Alert Notice 449: Outburst of the UGWZ Candidate BW Scl

October 25, 2011

Event: Outburst of the UGWZ Candidate BW Scl

As announced in AAVSO Special Notice #261 (M. Templeton), the UGWZ candidate BW Scl is in outburst. No previous outbursts have been reported in the AAVSO International Database; BW Scl is magnitude 17 at minimum. BW Scl is classified as a novalike variable, but is most likely a WZ Sge-type cataclysmic variable. Time-series observations are encouraged to help determine the nature of this object, which has never been studied before. Since BW Scl is so bright, the use of filters for instrumental observations is encouraged, and observers should be able to obtain good time resolution with good signal-to-noise during early stages of the outburst at least. Visual observations are also encouraged.

Discovered by: Mike Linnolt, Ocean View, HI

Discovery Date: 2011 Oct. 21.3146 UT (JD 2455855.81458)

Discovery Magnitude:  visual magnitude 9.6

Coordinates: R.A. = 23 53 00.85 Decl. = -38 51 46.4 (equinox 2000.0)

Charts: Finder charts for BW Scl (AUID 000-BCX-185) may be plotted by entering the name or the coordinates above into VSP:

Reporting Observations: Please report all observations to the AAVSO International Database as BW SCL.

Observations reported to the AAVSO International Database:
Over 4,900 observations have been reported to the AAVSO since the outburst began. BW Scl brightened to magnitude 8.912 CV by Oct. 21.574988 (JD 2455856.074988, Peter Starr, Coonabarabran, NSW, Australia). The most recent observation shows BW Scl at visual magnitude 9.5 (Larry Wade, Belzoni, MS). To see a light curve of the data, use the AAVSO Light Curve Generator:

a.confirmed by A. Plummer, Linden, NSW, Australia, at visual magnitude 9.4 on 2011 Oct. 21.3424 UT (JD 2455855.84236).

b. Analysis by several individuals, including Taichi Kato (vsnet-alert 13786) and Tomohito Ohshima (vsnet-alert 13792), of data gathered by Josch Hambsch, Hiroyuki Maehara, Peter Starr, and others submitted to the AAVSO International Database, yield a superhump period of 0.05434 +/0.00002 day.

c. Orbital period = 0.05431 day = 78.2 min (Augusteijn, T. & Wisotzki, L. A&A 324, 57-60, 1997).

Congratulations to Mike Linnolt on his discovery!

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen.


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: