iraf.net

Hello all! I need to explane me somebody how i can auto-rotate images.
I have sum of 20 images of Lyra: http://donastro.jino-net.ru/1/Lyra_20cadrs_4sec_ISO1600_fullMoon_corrected.jpg
So, what i must to do for de-rotate all images before summ it?
Tnx!

By 'de-rotate' and 'auto-rotate' do you mean remove the star trails caused by the Earth's rotation from each frame, or determine the rotation between each image? In either case I don't think there is a task in the system that will currently do this automatically. If you know a star's position in the field you can measure the start/end point of the trail and given the exposure time compute it interactively (and perhaps even create a script for it), but I don't know of a way to process the images in batch mode.-Mike

[quote:9d9da84a2a="fitz"]By 'de-rotate' and 'auto-rotate' do you mean remove the star trails caused by the Earth's rotation from each frame, or determine the rotation between each image? In either case I don't think there is a task in the system that will currently do this automatically. If you know a star's position in the field you can measure the start/end point of the trail and given the exposure time compute it interactively (and perhaps even create a script for it), but I don't know of a way to process the images in batch mode.
-Mike[/quote:9d9da84a2a]
I mean [b:9d9da84a2a]"remove the trails caused by the Earth's rotation from each frame"[/b:9d9da84a2a]. So, what steps i must to go for correct it? What commands i must to use? I don't have any ideas...
Or what software i need to use if in the IRAF i can't to do what?
For me will be best way - do it in the IRAF, of course!
Thanks!

Sorry, but there is no task for removing star trails in the system or any external package that I know of. I suppose if you could derive some sort of deconvolution kernel for the movement it is possible, but still very, very difficult.-Mike

And what about gemini package? Or STSdas? Command "imcoadd"...

You can look around on the net, but the list of external packages is much longer than you mention (see https://iraf.net/article.php/20051211115253923) and nothing I know of removes star trails.-Mike

May be you not correctly understand me?
I mean calculation rotate angle image to image in list.
For example: i have 20 images of Lyra. time from first to last image - 15 minutes. Every image has no star trails, but have a bit of rotation angle with center in the center of image. So, i need to calculate this rotation angle every next image with comparison of FIRST image.
I need something like:
[code:1:a8ac66e5f8]
xrotationregister @lya_list lyra1 rotate.db
[/code:1:a8ac66e5f8]
Of course, "xrotationregister" hypothesiс command...

I'm confused again. In your clarification above you say[quote} mean "remove the trails caused by the Earth's rotation from each frame". [/quote]This cannot currently be done. If you know the time each image was taken you can calculate how far the earth rotated during that time and a task like IMLINTRAN can "de-rotate" the image (and shift a center point if necessary) but it will not remove the trail of each star left because the sky was moving during the exposure.-Mike

I was mean what trails on the sum image(after imcombine) of ALL images! On the single image NO TRAILS, but after sum i SEE trails
Now i know how to do what i need - [b:87f717250e]imcoadd from GEMINI(gemtools)[/b:87f717250e]!
Thx for discuss...

There is probably not a quick way to do this with an @list, but your problem is certainly solvable. It looks like you are taking a sequence of images from a camera not mounted to de-rotate the sky (equatorial mount or 3-axis alt-az-rot). If so, then each of your images will be rotated by a fixed amount relative to the parallactic angle (which changes with time and position on the sky). You will need an accurate time tag to calculate the parallactic angle. If you simply want a relative rotation from one frame to the next, you can match any two stars in a pair of images (4 coords total) and calculate the relative rotation with simple trig.Your other option is to solve for the WCS on each image individually (see msccmatch task) and then use something like drizzle or SWarp to combine them.Dave - LBT Observatory

Ok. Now i use next:
[code:1:4b02b786bf]
imcoadd @m31_list asection="[770:1400,1000:1700] [1700:2100,1000:1500]" alignmethod=twodx rotate+ scale+
[/code:1:4b02b786bf]
If software found too much stars, i use "gain" parameter with low than default value. For example:
[code:1:4b02b786bf]
imcoadd @m31_list asection="[770:1400,1000:1700] [1700:2100,1000:1500]" alignmethod=twodx rotate+ scale+ gain=0.3
[/code:1:4b02b786bf]
About "too much stars": NORMAL value is near 300-700 stars. Too high value is >1500.
On my Celeron D 2.8GHz(up to 3.3GHz) with 1Gb RAM and SATA harddrive(AHCI mode), centering of 10 FITS files with 673 stars take a time near 10-12 minutes(with colebration by darks,flats and biases). But in the DeepSkyStacker under WinXP SP2 indentical task take near 1 hour!!!
IRAF + Linux = ultra high speed!
All what i wrote is "IMHO"...