Special Notice #90: Update on Request to Monitor EF Eri for Hubble Space Telescope Observations

January 14, 2008: Further to AAVSO Alert Notice 365 (Request to Monitor EF Eri):  We are approaching the time when Space Telescope ground controllers decide whether it is safe to observe the intermediate polar EF Eri. The observing window is currently scheduled to open on 2008 January 17 01:30 UT (JD 2454482.5625), and closes on 2008 January 17 16:15 UT (JD 2454483.1771).
Observations are requested to confirm that EF Eri is fainter than m(V) = 14.0 and thus safe to observe with HST. Visual magnitude estimates and CCD observations -- including "fainter-than" observations -- are requested now though the close of the observing window. Please report all observations promptly via WebObs; they will be distributed in real-time to AAVSO staff and to the science Principal Investigator, Dr. Paula Szkody.
For visual observers, please use the faintest comparison star you can confidently report when providing fainter-than estimates. For CCD observers, please obtain a S/N of at least 10 whether you are reporting a fainter-than measure or a magnitude for EF Eri itself. Filters are not required, but please specify whether you are imaging with or without them. The "145" and "148" comparison stars immediately adjacent to EF Eri are ideal for making fainter-than estimates, but if you can reach fainter comparison stars in reasonable time, please do so.
For a complete discussion, see Alert Notice 365.
EF Eri is at RA = 03:14:13.20 , Dec = -22:35:43.0 (J2000).
Charts for EF Eri may be generated via VSP at the following URL: http://www.aavso.org/observing/charts/vsp/index.html?pickname=EF%20Eri
This AAVSO Special Notice was prepared by Matthew Templeton.

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