Ground Truth for August ’05

Irregular (what else?) measurements of sky brightness using a Unihedron Sky Quality Meter at my observing site.

Date and local time-weather-sky brightness (mag./sq.arcsec)

August 30 1.30 am – clear – 17.66

August 29 4.00 am – mostly cloudy with moon occasionally visible – 15.88

August 27 11.00 pm – clear but hazy – 17.07

August 26 – 10 pm – clear -16.98

August 25 11.00 pm – partly cloudy – 17.07 but highly variable – pointing at clouds gave a reading of 16.74, while carefully aiming at a sucker hole gave a reading of 17.23

August 25 2.00 am – clear, bright moonlight, with Mars just a few degrees south of the Moon – 17.07 with Moonlight striking the sensor, 18.01 with the sensor aimed slightly north and angled to avoid direct moonlight

August 24 10.30 pm – clear, lots of local lighting – 17.83 – nothing half as good as earlier. Supposed to be some aurora, but can’t see it

August 24 2.00 am – clear, bright moonlight, with the moon high in the sky – 16.90 with the moonlight striking the sensor, but 18.04 with the sensor aimed slightly north and angled so as to avoid the direct light of the moon. This is probably as good as it gets here in the city with moonlight (too bad this isn’t a weekend, as I would have observed if I didn’t have work in the morning). Visual limit about 4.5 m

August 23 11.30 pm – mostly clear, bright moonlight – 17.90

August 22 12.30 am – clear, bright moonlight – 17.58

August 20 – mmm, teppanyaki. No reading – I’m too full!

August 19 – torrential rains! OMG! Flooding! I’m not taking a reading while standing in ankle deep COLD water! My equilibrium is punctuated!

August 18/19 about 1 am/Overcast/15.46

August 17 about 11.30 pm/Mostly cloudy, some stars visible at zenith/16.63

August 16 about 11.30 pm/Clear but with poor transparency/17.34

Leave a Reply