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eclipsing variable

Variable Stars and the Stories they Tell

What are variable stars and why are astronomers interested in them?

Special Notice #9: V1343 Aql (SS433) Suzaku Observing Campaign Support

March 30, 2006: Kaori Kubota (Kyoto University) has asked for observations of V1343 Aquilae (a.k.a. SS433) in support of an observing campaign using the Suzaku X-Ray satellite. V1343 Aql is listed as an eclipsing X-Ray source according to the GCVS 3rd Edition. It consists of an early type star and a neutron star or black hole with relativistic jets detectable at X-Ray and radio wavelengths. Kubota reported it currently at 14th magnitude.

Its location is: R.A.: 19:11:49.6 Decl.: +04:58:57.9 (J2000)

Special Notice #192: Update on the epsilon Aurigae eclipse

February 3, 2010: Epsilon Aurigae continues to progress through its first eclipse since 1982-84. Visual and photometric observation means place it at around magnitude 3.7-3.8. Totality was likely reached sometime in January, but it will take some time to analyze the data to establish a specific date. Totality is expected to last about 15 months, but the system is not expected to remain quiet during this time. Small amplitude modulations are being detected which are likely not associated with the eclipse itself. However, their exact source is still debated.

Alert Notice 228: Request to monitor 1804+67 HS 1804+6753 for observations with Hubble Space Telescope

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AAVSO ALERT NOTICE 228 (September 6, 1996)


Alert Notice 351: Campaign for a New Eclipsing Cepheid

June 8, 2007

TYC 1031 01262 1
ASAS 182611+1212.6
1821+12B (Harvard Designation)
ASAS182612 (AAVSO name)

Discovered by:
Pojmanski, G., Pilecki, B., Szczygiel, D. 2005, AcA 55, 275
Antipin, S.V., Sokolovsky, K. V. and Ignatieva, T. I. 2007, astro-ph/0705.0605

Position (from Sonoita Research Observatory, UCAC2):
18:26:11.50 +12:12:35.0 (+/- 100mas)

Alert Notice 401: Monitoring of EX Hya and DQ Her

August 13, 2009

Kunegunda Belle, Don Hoard and Steve Howell are observing two cataclysmic variables with Spitzer during the next couple of weeks.  They request ground-based light curves spanning the observation intervals so that they can identify the state each variable is in during the Spitzer visits.

1. EX HYA (12:52:24.20, -29:14:56.0, AUID 000-BBT-323)

The observations for EX Hya are scheduled for:

2009-08-18  19:25:01.1 UT 3.6micron single exposure
2009-08-18  19:26:52.9 UT 4.5micron light curve

Special Notice #219: Eclipse of the symbiotic star CI Cygni

October 12, 2010: As noted by U. Munari et al (ATel #2913, 2010 October 9), the symbiotic star CI Cygni is currently undergoing an eclipse of the outbursting star.  CI Cyg has declined from about magnitude 9.7 in late August 2010 to V=11.1 currently.

How to Use the EB Ephemeris

The AAVSO Eclipsing Binary Ephemeris provides the predicted time of mid-eclipse for eclipsing binaries in the AAVSO Eclipsing Binary observing program. These times appear in Universal Time in the body of the ephemeris table. The time is rounded to the nearest half hour, which provides sufficient accuracy to plan an observing session while, hopefully, leaving sufficient doubt about the exact time in order to eliminate anticipatory bias. The ephemeris is designed for use by observers at American longitudes.

Variable Star of the Season Archive

The following articles contain useful and interesting information on individual variable stars. Many of the most popular stars in the AAVSO observing program are featured.  From December 1998 until December 2002, the collection of articles comprised the "Variable Star of the Month" series. Since that time, they have all been published as part of the "Variable Star of the Season" (VSOTS) collection. Each article is available in either .html or .pdf format.

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