Tag Archives: Narrowband

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

NGC 2264 – Cone Nebula and Christmas Tree Cluster in HaRGB

Located in the constellation of Moneceros, this image shows both the Cone Nebula and the Christmas Tree Cluster, located around 2600 light years from earth the Cone Nebula being an emmision Nebula

Image Details:

101x150S in R
101x150S in G
101x150S in B
101x300S in Ha

Total capture time: 21 Hours

Acquisition Dates: Jan. 9, 2019, Jan. 31, 2019, Feb. 3, 2019, Feb. 14, 2019, Feb. 15, 2019, Feb. 23, 2019, Feb. 24, 2019, Feb. 25, 2019, Feb. 26, 2019, Feb. 27, 2019, Feb. 28, 2019, March 24, 2019, March 25, 2019, March 26, 2019, March 28, 2019, March 29, 2019

The NBRGB Script in PixInsight was used to blend the Ha into the RGB Image

101 Darks, Flats and Flat Darks were used in the frame calibration

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 RGB and Ha
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

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

PrimaluceLabs Sesto Senso Robo Focuser

Getting the best FWHM in your images is something that I have struggled with when imaging a whole night. As the temperature fluctuates, so does the FWHM in your images, this was a problem I had with my images at the beginning of the season. I looked around and the only focuser I could find was not a stepper motor focuser, so it didn’t offer predictable results. Since I am using the stock focuser for my Sky-Watcher Quattro 8-CF (and it’s a solid focuser at that), I did not really want to change focuser mid-season, so I did some research and landed upon the PrimaluceLabs Sesto Senso ROBO Focuser.

Now my expectations here were pretty low since I tried an electronic focuser and tried to use some sort of Auto Focus routine without any length of success, but when the Sesto Senso arrived I was excited as I looked at it and thought to myself that this would do the job.

Out of the box the Sesto Senso is very solid, good quality feel to it, and came with a bunch of different adapters for different focusers, one specifically for my Sky-Watcher Focuser too. I read the installation instructions a couple of times and set to work on upgrading my scope.

Installation
Installation was fairly easy and straight forward, I removed the slow focusing knob off the focuser and attached the adapter for the Sky-Watcher that came with the Sesto Senso, so within 30 minutes it was successfully fitted. And I can still manually focus with the fast focusing knob on the other side of the focuser:

After all the physical installation was done, I then needed to install the software on the observatory PC, since I image using Sequence Generator Pro, I proceeded to install Sesto Software and the ASCOM driver so that SGPro could talk to the focuser, again this was relatively simple to do. Once this was completed it was important to load up the Sesto software and perform a calibration so that the Sesto Senso knows where the most innner and outer focus positions are.

Setting the Focus Control module in SGPro was a breeze, for this I used a Focusing Mask to get a rough focus and set that point for all of my filters, now the following setting are what works for me really well, but basically:

  • I use 20 data points to achieve focus.
  • Step size between focus points is 20
  • Focus frame is 10 seconds for all filters, this is to get a better normalised focus frame, I was finding 5 seconds was too short and gave un-predictable results.
  • I set it to re-focus after a temperature change of 3.0 Degrees C since the last focus.
  • I re-focus on any centering action which is useful if you use a mirrored telescope like me.
Sequence Generate Pro Auto Focus settings
You can see here that my start off point is 50146, so it will go 10 points either direction of this point at 20 steps per point

I have now been using the Sesto Senso for a few months now and it has not failed me, I maintain a good FWHM value throughout the night and it an awesome piece of kit, well done Primaluce Labs. Is there anything that I would change about it?

Only one thing…….It requires separate power, which in all honesty I can understand why but if I could run the power through USB that would be a bonus.

One problem I have with the Auto Focus routine in SGPro is that in the image sequence, since my filters for LRGB are all parfocal, but my Narrowband filters are not, I only wish to focus on a filter change if it’s going from LRGB to Narrowband to LRGB or Narrowband to Narrowband, unfortunately SGPro doesn’t have that intelligence in the sequence, I am trying to persuade Jared to have that in there to make life that bit more simple.

Anyway I hope this review inspires you to consider this awesome piece of kit, it’s certainly helped me!

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

M97 and M108 – Owl Nebula and Surfboard Galaxy in LRGB

M97 and M108

The Owl Nebula (also known as Messier 97, M97 or NGC 3587) is a planetary nebula located approximately 2,030 light years away in the constellation Ursa Major.  It was discovered by French astronomer Pierre Méchain on February 16, 1781

Messier 108 (also known as NGC 3556) is a barred spiral galaxy in the constellation Ursa Major. It was discovered by Pierre Méchain in 1781 or 1782. From the perspective of the Earth, this galaxy is seen almost edge-on.

The image consists of the following
23x180S – Red
23x180S – Green
23x180S – Blue
25x180S – Luminance

25 Darks, 25 Flats and 25 BIAS frames have also been applied

Equipment Used:-
Imaging Scope: Sky-Watcher Quattro Series 8-CF F4 Imaging Newtonian
Flattener: Sky-Watcher Aplanatic Coma Corrector
Imaging Camera: Atik Cameras 383L+ Mono CCD -20C
Guide Scope: Celestron Telescopes C80ED Reftractor
Guide Camera: Qhyccd QHY5L-II
Mount: Sky-Watcher EQ8 Pro
Filterwheel: Starlight Xpress Ltd 7x36mm EFW
Filters: Baader Planetarium 36mm Unmounted LRGB
Image Capture: Main Sequence Software SGPro
Image Stacking: Maxim-DL
Image Processing: PixInsight

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