Tag Archives: HA

The source to the halo around bright stars

When I moved to the Sky-Watcher Quattro telescope I noticed some bizzare halo’s around bright stars in my images, this was evident in both my Atik 383L+ CCD Camera as well as my QHY183M ColdMOS Camera when using the Quattro 8-CF at F4, if you browse my galleries you will see what I mean, and it was more noticable in my Narrowband images. Below is one of my recent images where you can see the halo around Magnitude 3.9 star 15 Mon in the Christmas Tree Cluster / NGC2264.

I contacted Baader back in February 2019 since all of my filters were Baader, and I noticed that the Halo was present in all of my filters but significantly less in Red, but more prevalent in Narrowband filters, so the logical cause would be the filters. Baader immediately dismissed this to be the fault of their filters and suggested that my Coma Corrector be the root cause.

Not convinced that the Coma Corrector was causing the issue, I did some research online and came across a brilliant page on the Astronomik website where they claim to have resolved the majority of the Halo issue, and after reading the following line from the page I was convinced the filters were my issue:

In recent years very fast optical systems have become popular for imaging. The energy in a filter induced halo grows exponentially as the f-ratio decreases. Additional to this, the smaller the FWHM band pass of the filter, the stronger the halo.

The above line described my issue perfectly so I mentioned this to Baader who again dismissed the possibility of it being their filters and again put the blame firmly to my optical train. Again not happy, I contacted Astronomik and Eric emailed me back very promptly and offered to send me out one of their 6nm Ha filters to test. A few days ago the filter arrived and I was able to perform some testing against the Baader filter also for comparison on the same star.

Since the star in my image above was of magnitude 3.9, I wanted to find something similar, so I found star Alhaud VI and proceeded to obtain 15x300S Exposures for each filter, and here are the results:

Astronomik 6nm HA filter, 15x300S with Darks and Flats applied
Baader 7nm Ha filter, 15x300S with Darks and Flats applied

So as you can see the Baader filter shows a high amount of Halo around the bright star and the Astronomik filter does not, now if this was something to do with the rest of the optical train there would be evidence in the Astronomik filter also.

Now I agree there will be some reflection in the optical train, all that glass in the coma corrector, the glass on the camera etc, so I thought I would have a look at both images in a bit more detail, zoomed in on the stars there is what appears to be a slight halo in the same place on both images:

Astronomik 6nm Ha Filter
Baader 7nm Ha Filter

So both filters show the Inner Halo which in my opinion would not be visible in an image, but again clearly the Baader filter has some reflection issues happening as you can clearly see two additional Halos. The interesting thing about all three Halos is that the central one visible in both filters has no relationship to the distances between the other two in the Baader, however the two outer Halos on the baader are the same distance apart as the middle halo is from the star, so clearly this is some sort of reflection.

Conclusion:
Astronomik have done a fantastic job at eliminating Halo artifacts around bright stars, clearly the Baader filters are causing major Halo artifacts because if this was the optical train then it would be evident in the Astronimik filters also, I suspect that the Baader filters are not optimised for faster focal ratio imaging systems. I have provided this information to Baader and await a response from them.

Good job Astronomik Filters

IC36 Y Cas Nebula in SHO

Located in the constellation of Cassiopeia this rather feint nebula is illuminated by a very bright Magnitude 2.15 star Navi

Image Details:
101x300S in SII – Red Channel
101x300S in Ha – Green Channel
101x300S in OIII – Blue Channel

Total integration time: 25.2 Hours

101 Darks, Flats and Dark Flats applied

Acquisition Dates: Oct. 27, 2018, Dec. 13, 2018, Dec. 27, 2018, Jan. 1, 2019, Jan. 2, 2019, Jan. 4, 2019, Jan. 8, 2019, Jan. 9, 2019, Jan. 11, 2019, Jan. 18, 2019, Jan. 20, 2019, Jan. 23, 2019, Jan. 27, 2019, Jan. 28, 2019, Jan. 30, 2019

Equipment Details:
Imaging Camera: Qhyccd 183M Mono ColdMOS Camera at -20C
Imaging Scope: Sky-Watcher Quattro 8″ F4 Imaging Newtonian
Guide Camera: Qhyccd QHY5L-II
Guide Scope: Sky-Watcher Finder Scope
Mount: Sky-Watcher EQ8 Pro
Focuser: Primalucelab ROBO Focuser
FIlterwheel: Starlight Xpress Ltd 7x36mm EFW
Filters: Baader Planetarium Ha, SII and OIII
Power and USB Control: Pegasus Astro USB Ultimate Hub Pro
Acquisition Software: Main-Sequence Software Inc. Sequence Generator Pro
Processing Software: PixInsight 1.8.6

NGC6888 – Crescent Nebula in SHO Narrowband

This object is a little tricker for me since I only have a 3-3.5 hour window per evening due to trees and the house blocking my view, this is also the first image that I used the drizzle function within PixInsight to be able to provide a detailed up close version of the image, I was very happy to have captured the brown “Globules” within the nebula to

Crescent Nebula in SHO Narrowband
Same object but with a 2x drizzle function in PixInsight applied

Image Details:
Red Channel – SII Data – 89x300S
Green Channel – Ha Data – 64x300S
Blue Channel – OIII Data – 109x300S

101 Darks, Flats and BIAS Frames used 

Equipment Used:-
Imaging Camera: QHY183M Mono ColdMOS Camera at -20C
Imaging Scope: Skywatcher Quattro 8″ F4 Newtonian
Guide Scope: Skywatcher Finder Scope
Guide Camera: QHY5L-II
Mount: Skywatcher EQ8 Pro GEM Mount
Focuser: PrimaluceLabs ROBO Focuser
Filterwheel: StarlightXpress 7x36mm EFW
Filters: Baader 7nm Ha, SII and OIII
Acquision Software: Main Sequence Software Sequence Generator Pro
Processing Software: Pixinsight 1.8.5

M81 and M82 Bodes Galaxy and Cigar Galaxy in LHaRGB

After much waiting, I finally have the RGB Data to go with the luminance layer, a new learning curve was the HDR Compose process in PixInsight, I used this to include the 300S Exposures I had previously that were burning out the core.

Equipment Used:
Imaging Camera: Qhyccd 183M Back Illuminated ColdMOS Camera at -20C
Imaging Scope: Sky-Watcher 8″ Quattro F4
Mount: Sky-Watcher EQ8 Pro
Guide Camera: Qhyccd QHY5L-II
Guide Scope: Sky-Watcher 90×50 Finder
Filter Wheel: Starlight Xpress Ltd 7x36mm EFW
Filters: Baader Planetarium LRGB + 7nm Ha
Image Acquisition: Main Sequence Software SGPro
Image Processing: PixInsight

Image Details:
101x150S in LRGB, Total 16.83 Hours
25x300S in LRGB, Total 8.33 Hours
25x600S in Ha, Total 4.16 Hours
Total exposure time: 29.32 Hours
BIAS, Darks and Flats subtracted
Target: M81 and M82 in Ursa Major
Acquisition Dates: Feb. 11, 2018,  Feb. 12, 2018,  Feb. 16, 2018,  Feb. 23, 2018,  Feb. 24, 2018,  March 13, 2018,  March 14, 2018,  March 15, 2018,  March 16, 2018,  March 19, 2018,  March 20, 2018

M97 / NGC3587 – Owl Nebula in LHaRGB

I have imaged this before in the same frame as the Surfboard Galaxy, however the 0.62 Arcseconds Per Pixel the Qhyccd 183M gives me on my Sky-Watcher Quattro 8″ F4 gives me a much higher resolution image, so here it is, the Owl Nebula in the constellation of Ursa Major at a distance of 2030 Light years from Earth

Gear:
Imaging Scope: Sky-Watcher Quattro 8″ F4 Imaging Newtonian
Imaging Camera: Qhyccd 183M 20mpx ColdMOS Camera at -20C and DSO Gain
Mount: Sky-Watcher EQ8 Pro
Guide Camera: Qhyccd QHY5L-II Mono
Guide Scope: Sky-Watcher 50×90 Finder Scope
Filter Wheel: Starlight Xpress Ltd 7x36mm EFW
Filters: Baader Planetarium 36mm RGB
Coma Corrector: Sky-Watcher Aplanatic Coma Corrector
Image Acquisition: Main Sequence Software SGPro
Image Processing: PixInsight

Image Details:
Target: M97/NGC3587 – Owl Nebula
Constelation: Ursa Major
Red: 27x300S
Green: 27x300S
Blue: 27x300S
Ha: 25x600S
Darks: 51x300S
Flats: 101
Bias: 251 converted to SuperBIAS and deducted from Flats
Imaging Dates: Feb. 12, 2018,  Feb. 16, 2018,  Feb. 24, 2018,  Feb. 25, 2018

PixInsight Image processing workflow:
1. Calibrated against darks and Bias Subtracted Flats
2. Star Alignment for all RGB and Ha Frames
3. Least noise frame from each colour chosen as Normalization Frame and Dynamic Background Extraction Performed
4. Normalization of all frames
5. Stacking of frames and generation of drizle data (for larger quality image in future)
6. Performed LinearFit using Red stacked image as reference for RGB Frames
7. Performed DynamicCrop on all channels and Ha
8. Performed MultiMedianTransformation to reduce background noise
9. Performed SCNR to remove excessive green in image
10. Stretched the image using HistogramTransformation
11. Performed an Unsharp Mask on RGB and HA Data
12. Performed an ATWT on the Background
11. Merged the Ha Data using the HaRVB-AIP Script in PixInsight
12. Performed a CurvesTransformation to bring out the star colour

QHY183M Review – Part 2

As promised, now that I have done some imaging with my new QHYCCD 183M Mono ColdMOS Back Illuminated camera here’s the second part of my review on the camera.

Pixel size:- The pixel size on the 183M is 2.4um which I absolutely love, on my Sky-Watcher 8 Inch Quattro F4 the camera gives me a field of view of 0.62 Arcseconds/Pixel, which is a fantastic resolution, I remember when I had my Atik 383L+ and my Astro-Tech AT8RC F8, that offered me a resolution of around 0.63 Arcseconds/Pixel, so I am now imaging at almost the same field of view but at F4 and at 20mpx, but let’s just put that into comparison on the same scope, the first image below is IC434 taken with the Atik 383L+ on the Quattro, and the second image below is taken with the QHY183M on the same telescope, you can see what impact it has on the field of view:

FOV on Atik 383L+ with 8″ Quattro F4

FOV on QHY183M with 8″ Quattro F4

As you can see from the above two images the difference in the field of view due to the chip size.

Camera Sensitivity:- Since moving to the QHY183M I have had to make changes to how I image, having owned the Atik 383L+ for a good few years, I got used to imaging with it, so when I moved to the QHY183M I suddenly noticed that this camera was quite a bit more sensitive, the first image above consists of 300 second frames for the LRGB whereas the second image consists of just 150 second frames, yes 150 second frames!!!

When I first started imaging M81/M82 with the QHY183M, I immediately started with 300 Second frames, I ended up with the same amount of 300 second frames that I had with the Atik 383L+ but I just could not process it, after further analysis I noticed then that the lights were severely clipped, to put this into perspective, below is the Sequence Generator Pro Histogram for both the 300 second exposure (left) and the 150 second exposure (right)

As you can see the histogram on the left for the 300 second exposure is severly clipped on the right side of the histogram indicating that the exposure was too long, the histogram on the right for the 150 second exposure is a lot better, there is still some slight clipping happening but this was a luminance frame, this clearly indicates that the 183M is much more sensitive than my previous CCD imager.

The following two images were produced with the 183M, firstly IC434 consists of 19×300 Second Exposures in RGB and the Second Image of The Owl Nebula consists of 27×300 second exposures in RGB + 25x600S in Ha

Software Integration:- As you probably know already, I use Sequence Generator Pro for my image acquisition and the integration with the camera has been pretty seemless, the ASCOM platform driver works pretty well, and I have the camera set to the default gain and offset setting that QHY have provided which is 16 of Gain and 76 for offset:

UV/IR Sensitivity:- I have read online that the 183M is a little bit sensitive to UV/IR Light, so I asked the guys at QHYCCD about this abd they informed be that the window on the senor is straight clear glass, so it also lets in UV/IR Light, which for me is not an issue as all of my Baader filters are UV/IR Blocked anyway, but it is something to consider if I ever change filters.

Conclusion
The camera has performed way beyond my expectations, had to change some of my approaches to image acquisition but that was to be expected, I am extremely happy with the camera and look forward to getting more data to compliment the Luminance for M81/M82 in the not so distant future.

If you are considering the QHY183M as an imaging camera, and would like to discuss, then feel free to reach out to me.

Clear Skies

Leo Triplet of Galaxies

Leo Triplet In LRGB (above) and LRGB+HA (below)

The Leo Triplet consists of three galaxies at a distance of around 35 million light years, M65 (top right), M66 (bottom right) and NGC3628 (left).  I have always aimed at imaging the triplet since I started imaging but never got around to it.

M65 (NGC 3623) and M66 (NGC 3627) are classed as intermiediate spiral galaxies and NGC3628 is also known as the Hamburger Galaxy or Sarah’s Galaxy and is classed as an Unbarred Spiral Galaxy.

The image consists of:-
29x300S of Luminance
14x300S Red, Green and Blue
15x600S of 7nm HA in the LRGB+HA Image
25 Darks and flats subtracted from all frames

Equipment Details:
Imaging Telescope: Sky-Watcher Quattro 8-CF F4 Imaging Newtonian
Imaging Camera: Atik Cameras 383L+ Mono CCD
Coma Corrector: Sky-Watcher Aplanatic Coma Corrector
Guide Camera: Qhyccd QHY5L-II
Guide Scoope: Celestron Telescopes C80ED Refractor
Mount: Sky-Watcher EQ8 Pro
Filter Wheel: Starlight Xpress Ltd 7x36mm USB EFW
Filters: Baader Planetarium LRGB + 7NM HA

Image Aquisition: Main Sequence Software SGPro
Image Pre-Processing and STacking: Maxim-DL
Post Processing: PixInsight

In my opinion, there’s only a subtle difference between the LRGB and LRGBHA images, personally I preffer the LRGB Version, the data was captured over multiple nights since the beginning of 2017 but in total gives 5.91 Hours on the LRGB Image and 8.41 Hours for the LRGB+HA Image

NGC2264 – Cone Nebula in SHO Narrowband

My latest image, I feel like I need more SII and OIII Data though to be perfectly honest, I captured quite a lot of dust even with narrowband mainly due to the high amount of HA frames I suspect, well here it is

Image Details:
27x 600S in 7nm HA
18x 600S in 7nm OIII
18x 600S in 7nm SII

25 Darks and Flats subtracted from lights

Data was acquired on the following dates: 18th, 19th, 20th and 21st January 2017, 13th and 18th February 2017

Equipment Used:
Imaging Scope: Sky-Watcher​ Quattro 8-CF Imaging Newtonian @F4 with the Skywatcher Aplanatic Coma Corrector
Imaging Camera: Atik Cameras​ 383L+ Mono CCD Cooled to -20C
Guide Scope: Celestron Telescopes​ C80ED Refractor
Guide Camera: Qhyccd​ QHY5L-II Mono
Mount: Sky-Watcher EQ8 Pro
Filter Wheel: Starlight Xpress Ltd​ 7x36mm EFW
Filters: Baader Planetarium​ 7nm HA, OIII and SII 36mm Unmounted
Image Acquisition: Main Sequence Software​ SGPro
Stacking and Combining: Maxim-DL
Processing: PixInsight​

Atik 383L+ Cooled Mono CCD Imaging Camera

After owning the Atik 383L+ Mono CCD Camera for over three years now, I would say I am definitely qualified to write a review.  I bought my camera back in 2013 when I lived in Ireland it was during the time when I transitioned from imaging with a Cooled and Modified DSLR Camera to Mono CCD Imaging.  At the time I was considering one of two cameras, the QHY8 Mono CCD and the Atik 383L+ Mono CCD, at the time the QHY was slightly cheaper but the Cooling Delta and Readout Noise was better on the Atik despite the fact that they both used the Kodak KAF8300 chip.

When I first received my camera, I was thoroughly impressed with the build quality, the red aluminium casing gave it a really professional feel to the camera and came complete with USB Cable, 12v Cigarette Power Cable and Software Media, all packaged really well, and when taking the camera out of the box, you could tell that Atik had put a lot of effort and consideration into their build quality and finish of the camera.  So far so good!

People quite often ask me how big the camera is, it just so happens that at the time I got my camera, I took a picture of the camera next to a AAA battery, just for comparison you can see that it is a fairly compact camera and at around 700g wasn’t too heavy either.

Because I couldn’t wait until my filterwheel had arrived, I wanted to test the camera functionality, so I installed all of the software onto my desktop PC and plugged the camera in.  At the time I got the camera, I was using Nebulosity to perform my image acquisition, so the first thing to do was build my dark frames at my desired temperature of -20C.  The dark frames showed very little in the way of noise which I was extremely happy with.  The installation of Drivers and  ASCOM Platform drivers all went perfectly without any problems, and Nebulosity worked well using the ASCOM Camera platform driver.

Once my filterwheel had arrived from StarlightXpress it was time to get the camera aquainted with the telescope, and at the time I was using an Astro-Tech 8 Inch Ritchey Chretien telescope on my already 3 Year Old NEQ6-Pro mount. Mating the camera to the filterwheel was relatively easy, I placed a thin cork shim onto the male thread of the filterwheel and screwed the camera on and adjusted the rotation of the filterwheel adapter to make sure the camera was at the right angle, I used the rubber shim to stop the metal to metal binding which makes it difficult to remove later, adding in the cork shim still allows it to be tightened up.

Since I had built my dark frame library, it was time to build my flat frames library, for this I used an EL Panel, one of the things I noticed was that a short exposure time of <1.0 seconds left a dark area to the lower right of the frame, after speaking with Atik they confirmed it was just the mechanical shutter, so I had to reduce the light on the EL Panel in order to increase the exposure time to get around this, other than that my flat frame library was built.

My first light for the camera was going to come from NGC7635 – Bubble Nebula in Narrowband, and whilst I must admit my imaging has come a long way since I took this picture, it is what it is and I was very happy with the results of sensitivity the camera delivered especially as this image is only 3x1800S frames for HA, OIII and SII.  Since I have had the camera, I have produced a substantial number of images to date and continue to do so using my Atik 383L+ Mono CCD Camera.

So how does Atik fair with me as a company, well it just so happens that I had to send my camera away for service due to excessive moisture causing Ice Crystals during cooling, I filed a support ticket with them and within a few days I got my camera back completely moisture free, I do not blame the camera here for the moisture, but more the fact that when I had my observatory located 15 miles away, I used to forget to switch the camera power off which would push a lot of moisture through the camera.  But the service from Atik was simply awesome.

Here’s a picture of the camera still used today attached to my F4 Quattro, I use Sequence Generator Pro for all my target acquisitions today but still using the ASCOM Camera Driver which is extremely stable

Just to recap why I am happy with the camera:

  • Build Quality
  • Size and Weight
  • Software Deployment
  • Sensitivity
  • Quietness of the camera

What could have been better?

  • Power cable – This could have been a stretchable power cable as I did run into a problem recently where the cable became snagged and it ripped the wire out of the jack plug that plugs into the camera, fortunately it didn’t damage the plug in port of the camera
  • Heated chip chamber, most cameras seem to have this now
  • Different colour options – I would have loved the camera in Blue or Green

You can see many of the images I have taken with this camera in my CCD Image Gallery Section here

 

 

M81 and M82 Galaxies in LRGB+HA

By far my biggest challenging project to date, maybe not by image acquisition, but by processing.  The above two galaxies caused me lots of grief when trying to process, they just did not come out right with my normal method of processing, so I turned to PixInsight to process them, and I anm so glad I did, the whole learning curve put me back to almost the same level I was at in 2008, but the steep learning curve paid off

M81 and M82 Galaxies in Ursa Major

Image Details
29x300S in LRGB
17x600S in 7nm HA
25 Darks and 25 Flats applied

Equipment Details:
Mount: Sky-Watcher EQ8 Pro
Imaging Scope: Sky-Watcher Quattro 8-CF 8″ Newtonian F4
Imaging Camera: Atik Cameras 383L+
Guide Scope: Celestron Telescopes C80ED
Guide Camera: Qhyccd QHY5L-II
Filter Wheel: Starlight Xpress Ltd 7x36mm
Filters: Baader Planetarium LRGB+HA 36mm Unmounted

Proccessing:
Stacking and Combining: Maxim DL
Processing: PixInsight 1.8 x64

The images were taken over a number of nights since the beginning of december and totals 12.5 Hours of exposure time