Observing Campaign to monitor EF Eri for Hubble Space Telescope Observations

Hubble Space Telescope (Courtesy: NASA)

From AAVSO Alert Notice 365:

Dr. Paula Szkody (University of Washington) has requested our help in monitoring the magnetic cataclysmic variable EF Eri for upcoming Hubble Space Telescope observations. Confirming observations are requested to ensure that EF Eri is fainter than the safe observing threshold during the HST observing window on 2008 January 17 UT.

EF Eri is at RA = 03:14:13.20 , Dec = -22:35:43.0 (J2000).

....AAVSO observers are asked to begin monitoring this star nightly beginning immediately, and to monitor this object intensely immediately prior to and during the observing window beginning 2008 January 17 01:30 UT (JD 2454482.5625) and continuing through the closing of the observing window at 2008 January 17 16:15 UT (JD 2454483.1771).

Both positive and "fainter-than" observations are useful for this campaign. Visual observers are asked to report the faintest comparison star they can reliably detect, with the two nearby stars at m(V) = 14.5 and m(V) = 14.8 being ideal. CCD observers should observe such that they obtain a signal to noise of 10 in the faintest comparison star they can reliably detect in reasonable time. EF Eri is currently around m(V) = 18.1; if you are able to detect EF Eri with S/N of 10 in reasonable time using a CCD, please do so. Filtered CCD observations are not required, but please indicate which if any filters you are using when submitting observations. Please report all observations promptly via WebObs.

Please note that EF Eri is approximately 20 arcseconds East of the m(V) = 14.8 comparison star, so please make sure you are measuring (and reporting) EF Eri rather than this comparison. For those of you who print charts from DSS using VSP, be aware the DSS plates for this field were taken when EF Eri was in a high state -- it will appear much fainter now.

Charts: EF Eri via VSP

Observing Window:

Intensive Observing Window:

Both visual and CCD observations are useful, including both positive and "fainter-than" observations. For imaging, please integrate so that you obtain a signal to noise ratio of 10 for the faintest comparison star you are reporting.