Odd abnormality in my M45

[Larry 1969]

Good day all!
I recently had a bit of short lived success with M33 and that got my hopes up that maybe I was out of my slump...
I rotated my camera approx 90 degrees in order to frame M45 at 840mm and I spent about 5 hours on it.
I took new flats and dark flats because of the rotation and ran it all through DSS. After processing in StarTools I had this.

Not only was the result disappointing, I noticed these weird artifacts (circled)...
I have to say that, even though I started imaging almost 1 hour after astronomical darkness, my first 15 - 20 images seemed much brighter than the rest and their score for sky background in DSS was very high. I tried eliminating them from my stack but my results were no better and the artifacts were still present although not as obvious...

Any ideas what could be causing these?

Thanks!

Larry

[bobharmony]

Interesting, Larry. My first thought was some sort of reflection in the optical train, but I'm guessing the only glass in the path is the coma corrector. There is some nice detail showing in any case.

A note for future, taking flats when you rotate the camera is a good thing, but you don't need to do new dark flats. I know it doesn't take much time, but as long as the new flat parameters match the old ones you can reuse the old dark flats.

About the brighter background in early sub - I get this a lot as my target climbs out of Hartfords light dome. Might you be seeing something similar?

Bob

[Larry 1969]

Thanks Bob.
Yes. The only glass is the CC unless you count the IR/UV cut filter that I have screwed to the CC.
I'm not aware of anything to my east except for a church about 1 mile from me that installed one of those super bright LED billboards.
I can't say I notice it from my place but do you think the camera might pick up on it?

As for the flats, I'm still trying to find a good solution so my exposure time varies for now.

Larry

[Larry 1969]

Looking closer, it seems these anomalies are in the same pattern as the bright stars...
I didn't notice this initially...

Larry

[Shabadoo]

Aliens?

[Larry 1969]

Aliens?

The "experts" on Facebook already suggested that...

Larry

[bobharmony]

Looking closer, it seems these anomalies are in the same pattern as the bright stars...
I didn't notice this initially...

Larry

There is even one you don't have circled in the dust cloud surrounding Merope. Maybe there is some kind of reflection going on there.

Bob

[Larry 1969]

There is even one you don't have circled in the dust cloud surrounding Merope. Maybe there is some kind of reflection going on there.

Bob

I saw that after I put it all together.
I think I'm going to try it without the IR/UV filter.

Larry

[bobharmony]

I saw that after I put it all together.
I think I'm going to try it without the IR/UV filter.

Larry

It will be interesting to see if that makes a difference. I am no expert in these things. Hopefully someone with expertise will come along and comment.

Bob

[Larry 1969]

UPDATE:

I set up last night despite the high clouds and was able to get 150X3min exposures on M45 WITHOUT my IR?UV cut filter.
Conditions were so poor that, out of that 150 I kept 39 and even they were questionable.
I stacked them with my previous calibration frames (I even re-used the flats after removing the filter) and got this.

1:57 total exposure and, like I said, even these frames were pretty poor.

I'm going to leave out the filter and revisit some of the targets that have been torturing me.

[STEVE333]

Wow Larry, it looks much cleaner to me. Does this mean that the IR/UV cut filter was the culprit?

I know many people use an IR/UV cut filter. Maybe it depends on which manufacturer you use? Not fair!!

Steve

[Juno16]

Hi Larry,

Definitely much clearer, but the latest image is a huge difference in process. Depending on the camera, you might really need a “good” uv/ir cut filter. As I have understand it, most ASI OSC cameras need one.

Still no help with your anomaly’s though. Ether way, a nice image Larry!

[Larry 1969]

Wow Larry, it looks much cleaner to me. Does this mean that the IR/UV cut filter was the culprit?

I know many people use an IR/UV cut filter. Maybe it depends on which manufacturer you use? Not fair!!

Steve

I believe the filter was the culprit of the reflections. More time will tell...

Larry

[Larry 1969]

Hi Larry,

Definitely much clearer, but the latest image is a huge difference in process. Depending on the camera, you might really need a “good” uv/ir cut filter. As I have understand it, most ASI OSC cameras need one.

Still no help with your anomaly’s though. Ether way, a nice image Larry!

Yes. I processed the images a bit differently. The original was processed with StarTools 1.6 and I processed the latest with StarTools 1.7 alpha but the data was SOOO much easier I think I could have achieved similar results with 1.6.

I'm hoping to revisit some troublesome targets without the filter to compare.

Larry

[bobharmony]

That is a much cleaner image! I don't think the switch from 1.6 to 1.7 is enough to account for it. The original image almost looks foggy, where the new one is much crisper.

Bob

[Larry 1969]

That is a much cleaner image! I don't think the switch from 1.6 to 1.7 is enough to account for it. The original image almost looks foggy, where the new one is much crisper.

Bob

And the initial image was captured under pretty nice skies while I suffered with high clouds the entire second session.
The data from the first session should have been much cleaner and the result was terrible...

The funny thing is I've never had any luck with filters. When I was using a DSLR I got an Astronomik CLS/CCD filter and it hurt my images.
Now this IR/UV cut filter seems to be doing the same. I'm going to leave it out for my next several sessions before I pass judgement though.

Larry

[bobharmony]

As I understand it the main reason for the cut filter is to prevent star bloat from the IR signal. I'm not sure that is as important in reflectors as it is in refractors as there is less diffraction by the optics in a reflector.

My experience with DSLRs and filters was not positive and I abandoned them pretty quickly. I didn't like dealing with weird color casts they generated.

It will be interesting to see what you get from dropping the cut filter.

Bob

[Larry 1969]

I was having pretty good success before the filter (at least good for me).
I just occurred to me... Since the filter screwed on to the base of my CC, what if there was some fogging or even frost occurring due to the air in between the filter and CC having some humidity or something?

If that were the case, how might one prevent it?

Thanks!

Larry