Tag Archives: skywatcher

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

M101 / NGC 5457 – Pinwheel Galaxy in RGB

M101 / NGC5457 or most commonly known as the Pinwheel Galaxy is a face on spiral galaxy in Ursa Major and has a distance of around 21 million light years from Earth.

The QHY183M picks up quite a lot of the Ha detail in this galaxy without me having to image separate Ha Filter data

Image Details:
101x150S in R
101x150S in G
101x150S in B

Total Capture time: 12.6 Hours

Acquisition Dates: Feb. 27, 2019, March 29, 2019, March 30, 2019, April 1, 2019, April 11, 2019, April 12, 2019, April 14, 2019

All frames had 101 Darks and Flats applied

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
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

NGC4565 – Needle Galaxy in RGB

The Needle Galaxy is located int he constellation of Coma Berencies and is an edge on spiral galaxy at a distance of 30-50 million light years from earth

Image Details:
101x150S in R
101x150S in G
101x150S in B

Total Capture time: 12.6 Hours

Acquisition Dates: Jan. 28, 2019, Feb. 3, 2019, Feb. 25, 2019, Feb. 26, 2019, Feb. 27, 2019, March 26, 2019, March 29, 2019, March 30, 2019, April 1, 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 RGB
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

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

M78 / NGC 2068 in RGB

This is the first time I have ever imaged this object, I will re-visit next year when I will image at F2.8 with a wider field of view using a keller reducer.

Since this object is in the southern area of sky, I am limited by trees and the house on the data I can capture in a single night

Image Details:
101x150S – Red
101x150S – Green
101x150S – Blue

101 Darks, Flats and Dark Flats

Image Acquisition Dates: Jan. 1, 2019, Jan. 2, 2019, Jan. 8, 2019, Jan. 9, 2019, Jan. 27, 2019, Jan. 28, 2019, Jan. 30, 2019, Feb. 10, 2019, Feb. 20, 2019, Feb. 23, 2019, Feb. 24, 2019, Feb. 25, 2019

Equipment Used:
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

IC5146 / Cocoon Nebula in HaRGB

This is my first time ever imaging this target, and like the Crescent Nebula and Pelican Nebula I am limited to a 2.5 hour window per night to acquire data due to trees / house getting in the way, luckily I managed to get a lot of Ha data on this subject to blend this into the RGB image which smoothed out the lack of data for RGB somewhat, I would have liked to have got more RGB Data and I may re-image this with longer exposures on RGB next time also

Cocoon Nebula in HaRGB
Cocoon Nebula in HaRGB with PIxInsight 2x Drizzle

Image Details:
56x150S in R
56x150S in G
66x150S in B
101x300S in Ha

Acquisition Dates: Sept. 25, 2018, Sept. 27, 2018, Sept. 29, 2018, Oct. 20, 2018, Oct. 22, 2018, Oct. 26, 2018, Oct. 28, 2018, Oct. 29, 2018, Nov. 14, 2018, Nov. 17, 2018, Nov. 18, 2018, Nov. 30, 2018, Dec. 7, 2018, Dec. 9, 2018, Dec. 12, 2018, Dec. 13, 2018, Dec. 27, 2018, Jan. 4, 2019

All frames had 101 Darks and Flats applied, the Ha layer was blended using the new NBRGB Script in PixInsight 1.8.6, the more zoomed in picture is of the same data but with a 2x drizzle applied then cropped

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

Flickr Link: https://www.flickr.com/…/465843…/in/album-72157688487449350/

AstroBin Link: https://www.astrobin.com/384658/

Pegasus Astro Ultimate PowerBox

I spent a lot of time looking at PowerBoxes/USB Controllers, the late Per Frejvall had developed a very nice Remote USB Hub but of course with the passing of Per, these are no longer available. I looked at two hubs, the HitechAstro Mount Hub Pro abnd the one I settled for was the Pegasus Astro Ultimate PowerBox.

Unboxing the PowerBox I was pleased with the build quality, they even ship mounting brackets for you to be able to mount it onto your setup, here’s an image of mine mounted on top of my Sky-Watcher Quattro:

Pegasus Astro Ultimate PowerBox on Imaging Setup

I loaded up the software onto the observatory PC and again pleasantly surprised at how easy it was to get started and configure the names of the powered devices connected as well as names for each of the dew heaters, in the following image you can see my power connected devices and my dew heater for my guider camera:

Screenshot of Control Software

I configured the software to automatically power my devices the moment the unit is switched on, so what do I have connected to the PowerBox?

  • QHY5L-II Guide Camera
  • StarlightXpress USB Filterwheel
  • PrimaluceLabs ROBO Focuser
  • EQ8 Pro Mount PC-Direct Cable

I didn’t connect my QHY183M at the moment as I discovered that during image download it seemed to cause a timeout on the QHY5L-II Camera, I have raised a ticket with Pegasus Astro on this one. From a Power perspective, I only have my QHY183M and my Rear Fan assembly/heater connected as I currently do not have the power cable to connect directly to the hub for the EQ8 Pro (On Order). There is also a temperature sensor for the ultimate version, which works well as an interface for Sequence Generator Pro and my Auto Focuser routines.

I have been using the Hub now for a good few months, I am pretty happy with it, am I totally happy you might ask, well to be honest there’s a couple of niggly things that I have emailed Pegasus Astro about (awaiting a response):

  • Voltage. I am running 13.8V regulated bench power supply capable of delivering up to 15A which is powering the hub, however when devices such as the camera, dew heater, fan assembly are all running, the voltage level drops down to around 12V according to the software, I would not expect this to do so, I would expect it to remain 13.8V. My EQ8 Pro mount is powered by the same supply (but not through the hub currently) and during slew the voltage in the software does not change, so it’s obviously something being caluclated within the hub somewhere.
  • Issue with USB3 Camera (QHY183M) is still outstanding
  • When you set the power to the dew heater for example I always run it at 170, however when the software restarts you have to manually go and set this again
  • Ability to reboot or “Disconnect” a specific USB Port remotely would have been nice.

The main reason I wanted something like this was the ability to reboot the hub remotely, with standard USB Hubs this is not possible, as above, I would love to have a bit more granularity on this and have it on a per USB port but it works well for me right now.


Skywatcher Quattro 8-CF Imaging Newtonian

After much deliberation and conversations back and forth with Bernard at Modern Astronomy, I finally decided to go for the Skywatcher Quattro 8-CF 8” F4 Reflector, there was a number of factors that helped me reach this decision, most of it was the British weather being so unpredictable that I needed to get as many photons for my images in the shortest available time.  I was used to imaging at F7.5 that the F4 was going to give me significantly faster optics, I also opted for the Carbon Fiber version purely from a thermal expansion perspective as it was going to perform better than the steel tube version.  I also opted for the 8” as the Native focal length of 800mm suited me perfectly, and I plan on getting the Keller reducer to bring it down to 560mm @ F2.8.

Setup and Collimation
When I received my telescope and optically matched Aplanatic Coma Corrector, I was impressed with the build quality of the scope itself, internal baffles to boost contrast as well as eliminate stray light, and the focuser is pretty sturdy for a stock focuser, and quite easily handles the weight of my CCD and Filterwheel.  I mounted the telescope next to my Guide scope on my Skywatcher EQ8, I wish they had provided a Losmandy plate with the telescope, but the Vixen style bar still worked out well.  After balancing the scopes on the mount I was ready to check the collimation, for this I used my Farpoint Collimation Kit, firstly the laser to ensure it hits the centre spot of the primary, and the laser return reached the centre point of the laser collimator itself, the adjustments required were very minor.  After this I verified the collimation with the Farpoint Cheshire and it verified that the collimation was correct, only thing left to do was a star test, for this I used a 10mm Eyepiece and a fairly bright defocused star, the star was spot on, I could see all the concentric rings.  I then proceeded to perform the same star test with the CCD and the Aplanatic Corrector to verify, which of course it did.

Scope Details:
Focal Length: 800mm
Apperture: 8 Inch
Focal Ratio: F4
Tube Composition: Carbon Fiber
Focuser: 2″ Dual Speed Linear Power Focuser

First light
My first target for 2016 is the Iris Nebula, my first set of frames came through and for a 5 minute exposure I was impressed with how much data I had collected, data that would have taken over 15 minutes to collect on the F7.5 refractor I now use as a guide scope, I managed to finish a target off within a few days of imaging rather than over a multitude of nights

I have also not had to re-collimate the scope or adjust the focuser on the scope over the few weeks I have had it, so overall I am above and beyond happy with my decision and I am now able to image targets in a shorter timeframe which in the UK you have to grab every clear sky you can

A few months on
I have had to re-collimate the scope 0 times, even after removing the primary mirror assemply for cleaning, the focuser is still rock solid and holds the camera gear extremely well.   I have made an addition to the scope, I have added a fan system to the rear of the primary mirror, the fan also has some nichrome wire which allows the air being blown around the primary to be just above the dew point which prevents dew forming on the primary and believe it or not the secondary also, even in high humidity sessions.

Build Quality: Extremely pleased with the build quality of the scope, even the focuser is sturdy and holds all of my gear really well

Collimation: Extremely easy with the right tools, it has required no further collimation in the months that I have now owned the scope

Improvements: Could have come with a fan assembly, most of the other F4 scopes from other vendors do

Conclusion
After months of usage, I have produced some really good images in short timeframes due to the fast F4 ratio, I am looking forward to using this scope again next season with 3nm NarrowBand filters and possibly the Keller Reducer to bring it down to F2.8