SQM-L straylight blocker.

[PeterW]

Some of the places I observe (Like home) have a few stray street/house lights. Wanting to get a better estimate of light pollution with an SQM-L I have always worried that some of this stray light might mess up the readings by scatter/diffraction off the window on the top of the device. So I made a simple push on straylight cone which is lined with flock paper. The come half angle is 30degrees, chosen so it won’t affect the SQM-L readings. Quick test indoors with a ceiling light seems to be blocked quite well.

Need to make a lid or store it upside down to avoid (non black) dust getting in!

Peter

[PeterW]

Managed to gain 0.5mag on my skies using this.. blocking bright sources out of the main measurement angle. Skies seem darker, probably are (a little). Should test this at a dark sky location when the effect of using this should be close to zero.

 

PEter

[Captain Scarlet]

I must admit I do notice a difference when shielding my Sqm-l just with my hand from my house lights when taking readings. If you could rustle one up for me too I’d be grateful ... 😬

M

Edited February 20, 2020 by Captain Magenta

[JamesF]

Looks like an excellent idea.  I shall try to remember this when I build one.

James