Proposal #43

PROPOSAL: To image CY Aqr using multiple AAVSOnet telescopes spaced in longitude (E and W continental US, Hawaii, W Australia, and Israel) sequentially over a 72 hour period to be scheduled this fall as telescope time permits. A time series of 3 stacked images in each of B, V, R, and I bands with a 15 minute cadence would be imaged on one instrument ceasing as the target approaches the horizon. The next telescope westerly in longitude would subsequently repeat the process, continuing around the globe. All data world be air mass corrected and transformed. Using this technique combined with an Alert Notice, a nearly complete 3 day light curve would be generated (to the extent that nights of clear weather permit).

RATIONALE: CY Aqr is a SXPHE star, a metal-poor, DSCT-like variable. SXPHE variables are pulsating sub-dwarfs of the old disk galactic population. These stars may be gaining in mass and luminosity from a binary companion, or by merging with one. Despite being relatively bright (mag 10.42-11.20), CY Aqr has been observed only intermittently as noted in the last 1500 day AAVSO light curve.
Twelve partial nights of observations of CY Aqr from 2011 were published by Sterken et al (2012JAD….18….2S) using a single 250mm instrument which yielded 29 new maxima. The authors comment that “it will require at least another half decade of additional monitoring before any significant update to the present model can be considered.” By using the power of AAVSOnet’s multiple instruments to generate a much longer and nearly continuous light curve, new insights as to whether or not the binary model can fully account for the period variability of this star could be revealed.

FROM: David Cowall (cwd)