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Inaccurate coordinates from SkyCoord.from_name('HD....')

See original GitHub issue

Coordinates returned by SkyCoord.from_name for HD identifiers are almost 1 arcminute from the actual position, e.g., HD97658 = HIP 54906

>>> c_from_hd = SkyCoord.from_name('HD97658')
>>> c_from_hd.to_string(style='hmsdms')
'11h14m32.976s +25d43m19.56s'
>>> c_from_simbad = SkyCoord('11 14 33.161', '+25 42 37.39', unit='hour,degree')
>>> c_from_hd.separation(c_from_simbad).to_string()
'0d00m42.244s'
>>> c_from_hip = SkyCoord.from_name('HIP 54906')
>>> c_from_hip.to_string(style='hmsdms')
'11h14m33.1619s +25d42m37.3902s'
>>> c_from_hd.separation(c_from_hip).to_string()
'0d00m42.2446s'
>>> c_from_hip.separation(c_from_simbad).to_string()
'0d00m00.012s'

EDIT: Code formatting

Issue Analytics

State:
Created 4 years ago
Comments:6 (4 by maintainers)

Top GitHub Comments

3reactions

tbochcommented, Sep 23, 2019

It seems the issue is due to very inaccurate positions of Draper catalogue, used by the VizieR resolver. I’ll forward this to my CDS colleagues.

1reaction

tbochcommented, Oct 7, 2019

I have more information to share: when querying Sesame asking for all resolvers (A flag), you can have indeed have multiple resolvers giving a coordinate. In such a case, it is advised to give priority to Simbad coordinates (the section starting with #=S) if it is present. We can provide with a PR if that helps. cc @bmatthieu3

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