AAVSO: American Association of Variable Star Observers

Proposal #140

Proposer (2728) Dennis Means (dlm4570@triconet.org) obscode: MSD
Assigned To(3663) Dirk Terrell
Date SubmittedApril 16, 2020

My name is Dennis Means, Obs code MSD. I am submitting this proposal in support of Frank Schoor's LPV Humps Project. In talks with Frank we decided observation of these three stars could bennifit the project. The three stars are S UMi (000-BBW-210), S Cep (000-BCP-063), and BH Cru (000-BCV-591). The data gathered would be used to help study the LPV humps and to enrich the AID for these stars. Images should be placed in my Vphot account.

S UMi images, V 4 @ 5", B 4 @ 30", SR 4 @ 3", I 4 @ 2.5". Cadence 2 days. Request BSM_NH2 as star is at +78.
S Cep images, V 4 @ 4", B 4 @ 40", SR 4 @2.5", I 4 @ 2", Cadence 4 days. Request BSM_NH2 as star is at +78.
BH Cru images, V 4 @ 5", B 4 @ 40", R 4 @ 2.5", I 4 @ 2". Cadence 5 days.

Plan would be to monitor each star and if hump detected to request cadence change to 1 day for duration of hump. And to change cadence to 1 day during maximum to allow for best timing of hump activity during cycle.

Target RA (H.HH) Dec (D.DD) Magnitude Telescope Observation Frequency Expiration Date Proprietary Term
S UMi 15.492936 78.63342 13.2–7.5 BSM_NH2 2 Oct. 20, 2020 1 Year
S Cep 21.586897 78.62450 12.9–7.4 BSM_NH2 2 Oct. 20, 2020 1 Year
BH Cru 12.271331 -56.28600 10.1–6.5 BSM_S 2 Oct. 20, 2020 1 Year


(3663) Dirk Terrell — April 19, 2020, 10:41 p.m.

A note form Arne:

"These stars have a (B-I) of 7 to 9, so the exposures listed will need to be adjusted. The I-band exposures are about right, but everything else needs to be adjusted. We won't know for sure until the first set or two of images. Because of the extreme red color, Dennis may also have to use different comp stars in the red and in the blue, so they are non-trivial targets. What I recommend is lots of short exposures and then stack to increase the dynamic range. That also can handle the couple of magnitudes of variation without saturation, which would be an issue with fixed longer exposures. BH Cru is in a pretty crowded field, so the observer should be cautious when the star is near minimum, as there may be a background star that contaminates the photometry. The adjustment to 1-day cadence during the hump may not be the best way to handle the light curve. I strongly suggest always using 1-day cadences so that the beginning of the hump is also detected. It means a little more work analyzing a higher flow of data for the researcher, but will result in better science."

(4726) Kenneth Menzies — April 23, 2020, 8 p.m.

Plan created. Committed to NH2

(4726) Kenneth Menzies — April 23, 2020, 8:16 p.m.

BH Cru committed to BSM_S and BSM_Berry

(4726) Kenneth Menzies — April 29, 2020, 9:57 a.m.

Exposures increased slightly to improve SNR.

Comments on this proposal are closed.