Description of source "G328.24-0.55" from Ellingsen (2007)

this pair of sources is separated by 83 arcsec and was detected in the two largest surveys of south-ern 6.7-GHz methanol masers (Caswell et al. 1995b; Walsh et al. 1997). It has also been studied at high resolution by Phillips et al. (1998) and Dodson, Ojha & Ellingsen (2004) who found both sites of maser emission to be offset from nearby radio continuum emission.

Somewhat unusually for a moderately strong methanol maser, this source has demonstrated signicant variability in the strongest spec-tral features. Goedhart et al. (2004) monitored this source for 4 yr and their observations show that the ux density of the emission at 44.7 km s1 monotonically increased from around 550 Jy in 1999 to 800 Jy in 2003. Fig. 3 compares two observations of this source separated by a decade (the spectrum from Ellingsen et al. 1996b uses a dashed line), and shows that the increase in the strongest emission feature has continued and in late 2005 it had a peak ux density of nearly 1000 Jy.