TheSkySearchers

Hello everyone!
This isn't really a processing question at all but, rather a "What is causing this?" question.
Every time I set my sights on M78 this happens. I've tried it 3 years in a row from different parts of my rather large driveway and different times of night. This is 35 x 3 min frames captured after moonset. Capture time started at 01:30 so outside lighting was not an issue. I'm becoming convinced that there is a bright star just outside my frame that is ruining it.

What would be a good next step in identifying the source?

I was thinking of rotating the camera from 0 degrees to 90 degrees and see if it follows.

Thanks!

Two very bright stars (Alnilam and Alnitak) are both off in the direction that could cause the "rings" you are seeing. However they are quite a ways out of your FOV.
Have you checked to make sure there aren't any reflective surfaces on the inside of your telescope tube that could be causing the reflections?

Steve

STEVE333 wrote: ↑Sun Dec 04, 2022 4:14 am Two very bright stars (Alnilam and Alnitak) are both off in the direction that could cause the "rings" you are seeing. However they are quite a ways out of your FOV.
Have you checked to make sure there aren't any reflective surfaces on the inside of your telescope tube that could be causing the reflections?

Steve

I checked that last year. All I could see was the screws for the focuser were shiny silver so I painted them flat black.
It's just strange that it only happens with this target. I had nothing at all in my M45 image and there are quite a few very bright stars in that.

Thanks.

Larry

Larry 1969 wrote: ↑Sat Dec 03, 2022 10:05 pm I'm becoming convinced that there is a bright star just outside my frame that is ruining it.

What would be a good next step in identifying the source?

I was thinking of rotating the camera from 0 degrees to 90 degrees and see if it follows.

Thanks!

I agree with all said above and by the good comments from others. Pic from Stellarium attached to help visualize the problem. However, identifying the offending reflection spot in your scope is very difficult. Even flat black reflects a bright spot when the incident angle is just right, that's why it is best to have everything turned with threads, but extremely expensive (if not impossible) in amateur gear.
Good luck,
Steve

Seems as though Alnitak is your culprit....

AstroBee wrote: ↑Mon Dec 05, 2022 1:14 am Seems as though Alnitak is your culprit....

I'm suspecting as much as well.
How did you manage that overlay? That's pretty awesome!
Any suggestions for avoiding that? I was thinking about reframing it a bit. Maybe picking a different center. Something a bit more to the right. Maybe splitting the difference between the ringing and the actual target?

Larry

Larry 1969 wrote: ↑Mon Dec 05, 2022 2:30 am How did you manage that overlay? That's pretty awesome!
Larry

Fairly easy. I took a screenshot of your image while viewing it full-size, then took a screenshot of the region in Stellarium.
Brought both images into Photoshop and put your photo on top of the Stellarium background. Made the transparency of your layer 50% so I should see the background through it and then took your layer and adjusted the size and rotation until it matched the background. Change the transparency back to 100% and export to jpeg.

AstroBee wrote: ↑Mon Dec 05, 2022 2:38 am Fairly easy.

Larry 1969 wrote: ↑Mon Dec 05, 2022 2:30 am
Any suggestions for avoiding that? I was thinking about reframing it a bit. Maybe picking a different center. Something a bit more to the right. Maybe splitting the difference between the ringing and the actual target?

Larry

Any or all might work, just trial and error. I have the same problem imaging the Horsehead from zeta Orion, just recentered a tiny bit and it goes away.

All one big mystery of imaging,
Steve

sdbodin wrote: ↑Mon Dec 05, 2022 4:11 am Any or all might work, just trial and error. I have the same problem imaging the Horsehead from zeta Orion, just recentered a tiny bit and it goes away.

All one big mystery of imaging,
Steve

I just wish I could make it out in a single exposure. Then I could make the adjustments in real time.

Larry

Larry 1969 wrote: ↑Mon Dec 05, 2022 11:28 am

sdbodin wrote: ↑Mon Dec 05, 2022 4:11 am Any or all might work, just trial and error. I have the same problem imaging the Horsehead from zeta Orion, just recentered a tiny bit and it goes away.

All one big mystery of imaging,
Steve

I just wish I could make it out in a single exposure. Then I could make the adjustments in real time.

Larry

M78 is such a beautiful target.
Is there anyway to save the date you already have my remediating the halo somewhat?

Juno16 wrote: ↑Mon Dec 05, 2022 12:51 pm
M78 is such a beautiful target.
Is there anyway to save the date you already have my remediating the halo somewhat?

I downloaded the jpeg image into Pixinsight, removed the stars, did some CloneStamping and then replaced the stars to see if it helped. The result is shown below. The approach looks promising.


Steve

STEVE333 wrote: ↑Mon Dec 05, 2022 7:39 pm

Juno16 wrote: ↑Mon Dec 05, 2022 12:51 pm
M78 is such a beautiful target.
Is there anyway to save the date you already have my remediating the halo somewhat?

I downloaded the jpeg image into Pixinsight, removed the stars, did some CloneStamping and then replaced the stars to see if it helped. The result is shown below. The approach looks promising.


M78.jpg


Steve

Excellent work Steve!

I’m sure it too “a few” stamps to accomplish, but you really improved the image!

Juno16 wrote: ↑Mon Dec 05, 2022 12:51 pm M78 is such a beautiful target.
Is there anyway to save the date you already have my remediating the halo somewhat?

I've been trying this for 3 years and failed every time. It's an awesome target and I'm not giving up! Although, I'll probably toss this data. It's not that big of a deal. This was only 90 min TOT.

Larry

STEVE333 wrote: ↑Mon Dec 05, 2022 7:39 pm I downloaded the jpeg image into Pixinsight, removed the stars, did some CloneStamping and then replaced the stars to see if it helped. The result is shown below. The approach looks promising.


Steve

Thanks Steve!
Your process does show some promise, but my processing skills aren't anywhere near that. I'm much better off with clean data. This was only 90 minutes worth, so not a big loss.

Larry

Larry, I'm not sure how you are processing your data but if you are using PixInsight, Adam Block has a tutorial on eliminating these types of reflections in your image. Sort of like the process that Steve did in his correction but he goes into great "typical for Adam, too much" detail on how to do it.

AstroBee wrote: ↑Mon Dec 05, 2022 11:17 pm Larry, I'm not sure how you are processing your data but if you are using PixInsight, Adam Block has a tutorial on eliminating these types of reflections in your image. Sort of like the process that Steve did in his correction but he goes into great "typical for Adam, too much" detail on how to do it.

Thanks for that! I'll give it a look.

Larry