[Aavso-photometry] Uncertainty limits
Keith Graham
kag at core.com
Thu Nov 10 11:49:54 EST 2005
I have a question regarding useful observations and uncertainty limits. I have noticed, not surprisingly, that my uncertainty readings on moonlit nights are higher than on darker nights. When I get down to 16th mag and dimmer on "bright sky" nights, the uncertainty can sometimes be .2, and I have even gotten as high as .8. These numbers are certainly worse than expected visual uncertainties, but, I can see from my images that the mags are pretty reasonable when the variable is compared to the dimmest comps on the image. So, I was wondering if it is best to simply scrap observations with such a high uncertainty? My thinking is that even with such a high uncertainty, the information is still better than a < observation. If I can see the star on an image, is it better to attempt a measurement with a high uncertainty than to simply use < reading? I do realize I can improve the uncertainty with either longer exposures or by stacking images, but I sometimes do not catch how dim the target is when I am doing a run of many different stars in one evening.
Thanks,
Keith Graham
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