What the comets Elenin, Garradd and PANSTARRS will (perhaps) look like in your sky

Three comets are approaching right now that could be good or even really good: Elenin in 2011, Garradd in 2012 and PANSTARRS in 2013. Here are general visibility conditions calculated for Bonn (51°N), La Palma (28°N) and Jo'burg (26°S), with the brightness based on current visual observations (available only for Elenin and Garradd) and further behavior as assumed by the JPL's HORIZONS on-line solar system data and ephemeris computation service which is also used for the topocentric situation. In a nutshell: Elenin this October will never be easy and/or impressive but fine for specialists, Garradd coming February will be very easy but only at +6 mag. - and PANSTARRS (the orbit is still improving every few days) should cross the zero magnitude boundary but will be close to the horizon whereever you are.

• C/2010 X1 (Elenin) - Bonn:
  • Early til mid-September: extremely low at dusk at 5 to 4 mag., then lost
    
  • Ca. October 3: rapid reappearance at dawn at 4.5 mag., better each day
    
  • October 6: Already 10° high when astronomical twilight begins; still 4.5 mag., no Moon
    
  • October 9 (best view): At 20° when twilight begins; 4.5-5.0 mag., Moon just set
    
  • October 10-15: at 30-45° when twilight starts, 5.0 mag., bright Moon interferes!
    
  • October 21: already at 30° when waning crescent rises, 5.5 mag.
    
  • October 25-30 (pretty good): transits at 69° just before twilight begins, Moon gone, 6.0-6.5 mag.
• Elenin - La Palma:
  • Early September: about 5° high in nautical evening twilight at 5 to 4 mag., window disappearing by mid-month
    
  • Ca. October 3: rapid reappearance at dawn at 4.5 mag., better each day
    
  • October 5: at 10° when astronomical twilight begins, 4.5 mag.; no Moon
    
  • October 10 (best view): at 25° when twilight stars, 5.0 mag. just no Moon which interferes later
    
  • October 25 (pretty good): comet near zenith, no Moon, 6.0 mag.
• Elenin - Jo'burg:
  • September 3-13: up to 20° in nautical evening twilight at 5 to 4 mag., but with brightening Moon always present
    
  • October 10: morning reappearance at 10° with 5.0 mag.
    
  • October 25-30: transits without Moon at 30° with 6.0-6.5 mag.
  
  
• C/2009 P1 (Garradd) - Bonn (situation similar but altitude lower when farther to the South):
  • January 19-29, 2012: rising from 0° to 50° in the 2nd half of the night, 6.5 mag., no Moon
    
  • February 15-25: rising from 15° to 70° through the night, 6.0 mag., no Moon
    
  • March 14-28: setting from 70° to 40° through the night, 6.5-7.0 mag., no Moon
  
  
• C/2011 L4 (PANSTARRS) - Bonn:
  • March 10, 2013: at 3° in bright evening twilight, but with -0.6 mag. = maximum brightness
    
  • March 13: at 6° in bright twilight, with -0.3 mag.
    
  • March 16: at 6° in deep evening twilight, with +0.3 mag.
    
  • late March: at 10° without twilight, with 2 to 3 mag. but bright Moon interference
    
  • March 31: at 10° in dark sky, with 3.5 mag., Moon just gone
• PANSTARRS - La Palma:
  • March 6, 2013: 3° in bright dusk, but at -0.3 mag.
    
  • March 8: 3° in bright dusk, at -0.5 mag.
    
  • March 10: 5° in bright dusk, at -0.6 mag. = maximum brightness
    
  • March 15: 6° in dusk, at 0 mag.
    
  • March 20: 7° in dusk, at +1.5 mag.
• PANSTARRS - Jo'burg:
  • March 15, 2013: deep in evening twilight with 0 mag., little improvement til end of March

Speaking of comets, there is another Elenin now (more), pictures of 45P/Honda-Mrkos-Pajdusakova of July 27 (more) and July 26, a visual report and pictures of Garradd of July 30, July 29 (more, more and more), July 28, July 26 and July 25 (more), SOHO observations of fading Hartley 2 - and a paper and CBET on a new meteor shower that may indicate an unknown comet threat. • Stories about a meteorite fall in Kenya, a fireball in Texas and a big meteorite (more, more) in China.

Turning to asteroids the campaign to observe a star occultation by double asteroid (90) Antiope in the US was a major success, as these chords demonstrate; more reports here and here, plus a lightcurve. • The first Trojan of the Earth has been found: a paper, animations, an extrapolation, press releases here, here, here and here and stories here, here, here, here, here, here, here, here, here, here, here, here, here, hier, hier and hier. An alleged Uranus Trojan (which would also be a first) is pretty dubious, though (more).

• A fourth satellite of Pluto has been found in HST images - and its correct name is S/2011 (134340) 1 and not "P4": a CBET, press releases here, here and here and stories here, here, here, here, here, here, here, here, here, here, here, here, here and hier. (Before someone asks: Having one or more satellites has nothing whatsoever to do with an object being a planet, dwarf planet or minor planet - just look at the long table of minor planet moons already found!) Also more on the star occultation by Pluto and Haumea's ice. The Moon & Mars from Oz on July 28. And the successful demonstration of the elliptical orbit of the Moon!

In other news on the Sun there are 3 nice groups right now (with an M9 flare on July 30), and there was a cool eruption, while science-wise TSI measurements are problematic, the GIOVE satellites watch for radiation and Alfvén waves are again blamed for coronal heating effects: press releases here and here and stories here, here, here, hier, hier, hier und hier. Plus aurora observations during STS-135. • Amateurs found yet another planetary nebula (more, more - and a weird story ...). • More NLCs from Germany on July 26, the UK on July 23, the UK and Finland on July 22 and the UK on July 18.

• The fiery return of STS-135, Atlantis' final Sun transit (more), many ISS pics in front of the Sun, the ISS in daylight, the ISS & Atlantis over Oz (more, more) and the docked pair crossing the Sun. • Highlights of August 2011 include a - not that - close approach by (3103) Eger on Aug. 4, the Opposition of (4) Vesta on Aug. 5 (with Ceres in the vicinity, too), the Moon-swamped Perseids on Aug. 13, a close approach of comet 45P on Aug. 15, Neptune's opposition on Aug. 23 and the conjunction of (15) Eunomia and 42 Per on Aug. 25.