[AstroPy] got flux-conservative rebinning?

Marshall Perrin mperrin at stsci.edu
Thu Apr 19 13:50:04 EDT 2012



While we're fishing for useful algorithms, does anyone have a convenient implementation of flux-conservative rebinning? The image interpolations in  scipy.ndimage are not conservative.  Montage can do this, of course, but that seems like overkill (and adds a lot of interface complexity) if I just want to scale an image by 75% while conserving energy...  Thanks in advance,

 - Marshall






On Apr 13, 2012, at 11:47 AM, Wolfgang Kerzendorf wrote:

Hey all,

Thanks for the many suggestions, there seem to be quite a few gems among it. For future reference I have put the suggestions on the astropy wiki (very quick and dirty for now), but hopefully that will help us in the long run when looking for these (only seemingly) simple algorithms to center on an object. Feel free to edit and add to it: https://github.com/astropy/astropy/wiki/2ddata_centroid

I also created a root page for 2ddata utilities at : https://github.com/astropy/astropy/wiki/2ddata_util

Cheers
   Wolfgang

On 2012-04-13, at 5:19 PM, Warren J. Hack wrote:

Wolfgang,

There is a star-finding routine in the soon-to-be-officially-released
drizzlepac package available from STScI.  This routine can be run on its
own (it is all in Python after all), but a stand-alone interface to run
just the star finding has not been documented yet.  It is just a single
function call that requires a numpy array of the image and a few
numerical parameters and I can point you to examples where it is run
within a larger task if you contact me directly. Anyone familiar with
DAOFIND from IRAF will be able to use this code easily.  If you want to
check it out, you can get this code in pre-release beta form (in binary
for Mac or source for other platforms) from:

    http://stsdas.stsci.edu/irafx

We have found that it can provide RMS on point sources of <0.1 pixels
(and seen 0.03 pix RMS in some cases), but your mileage may vary.

Warren Hack
Science Software Branch
STScI

Hey all,

I just wanted to know if anyone has a quick and smart centroid script in any of the python libraries (easily installable). Even better would be star finding algorithms like sextractor.

Cheers
    Wolfgang
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