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Alert Notice 592: V404 Cyg observations needed tonight for Chandra observations

August 11, 2017: Dr. Gregory Sivakoff (University of Alberta) and colleagues have requested AAVSO observers' assistance in observing the black hole X-ray transient LMXB V404 Cyg in support of Chandra observations taking place TONIGHT. The Chandra schedule is

2017 Aug 11 23:49:04.072  - 2017 Aug 12 13:42:14.730 UTC

Alert Notice 522: V404 Cyg HST multiwavelength observations scheduled

Correction: In the text below, the date of the detection by the Swift satellite was incorrectly given as 2015 June 16.77197 UT. The correct date is 2015 June 15.77197 UT.

Our sincere apologies for this error!

July 1, 2015:

Alert Notice 520: X-ray nova and LMXB V404 Cyg in rare outburst

Campaign extended until further notice: As V404 Cyg's behavior following outbursts is clearly unpredictable, AAVSO observers are asked to continue obtaining multicolor photometry as well as visual observations. - April 2017

June 18, 2015: V404 Cyg, an X-ray nova and a low mass X-ray binary (LMXB) with black hole component, is undergoing its first reported X-ray and optical outburst since 1989. Large scale, rapid variations are being reported in wavelengths from X-ray to radio by professional and amateur astronomers worldwide.

Alert Notice 324: 1614-15 V818 Sco - Request for observations to support Spitzer observations

August 17, 2005: Our assistance has been requested by Dr. Stefanie Wachter, Spitzer Science Center, Caltech, in observing the low-mass x-ray binary V818 Sco (Sco X-1) in support of her upcoming Spitzer observations of this object.

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