Since April 14 when M. Simonsen detected an outburst (vsnet-campaign-dn 649), observations reported to VSNET indicates the object became much active. This outburst continued until April 21 (vsnet-campaign-dn 686), and then, finished. However another outburst occurred within a week (vsnet-campaign-dn 696). The duration of this outburst is relatively short. The object started fading and returned to 14.2mag on early May (vsnet-campaign-dn 740). It again brightened and reached 13.5mag on May 13 (vsnet-campaign-dn 773). After this outburst, the strong oscillations between 14.8 - 13.4mag were seen throughout 2001 May (vsnet-campaign-dn 804).
The object looked relatively calm at around 14.2mag in early June (vsnet-campaign-dn 879), and then, again brightening to 13.8mag on June 13 (vsnet-campaign-dn 910).
Other related articles: vsnet-campaign-dn 656, 663, 676, 709, 723, 764, 786, 789, 791, 794, 809, 819, 956,
Preprint: T. Kato et al. "The Second Supercycle of the Helium ER UMa Star, CR Boo", IBVS 5120
(vsnet-perprint 43 or ftp://ftp.kusastro.kyoto-u.ac.jp/pub/vsnet/preprints/CR_Boo-2/ )