To give you some idea of objective testing of light pollution, you can obtain very useful data by taking photographs and using a Sky Quality Meter SQM. I find this an efficient way of letting me know is it worthwhile carrying out an observational run, where you need long exposures to achieve a certain magnitude threshold.
The Sky Brightness Map is based on work by Cinzano, Thiene, Italy (1998) see table. It is colour coded according to the Bortle scale. Kingsland is located in the grey area which is a rating of 2 on the scale and has a limiting magnitude of 7.1-7.5. For example, an exceptional record on sky brightness was achieved on March 22/23, 2008 when a reading of 21.74, taken at Kingsland Observatory using a Sky Quality Meter (SQM) from Unihedron. This exceptional reading was due to a 1.5 arc second reading of transparency taken by an STV camera. Routine measurements are taken every clear night with readings on average of 21.55 +/-0.5. These measurements are taken at zenith with a Moonless sky.
Color Mag.
Bortle Class-- Sky Brightness mag/arcsec²
Sky Brighness Artificial/Natural
7.6 - 8.0
1
>21.6
<0.01
7.1 - 7.5
2
21.6 to 21.5
0.01 to 0.11
6.6 - 7.0
3
21.5 to 21.3
0.11 to 0.33
6.3 - 6.5
4
21.3 to 20.8
0.33 to 1.0
6.1 - 6.3
5
20.8 to 20.1
1.0 to 3.0
5.6 - 6.0
6,7
20.1 to 19.1
3.0 to 9.0
5.0 - 5.5
8
19.1 to 18.0
9.0 to 27.0
<4.5
9
<18.0
>27.0
Light bubble images is a useful way of determining the extent of the pollution:
Light bubble images were generated by a series of photographs taken with a wide-angle lens on December 12/13, 2007. The images are stitched together to form a panoramic. The exposures are 60 seconds except the second and last images which are 120 seconds. The bubble from Boyle is the brightest and reaches a maximum height of 13.5 degrees. Bubbles from Sligo , Ballaghadereen and Castlerea are also visible with less than 4 degrees in height. Even smaller bubble can be seen with less than 2 degress in height from Carrick to the east.
Eamonn A
kingslandobservatory.com
  