[AstroPy] Using oblique SIN projections in astropy

[Tim Cornwell]

Hi Tom,

Yes, I will do. It’ll take a little time.

Thanks for the help,

Tim

-- 
Tim Cornwell
Sent with Airmail

On 15 December 2016 at 7:57:36 pm, Thomas Robitaille (thomas.robitaille at gmail.com) wrote:

Hi Tim,

Could you share a minimal example script showing what you have tried, just so that we can reproduce the issue?

The correct package to use here is reproject, so it should just be a matter of setting the output WCS correctly. If you can provide an example, I can investigate why it may not be working.

Thanks,
Tom


On 15 December 2016 at 17:48, Tim Cornwell <realtimcornwell at gmail.com> wrote:
Hi Tom,

It’s from an oblique SIN projection to a non-oblique SIN projection. It’s a standard use case for dealing with large fields in radio interferometry. The obliquity varies with time so we reproject a series of snapshot images and add them in non-oblique coordinates.

-- 
Tim Cornwell
Sent with Airmail

On 15 December 2016 at 5:01:01 pm, Thomas Robitaille (thomas.robitaille at gmail.com) wrote:

Hi Tim,

Just to make sure I understand, you are trying to reproject an image to the -SIN projection? What projection is the image originally in?

Cheers,
Tom


On 15 December 2016 at 11:34, Tim Cornwell <realtimcornwell at gmail.com> wrote:
Hi,

I’m trying to use oblique projections in astropy for the SIN (Slant Orthographic) projection. This is well-defined in the Greisen/Calabretta papers and in WCSLIB. I’m confident that casacore can do it but I’d prefer not to have to build CASA for this purpose (a reference library of calibration and imaging algorithms).

In astropy, I can see two different approaches:

- Use the reproject package
- Use astropy.modelling.projections package

I’m struggling with the former. The results do not seem correct. Before diving deeper (which would require building casacore for some comparisons), I’d like to know if trying the second approach is likely to work. What is the relationship between the two packages? 

Thanks,
Tim Cornwell

-- 
Tim Cornwell
Sent with Airmail


_______________________________________________
AstroPy mailing list
AstroPy at scipy.org
https://mail.scipy.org/mailman/listinfo/astropy


_______________________________________________
AstroPy mailing list
AstroPy at scipy.org
https://mail.scipy.org/mailman/listinfo/astropy

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/astropy/attachments/20161215/2f372b61/attachment.html>