Unihedron Sky Quality Meter: observations in Victoria

[JimIrish (Jim)]

colleagues,

I recently purchased a Unihedron SQM. I've had to wait several months before there were cloudless, moonless nights at my home at Hoppers Crossing (near Werribee; a western suburb of Melbourne). I've recently made some measurements which I'll submit to the International Dark Skies website using the standard format.

Other members may wish to share, via this thread, their quantitative experiences rather than qualitative ideas of where (relatively) dark skies can be found.

The following are measurements made on moonless, cloudless times after the end of Astronomical Twilight, in the standard unit of magnitudes per square arc second, for the spectral response of the instrument.

Incidentally, I've noticed that the end of the evening astronomical twilight (when the sun reaches 18 degrees below the horizon) corresponds well with the time when my SQM measurements made at five minute intervals reach a plateau.

Hoppers Crossing: Generally about 19.1 mags/arc-sec^2
South Werribee: (agricultural areas south of M1): 19.4 to 20.8 units, with the best a few hundred metres back from the coast.
west of Werribee C703, towards Melton and beyond the V/Line train line to Geelong): 20.3 units.
Kerang: about 20.1 units.
Pyramid Hill: similar to Kerang.

I hope to make some more measurements tonight northwest of Hoppers Crossing to delineate the relationship with distance from the CBD.

I'm considering a paper along the lines of that by J.D. Biggs et al., Measuring and mapping the night sky brightness of Perth, Western Australia, Mon. Notices of the Royal Astron. Soc. 421, 1450-1464 (2012), for central Victoria. Anyone wishing to collaborate??

I'm interested in measurements made in other states. I'm aware of the excellent data for Adelaide.

[stefang (Stefan)]

We had a 22.6 at Wiruna , Ilford NSW Saturday night

[markbakovic]

No assistance or measurements to offer, but wanted to express my appreciation and encourage you guys: wish there was more reliable data on this sort of thing.

[ausastronomer (John Bambury)]

Originally Posted by stefang

We had a 22.6 at Wiruna , Ilford NSW Saturday night

That reading is not accurate. The theoretical maximum reading is 22.0. Either the batteries needed changing or the SQM needs re calibrating.

Wiruna normally runs 21.4 to 21.6 when the milky way is overhead and 21.6 to 21.8 when the Milky way is low, which it is at the moment.

Cheers
John B

[ausastronomer (John Bambury)]

Or you may have meant to type 21.6 not 22.6