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<p style="margin: 1.2em 0px ! important;">You can, as David
suggests, initialize an astropy.wcs.WCS object from a FITS
header.</p>
<p style="margin: 1.2em 0px ! important;">You can also create the
SIP coefficients programmatically, as in the following example:</p>
<pre style="font-size: 0.85em; font-family: Consolas,Inconsolata,Courier,monospace;font-size: 1em; line-height: 1.2em; overflow: auto;margin: 1.2em 0px;"><code style="font-size: 0.85em; font-family: Consolas,Inconsolata,Courier,monospace;margin: 0px 0.15em; padding: 0px 0.3em; white-space: nowrap; border: 1px solid rgb(234, 234, 234); background-color: rgb(248, 248, 248); border-radius: 3px; display: inline;white-space: pre; border-radius: 3px; border: 1px solid rgb(204, 204, 204); padding: 0.5em 0.7em;display: block; padding: 0.5em; color: rgb(51, 51, 51); background: none repeat scroll 0% 0% rgb(248, 248, 255);">from astropy import wcs
import numpy as np
w = wcs.WCS()
sip = wcs.Sip([[1.03, 0.98], [1.03, 0.76]], [[1.03, 0.98], [1.03, 0.76]],
[[1.03, 0.98], [1.03, 0.76]], [[1.03, 0.98], [1.03, 0.76]], [0, 0])
w.sip = sip
print w.all_pix2world([[2, 3]], 1)
</code></pre>
<p style="margin: 1.2em 0px ! important;">The <code
style="font-size: 0.85em; font-family:
Consolas,Inconsolata,Courier,monospace;margin: 0px 0.15em;
padding: 0px 0.3em; white-space: nowrap; border: 1px solid
rgb(234, 234, 234); background-color: rgb(248, 248, 248);
border-radius: 3px; display: inline;">Sip</code> constructor
is documented further here: <a
href="http://astropy.readthedocs.org/en/latest/api/astropy.wcs.Sip.html#astropy.wcs.Sip">http://astropy.readthedocs.org/en/latest/api/astropy.wcs.Sip.html#astropy.wcs.Sip</a><br>
and don’t hesitate to ask with further questions.</p>
<p style="margin: 1.2em 0px ! important;">Cheers,<br>
Mike</p>
<p style="margin: 1.2em 0px ! important;">On 12/16/2014 05:22 PM,
David Shupe wrote:</p>
<p style="margin: 1.2em 0px ! important;"></p>
<div class="markdown-here-exclude">
<p></p>
<blockquote
cite="mid:73FF2819-F75D-4BBD-AA3F-51689BB63C0C@ipac.caltech.edu"
type="cite">
<meta http-equiv="Content-Type" content="text/html;
charset=UTF-8">
<br class="">
<div>
<blockquote type="cite" class="">
<div class="">On Dec 16, 2014, at 11:50 AM, Brian York
<<a moz-do-not-send="true"
href="mailto:york@stsci.edu" class="">york@stsci.edu</a>>
wrote:</div>
<br class="Apple-interchange-newline">
<div class="">On 2014/12/16 13:59 , "Paul Kuin" <<a
moz-do-not-send="true" href="mailto:npkuin@gmail.com"
class="">npkuin@gmail.com</a>> wrote:<br class="">
<br class="">
<blockquote type="cite" class="">see<br class="">
Shupe, D.L., et al., 2005, Astronomical Data Analysis
Soft-<br class="">
<br class="">
ware and Systems XIV ASP Conference Series, Vol. 347,
Proceedings of the<br class="">
Conference held 24-27 October, 2004 in Pasadena,
California, USA. Edited<br class="">
by P. Shopbell, M. Britton, and R. Ebert. San
Francisco: Astronomical<br class="">
Soci- ety of the Pacific, 2005., p.491<br class="">
</blockquote>
<br class="">
Thank you. This is definitely a helpful resource. What
it does not have is<br class="">
any information about modifying an astropy.wcs.WCS
object to include these<br class="">
coefficients (given that I am building one
programmatically). Do you have<br class="">
any suggestions on that?<br class="">
<br class="">
<span class="Apple-tab-span" style="white-space:pre"> </span>-Brian<br
class="">
</div>
</blockquote>
</div>
<br class="">
<div class="">Brian, I have extensive experience in converting
polynomials in various formats to WCS and SIP keywords
suitable for inclusion in FITS headers. I haven’t worked
much yet with the astropy.wcs.WCS class, but it does look
like the constructor can take a dictionary of the keywords.
I have some conversion functions written in Python and I’d
be happy to help you off-list with converting your
polynomials.</div>
<div class=""><br class="">
</div>
<div class="">Regards,</div>
<div class=""><br class="">
</div>
<div apple-content-edited="true" class="">
<div style="color: rgb(0, 0, 0); letter-spacing: normal;
orphans: auto; text-align: start; text-indent: 0px;
text-transform: none; white-space: normal; widows: auto;
word-spacing: 0px; -webkit-text-stroke-width: 0px;
word-wrap: break-word; -webkit-nbsp-mode: space;
-webkit-line-break: after-white-space;" class="">David
Shupe</div>
<div style="color: rgb(0, 0, 0); letter-spacing: normal;
orphans: auto; text-align: start; text-indent: 0px;
text-transform: none; white-space: normal; widows: auto;
word-spacing: 0px; -webkit-text-stroke-width: 0px;
word-wrap: break-word; -webkit-nbsp-mode: space;
-webkit-line-break: after-white-space;" class="">IPAC/Caltech</div>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
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</pre>
</blockquote>
<p></p>
</div>
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<pre class="moz-signature markdown-here-signature" cols="72">--
Michael Droettboom
Science Software Branch
Space Telescope Science Institute
<a class="moz-txt-link-freetext" href="http://www.droettboom.com">http://www.droettboom.com</a></pre>
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