Hi Bill

I have been using GUIDE to do computations for the southern
hemisphere geostationary solar flare season and found I was
getting different answers to that provided by other participants.
It looks like we have isolated the problem and it would appear
to lie in GUIDE :-((

I was using the position of the sun as given in GUIDE, both when
plotting the sun on a chart and in the QUICK INFO section. For
example 5th April 2007 at 19h34m22s SAST ( South African
Standard time) = 17h34m22s UT I get the sun at RA 00h56m56.06s
Dec +06d 05'11.0". The answer obtained by others - eg CIEL ,
EPOCH 2000 etc is RA 00h57m18.3s Dec +06d07'19" (approx)-
there is a small spread in the sec time/sec arc values and the
conclusion is that GUIDE is showing the ASTROMETRIC position
and not the APPARENT position so is neglecting the aberration
of light.This was supported by what the USNO Interactive
Computer Ephemeris (ICE) supplies.

When I click on the sun at the required time the INFO gives the
correct position "Mean position at current epoch" as
RA 00h57m19.116s Dec +06d07'23.12" which is the correct
value.

Okay I know we are talking about small differences but wouldnt
it have been more correct to use the apparent position in the
QUICK INFO section ? I made the assumption that it was.

Many thanks
Greg