Special Notice #371: BB Ari observations particularly crucial now

September 24, 2013: HST/COS is scheduled to observe the SU UMa-type variable BB Ari:

BB Ari  2013 September 27 03:01:26 through 06:29:37 UT

The HST scheduling team will likely make their final decision early on September 26, so your observations are essential NOW.

Observations are even more important than they would usually be at this point in the timeline because recent observations of BB Ari - which are somewhat conflicting - indicate that THE SYSTEM MAY BE BEGINNING A NORMAL OUTBURST. If the outburst really is occurring the HST observations would have to be cancelled, so knowing for certain is absolutely essential. BB Ari had a superoutburst in August.

Please monitor BB Ari through September 28. AAVSO observations show BB Ari can be as faint as magnitude 19.898 V at minimum and may be as bright as 13.576 V at maximum.

Coordinates (2000.0):
BB Ari    R.A. 02 44 57.71   Dec. +27 31 09.3

Charts may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp).

Please report observations as soon as possible to the AAVSO International Database using the name BB ARI. If an outburst is detected, please report observations immediately. Many thanks!

Details of the HST/COS CV campaign and specific observing instructions may be found in AAVSO Alert Notice 471 (http://www.aavso.org/aavso-alert-notice-471). Related AAVSO Special Notices may be found via the Observing Campaigns page (http://www.aavso.org/observing-campaigns). AAVSO Special Notice #370 (http://www.aavso.org/aavso-special-notice-370) is the most recent one that pertains to the campaign.

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



Information on submitting observations to the AAVSO may be found at:


A Special Notice archive is available at the following URL:

Subscribing and Unsubscribing may be done at the following URL:


Please support the AAVSO and its mission -- Join or donate today: