Celestia Forums

Probably a very stupid question, but....

I'm trying to work on some double systems for the new release, and when I look up RA and Dec for a star, all I can ever find is the info in units of hours and minutes. How, or where, does one find these in the decimal fractions that are used in the stc files?

...John...

The decimal form of the coordinates is found like this:

hours + minutes/60 + seconds/3600

Brendan

Unfortunately, STC files want degrees of Right Ascension, not Hours.

degrees = 15* (hours + min/60. + sec/3600.)

If you'd rather not do the arithmetic yourself, there are preprogrammed Web calculators available.

If you're placing real stars that are in Simbad's database, then you can use the Precess tool that's on the Chandra X-Ray satellite observation planning site.

http://cxc.harvard.edu/toolkit/precess.jsp

Type one the star's catalog names into the field titled "Target Name:" (E.G. HIP 71683) and click on the button "Resolve Name". When the position has been returned (in H:m:s at the top of the form), verify that the output format is "Equatorial (J2000)" and then click on the button "Calculate". It'll display the location in decimal degrees down at the bottom of the form.

Is this useful?

Very useful, thank you!

Once I get back into the proper frame of mind, I'll have another go at making barycenter stc's....

...John...

It's probably a useless gesture after Seldens excellent link, but you could also take a look in my STC-guide (from the motherlode), there you will find the calculation method from RA in h:m:s to RA in deg and Dec in deg:m:s to Dec in deg.

Regards,

Guckytos

Not a useless gesture at all. Multiple links is a GOOD thing, especially if one site or another happens to be down for some reason.

Thanks!

...John...