Special Notice #384: SBS 1108+574 HST/COS obs next week

May 9, 2014: The HST/COS observations of the cataclysmic variable SBS 1108+574 described in AAVSO Alert Notice 501 have been pushed back a few days. The new exact time of the observations is:

                 SBS 1108+574      2014 May 16 06:19:04 - 15:16:56 UT

The scheduling team will likely make their final decision early on May 15. Your observations will be very important now through May 18, and crucial May 12-16. During quiescence SBS 1108+574 is around magnitude V=18 and during outburst around V=15.

Nightly V snapshots are requested from now through May 25. More frequent observations are requested May 12-16 (2-3 per night). Simultaneous photometry/time series is not needed. Visual positive observations and fainter-than observations fainter than 15.0 are welcome.

As in similar campaigns, it isn't just that it is important to know how bright the variable is 24 hours before the scheduled HST observation time, it is critical to know that the variable is not brighter than the safe limit on the HST instrumentation. Thus, observations during the two to three nights before the HST time are absolutely essential.

Coordinates:  R.A. 11 11 26.87  Dec. +57 12 38.9  (2000.0)

Charts for SBS 1108+574 may be created using the AAVSO Variable Star Plotter (VSP) at http://www.aavso.org/vsp. Photometrists should use the data table supplied in VSP.

Please submit your observations to the AAVSO International Database as soon after making them as possible. If you see the variable in outburst, please contact the AAVSO immediately and post a message to the Observations and Campaigns & Observations Reports forum (http://www.aavso.org/forum).

The primary name for this object in VSX is CSS 120422:111127+571239. When submitting your observations, please use either this name or the name SBS 1108+574 [be sure to include the space between the two parts of the name].

Your observations and timely reporting are essential. Many thanks for your contributions!

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


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