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About flux unit of input images
07-05-2013, 04:23
Post: #1
About flux unit of input images
Hi~ I have a question about input images. Whether is there any requirement of flux unit for input images by SWarp e.g., flux density such as Jy, or surface brightness such as Jy/sr? I think that it would matter, because SWarp adjusts pixel scale of input images, and thus may need different algorithms for different units.

Thanks in advance.
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07-28-2013, 13:09
Post: #2
RE: About flux unit of input images
Hi ywmao,

SWarp deals with (dimensionless) pixel values, which may be considered as ADUs per unit of pixel area. Depending on the FSCALASTRO_TYPE configuration parameter, these values are either conserved (NONE) or scaled to account for changes in pixel scale between the input and the output (FIXED or VARIABLE). Now, you may apply an extra multiplicative factor to convert pixel values in the units of your choice using a dedicated FITS keyword in each input image header (FLXSCALE is the default keyword name).
- Emmanuel.
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