Alert Notice 696: R Aqr photometry (especially B) and spectroscopy needed


Note: Continued observations, particularly in B, V, and visual, are needed now and through the coming year. R Aqr is presently approaching solar conjunction and observations are very difficult, but they are extremely important as R Aqr is also approaching minimum. Please observe as long as possible now and pick up again as soon after conjunction as possible.  -  Elizabeth O. Waagen, 1 February 2021

February 3, 2020

AAVSO Forum threads (scroll to the bottom of a thread for latest posts):
- Campaigns and Observation Reports:
- Long Period Variables:
- Spectroscopy:

The symbiotic binary (Mira + white dwarf) R Aqr has been the target of numerous observing campaigns and AAVSO Alert Notices, most recently AAVSO Alert Notices 689 and 665 .

R Aqr is presently undergoing the eclipse that occurs about every 40 or so years. Photometry obtained to date shows extremely interesting short low amplitude variations with a timescale of 10 to 20 days, as well as what appear to be spikes. These variations are most significant in B.

Researchers, including Dr. Margarita Karovska (Center for Astrophysics|Harvard & Smithsonian), Dr. Lee Anne Willson (Iowa State University), and Dr. George Wallerstein (University of Washington), are requesting continued close coverage of R Aqr in order to study these variations and other behaviors seen during this eclipse. Particularly crucial are B and V photometry - the B is critically important.

Starting now, photometry is requested in UBVRIH (mid IR if possible). Nightly observations should be made. However, B (and V) observations should made twice per night, spaced 6-10 hours apart if possible so as to be most useful in studying the modulations seen in B. Nightly spectroscopic observations are also requested. Please continue these observations until further notice.

Dr. Willson comments on the spikes seen in B that may be short-term outbursts. To help confirm if these spikes are real and, if so, to investigate their periodicity, she requests that anyone picking up a sudden rise in brightness follow it with time series. She adds that: "The reason why this is interesting is, in part, because we are probably looking at what is going on around the companion, and the time scales give us some limits on the sizes of the regions involved."

R Aqr has a V range of 5.2 - 12.4. Current magnitudes from the AAVSO International Database are 12.4572 V +/- 0.0385 on 2020 Feb. 01.03461 UT (V. Buso, Rosario, Argentina) and 12.9897 B +/- 0.0364 on Feb. 01.03362 UT (Buso).

Coordinates (J2000): R.A. 23 43 49.46  Dec. -15 17 04.2

Charts with comparison stars for R Aqr may be created using the AAVSO Variable Star Plotter (VSP).

Please report all photometry observations to the AAVSO International Database using the name R AQR.

Spectroscopy reports should be submitted to the AAVSO Spectroscopy Database ( and to Dr. Karovska (

This Alert Notice was compiled by Elizabeth O. Waagen.

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