Sam Dean alias Planetaryscience stellt auf der Mailingliste die Vermutung an, der Asteroid 2005 YB210 könnte ein verdeckter Komet sein. Grund sind die Helligkeitsausbrüche. Sam bittet darum, ihn im Auge zu behalten. Er steht derzeit im Stier und bewegt sich bis Mitte Oktober in die Zwillinge (unweit Pollux).
While hunting around for misidentified comets, I found another object that actually might be observable right now:
2005 YB210 was discovered originally by LINEAR about 2 years after perihelion, observed around magnitude 19-20. Shortly after, more observations from 2004 (much nearer to perihelion) were found around magnitude 21 - clearly showing that strange things were taking place already.
It was recovered again in August 2019 by PANSTARRS at magnitude 22, brightened to magnitude 21 by a few weeks later, and would once again be seen in November 2020 by Mount Lemmon at magnitude 21.
I found further images from 2013 (when it was closer to its aphelion distance than perihelion) at magnitude ~20.5, and more from August and September 2019 showing an increasingly faint but unrelentingly pointlike object - at magnitude 22.1 by September 26.
All of these are remarkably consistent magnitudes considering its heliocentric distance varies between 2.1 and 5.6 AU from the Sun over the course of its 8-year orbit. This huge magnitude variation (magnitude 19 when it should have been 22.5 in 2005, magnitude 20.5 when it should have been 23.5 in 2013, and magnitude 22.1 when it should have been 20.5 in 2019) along with its unstable orbit leads me to conclude that this is another comet prone to irregular outbursts... even if I have yet to spot a tail or any nebulosity in any images.
Importantly, though, 2005 YB210 only reached perihelion mid-2019, and clearly has very irregular unpredictable outbursts that can reach at least 3 magnitudes, possibly more. My request is that when the comet reaches a higher elongation (around October of this year) that anyone who is able may search for outbursts of it... given its history so far, outbursts will usually last one to two months and may achieve up to 3 magnitudes, possibly more. Unfortunately that means it should only reach magnitude 20-21 unless something spectacular happens... Anyway, the most important part would be searching for a coma or tail, because it seems to have hidden these very successfully for the last three perihelia so far, and I'd very much like to know why! And of course have it officially confirmed as a comet...