Alert Notice 382: Outburst of the symbiotic star CI Cygni

August 31, 2008 : Further to AAVSO Special Notice #121, we urgently request visual
observations and instrumental photometry of the outbursting symbiotic variable star CI Cygni, beginning immediately (2008 August 31; JD 2454710) and continuing for at least the next several weeks as the outburst evolves.

The last major outburst of CI Cygni occurred in March 1975.  We note that CI Cyg should be in or near eclipse according to the ephemeris published by Fekel et al. (2000, AJ 119, 1375); their ephemeris predicts an eclipse date of 2454695.4 (assuming T0 = 2450426.4 and a period P = 853.8).

Both visual observations and instrumental photometry of this event are strongly encouraged.  Filtered time series observations are especially encouraged, particularly if the system goes into eclipse during the outburst.  Calibrated, filtered photometry may provide constraints on the physical properties of the primary and secondary stars in this system if and when the outburst source is eclipsed.

Observer G. Poyner (Birmingham, England) estimates that CI Cyg was at m(vis) = 9.8 on JD 2454709.515 (2008 August 31.015). For information about the course of the current outburst through 2008 August 31, see AAVSO Special Notice #121.

CI Cygni is located at RA: 19h 50m 11.8s , Dec: +35d 41m 03s (J2000)

Charts for CI Cygni may be generated with VSP:

Recently submitted observations for CI Cygni are available here:

[broken link]

Please report all observations to the AAVSO as CI Cyg (AUID 000-BCJ-172).

This AAVSO Alert Notice was prepared by Matthew Templeton.



Information on submitting observations to the AAVSO may be found at‭:‬


An Alert Notice archive is available at the following URL‭:‬

Subscribing and Unsubscribing may be done at the following URL‭:‬

Please support the AAVSO and its mission -- join or donate today: