Testing of program iauAtoc13

[VGrin]

Good day!

Testing of program

iauAtoc13,
Observed place at a groundbased site to to ICRS astrometric RA,Dec.
The caller supplies UTC, site coordinates, ambient air conditions
and observing wavelength.

Initial data –

NorthStar in NorthPole –

Longitude = 00h 00m 00s ==> 00° ==> 0 rad,
Latitude = 90° 00′ 00″ ==> 90° ==> 1.570796… rad,
Ra = 2h 31m 47.08s ==> 37.9461… ==> 0.6622…rad,
Dec = +89° 15′ 50.9″ ==> 89.2641… ==> 1.5579…rad
2000.01.01 12:00:00 ==> utc1 = 2451544.5, utc2 = 0.5;
Ambient air conditions and observing wavelength
– not taken into account

Get ICRS – coordinatess
int I = iauAtoc13
( “A”, Ra, Dec, utc1, utc2, 0.0, Longitude, Latitude,
0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
out double r, out double d
)
Output –
I = 0,
r = 1.0910…rad ==> 62.5098… ==> 4h 10m 35.47c,
d = 0.01288…rad ==> 0.01288… ==> 90° – ( 0° 44′ 18.13″ ) ==> 89° 15′ 41.87″,
Delta
R = Ra – r =
= ( 4h 10m 35.47s ) – ( 2h 31m 47.08s ) = 1h 38m 48.39s,
D = Dec – d =
= ( 89° 15′ 41.87″ ) -( 89° 15′ 50.9″ ) = 0° 0′ 9.03″.

Questions –
Why is the R – difference so big, 1h 38m 48.39s?

This is due to under-accounting of
air conditions and observing wavelength?

[Alex Bilger]

Hi,

I think you are on the wrong SOFA forum. You probably wanted to get help for this SOFA (https://www.iausofa.org/), but our SOFA is sofa-framework.org/.

Good luck.

Alex

[Author]

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