comp.lang.idl-pvwave archive: archive » Re: Coadd images that contain no stars

Home » Public Forums » archive » Re: Coadd images that contain no stars

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: Coadd images that contain no stars [message #80328 is a reply to message #80325]

Sun, 27 May 2012 08:19

spasoklampanas
Messages: 8
Registered: May 2012

Junior Member

On May 27, 6:05 pm, Russell Ryan <rr...@stsci.edu> wrote:
> On May 27, 10:56 am, spasoklampa...@yahoo.com wrote:
>
>> Hi,
>
>> I have two images from GALEX from a molecular cloud, that need to
>> be combined to create an image. The problem is that there are no stars
>> present. There is only the nebula. How is it possible to coadd these
>> two frames? On each image half of the cloud is present and there is
>> some overlap of course. Is there a way in IDL?
>
>> Thanks a lot
>
> Why cant you just add them? I'm confused....
>
> Do you need to align the images? If so, then you need to correlate
> the two images to find the appropriate shifts. Even then, and I know
> how careful you need to be, the GALEX PSF varies across the FoV
> significantly. So coadding frames of anything can be very tricky if
> they're not centered on precisely the same position in the sky.

Well the problem is that in the first frame half of the cloud
appears in the lower left of frame, while in the second frame the
other half appears in the upper right part of the frame. Since there
are no stars present on both images, how is it possible to estimate
the shifting to make the coaddition?

Report message to a moderator

[Message index]

		Re: Coadd images that contain no stars By: Mats Löfdahl on Wed, 30 May 2012 06:03
		Re: Coadd images that contain no stars By: Helder Marchetto on Wed, 30 May 2012 04:53
		Re: Coadd images that contain no stars By: Mats Löfdahl on Wed, 30 May 2012 04:17
		Re: Coadd images that contain no stars By: Helder Marchetto on Wed, 30 May 2012 01:58
		Re: Coadd images that contain no stars By: Russell Ryan on Sun, 27 May 2012 22:26
		Re: Coadd images that contain no stars By: spasoklampanas on Sun, 27 May 2012 08:19
		Re: Coadd images that contain no stars By: spasoklampanas on Sun, 27 May 2012 08:15
		Re: Coadd images that contain no stars By: Russell Ryan on Sun, 27 May 2012 08:05

Previous Topic:	Re: Lion Time Machine error
Next Topic:	VM Save File Problem

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Sat Oct 11 07:52:27 PDT 2025

Total time taken to generate the page: 0.79652 seconds