Context : Comet Hale–Bopp ( C/1995 O1 ) has been the single most significant comet encountered by modern astronomy , still having displayed significant activity at 25.7 AU solar distance in late 2007 .
It is a puzzling question when and where this activity will finally cease .

Aims : Here we present new observations with the ESO 2.2m telescope at La Silla to check the activity of Hale–Bopp at 30.7 AU solar distance .

Methods : On 2010-12-04 , 26 CCD images were taken with 180 s exposure times for photometry and morphology .

Results : The comet was detected in R and had a total brightness of 23 \aas@@fstack { m } 3 \pm 0 \aas@@fstack { m } 2 , referring to an absolute brightness of R ( 1,1,0 ) =8 \aas@@fstack { m } 3 .
The profile of the coma was star-like at a seeing of 1 \aas@@fstack { \prime \prime } 9 , without any evidence of a coma or tail extending farther than 2 \aas@@fstack { \prime \prime } 5 ( =55,000 km in projection ) and exceeding 26.5 mag/ arcs ^ { 2 } surface brightness .

Conclusions : The measured total brightness corresponds to a relative total reflecting surface , a _ { R } C , of 485 km ^ { 2 } , nine times less than three years before .
The calculated a _ { R } C value would imply a nucleus with 60–65 km radius assuming 4 % albedo .
This size estimate is in significant contradiction with the previous results scattering around 35 km .
Therefore we suggest that the comet may still be in a low-level activity , despite the lack of a prominent coma .
Alternatively , if the nucleus is already dormant , the albedo should be as high as 13 % , assuming a radius of 35 km .
With this observation , Hale–Bopp has been the most distant comet ever observed , far beyond the orbit of Neptune .