Table 3. Results of fitting a Gaussian function to the differences between observed SQM values and those expected based on the DMSP radiance observed at that location. The 2009–2012 dataset excludes a portion of the 2012 data, as described in the Methods.

Dataset	Observations	Mean	Fit σ	χ2/dof
2009–2011	1243	0.00	0.51	21.6/24
2012 all	863	0.27	0.49	30.0/21
2012 excl	705	0.11	0.45	28.6/21
2009–2012	1948	0.05	0.49	33.0/25