Sh2-257

[ollypenrice]

Paul captured and pre-processed this with an eye on using it to enhance our Orion-Monoceros mosaic, which I'll look into later.

Initially I found a very nice starfield and a very small nebula in the data:

However, looking at the nebula at full size, it proved surprisingly interesting so I did a close crop and a more intensive star reduction so as to present it like this:

RASA 8, ASI2600MC, NEQ6. 116x3 minute subs.

Edit: blended into our giant mosaic it looks like this, if you can find it! (Below the Monkey Head nebula.) https://ollypenrice.smugmug.com/Other/Emission-Nebulae/i-G8HJCM3/A

Olly

 

Edited February 13 by ollypenrice

[Stuart1971]

5 hours ago, ollypenrice said:

Paul captured and pre-processed this with an eye on using it to enhance our Orion-Monoceros mosaic, which I'll look into later.

Initially I found a very nice starfield and a very small nebula in the data:

However, looking at the nebula at full size, it proved surprisingly interesting so I did a close crop and a more intensive star reduction so as to present it like this:

RASA 8, ASI2600MC, NEQ6. 116x3 minute subs.

Edit: blended into our giant mosaic it looks like this, if you can find it! (Below the Monkey Head nebula.) https://ollypenrice.smugmug.com/Other/Emission-Nebulae/i-G8HJCM3/A

Olly

 

Olly, with these superb broadband images you regularly post, and are using a 2600 OSC camera, do you use any filters at all, ie, any light pollution suppression such as an L-Pro or similar…? Or are they totally unfiltered…?

[ollypenrice]

28 minutes ago, Stuart1971 said:

Olly, with these superb broadband images you regularly post, and are using a 2600 OSC camera, do you use any filters at all, ie, any light pollution suppression such as an L-Pro or similar…? Or are they totally unfiltered…?

From memory, I think the camera has a cutoff filter built in. We certainly don't use any external LP or narrowband filters. Neither I nor anybody else I can think of has ever used an LP filter here because it isn't necessary. This is a dark site reaching SQM22. I've also used CCD OSC cameras here, again with no additional filtration.

The degree of NB capture we get from the otherwise unfiltered OSC varies. No sign of the Squid, for instance, but Goran showed that the same setup can do a great job on it with a dual band filter.  We got very little signal from Simeis 147 (Spaghetti Nebula) in Ha, either, but many Ha objects come through beautifully.

What I like is that the proportion of dust to gas is swung in favour of the dust on many familiar targets, meaning we get a new look.

Olly

 

[petevasey]

Hi, Olly,

Wow that's one heck of a project!  And the image of Sharpless 257, when in the vertical configuration, puts me in mind very much of Dan Dare's arch enemy 'The Mekon', particularly with a colour adjustment.   I wonder if calling it 'The Mekon Nebula' will ever catch on 🤡

Cheers, Peter

Edited February 13 by petevasey

[AKB]

13 minutes ago, petevasey said:

puts me in mind very much of Dan Dare's arch enemy 'The Mekon', particularly with a colour adjustment.

...and in a slightly yellower treatment, it could surely be Homer Simpson??

[ollypenrice]

11 hours ago, petevasey said:

Hi, Olly,

Wow that's one heck of a project!  And the image of Sharpless 257, when in the vertical configuration, puts me in mind very much of Dan Dare's arch enemy 'The Mekon', particularly with a colour adjustment.   I wonder if calling it 'The Mekon Nebula' will ever catch on 🤡

Cheers, Peter

When I started processing the crop I had it in a vertical orientation and there was something slightly disconcerting about it. It made me feel distinctly uncomfortable and I think you've identified the reason why.  It was a relief to find that its orientation for us was horizontal. Once rotated, I no longer felt spooked by the darned thing...

I do think that Paul's RASA has performed out of its skin, finding so much detail in a tiny object for a 400mm widefield focal length - and in broadband.  This is my answer to doubters who don't like its numbers on paper. In no small measure its success, here, is down tho the volume of signal it found in 5.8 hours. In the real wold of imaging the relationship between signal and resolution is complex. They cannot, on targets like this, be considered as independent properties.

Olly

[Stuart1971]

55 minutes ago, ollypenrice said:

When I started processing the crop I had it in a vertical orientation and there was something slightly disconcerting about it. It made me feel distinctly uncomfortable and I think you've identified the reason why.  It was a relief to find that its orientation for us was horizontal. Once rotated, I no longer felt spooked by the darned thing...

I do think that Paul's RASA has performed out of its skin, finding so much detail in a tiny object for a 400mm widefield focal length - and in broadband.  This is my answer to doubters who don't like its numbers on paper. In no small measure its success, here, is down tho the volume of signal it found in 5.8 hours. In the real wold of imaging the relationship between signal and resolution is complex. They cannot, on targets like this, be considered as independent properties.

Olly

So how do you stand in the age old Mono V OSC discussion…as you certainly seem to have taken to the OSC on the RASA…? Do you not feel that you miss mono imaging, as I know it’s pretty hard with the RASA set up with not being able to use a filter wheel.

[ollypenrice]

8 minutes ago, Stuart1971 said:

So how do you stand in the age old Mono V OSC discussion…as you certainly seem to have taken to the OSC on the RASA…? Do you not feel that you miss mono imaging, as I know it’s pretty hard with the RASA set up with not being able to use a filter wheel.

I miss mono less than I expected to for three reasons: 1) The RASA pulls is such a vast amount of signal that what is normally 'narrowband or nothing' often, but not always, appears bright and clear in OSC. 2) I have in stock, or can obtain through collaboration, NB where its essential. 3) A dual or triband filter remains an option for the future.

At F2 in both our current rigs (the Samyang 135 being the other) I'm enjoying OSC, but I still think it is too slow for slower systems. Using NB filters is itself a slow business but it is, in practice, a shortcut to getting faint emission signal to show in the final image. The isolated NB can be stretched harder relative to the other reds, which is why it's a shortcut.

I don't think I'd like OSC so much in more normal imaging systems.

Olly

[petevasey]

4 hours ago, ollypenrice said:

I do think that Paul's RASA has performed out of its skin, finding so much detail in a tiny object for a 400mm widefield focal length - and in broadband.  This is my answer to doubters who don't like its numbers on paper. In no small measure its success, here, is down tho the volume of signal it found in 5.8 hours. In the real wold of imaging the relationship between signal and resolution is complex. They cannot, on targets like this, be considered as independent properties.

Olly

Yes indeed, superb!  Of course the Dawes limit for an 8" optic is 0.57 arc-secs, and the resolution of the 2600 at 400 mm fl with its 3.76 micron pixels is 1.94 arc-secs per pixel - I would think easily obtainable at your location.   But I'm not sure how the one-shot colour affects that resolution.  Nevertheless to obtain the detail shown in your image with such a wide field is undoubtedly exceptional.  Your close up is similar to the field of view of my QSI 683 on my RC10.  But at its f8 ratio it would take 16 times as long to collect the same amount of data.  Ouch!  And of course my camera is far too large to go on an 8" RASA - I'd need to lash out on a 2600.  Nevertheless that target is now on my must do list.   Getting a bit late in the year for me now - I'm tied up in early March, but might get a chance under dark skies at Kielder - a weekend on 8th March coming up.  Probably my Sharpstar 140, at f 6.5 only 10 times slower than the RASA 😉

Cheers,  Peter

Edited February 14 by petevasey

[ollypenrice]

41 minutes ago, petevasey said:

Yes indeed, superb!  Of course the Dawes limit for an 8" optic is 0.57 arc-secs, and the resolution of the 2600 at 400 mm fl with its 3.76 micron pixels is 1.94 arc-secs per pixel - I would think easily obtainable at your location.   But I'm not sure how the one-shot colour affects that resolution.  Nevertheless to obtain the detail shown in your image with such a wide field is undoubtedly exceptional.  Your close up is similar to the field of view of my QSI 683 on my RC10.  But at its f8 ratio it would take 16 times as long to collect the same amount of data.  Ouch!  And of course my camera is far too large to go on an 8" RASA - I'd need to lash out on a 2600.  Nevertheless that target is now on my must do list.   Getting a bit late in the year for me now - I'm tied up in early March, but might get a chance under dark skies at Kielder - a weekend on 8th March coming up.  Probably my Sharpstar 140, at f 6.5 only 10 times slower than the RASA 😉

Cheers,  Peter

My feeling is that the debayering algorithms are so good that OSC loses nothing perceptible to mono in DS imaging. I also found this when comparing the OSC and mono versions of the Atik 4000 when I had one of each. I know that the mono is recording real information and the OSC uses interpolation, but at scale of four pixels I really don't think it matters.

Olly

[Pompey Monkey]

[AKB]

Aha!  “Mars Attacks”, I believe…