How reliable are the results from the MASCARA photometry project? It claims that HD 21856 is a pulsator varying at the 0.015 level in the clear passband. The standard error quoted for the determined period is very small, which lends credence to the result (if it is not a systematic effect). I’m surprised I have never heard of this survey.
Tom
looks like the small errors must be mean-errors-of-the-mean rather than an rms error. the per-observation errors look to be quite a bit larger. Probably legit for strictly periodic variables and where you have lots of data-points, as shown in the linked paper.
One reason you may not have heard of this survey is that the project is concluded. Someone, or several someones, ought to be running similar sorts of set-ups. Like a lot of such projects, this ran the f/1.4 lenses wide-open and unfiltered, producing all sorts of systematic problems. I would argue for sacrificing sheer efficiency for precision: use a filter, and stop the lens down a couple of stops until the images are sharp. The main thing here would be to have the software pipeline ready to ingest and process the data to get the photometry out.
\Brian