photo sharing and upload picture albums photo forums search pictures popular photos photography help login
strongmanmike2002 | all galleries >> Galleries >> The Location EAGLEVIEW > Very dark skies
previous | next

Very dark skies

Having taken many readings between early August and late December 2021, under varying clear sky conditions, using a calibrated Unihedron SQM
sky quality meter, the Zenith sky darkness readings at Eagleview, on typical clear moonless nights, generally range between 21.88 and 21.93
and on the very best, most transparent nights, with low humidity and no sky glow, SQM Zenith readings have hit 22.00 or even slightly higher!

The reading of 22.05 is the best reading pointing at or near the zenith over Eagleview, taken at 1am on 7 Sept 2021, It was New Moon
with superb dark conditions after a snow front had passed through the day before and a high pressure system had settled in and there was no
Milky Way or clouds overhead and fortuitously fog has settled over much of Canberra, 55km to the north. The SQM meter was pointed at the vacant
Galactic pole area of the sky in the constellation of Sculptor. At the time these measurements were taken, I could make out the super faint Zodiacal
Bridge, a very faint band of light that follows the entire Ecliptic, caused by sunlight being scattered off the tenuous dusty disc left behind
after the formation of our Solar System, this is a rare phenomenon to be able to see. The Gegenschein was also visible, a faintly bright spot
in the night sky centred at the antisolar point. Earlier in the evening, the central bulge of the Milky Way, passing overhead, spanned a whopping
60deg or more in breadth!! and cast an obvious shadow, making for a magnificent, awe inspiring sight! Extensive at or near zenith readings were
taken over three separate clear nights, between 6 Sept and 12 Sept 2021, when the Milky Way was not overhead. Readings were consistently well over
21.90 with several readings hitting or squeaking just over 22.00 mag/squ arc sec. So!...that's good empirical evidence that it's bloody dark and
indicates that while technically it is classed as a Bortle class 2 site, Eagleview, on the very best nights, displays most qualities of a
Bortle Class 1 observing site, making for a truly magical and breathtaking scene overhead!

This is the device I used for the measurements:

other sizes: small medium large original auto
comment | share