The Jellyfish Nebula - artistic non-OIII version (24.6 hrs)

[ollypenrice]

2 hours ago, AstroGS said:

@ollypenrice this is how it looks after (my personal best) stretching. I tried through the available Pixinsight tools (that I know of) to remove the halos but, since they are integrated in the nebulosity, I am finding it difficult to remove without leaving a residual shadow.

I don't see why the version below wouldn't work.

This was given a soft stretch in Ps Levels and de-starred in StarXt. The artifacts from the two big stars were lassoed and given Content Aware Fill before the stretch was taken further using custom shaped curves. Terrible shame to throw it away!

(If it would be any good to you I could dropbox you the 16 bit Tiff. Just PM me an email address.)

Olly

 

Edited February 18 by ollypenrice

[AstroGS]

Very impressed - thank you.

I will most certainly do so.

[Adam J]

On 18/02/2024 at 13:03, AstroGS said:

@ollypenrice this is how it looks after (my personal best) stretching. I tried through the available Pixinsight tools (that I know of) to remove the halos but, since they are integrated in the nebulosity, I am finding it difficult to remove without leaving a residual shadow.

Interesting that you are getting microlensing from a ASI2600mm?? Anyone else ever had this? Are you sure your filter is the correct way around?

Adam

[Stuart1971]

9 hours ago, Adam J said:

Interesting that you are getting microlensing from a ASI2600mm?? Anyone else ever had this? Are you sure your filter is the correct way around?

Adam

Yea, my thoughts too, I have only ever seen this from the ASI1600..🤔

[AstroGS]

10 hours ago, Adam J said:

Interesting that you are getting microlensing from a ASI2600mm?? Anyone else ever had this? Are you sure your filter is the correct way around?

Adam

@Adam J @Stuart1971 I thought so too. We changed the orientation of the filter to eliminate this possibility and the results were more or less the same. Another thought was that Pertzval design OTAs might be more susceptible to such effects - especially on OIII @ 2.8nm. But, since the SII & Ha Antlia filters are excellent, I consider the OIII to be defective and will be returned.

[Stuart1971]

21 minutes ago, AstroGS said:

@Adam J @Stuart1971 I thought so too. We changed the orientation of the filter to eliminate this possibility and the results were more or less the same. Another thought was that Pertzval design OTAs might be more susceptible to such effects - especially on OIII @ 2.8nm. But, since the SII & Ha Antlia filters are excellent, I consider the OIII to be defective and will be returned.

The Petzval design should actually be better, as the flattener built into the scope is much further away from the sensor, to make a reflection such as what you are seeing,  so any reflections from that glass, going back to the sensor will be spread too wide by the time it reaches the sensor, your reflections are from a source much closer to the sensor itself.

My guess would have been the filter anti reflective surface that should point toward the sky is actually pointing at the sensor…but you have tested this so I am at a loss

Edited February 25 by Stuart1971

[Adam J]

32 minutes ago, AstroGS said:

@Adam J @Stuart1971 I thought so too. We changed the orientation of the filter to eliminate this possibility and the results were more or less the same. Another thought was that Pertzval design OTAs might be more susceptible to such effects - especially on OIII @ 2.8nm. But, since the SII & Ha Antlia filters are excellent, I consider the OIII to be defective and will be returned.

I don't think it's the scope. The filter is suspect in my view and if a new filter doesn't solve it maybe the coating on the sensor cover glass is defective. Definitely contact your supplier. 

It's actually potentially worse than what I have seen from the ASI1600mm pro on that target. On the 1600 it would be confined to only the two brightest stars and no others in that field of view. 

Edited February 25 by Adam J

[AstroGS]

32 minutes ago, Adam J said:

I don't think it's the scope. The filter is suspect in my view and if a new filter doesn't solve it maybe the coating on the sensor cover glass is defective. Definitely contact your supplier. 

It's actually potentially worse than what I have seen from the ASI1600mm pro on that target. On the 1600 it would be confined to only the two brightest stars and no others in that field of view. 

@Adam J if it was the sensor cover glass, wouldnt there be an issue with all filters - including the SII and OIII?

 

[Adam J]

On 25/02/2024 at 11:18, AstroGS said:

@Adam J if it was the sensor cover glass, wouldnt there be an issue with all filters - including the SII and OIII?

 

Doesn't have to be the case, the AR coating is not a single layer but a stack of layers that are optimised for different wavelength ranges. It is entirely possible (depending on quality control) for one of those layers to be messed up and the others to still work. 

However, until disproved with a different filter the OIII being defective remains the most likely issue. 

The most likely issue with the filter itself is that it is not cutting IR effectively and allowing light to pass in the IR that is potentially outside of the wavelength range covered by the sensor AR coating and so those micro lens diffraction patterns are generated by IR as opposed to the OIII part of the spectrum....not that it matters why in the end.

I say this as the its happening on even less bright stars yet at the same time the OIII line is still clearly well filtered given the signal you still gathered. 

Like I say just a theory to match the observed effects. 

Adam

Edited February 26 by Adam J

[900SL]

Can I ask a question about mono narrowband on the Jellyfish?

I've already shot 3 hrs of Ha a month ago, but then clouds and I'm running out of time now.  Here's a quick stretched starless Ha stack below, B5 location, Antlia Edge filters

So I may have a clear night with the moon not rising till late on the 3rd March.

Q: Is it better to shoot Sii or Oiii if you are limited in time? I may be able to bag another 4 hours but it's uncertain as to whether I can get any more this season.

HSS? or try to get the noisy Oiii which is pretty limited on this target, as I understand it, and which seems to need several hours to get the SNR up ?

 

[Stuart1971]

I would go with OIII, especially on that target, SII is in the red same as the Ha, so go with the Blue OIII, then you will have a great HOO image when processed…👍🏻 

[900SL]

@Stuart1971 My only thinking was that the Sii signal seems much more extensive than Oiii in the Jelly, so doing an HSS and mapping Sii to green and blue would give a nice multicoloured image, unless of course the Sii is coincidental with the Ha,

I do see the Oiii highlights in the Jellyfish on astrobin though, so I get where you are coming from here

 

[Stuart1971]

3 minutes ago, 900SL said:

@Stuart1971 My only thinking was that the Sii signal seems much more extensive than Oiii in the Jelly, so doing an HSS and mapping Sii to green and blue would give a nice multicoloured image, unless of course the Sii is coincidental with the Ha,

I do see the Oiii highlights in the Jellyfish on astrobin though, so I get where you are coming from here

 

Yes, I think maybe either way will give you a very fine image, if the SII is stronger then yes, your idea will be good…I maybe was getting mixed up with another target, as I thought the OIII was strong in the Jellyfish…

[AstroGS]

On 01/03/2024 at 10:38, 900SL said:

Can I ask a question about mono narrowband on the Jellyfish?

I've already shot 3 hrs of Ha a month ago, but then clouds and I'm running out of time now.  Here's a quick stretched starless Ha stack below, B5 location, Antlia Edge filters

So I may have a clear night with the moon not rising till late on the 3rd March.

Q: Is it better to shoot Sii or Oiii if you are limited in time? I may be able to bag another 4 hours but it's uncertain as to whether I can get any more this season.

HSS? or try to get the noisy Oiii which is pretty limited on this target, as I understand it, and which seems to need several hours to get the SNR up ?

 

Did not see it time for yesterday. OIII would have been my choice too but, it requires a good few hours (5+ I would say) @300 sec or even 600 sec exposures to really get some good signal. On the other hand my iteration of this image has no OIII at all and instead it is mainly Ha and SII, with RGB for stars.

Edited March 2 by AstroGS