Proposal #88

Requester: Phillip Sullivan
Obscode: SPP
Sustaining member
navillus@sonic.net

The VSX contains 121 RCB Stars. Of these, 33 have listed pulsation periods. The periods range from 27.8 days to 130 days. The amplitudes of the pulsation are described in the literature as 0.1 to 0.3 magnitudes. The purpose of this project is to see if the BSM system can be used to observe bright RCB stars (about 12 mag V and brighter, at maximum) in order to increase the number of RCB stars with known pulsation periods. More information on pulsations may lead to a better understanding of these stars

Target stars (only RCB stars that appear to be steady at maximum light based upon current AID data) would be observed at a cadence of 5 days in V and I (and B if this is practical). Bright RCB's without current AID data may also be observed to determine if they are steady at maximum and could be also observed for pulsations

BSM images would be sent to my VPhot account. Transformed V and I magnitudes would be submitted to the AAVSO database. If new pulsation periods are found these would be submitted to the JAAVSO.

The three target stars submitted in this proposal are all in the VSX and have AAVSO comp sequences.

The exposure times and number of observations per filter (for stacking) are guesses and may need to be adjusted once the observations begin. I would start with exposures of 300 seconds per filter. If the telescope is able to make unguided exposures of 60 seconds, than five 60 second exposures could be stacked for each filter.

Observations of these stars should start as son as possible and continue until they are no longer observable this year (estimated 6-8 weeks) or go into decline in brightness. If these observations show promise, I would submit proposals for other bright RCB stars as suitable targets become observable