Alert Notice 855: V711 Tau monitoring requested in support of XRISM spectroscopy observations

February 29, 2024

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Miki Kurihara (graduate student, University of Tokyo, ISIS/JAXA) and colleagues have requested AAVSO observers' assistance in monitoring the bright (5.71 - 5.94 V) RS CVn star V711 Tau (HR 1099) in support of X-ray satellite observations to be made with the X-Ray Imaging Spectroscopy Mission (XRISM).

The XRISM observations have been scheduled for 2024 March 06 - 10 UT (5 nights).

Photometry is requested beginning now and continuing through March 17. If flares in the X-ray band are observed (notification will be posted in the forum thread above), follow-up observations afterwords (~ a week) will be appreciated.

A single snapshot per night is requested, with minimum SNR = 50. Rc is the preferred filter, but all bands are welcome. Unfiltered observations reduced to a Rc or V zeropoint are also welcome. V711 Tau is an ideal PEP target. Because of its brightness, CCD/DSLR observers are reminded to take care not to saturate their images.

Kurihara writes: "This is a request for a campaign observation for RS CVn type binary stars coordinated with XRISM (X-Ray Imaging Spectroscopy Mission) observation. XRISM is an international X-ray satellite mission led by JAXA, NASA, and ESA. It was launched last September and has exhibited unprecedented energy resolution (R~1000 @ 6 keV) in orbit. As a part of the calibration program, XRISM will be pointing to HR 1099 (RS CVn type binary) next month for 400 ks in total. To make the most of this opportunity, (semi-)simultaneous observation with X-ray (Chandra, XMM-Newton) and optical (Japanese ground telescopes) are prepared. However, the visibility of ground telescopes in Japan is limited to only a few hours after sunset. Thus, we would like AAVSO astronomers to perform photometry observations of HR 1099."

Coordinates (2000.0):  R.A. 03 36 47.29  Dec. +00 35 15.9  (from VSX page for V711 Tau)

Charts with comparison stars for V711 Tau may be created using the AAVSO Variable Star Plotter (VSP). Comparison stars are being added by the AAVSO Sequence Team; if they do not show on a chart, please try again later. Recommendations regarding the comp and check stars for PEP observations will be posted in the forum.

Please submit observations to the AAVSO International Database using the name V711 TAU.

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen using information provided by Miki Kurihara.



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