AAVSO: American Association of Variable Star Observers

Proposal #332

Proposer (2092) Michael Heald (msheald@hotmail.com) obscode: HMH
Assigned To(3663) Dirk Terrell
Date SubmittedApril 8, 2023

Member Name: Michael A. Heald - HMH
1) Target Star: RR CET, a RRAB star with a period of 0.55302836 days
2) Rationale: A review of the AAVSO light curve suggests low amplitude magnitude changes of 0.03 to 0.05 or less (eyeball estimate from light curves rather than mathematical extrapolation) around the expected baseline. This variability is most pronounced at the star's maxima. Magnitude determinations close in time seem to vary more than the precision of the reported readings. This variability is noted between different observes who have submitted observations
I am no longer able to observe this star since I have moved out of the Las Cruces, NM area. I had wondered if the variability was a result of my technique or the microclimate of my observing site in Las Cruces, NM. However, the appearance of such variability among different observers, especially at the star's maxima when precision is expected to be highest, is puzzling.
CCD data became available in the International Database since 2006. RR CET is well studied in the professional literature. However, the curves I was able to locate had errors of about 0.03 magnitudes with the Fourier analysis of RR CET's period, so correlation between the International Database and published light curves is difficult. Additionally, it is possible that low amplitude variations might have been averaged out in the published data since the studies were designed to identify the main light curve shape and period of the star rather than identify if there were any low amplitude, high frequency fluctuations in the light curve itself. This averaging out of low amplitude, high frequency oscillations would occur if the frequency of such oscillations were not a harmonic of the main RR CET light curve frequency since observations over a number of nights were averaged to obtain the main light curve.
3) Plan for Data: Upload to the AAVSO International Database. I will also use this data to compare with past observations. The data will assist me in determining why my data shows such oscillations so that I can improve my photometry in the future by analyzing both my equipment and microclimate. Additionally, if the data shows possible magnitude oscillations, the data will help generate hypotheses for additional observations.
4) I Request Observations be sent to my VPHOT Account.
5) Magnitude Ranges: V Magnitude Range: 9.1 to 10.1.
6) Time Interval of Observations: 90 seconds - to match the frequency of the putative low amplitude variations.
7) Filter Requested: V
8) Exposure Times: 90 seconds in V and taken continuously for a 6.5-hour period. If the S/N is too low to see baseline trends of 0.03 magnitudes, every 2 images can be stacked in order to improve S/N.
9) Start Date and Times suggestion: 18:30 PM, 11/21/2023, MST (end of astronomical twilight) till 01:00 AM, 11/22/2023, MST. These times/dates would cover RR CET from about 30 degrees east to 30 degrees west from the location my observations when I lived in Las Cruces, NM, and allow me to coordinate my observational data with the BSM observations. These dates would also minimize the chance of poor weather since the "monsoon" season occurs from August till October in the Las Cruces area. However, comparison of the data obtained in similar locations is not as important as the data itself, so I defer the actual location to those with more experience than me

Target RA (H.HH) Dec (D.DD) Magnitude Telescope Observation Frequency Expiration Date Proprietary Term
RR CET 1.535603 1.34175 10.0–9.0 BSM_NM 0 Oct. 16, 2023 No


(4726) Kenneth Menzies — April 19, 2023, 5:30 p.m.

Do you actually want this time series run in November 2023??

(4726) Kenneth Menzies — April 19, 2023, 5:50 p.m.

Committed to NM in November 2023. One long time series.

(2092) Michael Heald — April 19, 2023, 11:38 p.m.

November was when the entire RR CET light curve can be visualized in one night, as I remember it. Best regards. Mikde

Comments on this proposal are closed.