Alert Notice 689: R Aqr monitoring needed in support of HST and Chandra observations

Note:  Please continue observations in all bands (particularly B and V) and spectroscopy - they are extremely important.  -  Elizabeth O. Waagen, 18 April 2023

Continued observations in all bands (particularly B and V) and spectroscopy are extremely important. Please continue nightly observations until further notice.  -  Elizabeth O. Waagen, 31 January 2020

Note: The exact schedules for the Chandra and HST observations of R Aqr (Alert Notice 689) are as follow:

Chandra (UT)  Note that this date is EARLIER than given in Alert Notice 689.
12 Jan 2020 00:13:21.409 - 12 Jan 2020 14:06:41

HST (times are UT)
13 Jan 2020 03:54:33 - 13 Jan 2020 04:48:21
13 Jan 2020 08:40:40 - 13 Jan 2020 09:34:54
14 Jan 2020 02:09:47 - 14 Jan 2020 03:58:31

- Elizabeth O. Waagen, 10 January 2020

January 3, 2020

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

Dr. Margarita Karovska (Center for Astrophysics|Harvard & Smithsonian) requests the assistance of AAVSO observers in monitoring the symbiotic binary (Mira + white dwarf) R Aqr in support of upcoming observations with Chandra and HST.

The HST observations are scheduled for 2020 January 13 and 14 UT. The Chandra observations are scheduled for the week of January 13 UT. [SEE NOTE ABOVE FOR REVISED DATE OF CHANDRA OBSERVATIONS]

Starting now, Dr. Karovska requests photometry (UBVRIH, mid-IR if at all possible), high speed photometry (UB), and spectroscopy. Visual observations are welcome. The cadence requested is twice a week, then nightly during the scheduled HST and Chandra observations, then twice a week for two weeks after the satellite observations. For Chandra nightly coverage, please make observations throughout the week of the 13th.

R Aqr has a V range of 5.2 - 12.4. Current magnitudes from the AAVSO International Database are 12.121 V +/- 0.046 on 2020 Jan. 3.0118 UT (F.-J. Hambsch, Mol, Belgium) and 12.687 B +/- 0.035 on Jan. 3.0137 UT (Hambsch).

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 (

R Aqr is presently undergoing the eclipse that occurs about every 40 or so years. In connection with this eclipse, it is the target of another campaign reported on in AAVSO Alert Notice 665.

This Alert Notice was compiled by Elizabeth O. Waagen.


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