On October 6, 1923 renowned astronomer Edwin Hubble discovered a pulsating star in the Andromeda Galaxy which quickly led to the revolutionary discovery that M31 is a galaxy unto itself 2.5 million light-years away, and not a gaseous cloud of stars within our own Milky Way.
That variable star is designated "M31 V0619" by the AAVSO. It pulsates between 18.5-19.8V every 31.404 days. It is a Cepheid type of variable star that has the distinct characteristic of revealing its distance by simply measuring its period and mean magnitude Last year I accidentally captured it at maximum light in a mosaic of M31 with my lowly 71mm f/5.9 refractor. The problem is that one hour of integration time barely recorded it. There is no way that I can capture it at minimum light. I need to trade up my equipment. That is not feasible given the lousy weather here so RoboScopes to the rescue!
I've looked at pretty much every combination of scope and camera. The best one is Pier 8: CDK 17 with the KAF-16803 sensor. According to my calculations in a single 30-minute exposure it can capture the star at minimum light (i.e. 19.8V) with a signal-to-noise ratio (SNR) of 85, and at maximum light (i.e. 18.5V) with SNR 250 without saturation. This is more than adequate to perform differential photometry.
(By the way it is OK that there is no Photometric "V" filter in the wheel. The luminance filter will be fine.)
So the problem becomes a matter of scheduling. I do have an ephemeris available to me that forecasts the moments of minimum and maximum light but what I'd really like to do is build a light curve of say 10 data points over a full cycle. Ideally this would require one frame to be acquired every 3 days. The problem is if I place a 5-hour order then RoboScope's scheduling algorithm will attempt to fill that order in one night if possible.
Does anyone have any ideas? I know that this pushes the limits of the business model.
Something I was thinking about is this: Put in a single order each week for as many weeks that are necessary to build a decent light curve.
Thanks,
Brian
EDIT: Actually Piers 3 and 10 are also well-suited and have a more attractive price point.