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AAVSO International Database

Special Notice #200: Outburst of the infrequently outbursting dwarf nova KX Aquilae

March 9, 2010: Observer Tomas L. Gomez (Madrid, Spain) reports that the infrequently outbursting dwarf nova KX Aql is currently in outburst. Gomez detected the star at an unfiltered magnitude of 13.58 on 2010 March 9.242 UT (JD 2455264.742). This system has been poorly observed over the past few months; the most recent observation of KX Aql was also by T.L. Gomez, who reported a fainter-than unfiltered magitude of < 15.12 on 2010 February 20.2617 (2455247.7617). Thus the starting time of the current outburst is not yet known.

Special Notice #201: Outburst of the symbiotic star V407 Cyg

March 12, 2010: Further to Maehara et al. (CBET 2199, D.W.E. Green, editor), the presumed symbiotic star V407 Cyg appears to be undergoing a very bright outburst, well outside of its previous range. This outburst was discovered independently by the team of K. Nishiyama (Fukuoka, Japan) and F. Kabashima (Saga, Japan), and by T. Kojima (Tsumagoi, Agatsuma-gun, Gunma-ken, Japan). Nishiyama and Kabashima observed the star at an unfiltered magnitude of 6.8 on 2010 March 10.813 (JD 2455266.313) and magnitude 6.9 on 2010 March 10.814 (2455266.814).

Special Notice #202: Classical nova event in V407 Cyg

March 14, 2010: Further to Munari et al. (CBET 2204, D.W.E. Green, editor), the presumed symbiotic star V407 Cyg is exhibiting spectral features clearly indicating a classical nova of the He/N type. This strongly suggests that the white dwarf component of the system is currently undergoing a nova outburst rather than a symbiotic-type outburst. The spectral evolution of this nova may be very fast given the likely large mass loss rate of the Mira-type donor star. We urgently request observations of V407 Cyg to provide photometric coverage of this unique event.

Special Notice #211: Outburst of EX Hya

May 22, 2010: Rod Stubbings has reported that the infrequently outbursting dwarf nova EX Hydrae is in outburst. Stubbings reported the star at a visual magnitude of 9.4 on 2010 May 22.667 (JD 2455339.167) and it remained at 9.4 through May 22.721 (2455339.221). Both visual and instrumental observations of EX Hya are urgently requested. CCD observers, please obtain time-series photometry if at all possible. Please follow this outburst through its completion; EX Hya is known to have short outbursts, so this outburst may be very brief.

Special Notice #210: Request for observations of high-mass X-ray binaries

May 19, 2010: Dr. Gordon Sarty, University of Saskatchewan, Canada, requests our continuing assistance in his ongoing observations of High Mass X-ray Binaries (HMXBs). Dr. Sarty provides the following text for the current request:

Special Notice #209: Nightly monitoring of TW Hya in support of HST observations

May 17, 2010: Dr. Michael Sitko (U. Cincinnati) requests observations of the young stellar object TW Hya in support of upcoming Hubble Space Telescope observations. TW Hya is believed to be a T Tauri star that varies between magnitudes 10.5 and 12.2. TW Hya will be observed with the HST STIS instrument as part of a larger program to study the properties of potentially planet-forming disks around young stars. The star will be observed in the ultraviolet to search for time-variability in the gas in the inner accretion disk.

Special Notice #208: Optical transient in Pegasus

May 8, 2010: CBET 2273 (D.W.E. Green, editor) reports the discovery of a bright transient in Pegasus by Dae-Am Yi (Yeongwol-kun, Gangwon-do, Korea). The object was discovered at magnitude 10.8 on 2010 May 6.77 (JD 2455323.27) on an image taken with a Canon 5D + 93-mm camera lens. The object brightened to magnitude 8.4 as observed on 2010 May 7.76 (2455324.26) on an image taken with a 400-mm lens. The transient object appears to be concident with GSC 2197:886 on discovery images, but this identification is not yet proven.

Special Notice #207: Possible Nova in Scorpius - N Sco 2010 No. 2

April 26, 2010: Central Bureau for Astronomical Telegrams CBET 2262 (Daniel W. E. Green, ed.) announces the discovery by Koichi Nishiyama, Kurume, Fukuoka-ken, Japan; and Fujio Kabashima, Miyaki-cho, Saga-ken, Japan, of a possible nova in Scorpius at magnitude 8.6 on two 40-s unfiltered CCD frames (limiting magnitude 13.1) taken around April 25.788 UT. They confirmed the new object on unfiltered CCD frames (limiting magnitude 17.3) taken around April 25.796 from which they measured the following precise position:

Special Notice #205: Rapid fading in the luminous blue variable S Doradus

April 15, 2010: Noel D. Richardson and Douglas R. Gies (Georgia State University) announced on 2010 April 14 (Astronomer's Telegram #2560) that S Doradus is currently fading in optical brightness, while its hydrogen Balmer line (H-alpha) brightness is increasing. The V-band magnitude of S Dor (as measured by ASAS-3; Pojmanski, G., 2002, AcA 52, 397) has been declining for more than a thousand days. The star began a more rapid decline earlier this year, and is now fainter than V=9.5.


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