Andrew Thornett

Instructions for processing images in Nebulosity and GIMP

The sets of instructions I have written based on advice I have been given or read so far….subject to later revision. Due to my limited knowledge of astrophotography, there may be errors in these documents.


How to remove light pollution from astronomy photograph in GIMP 250819

How to stack frames in Nebulosity 4 (without darks) Damian 310819

How to process dark frames in Nebulosity Damian 080919

Instructions on how to take dark frames from Damian 030919

Sorting out elongated star images (star trailing) in astrophotos 270819

Damian re-processes Andrew’s M101 image from 24/8/2019 in Nebulosity and Photoshop

Better outcome that my previous attempts. Also multiple small galaxies indentified by comparison with a better widefield image (not mine) – overlaid below – my apologies that stars don’t quite match



Damian’s version my M101 from 240819 on 080919 overlaid with better widefield M101 picture, showing multiple small galaxies, many of which are evident also in image above (due to poor alignment many stars appear twice close to each other):

Painting/staining of new HEQ5/EQ6 mobile base with Cuprinol now completed

Two layers of Cuprinol later (left over from my wife’s fence painting project earlier in the year), the new mobile wooden HEQ5/EQ6 will be ready for vanishing with yacht varnish once it dries – and with high humidity levels at present and low temperatures I think it might take a few days before it properly dries out from the water based Cuprinol. That’s the price you pay for using left over stuff!


Focusing QHY10 with Tele Vue TRF-2008 Reducer-flattener in situ for first time during day on Sky Watcher Equinox Pro 80mm OTA

I added my Tele Vue TRF-2008 Reducer-flattener into the imaging train for my QHY10 camera on my Sky Watcher Equinox Pro 80mm telescope today. As first step, I decided to try focusing it during the day. This needed me to reduce the aperture by 70% with aperture mask as well using minimum 1/10000 second exposure setting in Nebulosity 4 for the camera and also aim as the darkest part of the daytime garden.

Following image shows bottom garden in focus with QHY10 only attached to telescope:

In the following image, I added in my Tele Vue TRF-2008 Reducer-flattener and TS Optics off axis guider/flip mirror together into the imaging train – as you can see I could not obtain focus even when the focuser was fully racked in as far as it would go (needed to go in not out – could see focus improve as I did so):

Finally, in this image, you can see that I obtained focus with the Tele Vue TRF-2008 Reducer-flattener and QHY10 but without the TS Optics off axis guider/flip mirror, so sadly I won’t be able to use the TS OAG/FM with the TRF-2008 and my QHY10:

Focus was achieved at the end of the garden with QHY10 and Tele Vue TRF-2008 Reducer-flattener with a setting of 17mm on the focus tube of the Equinox 80mm OTA. Note 35mm of T2-adapters were used as spacer between the TRF-2008 and QHY10 as advised in the TRF-2008 manual.

Next step is to try focusing at night and find alternative way of finding my objects than the TS OAG/FM as I am keen to use the TRF-2008.


Trip to Jodrell Bank radio observatory 4/9/2019

Angella and Alan from RAG took me today to Jodrell Bank. We were accompanied by another of their neighbours and friend, Liam.

Jodrell Bank houses the Lovell Telescope (Mark I) and other radio telescopes and was the brain child of Sir Bernard Lovell.

I remember last visiting the site as part of a RAG trip around 10 years ago and following the planet trail (a scale model of solar system that involves running around trying to find the planets at scale distances from the Mark I telescope) with my son Rhys, who must have been around 6 at the time.

The activities available for visitors have increased significantly since then and more are planned for the future with a new visitor building about to be built.