I had heavy smoke at my site last night and took the opportunity to test the effect of smoke on SNR. It was also a full moon and the only star visible to my eyes was Vega. By extending my “normal” exposure times (CCD) I was able to achieve a good SNR with stacking. Then I begin to wonder if there are any effects other than SNR. Specifically, does smoke effect accuracy? Any thoughts/facts? …Lane
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Obviously, smoke, wet haze and fog should decrease SNR. There is special U comment code in the report form.
However, effect depends on the band and sensor - R or IR rays usually better penetrate haze, and sensors are usually more sensitive for them. My observing site is plased in the river lowland, so haze is usual thing. What to do. My last June LC of 14R star has been got on absolutely awful muddy white sky, when summer triangle was barely visible. In spite of broad scatter of points, resulting O-C value layd in the trend. So differential photometry is not capricious.
Of course, precise measurements in standard bands require good seeing, but for TOMs haze is not so important.
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Strictly from a “I want to produce good quality and useful phtometry point-of-view” the smoke we are exeriencing the last 5 or more years in the eastern USA leaves something to be desired in that hope. The last few months since Canada has caught on fire again I have stayed home at least 50% of the what the weather service calls clear nights because of unacceptable smoke conditions and we haven’t had very many clear nights anyway. I transform almost all my photometry which is either B V Rc Ic or at least B V Ic which helps but there are limits to even what that can do.
As the olde Ford Motor Co. advert. used to say, “Quality is job #1” and that is what we should all strive for.
- Transform you multicolor photometry and keep your comparison stars close if possible.
- If the skies look dismal or a deeply reddened Sun is noticed near sunset… the errors in your photometry are probably not very useful so stay home and get some sleep!
- Yes, you can even compare your observations against others so you may evaluate the photometry you produce. Quality over quantity should rule.
Jim (DEY)
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Well, it’s not a smoke but dawn. VPhot successfully processed images except white ones, with almost invisible stars. CR light curve has small scatter without final part with very low SNR. Of course, it is not standard band, but result is not so bad for white night (red circles on phase plot, where maximum was cut due to huge errors).
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