[vsnet-alert 10323] EF Eri of late, fading with a red shine

Berto Monard lagmonar at nmisa.org
Mon Jul 14 19:11:15 JST 2008

EF Eri has now faded from its recent activity, for a month already.

It was a request from Christopher W. Mauche that led to a more dense coverage of EF Eri over the period just after its solar conjunction. The fading behaviour of EF Eri that was observed cancelled any immediate plans for Chandra observations.

Herewith some observational data of EF Eri from CBA Pretoria showing the fade. Interesting is the colour change that this polar underwent during this stage, possibly just after the swich-off.

Unfiltered data:

2454554.242		13.8	CR
2454572.208		14.1	CR
2454577.195		14.1	CR
2454579.186		14.5	CR
2454624.628		14.9	CR
2454630.663		15.2	CR
2454633.669		17.5	CR
2454634.660		17.0	CR
2454644.670		17.3	CR
2454656.672		18.0	CR

In that period Rod Stubbings reported:

ERIEF          080611.788  <156  Stu.RASNZ
which is
2454629.288		<15.6       v

This apparent contradicting observation (of an assumed blue object) triggered a set of filtered observations at CBA Pretoria with magnitudes traceable to stars with Henden photometry: 

2454630.663		15.5	R  
2454630.663		14.3	I   
2454630.663		17.1	V  

which show EF Eri as a red object. 

In 1999 when A Henden calibrated the field he found EF Eri at minimum with
V=18.151  B-V=0.068, which reflects a faint blue object.

The above observations show that the polar EF Eri underwent strong reddening during its fading stage in June 2008.

Berto Monard
CBA Pretoria / Bronberg Observatory

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