Ken Crichton

Gamma cygni nebula

I was able to get out on Monday evening after work for a couple of hours. The Sadr region had just crossed the meridian by about 8ish so i decided on this target. I took a total of 17x8min subs in Halpha before heading indoors for an early start in the morning. This was processed along with 45x bias 25x darks (from darks library) and 25x flats. Very pleased and hope to add some colour when the moon has gone.

Ngc 7000 North American Nebula

I decided to start imaging the north American nebula this time because it crossed the meridian right after my son was put to bed at 8pm, giving me 5-6 straight hours of imaging. Sadly after preparation the clouds rolled in so it wasn’t until 11pm that i was able to start imaging. I finished off around 2:30am giving me around 3.5hrs of data in Halpha. Stacked and processed in pixinsight with 20 darks 20 flats and 35 bias. 8min exposures at iso 800 f5.

SGL Star Party 2018

Ken and I, plus RAG junior members Ben and Sam decided to brave the wild weather of Storm Callum this weekend and attended the Stargazers Lounge star party at Lucksall in Herefordshire. The weather gods co-operated in the standard way for pre-organised astro events and laid on some gale force winds, torrential rain and almost complete cloud cover, but this didn’t stop the whole thing being a lot of fun.
A marquee was set up for the event and some excellent talks were provided, including a very interesting one on sub millimetre astronomy, the limits of our current knowledge and how we’re pushing against them.
In addition there were a few practical activities laid on including rocket making and virtual reality exploration of the ISS and Comet 67p, plus some unofficial events:
– Welsh whiskey sampling (It’s a thing, apparently, and very nice too!)
– Watching ever larger pieces of debris glide past on a very swollen River Wye. We thought the mature Oak tree would be the largest, but then a pontoon with several large canoes still attached went flowing past.
– Speculating on whether the campsite would actually flood- the water was only a foot or so beneath the top of the defences when we left this morning.

There was also around an hour last night where the weather gods were clearly distracted and the cover broke a little and we played a game of pointing the dob at the gaps in the cloud as some of the easier to spot objects made an appearance. Altogether we managed to share views of the double-double, Bodes & Cigar, Andromeda, the Ring, the Double Cluster (easily the best sight, given the conditions), Albireo and Mars- albeit on a now you see it, now you don’t basis. Despite this, it was a great craic doing it with like-minded folks.

Fingers crossed next year there won’t be the same clash with the IAS- it would be great if more of us could enjoy both events.


Pixinsight Process

This time last year i tried a free one month trial period with the astronomy software pixinsight. It does appear daunting at first sight although as you start to use the software it becomes easier and familiar. I watched many tutorials on youtube but didn’t really find any that covered the whole process. I decided to create my own work process for the software combining different peoples methods on youtube. I hope it may be of interest to anyone starting out with the software.

Pixinsight Guidelines For Beginners

Process – Image integration

Add all bias frames, ignore format hints

Combination = average, Normalization = no normalization

Weights = don’t care, Scale estimator = meridian absolute deviation

Uncheck evaluate noise

Pixel rejection 1 = sigma clipping (no normalization)

Pixel rejection 2 = sigma low 3 sigma high 3

Execute and save master bias when complete (XISF or FITS)

Process – Image integration

Add all dark frames, Use the same settings as bias frames

Execute and save master dark when complete (XISF or FITS)

Process – Image calibration

Add all flat frames, ignore format hints

Specify output directory (create new folder for calibrated flat frames)

Output extension = .FIT   Postfix = _c

Select master bias (uncheck calibrate)

Select master dark (check calibrate plus optimize)

Uncheck master flat, Execute

Process – Image integration

Press reset parameters (bottom right)

Add all calibrated flats _c

Combination = average, Normalization = multiplicative

Weights = don’t care, Scale estimator = (ignore) Interactive k-sigma biweight mid

Uncheck evaluate noise

Pixel rejection 1 = Sigma clipping – Normalization = Equalize fluxes

Pixel rejection 2 = sigma low 3 sigma high 3

Execute and save master flat when complete (XISF or FITS)

Process – Image calibration

Add all light frames, Keep the same settings as before but add master flat (don’t hit calibrate under master flat)

Process – Image registration – Star alignment

Select reference image “file”

Add all calibrated light frames, Change output directory

Execute and save as _r  for registrar

Process – Image integration

Add registrar light frames _r          Hit reset settings for standard settings

Combination = average, Normalization = additive with scaling

Weight = noise evaluation, Evaluate noise checked

Pixel rejection 1 = sigma clipping (normalization = scale + zero offset)

Pixel rejection 2 = sigma low 3 sigma high 3

Execute and save as integrated light

Process – Geometry – Dynamic crop

Click image first, click reset, move box to cover image, execute

Process – Background modelization – Automatic background extraction

Target image correction = subtraction      Execute

Click on new preview mode and click on a dark area of the image creating a box (preview)

Process – Colour calibration – Colour calibration

Press reset, White reference – reference image = target image, Background reference = preview 1

Apply this and save as colour calibrated image

Press F12 and remove stretch

Process – Intensity transformation – Histogram transformation

Click real time preview, ensure 16 bit 64k

Middle slider to left and left slider slightly right trying to keep clipped pixels low, Apply and save as Histogram

Bottom left hand corner “zoom 1:1”

Click extract CIE L* component

Process – Intensity transformation – Invert

Click on tab and release on image, minimize mask keeping for later

(Remember white reveals, black conceals)

Click on icon “spying glass” to see image in real terms

Create new preview – encircle object (galaxy etc etc)

Process – Noise reduction – TGV denoise

Move edge protection until happy with details, Strength 5 ? Edge protection 3 ? Smoothness 2?

Click on image and apply, Save as TGV denoise

Remove mask

Process – Mask generation – Range selection

Preview, Click and drag, Lower limit – 0.240000 ? Smoothness – 75.5 ?

Close range selection , Apply mask to image

Preview – Process convolution – Unsharp mask

Open real time preview, click and drag middle slider until desired change

You can toggle on/off real time preview to see the difference

Apply to image and minimize mask

Process – Intensity transformation – Curves transformation

In “RGB/K” click two points of the curves line to tap down and move as desired

In “S” for colour transform move cursor to desired level and click apply

Eastern Veil

Frustrated with not being able to image last year when the moon was up i decided to purchase a Halpha filter. I wasn’t expecting too much as im currently using a Dslr which has a bayer matrix in front of the sensor for colour photos. I was able to capture 23x5min exposure with 5xdarks and 10 flats. Im happy with the result although i know i can definitely improve with more darks and longer exposures. I might have to look at getting a mono camera 😉

Anyway a good start to the year for me and lots of images to process!


M13 5.5.18

With the good weather last weekend a couple of us from the group decided to spontaneously meet up for some astronomy.

I always find that phd2 guiding performance is a direct indicator of conditions and on this occasion guiding was below 0.5″ all evening showing that we had exceptionally good seeing.

I started off with 35 images of M3 which will follow, and then when it was higher in the sky  i switched over to M13. Using Rob’s 14″ dobsonian we had some amazing visuals of M51 with the spiral arms just visible. Nick turned up later and whilst Rob was setting up his imaging scope we had a go at star hopping to M3 which we couldn’t find. It just shows that myself and Nick are far to reliant on technology! Rob took over and quickly found our target which was amazing! Later in the night we also had some fantastic views of the ring nebula, different shades of grey clearly showing where the various colours would be with an image.

On this occasion i didn’t take any darks or flats thinking that M13 would be an easy target given its brightness. That was clearly a bad decision but its also a learning experience.

This was taken with the Baby Q and canon 6d with an Idas d1 filter.

NGC 6207 is also clear in the image as well as several other NGC, PGC and IC objects.