[AstroPy] AstroPy Digest, Vol 122, Issue 11

Mihai Cara mihail.cara at gmail.com
Tue Nov 15 11:21:24 EST 2016


Flux conservation for a rotation resampling should not be of concern since
the |Jacobian| of an orthogonal rotation transformation is 1. If you are
also rescaling by the same scaling factor (let's say, "s") for each axis,
you can simply rescale the intensity of the rescaled image by 1/s^2.

Mihai Cara

On 11/15/16, 11:02 AM, "astropy-bounces at scipy.org on behalf of
astropy-request at scipy.org" <astropy-bounces at scipy.org on behalf of
astropy-request at scipy.org> wrote:

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>Today's Topics:
>
>   1. Rotate an image and create new FITS header with updated
>      astrometry (Marcio Melendez)
>   2. Re: Rotate an image and create new FITS header with updated
>      astrometry (Peter Teuben)
>   3. Re: Rotate an image and create new FITS header with	updated
>      astrometry (Marcio Melendez)
>   4. Re: Rotate an image and create new FITS header with updated
>      astrometry (Peter Teuben)
>
>
>----------------------------------------------------------------------
>
>Message: 1
>Date: Tue, 15 Nov 2016 09:26:21 -0500
>From: Marcio Melendez <marcio.melendez at gmail.com>
>To: Astronomical Python mailing list <astropy at scipy.org>
>Subject: [AstroPy] Rotate an image and create new FITS header with
>	updated	astrometry
>Message-ID:
>	<CAJ0xgiQfx9Ddd7JEF8V6F9oDOiFiDzyMUA_M6ENh+0Dm76L8FA at mail.gmail.com>
>Content-Type: text/plain; charset="utf-8"
>
>Hi all,
>Is there a similar function to IDL's  HROT in python, e.g., a function to
>rotate an image and create a new FITS header with updated astrometry.
>
>Thanks!
>
>-- 
>Marcio B. Melendez, Ph.D
>JWST ISIM Optics Support Scientist
>KBRwyle Science, Technology and Engineering Group
>NASA Goddard Space Flight Center  Greenbelt, MD  20771
>Bldg. 29 Rm. T29-10, phone: 301-286-8517
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>
>Message: 2
>Date: Tue, 15 Nov 2016 10:32:55 -0500
>From: Peter Teuben <teuben at astro.umd.edu>
>To: astropy at scipy.org
>Subject: Re: [AstroPy] Rotate an image and create new FITS header with
>	updated astrometry
>Message-ID: <0381c927-1026-2610-64d9-54e5611e5c2b at astro.umd.edu>
>Content-Type: text/plain; charset="windows-1252"
>
>the best is to use the python interface to montage. it's a contributed
>package for astropy.
>
>On 11/15/2016 09:26 AM, Marcio Melendez wrote:
>> Hi all, 
>> Is there a similar function to IDL's  HROT in python, e.g., a function
>>to rotate an image and create a new FITS header with updated astrometry.
>>
>> Thanks!
>>
>> -- 
>> Marcio B. Melendez, Ph.D
>> JWST ISIM Optics Support Scientist
>> KBRwyle Science, Technology and Engineering Group
>> NASA Goddard Space Flight Center  Greenbelt, MD  20771
>> Bldg. 29 Rm. T29-10, phone: 301-286-8517
>>
>>
>> _______________________________________________
>> AstroPy mailing list
>> AstroPy at scipy.org
>> https://mail.scipy.org/mailman/listinfo/astropy
>
>
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>------------------------------
>
>Message: 3
>Date: Tue, 15 Nov 2016 10:55:37 -0500
>From: Marcio Melendez <marcio.melendez at gmail.com>
>To: Astronomical Python mailing list <astropy at scipy.org>
>Subject: Re: [AstroPy] Rotate an image and create new FITS header with
>	updated astrometry
>Message-ID:
>	<CAJ0xgiRUSbZm=mc1EX8j2odG4JzVc1hCrgsmtpNO_dJb9f8EWg at mail.gmail.com>
>Content-Type: text/plain; charset="utf-8"
>
>Hi Peter,
>I use Montage mainly for display purpose, to get the correct sky
>orientation, but I have never used it to perform any operation. I see that
>there is a rotation utility, mRotate, but from the description "This
>module
>is meant for quick-look only; it is *not flux conserving*." which is not
>useful for what I need. Are there any other options?
>
>Thanks!
>
>On Tue, Nov 15, 2016 at 10:32 AM, Peter Teuben <teuben at astro.umd.edu>
>wrote:
>
>> the best is to use the python interface to montage. it's a contributed
>> package for astropy.
>>
>>
>> On 11/15/2016 09:26 AM, Marcio Melendez wrote:
>>
>> Hi all,
>> Is there a similar function to IDL's  HROT in python, e.g., a function
>>to
>> rotate an image and create a new FITS header with updated astrometry.
>>
>> Thanks!
>>
>> --
>> Marcio B. Melendez, Ph.D
>> JWST ISIM Optics Support Scientist
>> KBRwyle Science, Technology and Engineering Group
>> NASA Goddard Space Flight Center  Greenbelt, MD  20771
>> Bldg. 29 Rm. T29-10, phone: 301-286-8517
>>
>>
>> _______________________________________________
>> AstroPy mailing 
>>listAstroPy at scipy.orghttps://mail.scipy.org/mailman/listinfo/astropy
>>
>>
>>
>> _______________________________________________
>> AstroPy mailing list
>> AstroPy at scipy.org
>> https://mail.scipy.org/mailman/listinfo/astropy
>>
>>
>
>
>-- 
>Marcio B. Melendez, Ph.D
>JWST ISIM Optics Support Scientist
>KBRwyle Science, Technology and Engineering Group
>NASA Goddard Space Flight Center  Greenbelt, MD  20771
>Bldg. 29 Rm. T29-10, phone: 301-286-8517
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>------------------------------
>
>Message: 4
>Date: Tue, 15 Nov 2016 11:02:39 -0500
>From: Peter Teuben <teuben at astro.umd.edu>
>To: astropy at scipy.org
>Subject: Re: [AstroPy] Rotate an image and create new FITS header with
>	updated astrometry
>Message-ID: <c3123e19-61b3-f881-7d48-dba36726604b at astro.umd.edu>
>Content-Type: text/plain; charset="windows-1252"
>
>Marcio
>  I didn't know they didn't flux conserve. You should file a bug report.
>They love those.
>
> I know the equivalent routine in miriad (regrid) does conserve flux, but
>it's normally used on radio data with a well described beam. Not that
>your data doesn't have those, but in a bind that's another way.
>
>Alternatively you could use mRotate, and measure the flux in some large
>area, and rescale manually if need be.
>
>peter
>
>On 11/15/2016 10:55 AM, Marcio Melendez wrote:
>> Hi Peter, 
>> I use Montage mainly for display purpose, to get the correct sky
>>orientation, but I have never used it to perform any operation. I see
>>that there is a rotation utility, mRotate, but from the description
>>"This module is meant for quick-look only; it is *not flux conserving*."
>>which is not useful for what I need. Are there any other options?
>>
>> Thanks! 
>>
>> On Tue, Nov 15, 2016 at 10:32 AM, Peter Teuben <teuben at astro.umd.edu
>><mailto:teuben at astro.umd.edu>> wrote:
>>
>>     the best is to use the python interface to montage. it's a
>>contributed package for astropy.
>>
>>
>>     On 11/15/2016 09:26 AM, Marcio Melendez wrote:
>>>     Hi all, 
>>>     Is there a similar function to IDL's  HROT in python, e.g., a
>>>function to rotate an image and create a new FITS header with updated
>>>astrometry. 
>>>
>>>     Thanks!
>>>
>>>     -- 
>>>     Marcio B. Melendez, Ph.D
>>>     JWST ISIM Optics Support Scientist
>>>     KBRwyle Science, Technology and Engineering Group
>>>     NASA Goddard Space Flight Center  Greenbelt, MD  20771
>>>     Bldg. 29 Rm. T29-10, phone: 301-286-8517 <tel:301-286-8517>
>>>
>>>
>>>     _______________________________________________
>>>     AstroPy mailing list
>>>     AstroPy at scipy.org <mailto:AstroPy at scipy.org>
>>>     https://mail.scipy.org/mailman/listinfo/astropy
>>><https://mail.scipy.org/mailman/listinfo/astropy>
>>
>>     _______________________________________________ AstroPy mailing
>>list AstroPy at scipy.org <mailto:AstroPy at scipy.org>
>>https://mail.scipy.org/mailman/listinfo/astropy
>><https://mail.scipy.org/mailman/listinfo/astropy>
>>
>> -- 
>> Marcio B. Melendez, Ph.D
>> JWST ISIM Optics Support Scientist
>> KBRwyle Science, Technology and Engineering Group
>> NASA Goddard Space Flight Center  Greenbelt, MD  20771
>> Bldg. 29 Rm. T29-10, phone: 301-286-8517
>>
>> _______________________________________________
>> AstroPy mailing list
>> AstroPy at scipy.org
>> https://mail.scipy.org/mailman/listinfo/astropy
>
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>End of AstroPy Digest, Vol 122, Issue 11
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