Thursday, October 27, 2011

Bright spot emerges on Uranus - can amateurs track it (and thus help Hubble)?

Observations with one of the Gemini 8-m telescopes show a very bright spot that has suddenly appeared on Uranus and is at least 3 times brighter than the remote planet's disk: "If this is a convectively driven white feature it may evolve to larger size and brighter appearance on the next few days," says an unusual alert message distributed via The Astronomer network earlier today. Moreover amateur images of Uranus are now considered "essential to study this feature and its precise drift rate to assist possible observation with other highly-priority telescopes such as the HST." Uranus subtends 3.7" in the sky, and the bright cloud feature is at least 0.33 arc seconds making this feature potentially accessible to relatively modest telescopes. On 2011 October 26 at 08:06 UTC when the linked picture was taken the spot was at 323° west longitude and 22.5° north; the current estimate for the rotation period of this feature is 17.24 hours. • A slightly easier target is Jupiter, now in opposition: selected images from Oct. 24 (46 cm scope), Oct. 22 (20 cm - animation), Oct. 13 (1 meter), Oct. 3 (25 cm) and Sep. 26 (23 cm).

Comet Elenin has been recovered after all, now that the Moon is out of the way, but only as an extremely diffuse dust cloud with not one individual fragment brighter than 22.5 mag.: reports on the hunt and what one can see (or rather image) from Oct. 25, Oct 24 (more), Oct. 23 (more), Oct. 21 and Oct. 15, pictures of Oct. 24, Oct. 23 (more, more and with just 8 cm aperture), Oct. 22 (more), Oct. 21 (negative), Oct. 15 (positive after looking hard) and Oct. 14 (negative), another claimed visual observation (why such a small 'coma' size?), a long essay on visual comet observing - and a very stupid NASA press release asking for Elenin to "be forgotten". Rather forget such dumb advice and observe the most unusual ... thing that Elenin has turned into while it's still possible (it's now receding from both Sun and Earth).

In other comet news the first Jupiter Trojan comet has been found - and Bressi may be interesting. • Pictures of Honda-Mrkos-Pajdusakova from Oct. 15, Oct. 7 and Sep. 30 (with a mountain) and Garradd - which now has a nice plasma tail as well! - of Oct. 23 (more), Oct. 17 (more), Oct. 15 (more) and Oct. 14 (more). • Another - smaller - comet hit the Sun on Oct. 19 (earlier, still earlier), a video on the Oct. 1 case and 5 years of comets observed by the STEREO mission. • The physics of impacts on Earth, an observing guide for and JPL Release about coming NEO 2005 YU55, an asteroid crossing M 31 (movie) - where it was mistaken for a nova! - and a Subaru Release about Scheila's outburst.

In other solar system news Venus and Mercury low in the evening sky on Oct. 24 (USA) and Oct. 22 (Australia and - w/o Mercury - Austria) - the new evening apparition of Venus will end with the solar transit next June! • The equal diameters of Eris & Pluto also discussed here, here, here, here, hier, hier, hier and earlier here. • The Orionids delivered a nice show, only a maximum ZHR of 50, but it looked great for some (another and another night); also an all-sky sum image, a spectrum (more) and a picture. • From the Draconids a detailled story with pictures from the NE German campaign, another video from the NL, observations by ESA, a German video (AVIS2), the radiant from 6 video cameras and a Spanish composite image and report. • Also a night with 5 showers, no evidence for interstellar meteoroids and a German fireball. • This month's full moon was the smallest of the year: a comparision with the biggest one (alt.) and a list of big ones.

In other news there was an aurora outburst Oct. 24/25 over e.g. Germany and the U.S.: a great German timelapse video, a fine gallery, pictures from all over Germany, Alabama (w/video) and N. Germany and coverage here, here, here, here and here. The CME that caused it was launched on Oct. 22 as was another one that headed towards Mars; there was a lot to see on the Sun that day. • Weird NLC-like looking clouds may have been caused by the 1st S. American Soyuz launch, and a picture of Spektr R deep in space. • A German press release on that rare triple rainbow (with the full paper) - and a double rainbow with a stupid caption (as if it stretches from one place to another). • And then there was a bizarre paper on things in front of the Sun in 1883 which some rightly attacked (mehr) but others found at least intriguing. And as if ordered: a mystery crossing the solar disk just this month ...

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