Atik Cameras Forum

Images => Deep Sky Images => Topic started by: susan-parker on January 21, 2020, 03:22:54 pm

Title: Bortal 8+ Imaging from West London
Post by: susan-parker on January 21, 2020, 03:22:54 pm
Seeing conditions where I live are less than ideal with very few stars being visible even on cloud-clear nights, however and perhaps because of this I am interested in "seeing" the stars that I cannot see by eye; to remind myself that they are actually there.

Attached is an example, taken with a monochrome Atik Horizon (original):

Orion Belt and M42/M43 Sword/Dagger Nebulae, with NGC-2024 Flame and IC-434 Horsehead also visible.

Stack of 174 frames = 23 minutes and 12 seconds total exposure, with stars down into magnitude 14 visible in the original image. Scale at 33% from original image.

Atik Horizon monochrome camera with Nikkor 105mm f/2.5 @ f/2.8 with IDAS D1 filter, High Gain, 8 seconds per exposure, sensor at -15C. Date 20/01/20 @ 20:15 to 20:41 GMT. Bortle 8+ zone.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on January 21, 2020, 03:30:32 pm
The Orion Nebula region; with the main Orion nebula M42 centre with the adjoining M43 nebula, and the Running Man Nebula top left.

Stack of 213 frames with stars down to magnitude 15.

Tracking with a total 28 minutes 24 seconds exposure.

Some camera artefacts are visible in the background, e.g. horizontal lines from the sensor.

Atik Horizon monochrome camera with Tamron 500mm f/8 mirror lens, High Gain, 8 seconds per exposure, sensor at -15C. Date 29/12/19 @ 20:28 to 21:18 GMT. Bortle 8+ zone.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on January 21, 2020, 03:43:39 pm
Test run: Some stars, somewhere up in the Aries / Triangulum region.

Stack of 203 frames = 27 minutes and 4 seconds total exposure, 33% scale of original.

Atik Horizon monochrome camera with Tamron 500mm f/8 mirror lens, High Gain, 8 seconds per exposure, sensor at -15C.
Date 20/01/20 @ 18:43 to 19:17 GMT. Bortle 8+ zone.
Title: Re: Bortal 8+ Imaging from West London
Post by: CraigG on January 21, 2020, 03:46:16 pm
Nice images, especially considering your Bortle zone. Thanks for sharing!
-Craig
Title: Re: Bortal 8+ Imaging from West London
Post by: vince on January 22, 2020, 12:31:14 pm
Hello Susan,

Very nice images, especially seeing as you are imaging from West London! Will we be seeing you at Astrofest next week?

The Horizontal bands could be caused by interference, feel free to send use some fits files into support@atik-cameras.com and we can look into this for you.

Best regards
Vince
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on January 23, 2020, 09:39:26 pm
Orion Belt and M42/M43 Sword/Dagger Nebulae, with NGC-2024 Flame and IC-434 Horsehead.

The atmospherics were challenging and this night there were hints of thin high-altitude cloud, the finer whispier details in the nebulae are not showing because of this.

I used a narrow band IDAS NB1 filter in conjunction with a blue then a red filter for two separate sequences of images:
Blue: Stack of 201 frames = 26 minutes and 48 seconds total.
Red: Stack of 206 frames = 27 minutes and 28 seconds total.
Green: Synthesized from the Red and Blue channels with Astronomy Tools in Photoshop.

Scale at 33% from original image.

Atik Horizon monochrome camera with Nikkor 105mm f/2.5 @ f/2.8 with IDAS NB1 filter and R60 and B12 filters, High Gain, 8 seconds per exposure, sensor at -15C.
Date 21/01/20 @ 19:55 to 20:56 GMT. Bortle 8+ zone.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on January 25, 2020, 11:26:01 am
A 1 to 1 crop of the M42/M43 and Running Man nebulae from the previous 33% scale image, less aggressively processed to preserve finer (of what there is) detail.

The blue rings around the brighter stars are from the out of focus red bandpass end, which was not completely cut off by the B12 filter (the 12 being a clue here). I will be getting proper narrow-band filters soon, but this is what I currently have to hand.

With the 105mm f/2.5 Nikkor lens the blue was focused on infinity, whereas the red had to be refocused to be a little closer (c. 150 feet?). The chromatic aberration of the lens really makes that much difference.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on January 25, 2020, 11:52:22 am
… and a 1 to 1 crop of the NGC-2024 Flame and IC-434 Horsehead nebulae from the previous 33% scale image.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on February 02, 2020, 04:00:32 pm
The Orion M42/M43 and Running Man nebulae taken with my new William Optics "SpaceCat" telescope.

Stack of 921 frames from 970 total frames aquired = 122.8 minutes exposure.

Crop and 50% scale of the original (to meet 600KB file attacment limits). Some of the finer wispier details are lost in the JPEG compression.

Stars down to magnitude 16.85 (as per Stellarium).

Atik Horizon monochrome camera with William Optics "SpaceCat", Optolong 2" UHC filter, Dusk set at "High Gain", 8 seconds per exposure, sensor at -15C.
Date 01/02/20 @ 18:39 to 21:13 GMT. Bortle 8+ zone.
Title: Re: Bortal 8+ Imaging from West London
Post by: CraigG on February 02, 2020, 04:13:28 pm
Very nice Susan. Congratulations on the new SpaceCat!
-Craig
Title: Re: Bortal 8+ Imaging from West London
Post by: vince on February 03, 2020, 10:25:42 am
Hello Susan,

It's good to see you got the Space Cat all connected up OK.

It's a great image :)

Vince
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on February 09, 2020, 09:40:42 pm
Thanks Craig and Vince :)

Here is one taken on the 6th Feb of Orion's Belt.

A stack of 432 frames, for 57.6 Minutes total exposure. Stars down into Magnitude 16. 33% scale of original image.

Atik Horizon monochrome camera, William Optics "SpaceCat", Optolong UHC filter, High Gain, 8 seconds per exposure, sensor at -15C. Date 06/02/20 @ 21:432 to 21:53 GMT.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on February 14, 2020, 07:12:21 pm
From my previous Orion's Belt image; reprocessed and croped to focus on the Horsehead and Flame Nebulae next to Alnitak, with Alnilam upper-right.

The JPEG compression loses background detail so I have had to fettle the black-levels to made the nebulae detail more visible.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on February 24, 2020, 08:31:42 pm
My first full seven L-R-G-B-SII-Ha-OIII filter test with my SpaceCat and Horizon.

About 30 frames per filter; each L-R-G-B at 8 seconds, and each SII-Ha-OIII at 30 seconds. Seeing conditions didn't allow for more frames as clouds came in.

I had problems with the filter wheel control not showing up in Dusk (or SharpCap), however I could control independantly with Filter Wheel Runner. In Dusk the filter wheel was showing as connected in settings. Not sure what the issue was, probably looking in wrong place.

Processed in Astro Pixel Processor and Photoshop.
Title: Re: Bortal 8+ Imaging from West London
Post by: vince on February 25, 2020, 11:48:32 am
Morning Susan,

That's great! Especially given the short exposure time!

Let us know please if you continue to have filter wheel issues please. 

Best regards
Vince
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on February 29, 2020, 09:20:32 pm
Here is the latest version of the Orion Nebula in a big stack of over 1200 frames with all seven filter's frames from two seperate sessions on the nights of the 20th and 27th, plus the previous 921 Optolong monochrome frames taken on the 1st as additional luminosity.

So basically a combination of three sessions, with different orientations, gains and filters; stacked with Astro Pixel Processor.

The SpaceCat telescope has really good geometry, so these images have stacked together without bluring.

Slightly more detail in the wispier parts, although pragmatically I am up against the background light pollution levels and exposure times which is curently at magnitude 16.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on March 05, 2020, 08:35:39 pm
The Horsehead and Flame nebulae using the Hydrogen-alpha narrowband (7nm) filter only.

Stack of 175 frames, processed to show nebula detail, with stars down into magnitude 14.

Atik Horizon monochrome camera, William Optics "SpaceCat" with Atik NB Hydrogen-alpha filter, Gain @ 30, with 30 seconds per exposure, sensor at -15C.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on March 05, 2020, 09:03:13 pm
This is a "random" bit of sky, just under the head of Hydra.

The central bright star is HIP44030 at magnitude 6.65, and stars are down into magnitude 15.

Image is 33% scale, taken with Atik RGB filters, with 100 frames per colour of 8 seconds each (no luminance), and Dusk setting Hi Gain (30).

Given the sensitivity of the camera sensor to different wavelengths, is there a standard RGB ratio to compensate to get better accuracy for the colours of the stars, or does one tend to leave them "as shot"?

BTW Vince, the EFW2.2 filter wheel now seems to be working properly in Dusk; thanks. :)
Title: Re: Bortal 8+ Imaging from West London
Post by: vince on March 06, 2020, 02:33:58 pm
Hi Susan,

You can use a G2V star to calibrate you filters to work out the offset for each filter, there are many articles online if you search for 'rgb calibration star' or similar.

Good to hear the wheel is behaving.

Nice images BTW :)

Vince
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on March 07, 2020, 08:18:36 pm
An enhanced colour version of the Horsehead and Flame nebulae with Atik Hydrogen-alpha, Sulpher II and Oxygen III narrow-band filters for RGB, plus Optolong UHC filter for luminance.

This mosaic is a combination of all the sets taken of this area using the SpaceCat telescope and Horizon camera, including the previous Orion's Belt set.

The superb geometry of the SpaceCat allows the stacking with great star registration even when putting corners of one set into the centre of another.

This was a massive stacking sequence with the Astro Pixel Processor software that took most of the day to process on my 2nd gen i7 computer.

Stars are down into magnitude 16 in the original (for the 600KB limit I have had to go down to JPEG guality 7 in PhotoShop).

I have not tried to hide the stacking set edges in the mosaic.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on March 15, 2020, 09:02:01 pm
For comparison with my recent Orion images I have restacked four sets I took at the beginning of 2019 with my D800 and Nikkor 105mm f/2.5 lens at f/2.8, static mounted (i.e. no tracking), with the Astro Pixel Processor software (took a full day to process).

This is a crop and 25% scale from the new overall stack which came out of APP as a 9222 x 5492 pixel, 32bit depth RGB, 600MB image!!!

The faint redish blur to the top left is emission from the background wisps, not lens flare (although perhaps not very visible once crunched by the JPEG settings needed to get the image in under 600K).

Stack of 1556 frames of 2 seconds each (51 minutes and 45 seconds total exposure time) mostly at ISO800, with stars down to magnitude 15(ish) discernable in the original.

BTW I started with 5 sets of 2256 frames in total, but didn't have enough space on my empty 1TB SSD for the integration phase so had to dump one set.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on March 18, 2020, 08:43:58 pm
Beehive open cluster, from the 16th March.

33% scale of RGB filters image. Stars down to magnitude 16.

12 seconds per exposure - 100 frames per RGB.

SpaceCat, EFW2.2 with Atik filters, Horizon mono. Processed with Astro Pixel Processor and Photoshop.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on March 18, 2020, 08:45:19 pm
Close-up of the BeeHive, at a one-to-one pixel crop from the previous full frame.
Title: Re: Bortal 8+ Imaging from West London
Post by: Noah4x4 on March 18, 2020, 09:52:14 pm
Great stuff Susan.

Sorry to hear that your second generation i7 takes so long to process the stacks. Have you tried increasing RAM as a cheap fix?

I have adopted an end to end 4K UHD wireless system using Windows Remote Desktop and observe from indoors. I found that my seventh generation i5 quite often choked with 4Gb RAM and still struggled with 8 Gb. I now employ an eighth generation i7 with 16 Gb and it now processes stacks from my Atik Horizon in near real time. 

I suspect others might be frustrated by processing that might take hours, and I thought it might be helpful to indicate what processing power and RAM might be desirable for faster performance. Admittedly, 1080p HD might work fine with lesser computing power, but to use the Horizon's full 16 megapixel resolution with short stacked exposures potential needs a fair bit of ooomph.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on March 19, 2020, 06:27:01 pm
Great stuff Susan.

Sorry to hear that your second generation i7 takes so long to process the stacks. Have you tried increasing RAM as a cheap fix?



Hi Noah,

Thanks for your post :)

I had undated from 16 to 32GB of RAM last year, plus a SSD for the OS and another SSD one for working temp files, and updated to Windows 10. Overall ran better but still ran slowly for stacking and I continued to get the occasional "Blue Screens"... which wasn't reassuring.

I built the i7 machine 9 years ago, upgrading from a Pentium 4 keeping the case, and discs but with a new power supply.

I decided to update my computer (keeping the case, discs, and power supply so not really a new computer, honest) after the multi-session stacking of the Horsehead and Flame Nebulae; which was painful.

Now have an AMD 12 processor 24 core Threadripper and 64GB memory, plus the other bits to go with that. It is at a minimum 5 times faster!!!

At present my observations are out of the bedroom window, I am slowing moving to have something portable so I can try some "real" astrophotography :)
Title: Re: Bortal 8+ Imaging from West London
Post by: vince on March 20, 2020, 01:40:43 pm
Hello Susan,

Another nice image, this was the first DSO that I tried imaging with an SC1 modified webcam many years ago!

I can see a few weird colours on my monitor which could be the colour saturation has been pushed slightly high?

Stay safe

Vince
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on March 26, 2020, 06:35:37 pm
Over the course of the last three nights the sky has been good enough to get in a few frames of the area centred on Procyon (one of the few stars I can actually see!); 2000 in all.

Pic is 33% scale of original, stars down into magnitude 15. Processed with Astro Pixel Processor.

Stack of 1500 colour frames (500 each RGB), 8 seconds per frame, high gain (30) with Dusk. SpaceCat, EFW, Horizon as before.

Vince: the odd colours probably come from the amount of pushing the image to bring out the low level details - plus the "Increase Star Colour" in Astronomy Tools. My images are quite noisy because of the background light pollution and poor seeing conditions.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on March 26, 2020, 06:37:21 pm
... and this is a 1 to 1 pixel crop of the previous image.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on March 28, 2020, 01:55:55 pm
First section of my mosaic from last night - shot as luminance / monochrome only, and each frame is static.

Cropped the edges, so about 800 frames worth from the first 999 frames, 1.0 seconds per frame (Horizon CMOS sensor + USB3 made this possible), high gain (30).

The centreline of the equatorial grid is at about +5.5°. The crop Field of View is about 10° wide.

The two brighter vertical stars to the right are 63 and 66 Orion, and the brightest star towards the lower-left is 8 / Epsilon Monoceros A.

Despite the short exposure time, stars in the original are visible down into magnitude 15. I have had to scale this version down to 16.5% to make it under the 600KB maximum.

I have another 9000 frames to process !!!
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on March 28, 2020, 02:29:07 pm
... and a crop at 33% scale with Epsilon Monoceros A towards the lower-left.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on March 28, 2020, 04:11:33 pm
... and this is the starting point with the output from Astro Pixel Processor with a 10926 x 3723 pixel 32bit floating-point greyscale image (scaled to 22.5%).

There is about a 1.1° tilt as the camera is not perfectly aligned with the equatorial plane.

The dark band at the top is an artefact from the Horizon Sensor, which I assume could be ironed out with some lights (I now have a light-source so making some "lights" is on my "ToDo" list)?

Horizon sensor is at -15°C (down from about +22 to +24°C when I turn the camera on).
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on April 15, 2020, 04:11:19 pm
My current campaign; Algieba in the constellation of Leo.

A stack of 1690 frames collected over four nights (10th, 11th, 13th, and 14th April).

The NGC3226 and NGC3227 galaxies to the left are clearly visible smudges, other galaxy smudges are (just) discernable.

Pic is a 1 to 1 pixel crop from the original, with stars down to magnitude 16.5 (the final fractions depending on the star colour).

This is a R-L-B stack, where the Super-Luminance is used for the Green Channel, and the Red and Blue are as shot.

High Gain (30) with RGB filters at 8 seconds, L at 2.5 seconds, per frame. I am running the Dusk filter sequence at 50 frames per filter, and repeating the RGB sequence 4 times. So when the cloud comes, I still have some reasonable balance of frames acquired.

Although I have made adjustments, I have not specifically boosted the overall gain of the image (Photoshop "Levels").

William Optics SpaceCat, EFW2.2 with Atik filters, Horizon mono camera; processed with Astro Pixel Processor, Photoshop CS6, and DxO PhotoLab 3.
Title: Re: Bortal 8+ Imaging from West London
Post by: CraigG on April 16, 2020, 02:46:53 pm
Nice Susan!
- Craig
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on April 21, 2020, 06:36:20 pm
The Leo Triplet / M66 Group.

Combined stacks from the 19th and the 20th, with stars down into magnitude 16 and some structure visible in M65 and M66 as well as the band in the Hamburger.

1250 frames: 150 + 200 frames each from R, G, B, filters, and 200 for the L filter.

High Gain (30) with RGB filters at 8 seconds, and the L at 2.5 seconds, per frame.

This is another R-SL-B stack, where the Super-Luminance of all frames shot including Green is used for the Green Channel, and the Red and Blue are as shot.

This is a 33% scale from the original, with most of the frame (I only cropped the raged edges of the stack).

William Optics SpaceCat, EFW2.2 with Atik filters, Horizon mono camera; processed with Astro Pixel Processor and Photoshop CS6.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on April 21, 2020, 06:42:16 pm
... and a 1 to 1 crop of the Leo Triple.

Given how noisy the atmosphere is I am pleased to see some structural detail.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on April 27, 2020, 07:24:18 pm
New campaign:

Markarian’s Chain including Messier galaxies M84 and M86, with M88 towards the top left and M87 a bit below centre left.

33% scale from the original, with stars & galaxies down into magnitude 16.

800 frames: 200 frames each from R, G, B, filters, and 200 for the L filter. High Gain (30) with RGB filters at 8 seconds and the L at 2.5 seconds per frame.

R-SL-B stack; Super-Luminance of all frames shot including Green is used for the Green Channel, and the Red and Blue are as shot.

William Optics SpaceCat, EFW2.2 with Atik filters, Horizon mono camera; processed with Astro Pixel Processor and Photoshop CS6.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on April 27, 2020, 07:26:04 pm
Crop and 50% scale of the previous Markarian’s Chain image.

Messier M88 top left and M87 bottom left.

There are numerous galaxies in these images.

M88 top left is the only one with a hint of structure.

In M86 one can just see the much smaller and fainter NGC-4406B galaxy as a point of light (magnitude 14.3).
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on April 27, 2020, 07:27:28 pm
... and here is the 50% scale image annotated with the Galaxy IDs - 37 of them.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on May 01, 2020, 02:58:09 pm
The latest version of the Leo Triplet - crop and 50% scale  from the original.

Combined images from 5 sessions on the 19th, 20th, 21st, 22nd, and 25th April, giving a total of 520 minutes exposure.

The structure is better defined in both M65 and M66, and the band in the Hamburger is a bit sharper.

Stars down into magnitude 17.

R-SL-B stack, where the Super-Luminance of all frames shot including Green is used for the Green Channel, and the Red and Blue are as shot.

William Optics SpaceCat, EFW2.2 with Atik filters, Horizon mono camera; processed with Astro Pixel Processor and Photoshop CS6.
Title: Re: Bortal 8+ Imaging from West London
Post by: CraigG on May 01, 2020, 05:06:38 pm
Very nice Susan!

Craig
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on July 10, 2020, 11:35:40 am
I have been having a go at reprocessing one of my first narrow-band filter imaging campaigns of the Orion Nebula with my current SpaceCat setup (EFW2.2 filter wheel, full set of Atik filters, Horizon mono camera).

Frames were taken over two sessions at the beginning of March 2020 using Dusk for the capture. 30 seconds per frame on high-gain (30x), for 478 frames in total.

For this version I have used the traditional Hubble Pallet with the Sulphur II image to the red channel (R), the Hydrogen-alpha image to the green channel (G), and the Oxygen III image to the blue channel (B).

This assignment produces an image with an overall green hue; so I toned down the green and increased the strength of the other two colours by lowering the x value of the G channel to 0.2 and increasing the x value of the B and R channels to 1.100.

Stacked in Astro Pixel Processor, with further processing in PhotoShop and DxO PhotoLab3, as well as additional Topaz Labs AI sharpening.

This is a crop and 50% scale of the original image, which is showing considerably more detail than I have managed to achieve previously.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on July 11, 2020, 07:25:28 pm
The Eagle Nebula aka Messier 16 open-cluster in the centre of the image, with a glowing cloud called Sharpless 2-54 above.

From last night as an opportunity imaging with narrow-band filters only, and still with several percent cloud cover, so rather noisy.

Due to set-up issues with the Dusk acquisition software (which was dropping every other frame) I only got 104 frames, plus there was an issue with guiding which spoilt a number more.

104 frames, 30 seconds each: 40 frames SII, 40 frames Ha, 24 frames OIII

This area is full of comparatively faint gas clouds swaddling the clusters, so the background "noise" is in part from this.

This image is a 33% scale of the original, with stars down into magnitude 15.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on July 11, 2020, 07:28:18 pm
... and a 1 to 1 crop of the Eagle Nebula with "The Pillars of Creation" clearly visible.

And yes, this is ONLY from my own data taken last night; must have hit a sweet spot in the Horizon camera's image levels.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on July 12, 2020, 05:43:48 pm
Despite the Clear-Outside weather forecast being in the Red, I was able to get a further 180 frames of my M16 Eagle Nebula campaign last night; stars now down well into magnitude 15.
Title: Re: Bortal 8+ Imaging from West London
Post by: vince on July 13, 2020, 10:22:45 am
Hi Susan,

Those are great images especially from London!

M16 is too low for me in Norfolk.

Vince :)
Title: Re: Bortal 8+ Imaging from West London
Post by: oliverthom707 on July 15, 2020, 07:06:56 pm
Nice images, especially considering your Bortle zone. Thanks for sharing!
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on July 18, 2020, 05:03:28 pm
Thanks Vince and Oliver :)

At last some clearer skies last night and an opportunity to catch 188 more Hydrogen-alpha frames to add to my M16 Eagle Nebula image campaign.

There is noticeably more details in the dark filaments in the nebula regions.

This one is nominally using the Hubble Pallet (Ha assigned to the green channel), although I have SII and OIII frames most of the information is in the Ha.

1 to 1 pixel crop, with stars down to magnitude 16.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on July 23, 2020, 12:23:07 pm
M24 Small Sagittarius Star Cloud with dark nebulae Barnard 92 & 93 prominent, IC1284 HII region in centre of frame, additional Ha regions clearly visible.

Positions of the NGC6603 open star cluster and NGC 6567 Planetary Nebula just visible.

Session was an opportunity grab starting at 11 p.m. BST, through increasing to 20%+ cloud cover as the session progressed.

Atik 7nm narrowband Ha, SII and OIII filters (with Ha on red channel); 40 frames of 30 seconds each per channel, Atik Horizon with Dusk for capture, sensor at -15°C, High Gain (30x).

N.B. I have had to crunch the JPEG quality down to get under the 600K limit although the original is not unexpectedly rather noisy as well as busy with stars.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on July 25, 2020, 06:33:49 pm
M24 Small Sagittarius Star Cloud campaign update:

I got a chance to shoot a few more Ha frames last night in between the thicker clouds, and got 138 usable frames out of 238 taken.

So I now have 178 Ha frames, 40 SII, and 40 OIII in total, each 30 seconds exposure.

This is still through varying light cloud and background light pollution, but the added Ha really makes a difference. The image looks less punchy but that is from increased background presence. The black in Barnard 92 really is black, just little else in the frame is!!!
Title: Re: Bortal 8+ Imaging from West London
Post by: CraigG on July 26, 2020, 04:09:29 pm
Nice enhancement Susan. You've inspired me to check out M24 myself. How much do you think the SII channel contributed to your final image? I'm thinking about adding that filter to my toolbox.

Thanks!
-Craig
Title: Re: Bortal 8+ Imaging from West London
Post by: vince on July 27, 2020, 11:46:58 am
That's looking good Susan.

Vince :)
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on July 27, 2020, 05:50:25 pm
Hi Craig,

I am still relatively new to NB filter imaging, only got my filter-wheel working at end of February.

The M24 image is apparently a predominantly Hydrogen emission region, what I think I am seeing is that for more conventional nebula targets e.g. Orion Nebula, the normal practise seems to be to back off the Ha as it is a lot brighter than the other two SII and OIII channels to get a pleasing 3 colour RGB image, but this technique applied here would understate the Ha line.

In the M24 area the three filters are narrow-band filtering the normal range of "white" light plus any emission lines.

This image is the Ha 656nm as red with the SII 672nm (green) subtracted. These 7nm filters are very close together so it is reasonable to assume that the camera sensitivity and filter characteristics are similar enough to treat them as equal as far as "white" light is concerned, and therefore taking away the SII filter channel will leave the Ha. If there is some SII then that would be subtracted too, so the assumptions as to the Ha remain sufficiently valid since it is a lesser crime to underreport in this instance :)

The background mottling is from the much fewer SII frames (40) compared to the Ha (178) frames.

The stars down into magnitude 12 have been made blue to contrast with the red.

There seems to be a fair amount of Ha emission going on, above and beyond the background "white" light.

Perhaps someone more knowledgable would care to comment?

For other targets, a SII filter would be directly contributing to the final RGB image.

For fun, look at the human eye response, the Red and Green cones are shockingly close together compared to the blue:

E.g. https://upload.wikimedia.org/wikipedia/commons/3/32/Opsin_Absorption_Spectra.png (https://upload.wikimedia.org/wikipedia/commons/3/32/Opsin_Absorption_Spectra.png)

... then compare to a colour camera's coloured matrix filter which is much more evenly spaced.

Best,
Susan.

BTW Thanks Vince :)
Title: Re: Bortal 8+ Imaging from West London
Post by: CraigG on July 28, 2020, 01:30:54 pm
Hello Susan,

Thanks for the great info on your M24 image and for your analysis of the Ha/SII relationship in general. The absorption spectra angle/OSC matrix comparison is an interesting side note. I'm very impressed with your understanding of narrowband components and how they apply to astrophotography. I hope to one day at least approach the level of knowledge that you possess on the subject! As I'm also relatively new to the art of NB imaging, I look forward to your future posts. This forum has lots more potential for sharing details of image acquisition and best practices in a bit slower paced environment than say Astrobin, etc. Hopefully that activity will increase as time goes on! :)

Best wishes,
Craig
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on July 31, 2020, 07:15:19 pm
Messier M17 - The Omega Nebula in Sagittarius (aka the Swan Nebula) taken last night is poor seeing conditions

There was thin high cloud and the 85% moon was pretty bright and only 10 degrees off the field of view, so a lot of background noise (above and beyond the normal Bortle 8+ stuff).

The Messier M18 open cluster of stars is also present albeit not as dramatic towards the lower-centre of the image.

60 frames of 30 seconds each for each of the 7nm narrow-band Ha SII OIII filters.

This image is a crop of the full-frame at 50% scale.

Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on July 31, 2020, 07:23:53 pm
Hi Craig,

Thanks. Part of this is putting in a lot of time making multiple stabs at the processing. What works well for one image does not always give such good results for another, there is always tweaking and optimizing (as well as going back and redoing from scratch).

Further to the filter thing; here is an image of M17 showing the RGB breakdown by the separate narrow-band filters.

As can be seen for M17 there is substantial nebula emissions on all three channels; whereas for the previous M24 image most of that area was just Hydrogen-alpha.

The Atik 7nm bandwidth filters are definitely earning their keep at cutting down on the background light.
Title: Re: Bortal 8+ Imaging from West London
Post by: susan-parker on August 01, 2020, 12:29:12 pm
This is a quick-look mosaic of last month's narrow-band nebula campaigns, with my targets in bold.

Top to bottom:
Sharpless 2-54 Nebula
Messier M16 Eagle Nebula
Messier M17 Omega/Swan Nebula
Messier M18 Open Star Cluster
Messier M24 Small Sagittarius Star Cloud
IC-1283 Nebula
μ Sagittarius (Polis) Blue Supergiant Star (mag 3.86)

The three overlapped images represent approximately 10° of the sky in height.
The unscaled image is 4500 x 11500 pixels in size.