MaxIm settings and poorly shaped stars in PhotoshopCS3

[TheDecepticon]

Howdy.

I use MaxIm for my astro stuff, including plate solving with PinPoint LE. I down loaded the Guide Star Catalouge 1.1 to use with it, works great, except for the annoying little warning message I always get that says I would be better off using the corrected catalouge rather than the one I have. Of course, I would try the USNO2 catalouge, but that is a 6Gb download.

Is there a way to turn off this annoying little warning, as it is a great interrupter when I am tyring to use PinPoint for Astrometric alignment in the Combine dialouge applet as I have to sit there and click the warning off for each sub frame.

My next question relates to the shape of stars in photoshop CS3. In MaxIm, Deep Sky Stacker or CCDStack, my stars are reasonably shaped and roundish, with definite edges. In PSCS3, they are always sort of square and horridly shaped and the halo around the brighter ones shows tiny little squares. It is driving me nuts, as it makes me think I have really bad stars and puts me off processing my images cause I think I have bad data. Is this a setting I have missed or is it just PSCS3?

Thanks!

[multiweb (Marc)]

Originally Posted by TheDecepticon

My next question relates to the shape of stars in photoshop CS3. In MaxIm, Deep Sky Stacker or CCDStack, my stars are reasonably shaped and roundish, with definite edges. In PSCS3, they are always sort of square and horridly shaped and the halo around the brighter ones shows tiny little squares.

Are you saving 16bits TIFFs prior to go in PS or do you open as a FITS file?

[TheDecepticon]

Mmmmm....generally as fits files.

[multiweb (Marc)]

Originally Posted by TheDecepticon

Mmmmm....generally as fits files.

Could be clipping. Can you post any screen grab of the same area in Maxim or other then in PS to compare?

[jase (Jason)]

Originally Posted by TheDecepticon

Howdy.

I use MaxIm for my astro stuff, including plate solving with PinPoint LE. I down loaded the Guide Star Catalouge 1.1 to use with it, works great, except for the annoying little warning message I always get that says I would be better off using the corrected catalouge rather than the one I have. Of course, I would try the USNO2 catalouge, but that is a 6Gb download.

Is there a way to turn off this annoying little warning, as it is a great interrupter when I am tyring to use PinPoint for Astrometric alignment in the Combine dialouge applet as I have to sit there and click the warning off for each sub frame.

Truth be told, the message you are receiving shouldn't be dismissed. For the most part the standard GSC1.1 will work fine. Especially if all you are doing is using it to for astrometic image alignment. However, in the real world, there is really no reason why you shouldn't run the corrected version of GSC1.1 aka GSC-ACT. This will at least remove the warning you receive.

I'm going to assume you got your GSC1.1 from a reputable source and its working well. Keeping the directory structure is key. You have indicated that astrometic aligns do work, so we're on the right path.

There are two options;
You can download the corrected version in full here - ftp://cdsarc.u-strasbg.fr/pub/cats/I/255/
-or-
Pinpoint can make corrections on the fly to the original GSC1.1 if the GSC_ACT.DAT file is located in the same directory as Pinpoint.dll. What I am however uncertain of is how well this will work with Pinpoint LE. I use the full version of Pinpoint which actually comes with the correction .DAT file. The DAT file if you don't already have it can be downloaded here - http://home.gwi.net/~pluto/gsc_act.zip

Let me know how you get on.

[jase (Jason)]

Originally Posted by TheDecepticon

Is there a way to turn off this annoying little warning, as it is a great interrupter when I am tyring to use PinPoint for Astrometric alignment in the Combine dialouge applet as I have to sit there and click the warning off for each sub frame.

Cloudy night, having a break in processing another data set, this thread sparked interest as to the gains of Astrometric alignment versus "auto - star matching" or "manual - two stars". Test after test I measured the FWHM of subs that had been aligned/combined using the three algorithms. I could not tell the different from statistical figures between the alignment methods. This leads me to the conclusion that Astrometic alignment has no gain over regular pattern matching or manual 2 star matching. What it may assist with is the addressing the initial rotation or flipping of subs, alas this can easily be addressed with a manual 2 star alignment. The point being is while its probably pretty cool to platesolve and align an image, you're actually getting no better result performing the alignment task any other way. They'll all rotate, skew, shift to deliver the same end result in alignment.

You may wish to perform your own tests to validate and perhaps use another alignment method if you're still having concerns in getting the corrected GSC operational.

[TheDecepticon]

Originally Posted by multiweb

Could be clipping. Can you post any screen grab of the same area in Maxim or other then in PS to compare?

Hi Marc! Mmmm...I had forgotten, but it is interesting that you say that. When opening a fits file, Fits Liberator used to pop up and let me set the sliders etc, now Photoshop opens them automagically. I might try to find out why, before I go any further.

Originally Posted by jase

Truth be told, the message you are receiving shouldn't be dismissed. For the most part the standard GSC1.1 will work fine. Especially if all you are doing is using it to for astrometic image alignment. However, in the real world, there is really no reason why you shouldn't run the corrected version of GSC1.1 aka GSC-ACT. This will at least remove the warning you receive.

I'm going to assume you got your GSC1.1 from a reputable source and its working well. Keeping the directory structure is key. You have indicated that astrometic aligns do work, so we're on the right path.

There are two options;
You can download the corrected version in full here - ftp://cdsarc.u-strasbg.fr/pub/cats/I/255/
-or-
Pinpoint can make corrections on the fly to the original GSC1.1 if the GSC_ACT.DAT file is located in the same directory as Pinpoint.dll. What I am however uncertain of is how well this will work with Pinpoint LE. I use the full version of Pinpoint which actually comes with the correction .DAT file. The DAT file if you don't already have it can be downloaded here - http://home.gwi.net/~pluto/gsc_act.zip

Let me know how you get on.

I have the demo version of Pinpoint. I didn't find a pinpoint.dll file in the Pinpoint folder, but I did find the same file in MaxIm that is in Pinpoint, so I downloaded the data file and popped it into MaxIm. It seems to have done the trick.

Originally Posted by jase

Cloudy night, having a break in processing another data set, this thread sparked interest as to the gains of Astrometric alignment versus "auto - star matching" or "manual - two stars". Test after test I measured the FWHM of subs that had been aligned/combined using the three algorithms. I could not tell the different from statistical figures between the alignment methods. This leads me to the conclusion that Astrometic alignment has no gain over regular pattern matching or manual 2 star matching. What it may assist with is the addressing the initial rotation or flipping of subs, alas this can easily be addressed with a manual 2 star alignment. The point being is while its probably pretty cool to platesolve and align an image, you're actually getting no better result performing the alignment task any other way. They'll all rotate, skew, shift to deliver the same end result in alignment.

You may wish to perform your own tests to validate and perhaps use another alignment method if you're still having concerns in getting the corrected GSC operational.

I like the Astometric approach as I use it for mount alignment and alignment refinement and when it comes to stacking, Im lazy and find it aligns just a little bit better for me than Auto does, especially on combining RGB. Thanks for the extra info.