Observation by David Davies: M4 skirting the trees

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David Davies


David Davies


2022 Jul 01 - 23:33


2022 Jul 03 - 17:41



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Field centre

RA: 16h23m
Dec: -26°34'
Position angle: -0°14'

Field size

1°23' × 1°03'

  • APM 107 refractor
  • QSI 683 camera
  • SW EQ8 mount

4 x 2-minutes RGB


Cambridge, UK

Target name

Messier 4, NGC 6161


M4 skirting the trees

About this image

I've always regarded M4 as being too low to observe from my observatory but on 1st July I could see that this lovely globular cluster would just graze the treeline at the edge of the field south of my garden. At 23:30 the sky is just dark enough to consider attempting a capture, but M4 is already past the meridian. I had no guide star as the orientation of the off-axis guider was looking into the trees for a star - I could see the dark shadows of the branches flowing through the field of view as I watched.

So this image is just four subs each of two minutes of RGB, unguided. It is rather noisy and I've had to do a bit of work to eliminate the lights of aeroplanes taking off from Stansted and to try and control the heavy background gradient due to the twilight sky and reflected light from behind the wood. You can see the dark shadow of the trees at the base of the image.

But I'm pleased with the result and can tick off M4 from my Messier list.

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Jeremy Shears
Jeremy Shears, 2022 Jul 03 - 18:49 UTC

Nice image, David. You can see the central “bar” well, which is prominent when observed visually 

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