Closer adherence to the FITS standard for position FITS files to ensure future compatibility
Bug #806100 reported by
Jack Ireland
This bug affects 1 person
| Affects | Status | Importance | Assigned to | Milestone | |
|---|---|---|---|---|---|
| Helioviewer.org |
New
|
Undecided
|
Unassigned | ||
Bug Description
The FITS standard includes more information about positioning an image than is currently implemented. A position in a FITS file is calculated as (assuming a helioprojective cartesian co-ordinate system)
position in arcseconds of pixel 'i' = CRVALn + CDELTn*( CRPIXn - i )
where n=1,2. Currently helioviewer.org assumes CRVALn is identically zero for all FITS files, which need not be the case. I don't know if JHelioviewer does the same; but in order to ensure that all FITS files can be properly overlaid, JHV and HV.org should query the FITS files for the value of CRVALn, and use the equation above to calculate the position of a pixel. Thanks!
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