J2000 epoch, we might as well do it properly. ;) Apr 10, 2020 at 12:15