Astrophotography – deep sky

North America and Pelican in Ha

First Image in more than three years…. just a screen grab as it’s not good enough for a full size jpeg.

A quick process to re-learn what we’ve forgotten in that time!

7x 600seconds taken at 385mm f/3.6. Dark and flat frames applied.

Calibrated and stacked in Nebulosity. Processed in Photoshop CC 2017.

Been out a few more times since then to try and sort out issues with guiding, mount control and the Robofocuser having stopped working – we’re slowly getting there!

Think now I have a total of 17 subs on this to sort. Then I’ll process again with a bit more care and attention to the finer details and stars. That should (hopefully) be the Ha sorted.

Next year we’ll try and get the SII and OIII to make up a false colour image.


Imaging Sadr and Observing the Veil

Good night on Tuesday- managed to get a good imaging session in as well as some observing. The picture is of Sadr/Gamma Cygni from 20x 300 seconds plus bias, darks and flats.

Had the dobs out whilst this was going on, first star hopping with Sam to the Hercules cluster and the Double cluster then alone after his bedtime. From the observing log:

West and East Veil- superb. Sinuous strands, beautiful. Spent a long time sweeping back and forth.
N America nebula- found Mexico but rest was a struggle.
Andromeda group. M31 dark lanes were visible in the 35mm eyepiece, first time from home.
Pleiades- first sight this year.
M33 pinwheel- v v faint. 20 minutes to find. Not worth it!!!
Kemble’s cascade & ngc1502

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!


Observing and Imaging 17th September


It’s been a sparse few months for imaging. As well as the short nights of the summer months I’ve also had a few problems with my DSLR, plus the roads around my house have all been fitted with tall bright LED lights (see photo below, showing how much bigger they are) rendering my light pollution filter useless and limiting me to subs <1min. To fight back I’ve invested in the new version of the IDAS filter which offers some relief, plus a second hand Canon 600d with the IR filter removed. Monday was my first chance to use it, and I decided to go for M31 for the purposes of comparison with previous camera and streetlights. After setup I had an hour to try it out and the results are quite promising- I think I’ve gained more from the new kit than I’ve lost from the LEDs. There are some further things that I can do to improve it (I think I can get away with longer exposures, plus I want to try and make a cooling unit for it)- but altogether I’m quite pleased. It’s 20x 180s exposures on a 130 pd-s, with guiding, plus dark, bias and flats.


Whilst the imaging rig was doing its stuff I went for some instant gratification with the Dob. Whilst the LED lighting has hurt the imaging it seems to be better for the visual. At a RAG meeting a while back there was discussion of how counting stars in Pegasus would give you a good indication of your light pollution levels. I went home and found I had a depressing big fat zero. Although the new lights are brighter, they are better directed and I can now see 3 or 4 (faint) stars. This realisation was a good start to an enjoyable session- transparency seemed pretty good, and I doubt there’ll be another session this year where it’s too warm for a jacket. From the observing log:

M71 – Struggled to get my eye in to start with and I found it a tricky find, but satisfying once in.
M15 – Really bright central core and with a ring of resolved stars around it covering around a quarter of the eyepiece at 220x
M2 – Was tighter and not quite so bright or widespread but still a nice view
M52 – Gorgeous open cluster- 30-40 bright stars and many much fainter ones. Tried it at 220x, 70x and 45x and the middle magnification was the best- really filling the view. Highlight of the night.
NGC7789 – Caroline’s Rose – Another nice open cluster- but quite faint, and I couldn’t really see the rose. Maybe it’s like one of those Magic Eye pictures.
M103 – A nice triangular shaped with a lovely red quite central in the Eyepiece.

Monday night’s a bit early in the week to stay up late, and the only downer was packing up as the skies were getting better still. At least I was heading to bed with a full memory card ready for the clouds and rain that have dominated the remainder of the week…


DSOs 10-11/08/2018

After imaging Mars, I moved on to image a couple of DSOs in Cassiopaeia.

NGC278 is a small face-on spiral, and after processing, was a pleasant surprise, with lots of character. I think I need to re-visit this one with more magnification at some point.

NGC185 is is a dwarf spheroidal galaxy located 2.08 million light-years from Earth. It is a member of the Local Group, and is a satellite of the Andromeda Galaxy.