#552 closed defect (fixed)
psSphereRot - Galactic to ICRS
| Reported by: | Owned by: | Paul Price | |
|---|---|---|---|
| Priority: | high | Milestone: | |
| Component: | PSLib ADD | Version: | unspecified |
| Severity: | normal | Keywords: | |
| Cc: |
Description
There may be a problem with the specifications for conversions from Galactic to
ICRS. With the given formulas, I do not get the given Galactic coordinates
detailed on p29 of the current ADD. For (a,delta) = (0,0), I get the following:
Result is (-107.102,-14.3528), expected (96.3373,-60.1886).
I could be wrong, but I don't see any reason for the difference in values unless
the formulas are incorrect. If you have another idea though, i'd be happy to
hear it.
For Ecliptic to ICRS, the ecliptic values all come out correct, except that the
sphere's r (RA) value comes back opposite (negative) of the specified values in
the ADD.
Change History (4)
comment:1 by , 21 years ago
| Status: | new → assigned |
|---|
comment:2 by , 21 years ago
| Resolution: | → fixed |
|---|---|
| Status: | assigned → closed |
comment:4 by , 21 years ago
I believe the inverse rotations described by (-phi, -delta, -alpha) fixed the
discepancies here. I also changed SphereRotApply to give all positive angles
instead of negative, ie. -180=180, -2=358.
I expect that there's something wrong with converting the Euler angles.
Bug 461 has a Perl script that performs the rotations correctly using
quaternions. Can you use that to help?