The following is note from visnet (worth reposting) on khi Cyg - an irregular long-period (~408 day) S-class variable that is currently nearing a 200 year maximum near mag. 3.9. When you look up at Cygnus around midnight, you may notice a third star between eta and beta Cyg that is normally not there. It is khi Cyg. khi Cyg is on the AAVSO Easy Variables observing list. If you are unfamiliar (as I am) with long period variables, this may be a good place to start. Burnham's _Celestial Handbook_ has a good entry on khi Cyg (Vol. II, p. 762-768). khi Cyg is also list item Kaler 21 in Kaler's _100 Greatest Stars_. Kaler also has a brief description of khi Cyg on his variable stars website: http://www.astro.uiuc.edu/~kaler/sow/chicyg.html An AAVSO finder charts are available at (enter as chi Cyg): http://www.aavso.org/cgi-bin/searchcharts3.pl?&name=CHI%20CYG http://www.aavso.org/cgi-bin/shrinkwrap.pl?path=/charts/CYG/CHI_CYG/CHICYG-A... An AAVSO light curve (recommend 1200 days) can be generated at (enter as chi Cyg): http://www.aavso.org/data/lcg/ Better look now. In about 170 days, khi Cyg will be mag 12! - Canopus56
-----Original Message----- From: vsnet-alert-bounces@... [mailto:vsnet-alert-bounces@...] On Behalf Of Taichi Kato Sent: 25 July 2006 01:03 To: variable_star_forum@yahoogroups.com; vsnet-alert@...; vsnet-alert@yahoogroups.com; vsnet-campaign@... Subject: [vsnet-alert 8957] exceptionally bright maximum of chi Cyg
(past records from [vsnet-lpv 92] by Eric Broens)
The 3.3-mag maximum was recorded at the end of 1847 (JDmax=2396014.8) and was observed by Argelander, Heis and Schmidt. Other maxima brighter than magnitude 4 are listed below (maxima reaching magnitude 4 are more common). I selected these maxima based on a visual inspection of the historical lightcurve of chi Cygni dating back to the date of discovery by Gottfried Kirch in 1686 up to 1998. The dates of the maxima are taken from [3]. I guess the historical 3.3 maxima is based on the brightest estimate. By visual inspection of the lightcurve I rather judge the mean maximum magnitude as magnitude 3.5. There is no sign of a maximum of magnitude 2.3 in the data. It is striking that these bright maxima only occur in the "ancient" observations. I compared the magnitudes of the comparison stars as they are listed in the references mentioned below and they cannot account for this. Maxima brighter than magnitude 4.5 occurred about 12 times in the period 1900-1998.
JDmax mag. Observers 2342812.9 >3.8? Gottfried Kirch 2395205.6 3.8 Argelander, Heis, Schmidt 2396014.8 3.5 (3.3) Argelander, Heis, Schmidt 2399680.7 3.6 Argelander, Heis, Schmidt, Winnecke 2402161.6 3.9 Heis, Schmidt
Many amateurs did and still do a fabulous job observing this "well-known" stars. Thanks to them the long term behaviour is logged excellent and unknown features are revealed. Did you know that chi Cygni has increased its period by about 1 day each century?
References: [1] Long-term visual magnitude estimates of the Mira variable chi Cygni I. 1686--1900 C. Sterken, E. Broens, 1998, Journal of Astronomical Data 4
[2] Long-term visual magnitude estimates of the Mira variable chi Cygni II. 1900--1998 E. Broens, C. Sterken, D. McAdam, M. Watanabe, 1998, Journal of Astronomical Data 4
[3] On the period history of Chi Cygni C. Sterken, E. Broens, C. Koen, 1999, A&A 342, 167-172
Best Regards, Eric
YYYYMMDD(UT) mag observer 20060701.948 65 (Gary Poyner) 20060702.926 61 (Marian Legutko) 20060703.851 62 (Guenther Krisch) 20060704.855 61 (Guenther Krisch) 20060708.531 56 (Atsuko Takahashi) 20060709.931 52 (Gary Poyner) 20060710.560 51 (Atsuko Takahashi) 20060710.849 51 (Guenther Krisch) 20060711.594 50 (Yutaka Maeda) 20060711.960 48 (Georg Comello) 20060712.656 50 (Yutaka Maeda) 20060713.508 49 (Yutaka Maeda) 20060713.951 48 (Gary Poyner) 20060714.560 46 (Hiroyuki Someya) 20060714.603 45 (Takuichiro Onishi) 20060714.631 48 (Kenji Nakai) 20060714.849 47 (Guenther Krisch) 20060715.608 48 (Yutaka Maeda) 20060715.641 48 (Ryosuke Naito) 20060715.642 47 (Yukiko Tsuchiyama) 20060717.914 43 (Gary Poyner) 20060718.010 42 (Georg Comello) 20060718.889 44 (Marian Legutko) 20060719.853 42 (Guenther Krisch) 20060720.547 42 (Atsuko Takahashi) 20060720.893 39 (Marian Legutko) 20060720.931 42 (Jose Ripero) 20060721.910 40 (Maciej Reszelski) 20060722.548 42 (Atsuko Takahashi) 20060722.981 44 (J. Toone) 20060723.555 38 (Atsuko Takahashi) 20060723.881 38 (Marian Legutko) 20060724.656 39 (Yutaka Maeda)
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