M17 Omega/Swan Nebula 2019-07-05 Manche, France (Replaced image)

[The Thing]

**I've revisited the image. DarkTable has a Haze reduction function and I overdid it. The misty bit at the bottom is widespread and is data, it's on some other examples of this object. Reduced some of the other processing as well.

This was in a good position last night after I had re-collimated the newt, i.e. above the neighbours house between the trees at 22^o altitude and it looked great on a 30s sub. Couldn't quite get the colour into the middle of the stars. Must get back into using Pixinsight now the darkness is back, then I can fix that.

14x250s, Gain 121, Offset 4, Temp-15C. No calibration applied.

Image date, time and location:   2019-07-05 02:00 Manche, France
Telescope aperture and focal ratio:   TS1506UNC f4, TS Komakorr
Camera and filters used:   ZWO ASI294MC Pro, Baader Neodymnium 1.25" filter
Processing applied:   DSS 4.2.0 Beta5, StarTools, DarkTable

50 px trim all round and 71% crop (a StarTools thing)

[Carole]

There is something wrong with the processing, especially Red and the swathe of green in the bottom half of the image.  But looks like there is some good data there.

Carole

[ApophisAstros]

I have found that shorter exposures are better for my cam , where i am at the mo, do you always do long exposures for yours?
Roger

[The Thing]

There is something wrong with the processing, especially Red and the swathe of green in the bottom half of the image.  But looks like there is some good data there.
Carole

I thought you liked leery astro images Carole, or have you had your eyes done! I have consulted other images on the web and there are others done like this. Maybe I have overdone the saturation.

I was wondering about the bottom part of the image. I think it may be light leakage up the bottom of the scope from laptop screens and various LEDs around the observatory. Then there is the dark shadow along the bottom. That may be OAG related. But its not in my second image of the night that I am currently processing. SO maybe not though the scope was point in a very different direction for each.

[The Thing]

I have found that shorter exposures are better for my cam , where i am at the mo, do you always do long exposures for yours?
Roger

I took a recommendation from SharpCap Pro sensor analysis which takes into account sky quality as well as the sensor capabilities to recommend an exposure. I told it I wanted integrations to 3 hours at unity gain and it said 250s offset 4. It seems to produce good data. I can do short exposures and end up with hundreds of subs but I don't seem to gain much.

[The Thing]

Hope you like the new version more Carole

[Carole]

It's better, but still doesn't look right to me, in particular that "haze" across the lower part of the image below the Nebula.  Compare it to your Cocoon, it looks so completely different in the processing.

You use a OSC and CMOS chip, and use completely different software to me for both stacking and processing, so I can't begin to work out what is going on.  You also have a number of problems to overcome with that camera.  So on that basis sorry I can't offer helpful advice. 

Carole

[The Thing]

I have found an example with the haze! Its real. Look for the two bright orange stars below in the slightly darker bit and then the same area in the example. I have just been very successful in showing the haze, presumably thin dust. There is a dark area under the dust in the example as well. I did think initially there was some sort of light leak from LEDs and the laptop getting into the OTA but no.

BTW The image is suffering from atmospheric dispersion which is why the stars are blue on top and red below. It was only at 22 degrees altitude, Mark covered that gotcha a while back.

[Carole]

The image is suffering from atmospheric dispersion which is why the stars are blue on top and red below.

Yes it's very low from here, and for you too.  But pretty frustrating never the less.
I have yet to image this target, not found it very enticing so far, so it got left until last, but when I do it will be in narrowband most probably. 

Carole

[Carole]

I have found an example with the haze! Its real. Look for the two bright orange stars below in the slightly darker bit and then the same area in the example. I have just been very successful in showing the haze, presumably thin dust.

I think we are talking about two different things here.

But I will leave it for now.

Carole

[ApophisAstros]

I have found that shorter exposures are better for my cam , where i am at the mo, do you always do long exposures for yours?
Roger

I took a recommendation from SharpCap Pro sensor analysis which takes into account sky quality as well as the sensor capabilities to recommend an exposure. I told it I wanted integrations to 3 hours at unity gain and it said 250s offset 4. It seems to produce good data. I can do short exposures and end up with hundreds of subs but I don't seem to gain much.

With a colour cam how do you get more luminance (for detail) than colour as with a mono and filter wheel. At the moment im binning RGB so as to get more Ha/Lum.
Roger

[The Thing]

I have found that shorter exposures are better for my cam , where i am at the mo, do you always do long exposures for yours?
Roger

I took a recommendation from SharpCap Pro sensor analysis which takes into account sky quality as well as the sensor capabilities to recommend an exposure. I told it I wanted integrations to 3 hours at unity gain and it said 250s offset 4. It seems to produce good data. I can do short exposures and end up with hundreds of subs but I don't seem to gain much.

With a colour cam how do you get more luminance (for detail) than colour as with a mono and filter wheel. At the moment im binning RGB so as to get more Ha/Lum.
Roger

You can only take what it gives you with OSC. There is no separate L, only RGB. Software can extract fake L for processing later but its not the same really.