Opened 18 years ago

Closed 17 years ago

#4 closed defect (fixed)

Incorrect assigning of velocity units from fits files produced from Livedata/gridzilla

Reported by: korinnem@… Owned by: Matthew Whiting
Priority: normal Milestone:
Component: FITS reader Version:
Severity: normal Keywords:
Cc: korinnem@…

Description

I believe I'm using version 1.05 (will be updated to the most recent version shortly, hopefully).

I am using data from the Parkes 6 GHz multibeam, which is constructed into image cubes in Livedata and Gridzilla (AIPS++ Version 1.9 Build 1041). Karma didn't seen to read the velocity units from Gridzilla if I used the vrad parameter to assign the velocity units, so I've been using the AIPS compatible version of velocity (velo-xxx in Gridzilla) instead as Karma does read it.

However, Duchamp does not seem able to detect the velocity keywords from the fits file:

Error: <fixUnits>: WCSUNITS Error, Code=10: Non-conformant unit specifications. Tried to get conversion from " " to km/s. :setting coordinates to 'xx' for clarity.

In the FITS header, for the AIPS version of velocity, that does not get picked up by Duchamp we have:

CTYPE3='VELO-LSR'

If I use VRAD (that for some reason is not being picked up by Karma) CTYPE3='VRAD'

and Duchamp can pick up the velocity units and convert accordingly.

I had found that a temporary fix seems to be adding the keyword: CUNIT3='m/s'

to the header of files with the AIPS definition, but I don't know whether this could cause problems elsewhere or whether I should be using a different keyword or whether anybody else is having a similar problem.

Change History (3)

comment:1 Changed 17 years ago by Matthew Whiting

Component: component1FITS reader
Owner: set to Matthew Whiting
Status: newassigned

I think I know how this is coming about, but I need the data to be able to reproduce the problem.

Could you provide me with the FITS file (or even just the full header)?

comment:2 Changed 17 years ago by Matthew Whiting

This seems to be fixed now, with the improvements to src/FitsIO/wcsIO.cc (from changesets [224] and [226]).

Either grab the latest version of this file and add it to v1.0.7 and recompile, or grab the "beta" distribution from the webpage and try it out, to make sure it works.

Matt.

comment:3 Changed 17 years ago by Matthew Whiting

Resolution: fixed
Status: assignedclosed

Resolving this as 'fixed' -- should have been done earlier!

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