AAVSO: American Association of Variable Star Observers

Proposal #234

Proposer (4655) Donald Collins (dcollins@warren-wilson.edu) obscode: CDK
Assigned To(3663) Dirk Terrell
Date SubmittedNov. 8, 2021

The triple-star system b Persei (magnitude 4.6 V) is expected to undergo a primary eclipse centered on December 23. 4 UT (JD: 2459571.9). I wish to use observations from three BSM's: BSM-NH2b; BSM-TX or BSM-NM; and BSM-Hawaii from December 16, 2021 through January 1, 2022 to record this event along with AAVSO observers. We need wide longitudinal coverage, especially the western N. America and the Pacific to cover as much of the 3 day eclipse as possible as well as the out-of-eclipse observations both before and after the eclipse. The high brightness of b Per requires that images either be de-focused or diffused with an engineered diffuser to spread out the star profiles to enhance the distribution of star pixels to avoid saturation. Spreading the star profiles also enables longer exposures, which will reduce scintillations. The observing runs should last as long as possible each clear night with airmass <= 2.0 with a cadence consisting of a burst of 5-10 rapid successive images every 30 minutes. The BSM-NM and BSM-NH2b were successively used in October 2020 to obtain good data. Because the star undergoes ellipsoidal variations of 0.06 mag peak-to-peak and a period of 1.52 d, the out-of-eclipse data are requested in order to verify that all the observations from different observers and telescopes can be offset to a common zero point. In the relatively short time (since 2013) since the AAVSO had first discovered that bright b Per experiences eclipses by the third star in the system we have discovered that the period of the third star's orbit is clearly 2 days longer than previously believed, but the period still has an uncertainty of about half a day. Every eclipse shows a different light curve pattern. With more eclipses observed we can become more hopeful that a solution for the remaining astrophysical parameters of the three stars in the system can be determined.

Target RA (H.HH) Dec (D.DD) Magnitude Telescope Observation Frequency Expiration Date Proprietary Term
b Persei 4.304033 50.29550 4.6–5.2 BSM_NH2 1 Jan. 1, 2022 No


(4655) Donald Collins — Nov. 12, 2021, 10:08 p.m.

Thank you for the notice. Do we have time with all three BSM's requested in the proposal?
Will someone contact me for any more questions?

My phone # is: 828-318-5778
Thanks, Donald Collins

(3663) Dirk Terrell — Nov. 12, 2021, 10:30 p.m.

Yes, Ken Menzies will contact you about observing details.

(4726) Kenneth Menzies — Nov. 13, 2021, 10:06 p.m.

Committed to NH2, NM and Hamren. Plan similar to that used in 2020.

There is a one night test run of limited duration (3 repeats). Report how that works out for exposure and defocus.


(4655) Donald Collins — Nov. 15, 2021, 3:14 p.m.

Please refresh for me how to access these images. Thanks.

I am so pleased to have the Hamren (Hawaii) BSM plans to observe!
Thanks, Don

(4726) Kenneth Menzies — Nov. 16, 2021, 1:56 p.m.

The 'you have data' email you receive after images are collected will have the link. Images are on your ftp folder and your vphot account.

BTW, Hamren is presently not operating.


Comments on this proposal are closed.