Hi Jane,
CADC require spectral axes to refer to the Barycentric
rest frame. But the source velocity is recorded in the header in the
LSR rest frame. So to compare them you need to get them into the same
rest frame. If, after setting System to VRAD, you do:
% wcsattrib fred.sdf set stdofrest lsr
(where fred.sdf is your NDF cube), do things look better?
David
On 30 November 2010 12:41, Jane Buckle <[log in to unmask]> wrote:
> Hi All,
>
> The JSA HARP/ACSIS reduced data come with the 3rd axis as frequency. After
> using fits2ndf to get the ndf file, and then wcsattrib to set system vrad,
> the velocity of the line is wrong. For instance, a cube with source velocity
> 7.5km/s, as in the fits header, shows in gaia with a line in the centre of
> the band around -10 km/s.
>
> Is there some default I need to change in the fits2ndf, or some attribute
> that I need to set, to get the line at the correct velocity?
>
> Cheers,
>
> Jane
>
>
> --
> Dr Jane V. Buckle
> Cavendish Astrophysics Group and Kavli Institute for Cosmology,
> Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge
> CB3 0HE
> Tel: +44 (0)1223 746436
>
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