"STELLAR TWINS" IN THE SLOAN DIGITAL SKY SURVEY

On Dec 1, 10:42 pm, Greg Crinklaw
wrote:
While it might be argued that hours of R.A. are not
necessary, there are very few (if any) reasons why degrees would be any
more useful.

I can offer a couple:
1. The apphot package in IRAF requires decimal degrees for input.
(Yes, this is a bug, but it won't ever be fixed.) It wouldn't
surprise me to learn there are other programs like this.
2. When writing one's own programs, decimal degrees allow a simple
numerical read rather than writing code to parse a text string. (If
you ever want to write such code, think carefully about declinations
between 0 and -1 degree! The job isn't as easy as you think, at least
if you want to allow a free input format rather than requiring fixed
columns.)

The 'skycoor' program in WCStools is quite useful for converting
between formats. It also precesses and converts between coordinate
systems. See
http://tdc-www.harvard.edu/software/wcstools/

Very few, if any, astronomers do spherical trigonometry on
their calculators

I do, but coordinate conversion is not a problem there. My calculator
has a built-in function to convert between decimal and sexagesimal
coordinates. I expect most programmable calculators have a similar
function. Of course the input format is rigid, but that's not a
problem when keying in data.

it is trivial to do unit conversions on the more
sophisticated math applications.

Yes, once you have the data in numerical form as opposed to a string.