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SQM last night and binocular observation (& additional SQM readings)

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The Yorkshire Dales NP and Nidderdale AONB are working towards IDA accreditation.  We are undertaking measurement of sky bright/darkness.

About 20:00 I went to out measure and found all the readings about 0.2 down on previous, around the 21.1 mark.  The light domes were up and transprency was obviously down.

Wind the clock forward to 04:25 this morning.  The sky was CLEAR and DARK.

SQM from my garden averaged 21.5, repeated 10 mins later.  The moisture had been 'frozen' out of the sky, about-8C.   This was an improvement of 0.2 on previous best taken in the early hours last year.   I'm sure many in remote areas have darker skies but this was an eyeopener for me.

The Canon 15 x 50 binoculars showed some spiraling in M51 and M81.  NGC 3077 (mag. 9.89) was a smudge near 81 & 82.  M101 didn't need searching for :)  The Needle Galaxy, NGC 4565 (mag. 9.6) showed good elongation.  M66 & 66 were quick spots in Leo.

:) Paul


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On 31/01/2019 at 03:57, clarkpm4242 said:

The moisture had been 'frozen' out of the sky, about-8C

Congrats for a fine session in a dark sky!

This is hugely important and also a bit of an issue for me here- at these cold temps there are times the ice crystals just keep coming, reducing my SQM. I think this ice lights up the sky more than normal moisture, dust etc as it really reflects light.I can be down up to .4mag from optimum because of this.

Great observation Paul!

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Nice report and fascinating to observe what effects sky conditions in different locations. Here on the edge of the Fens, moisture frequently ruins a promising-looking evening, and because it’s so flat there’s nowhere for it drain to, so it all ends up in the sky just above my head or pooling on my eyepieces and telrad!

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On ‎31‎/‎01‎/‎2019 at 10:57, clarkpm4242 said:

M101 didn't need searching for :)

Nice report and great to have such a dark garden.

Edited by Eastman
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Obtained a sequence of readings last night.

23:10   21.26

00:30   21.32

01:10   21.41

01:50   21.45

These are each 5 readings after the meter has 'settled down'.  Top and bottom discarded and remaining 3 averaged.

Clearly demonstrate the darkening of the sky and possibly the 'loss' of Milky Way interference.

Neat :)

Incoming cloud stopped further measurements.


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