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AAVSO Special Notice #215

Brightening of the symbiotic star CI Cyg

August 24, 2010: Observer Gary Poyner (Birmingham, UK) reports that the symbiotic star CI Cygni has noticeably brightened over the past few days.  Poyner reports the star at a magnitude of m(vis)=9.8 on 2010 August 23.92 (JD 2455432.42). CI Cyg has been in a slow rise for several months, beginning immediately after the end of the last outburst.  Continued monitoring of CI Cyg over the next several weeks and months will be useful for better understanding the nature of this star system and its outbursts.

Both visual and instrumental observers are encouraged to observe CI Cyg. The object is relatively bright, so instrumental observers should be able to obtain high signal to noise with relatively short exposures. S/N > 50 is encouraged.  We also encourage the use of photometric filters, and if you are able to fully calibrate and transform your data, they will be easier to compare with data from other observers.

CI Cyg (AUID 000-BCJ-172) is located at the following (J2000) coordinates:

       RA  19:50:11.83 , Dec  +35:41:03.0

Charts for CI Cyg may be plotted with AAVSO VSP:

Please promptly submit all observations to the AAVSO using the name "CI Cyg".

This AAVSO Special Notice was prepared by M. Templeton.



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