Any tips for controlling Alnitak?

[Icesheet]

I've collected some dual narrowband and RGB data on the horsehead but I'm really struggling to control Alnitak in what is an image I'm otherwise delighted with.

 

I've attached a screenshot of the STF of the RGB stack and the best draft I have come up with so far. To me it really distracts from the final image. I've tried masking while stretching with/ without stars. Clone stamping, star reduction. Nothing seems to control it or I'm left with a ugly artifact. Anyone out there with any Alnitak magic bullet?!

 

 

Edited November 15, 2023 by Icesheet

[Fegato]

It's hard to manage a very bright star like that, and Alnitak is a favourite bugbear! Even starless processing generally leaves stuff behind which only grows with the stretches. I must admit with mine, I just decided it was part of the glory of the image and let it shine forth! I much prefer a big bright star than any obvious artifacts.

 

[Fegato]

I should add that I use Pixinsight and BlurXTerminator - the latter definitely helps a bit with star size reduction as part of the overall process

[TerryMcK]

Try shooting shorter subs. That way the sensor will not become oversaturated. It will still pick up the wispy stuff and when stacked the image will be great and you will see Alnitak’s companion star. If I remember correctly I shot 120 second subs in Ha and S2 on this one below. There were a lot of subs and it takes some time to stack but I ended up with a good image not dominated by the star.

Most bright objects can be done this way and modern CMOS sensors work well with this method.

[Icesheet]

7 hours ago, Fegato said:

It's hard to manage a very bright star like that, and Alnitak is a favourite bugbear! Even starless processing generally leaves stuff behind which only grows with the stretches. I must admit with mine, I just decided it was part of the glory of the image and let it shine forth! I much prefer a big bright star than any obvious artifacts.

 

Fantastic image and I would happily take your Altinak in all its glory! Yes, StarNet and StarXterminator can’t remove everything and that doesn’t help matters. 
 

6 hours ago, TerryMcK said:

Try shooting shorter subs. That way the sensor will not become oversaturated. It will still pick up the wispy stuff and when stacked the image will be great and you will see Alnitak’s companion star. If I remember correctly I shot 120 second subs in Ha and S2 on this one below. There were a lot of subs and it takes some time to stack but I ended up with a good image not dominated by the star.

Most bright objects can be done this way and modern CMOS sensors work well with this method.

Another great image and it’s very well controlled here. I did think at the time that I should have taken some shorter exposures! I’ll try that next time I have a clear night. My dual narrowband subs have tighter stars as expected but I really don’t like the stars from the L-extreme filter. 
 

[AKB]

8 hours ago, TerryMcK said:

you will see Alnitak’s companion star.

Yes, exactly.  This, for me, is the litmus test on this target.

[tooth_dr]

9 hours ago, TerryMcK said:

Try shooting shorter subs. That way the sensor will not become oversaturated. It will still pick up the wispy stuff and when stacked the image will be great and you will see Alnitak’s companion star. If I remember correctly I shot 120 second subs in Ha and S2 on this one below. There were a lot of subs and it takes some time to stack but I ended up with a good image not dominated by the star.

Most bright objects can be done this way and modern CMOS sensors work well with this method.

There is a terrible background grid pattern in this image?  Any idea what caused it?

 

[tooth_dr]

10 hours ago, Fegato said:

It's hard to manage a very bright star like that, and Alnitak is a favourite bugbear! Even starless processing generally leaves stuff behind which only grows with the stretches. I must admit with mine, I just decided it was part of the glory of the image and let it shine forth! I much prefer a big bright star than any obvious artifacts.

 

Absolutely incredible @Fegato I’m sitting on hours of data I took over the last couple of weeks.  Need to find time to process it!

[The Lazy Astronomer]

Using GHS for stretching, applying RGB colour to Ha stars, and using Starnet to allow a seperate gentler stretch on the stars worked well enough for me I think.

[Icesheet]

7 minutes ago, The Lazy Astronomer said:

Using GHS for stretching, applying RGB colour to Ha stars, and using Starnet to allow a seperate gentler stretch on the stars worked well enough for me I think.

Another great image! How are you adding RGB colour to the Ha stars? 
 

I did use star removal and I can keep it small enough it’s really the halo that I’m struggling with. You don’t seem to have any here which I’m jealous of!

[The Lazy Astronomer]

21 minutes ago, Icesheet said:

Another great image! How are you adding RGB colour to the Ha stars? 
 

I did use star removal and I can keep it small enough it’s really the halo that I’m struggling with. You don’t seem to have any here which I’m jealous of!

Thank you! Although I'm looking at it now in comparison to the others here and thinking I can do better... I think I smell a reprocess coming along (I mean, what else have we got to do - certainly no new data captured recently!!)

This was from a couple of years ago, so I'm afraid I can't be very helpful with how I did it. I think I just applied Ha stars as luminance to the RGB stars then some saturation boosting.

Re: halos, I'm not sure how I got away with none on alnitak, but I'm currently working on a jellyfish nebula image with some fairly large halos around propus and tejat (in Ha and Sii, but not Oiii, interestingly). The tejat one was particularly tricky as it sat over areas of nebulousity as well as background sky; what seems to have worked well so far is to use the GAME script to create a luminance mask around the halo and massively increase the contrast to try and provide more protection to the non-background areas and use some pixelmath to reduce the impact of the halo.

It can also be done more simply with masking and curves - I wasn't able to get a satisfactory result with curves, but then I am something of pixel peeper..

[Icesheet]

Thanks, I’ll look into the GAME script too. Actually, made some progress last night so hoping I can get a satisfactory result.