Sky quality meter readings: sharing our October dataset

[Miguel Alvarez]

We finished the October round of measurements at eleven points in the municipality. Average zenith reading was 21.2 mag/arcsec², with the worst point at 19.8 next to the industrial estate and the best at 21.6 on the ridge.

Two observations that may be useful for others:

• Readings taken before 22:30 are consistently 0.2 to 0.4 magnitudes worse, almost certainly because of cars leaving the town.
• The difference between the two sides of the same hill is bigger than the difference between seasons, which says a lot about where lighting actually goes.

Happy to share the raw file if anyone wants to compare methodology.

[PNR]

Please do share it. We measure with a handheld device at fixed points but we are less disciplined about the time of night, and your 22:30 cut-off explains a discrepancy we had been blaming on the instrument.

[CANSTAR]

This is exactly the kind of material that should end up in the resource centre as a research item, with the method attached. If you upload it, we will link it from the dark-sky section so that all territories can reuse the protocol.

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