Do you need narrowband from your site?
Compare integration time multipliers for OSC, broadband, and narrowband filters at your sky brightness — relative to an ideal dark-site reference.
Inputs
Measured or estimated SQM at your imaging site
Results
Adjust the inputs to see results.
Brightness factor = 10^((21.7 − SQM) / 2.5). Time multiplier = brightness factor × filter efficiency. Reference SQM 21.7 ≈ Bortle 3–4 dark site.
All formulas verified by automated tests.