J2000 ecliptic coordinates incorrect

Bug #1366567 reported by De Mickey on 2014-09-07
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
Stellarium
Fix Released
Medium
De Mickey

Bug Description

The ecliptic coordinates (J2000) displayed when clicking on objects appears to be incorrect.
By my calculation, the error is around 12 arcMinutes for most (all?) objects.
12 minutes happens to be the amount of precession from J2000 to now.
So the calculation seems to using the equinox "of date" instead of the J2000 equinox.
The error can be verified by setting the current datetime back to 2000-01-01 12:00:00
and seeing what the ecliptic coordiniates should be for J2000.
(Use an object that is very distant, so that parallax, proper motion, topo/geo/heliocentric are not involved.)
Also, compare the J2000 ecliptic coordniates with another source, such as
http://lambda.gsfc.nasa.gov/toolbox/tb_converters_ov.cfm

I have only glanced at the source code, and so am unsure, but the fix may be as simple as
using the J2000 RA/DEC as input to the rectTSphe() conversion instead of the 'of date' RA/DEC.
In other word a 1-line change in StelObject.cpp changing getEquinoxEquatorialPos() to
getJ2000EqutorialPos().

Related branches

Alexander Wolf (alexwolf) wrote :
Changed in stellarium:
milestone: none → 0.13.1
assignee: nobody → De Mickey (daniel-de-mickey)
importance: Undecided → Low
importance: Low → Undecided
status: New → Fix Committed
Changed in stellarium:
importance: Undecided → Medium
Changed in stellarium:
status: Fix Committed → Fix Released
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