The Soul Nebula IC1848

[JohnH]

This is the Soul Nebula but in this orientation I see a newborn baby, shades of 2001.

I have tried to image this previously together with the neighbouring Heart Nebula when I was using a camera lens but it was a complete mess. This time my aim was a bit, off the plate solver obviously centered on the pair of bright stars in the centre of the image. However, I have not cropped the image because I think that there is a bit of detail on the right hand side (areas where stars are absent).

This was imaged on 25th January 2021 - The moon was 91% ~51.5 degrees away (I only seem to be able to image when the moon is > 90%).

Telescope Sharpstar HNT 15028, camera ZWO ASI1600MM Pro on iOptron CEM25P.

HaRGB

Ha (Luminance): 300s x 20
R: 45s x 45
G: 45s x 43
B: 45s x 21 (cloud came over and I lost over half)

Processing: PI finished off with Topaz Sharpen AI in Photoshop.

Unusually, there were no real disasters whilst I was imaging this apart from cloud. Even my guider seemed steady although comparatively short subs are not a real challenge.

If I look hard there is some coma in the stars around the edge but I think my collimation is reasonable and I am reluctant to experiment with the flattener which might fix that or make it worse.

Here is to clearer skies,

John

[Carole]

You've done a pretty good job with that John. 

Coma is improved by getting the correct spacing between the lens of the flattener and the sensor, and this will vary with each brand and something I took years to get right.

Do you by any chance have Oiii and Sii filters as this particular target gives a very good result in SHO. 

Carole

[JohnH]

Thanks Carol,

I only have Ha. I am still too impatient and too inexperienced to use all narrow band.

Is there any way to assess coma and the effect of moving the flattener without using/losing imaging time?

John

[Carole]

I am no expert on this,

A:  I  get the specs from the Flattener manufacturer this should be the distance from sensor to the lens of the Flattener.

B: Then find out the distance of the sensor to the end of the camera and the thickness of the EFW and subtract B from A to get the size space you need. 

Using an electronic set of calipers will help measure the space more accurately.  With a caliper you can measure the entire length of the spacing provided you know exactly where the FF lens and sensor are.

Of course getting a spacer the right thickness is also another matter.  I ended up having to buy a set of thins shims to make up the small difference. 

It's a right PITA and one I struggled with for a long time.

I think the guys who are more technical than me might be more help.

Carole 

[The Thing]

Nice one John. Maybe try it monochrome! Works for Fays Ha only offerings.

Spacing is critical. With my ASI294MC ZWO supply some very thin t-sized shims for just this sort of tweaking. My 294 has 6,5mm from the front of the camera body to the CMOS surface according to ZWO, knowing that makes measurement a lot easier. I use old fashioned manual callipers, accurate as long as you use the Vernier scale. My coma corrector requires 52mm for my newt, but for my Sharpstar 61EDPH it's 55mm and LX90 with Baader Alan Gee II corrector 190mm(!!!).

(From Teleskop Service site)
TS-Optics GPU superflat 2" Coma Correktor for Newtonian telescopes, 4-element

? Focal length up to 600 mm - working distance 52 mm
? Focal length 610-690 mm - working distance 53 mm
? Focal length 700-790 mm - working distance 54 mm
? Focal length 800 mm and more - working distance 55 mm

Scope TS1506UNC platesolved at 605mm
1100D 52-44=8mm
ASI294 52-6.5=45.5mm

Good luck and yes it does eat imaging time up checking you did it right (but not if you got it right )

[JohnH]

Thanks,

The stated spacing is 55mm but a Sky and Telescope review suggested that coma could be reduced/removed by reducing this (amount unstated). I suppose that I will have to try sometime.

This is the Ha image which I used as L layer (and blended with the R layer). It is certainly detailed but I like the challenge of a colour image.



Regards,

John

[The Thing]

I like the mono version.

I have found that the movement of the mirrors during collimation makes enough focal length distance change affect the spacing a tad.

[RobertM]

Likewise the mono version.

As others have mentioned, sorting all this spacing/tilt and collimation out is a right royal pain.  That seems to afflict most of us poor souls is testament to how well these bits of kit are designed and manufactured

Keep at it - the relief when it all slips into place is worth waiting for.

Robert

[MarkS]

I prefer the mono version as well.

In my opinion the Soul Nebula looks far more like a pussy cat.

Mark

[JohnH]

Thanks all. I have had a go at reprocessing, at least I think that I have got rid of some of the lurid colour.



I have used the Ha image as Luminance on RGB with a High-Pass filter in Photoshop.

Regards,

John

[Hugh]

I see what you mean Mark.  A nice case of Pareidolia strikes again! 

Hugh

[NoelC]

Very nice reprocess John.
Definitely an upside down baby.
Noel

[Carole]

I can't see a cat but I see a baby.

Carole

[RobertM]

Very peculiar, I can see the cat, the baby and a smiling face

[Carole]

I think I can see a cat now, but took a bit of concentration.

Carole