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Blooming on NGC 3324. Is this something that can be dealt with through post processing?


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Hi all,

I have been using itelescope.net to learn about astrophotography. Obviously I'm quite the beginner here, but on the T9 camera in Siding Springs the telescope information suggests that stars will bloom on exposures above 120 sec. I set it to take 3 frames each of luminance, Red, Green, Blue, Ha and Oiii at 90 sec each, but was still left with some pretty drastic blooming on one star in particular. 

Here is a luminance layer which i have stretched in Photoshop to bring out the details.. Im VERY pleased that the nebulosity of the clouds has shown up so well, but the white stripe has annoyed me somewhat. 

post-11973-0-06468100-1422808260_thumb.j

What say you fellow astronomers? Do any of you have any expertise in this area? 

Im hoping that one of you will laugh at my beginner chops and hand me a solution!

Thanks,

Ianladd

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Hi,

The white strip is blooming. This normally occurs when the charge generated overflows and overcomes the anti blooming system of the sensor.

If you stick with the same sensor - you'll need to reduce the light, or reduce the exposure time - then use the bloom as a mask so that the white bloom is replaced with data from a second set of images..

Nick

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then use the bloom as a mask so that the white bloom is replaced with data from a second set of images..

Would this be possible in Photoshop? Also, I have some of the Red Green and Blue Subs that I need to look at. Would it be possible to use them as a mask to replace the white bloom data in the image?

Apologies.. I'm a bit of a noob at this.

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You may well have been using a scientific camera without anti-blooming gate. These have a more truly linear response than the cameras amateurs use to take aesthetic images. They tend to be particularly good in narrowband.

You can do a Photoshop fix for regions where the bloom passes over background sky. That's easy. Where the bloom passes over nebulosity you have no data for the missing nebulosity but 'context aware fill' can help.

Many stacking programmes have a 'repair bloom' function which guesses at what lay behind the bloom. Astro Art 5 is the one I use.

The perfect solution is to turn the camera through 90 degrees to send the bloom the other way and use that image to fill in behind the bloom. This is probably not going to happen!!

Olly

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Thanks for the reply Olly.

The telescope used was the RCOS 12.5" Richey-Chretien. Im guessing that although itelescope.net provides easy and affordable access to high end technology, the downside is for a beginner it's like learning to drive in a supercar rather than a 1 litre Fiesta.

I'll crack on with trying to find a way to process the image effectively (I'll check out some more stacking software options and possibly order me some reading materials!)

Thanks again for your help folks!

Ian.

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