NGC 7380 – The Wizard Nebula – in SHO False Colour

I’ve been working on capturing NGC 7380 – The Wizard Nebula – for a couple of weeks now. I imaged a set of Ha subs at the start of July and they suggested that this would be a good candidate for a longer set of narrowband images. The weather has been pretty abysmal so it was only in the last two weeks I managed to get any serious imaging time done.

The Wizard Nebula is a gaseous cloud in the constellation of Cepheus that surrounds the open cluster NGC 7380. It is approximately 7,000 light years away and spans an area of around 100 light years across. It’s common name comes from the image of a sorcerer that appears to be coming out of the sky.

The image was captured using Ha, SII and OIII filters and, in total, comes to just under 6 hours total integration. The breakdown of total subs is:

Ha: 34 x 180 secs
OIII: 61 x 180 secs
SII: 20 x 180 secs

All subs were captured on the QHY163m at unity gain of 139, offset 21 over three nights. They were calibrated in Pixinsight using 25 darks and 25 flats (a new set of flats taken after each imaging session) before being star aligned and stacked into three master lights.

I duplicated the Ha master light as a false luminance light which I processed for greater contrast as well as applying deconvolution to bring out finer details before combining into a LRGB colour image.

I opted for a SHO palette as I felt it gave the nebula a more dramatic “on fire” look. When shooting narrowband, colour palette is purely a personal choice anyway as any palette is false. Finally, I boosted the saturation to bring out the blue of the OIII as well as to deepen the red/orange of the Ha.

The finished image!

You can also see a higher resolution version on my Astrobin page. Overall, I am pretty pleased with the results, especially given that it was taken in mid summer, near full moon and from my heavily light polluted garden.


Posted in Images, Latest Posts | Tagged , , , , | Leave a comment

Patience is key to building a great deep sky image

It’s not been a great summer so far, weather wise, which is really frustrating as I am a teacher and I get 6 weeks off every summer. What I want to be doing is imaging however, in Yorkshire, the weather has been terrible: rain, cloud, more rain … which teaches a valuable lesson – patience is most definitely a virtue; especially in astrophotography.

About a month ago, I made a start on NGC 7380, The Wizard Nebula. I was pretty impressed at how much detail I was getting on narrowband, especially given that it was mid summer and full moon. This is a stack of only 18 minutes of Hydrogen Alpha, imaged on my QHY163m camera, using unity gain of 139, offset 21 @ 180 second exposure.

The Wizard Nebula in Ha - 18 mins total exposure

The Wizard Nebula in Ha – 18 mins total exposure

I finally managed to get some clear skies last night although I managed to waste about 2 hours messing about with kit I really should have had tested as working before it got dark. I began imaging about 2am and let it run until 3.30am when it began to get noticeably lighter. I was gathering O3 data this time and managed to keep 18×3 minute subs out of all the data gathered.

I calibrated this in Pixinsight then croppped and aligned it to the Ha data already gathered and calibrated previously. The first problem was the rotation of the previous image compared to the latest data – I had to crop quite severely to allow for alignment.

I created a bi-colour image with a synthetic green channel made by combining the Ha and O3 data in Pixinsight. The image was then colour calibrated, with the background neutralised. I applied a masked noise reduction process on the background before reversing the mask and bringing out the finer details of the nebula. Finally, I applied a curves transformation on the background to increase the contrast and darken the background slightly.

The result is a bi-colour image that is a total of 1.2 hours integration of narrowband information gathered from a heavily light polluted area of north England. I plan to continue to add to the folder and hopefully complete another couple of hours on each channel, including S2, before the end of August. As a working piece, I am very happy with it so far:

Ha and O3 bicolour process of NGC 7380

Ha and O3 bicolour process of NGC 7380

I’m really impressed with my mount, the Skywatcher EQ6-R pro – it is helping me guide much more accurately and I am now getting to grips with EQMod as an alternative to using the handset. I’m still fine tuning PHD2 to work with it and my guide scope / camera configuration from AltairAstro so hopefully I can continue to refine my guiding and imaging processes.

Posted in Images, Latest Posts | Tagged , , , , , , , | 2 Comments

Collimating a Newtonian Scope

I shied away from using Newtonian scopes for imaging for ages as I listened to all the bogeymen stories online about how difficult they were to collimate, especially at faster FRs. My first imaging scope was a reflector – a Skywatcher ED80 – and, although I loved it and learned to image well with it, I still wanted something faster. There was no way I was going to be able to afford a faster APO refractor or Astrograph so the only realistic way was to go down the Newtonian route and learn to collimate!

I now own two Newtonian imaging scopes, both Skywatcher (you’ll spot a pattern emerging soon!); a 130pds and a 200pds. Both have low profile focuser draw tubes, although the 130pds now has an aftermarket Moonlite focuser and stepper autofocus motor.

I started by buying a couple of cheaper collimation kits – the ones with the laser and target system – but I found them to be completely unreliable. And yes, I know you CAN collimate with a lens cap with a tiny hole drilled into it, but I wanted something I could use quickly and reliably. Eventually the guy who sold me my 200pds showed me his Farpoint Collimator set and I was sold!

Farpoint Laser Collimator

Farpoint Laser Collimator

The quality is awesome – solid milled aluminium is always a winner – and it fits snugly into the draw tube. The kit comes with a set of adhesive triangles which you fit onto the primary mirror (a really easy job as they also provide a cellophane applicator) and these are sheer genius. Like most Newtonian scopes, the Skywatchers come with the plastic doughnuts adherred onto the primary mirror. This is all well and good, however everything you look at in collimation is circular so it gets very difficult to work out which bit is which. Not with the Farpoint triangles! They stand out and so make primary mirror collimation a breeze as all you have to do (having made sure the secondary mirror is circular in view) is move the triangle into the centre of the circle in the eyepiece. Quick and easy! The secondary is then collimated using the included laser.

I’ve also been working on standardising my kit setup, and in particular, working on streamlining my wiring. I have now attached as much onto the scope as I can (dew heater controller, focus controller and a powered USB 3.0 hub) as well as tucking in all wires. Hopefully this will reduce the potential for wires dragging or catching mid session. It does mean that making sure the scope is well balanced is especially important so time will tell if I have got it right.

Posted in Calibration, Latest Posts, Technique | Tagged , , , , , | Leave a comment