Saturday, April 30, 2016

Comets & Asteroids - Summary for April 2016

During the month of April 2016,  2 new comets were discovered and cometary activity was detected for 1 previously discovered object (earlier designated as an asteroid). NASA's Hubble Space Telescope spotted a small, dark moon orbiting Makemake, the second brightest icy dwarf planet — after Pluto — in the Kuiper Belt. Pioneer comet observer Elizabeth (Pat) Roemer died on April 09. Moreover the discovery of the binary nature of asteroid (5674) Wolff and the images of a new satellite of asteroid (130) Elektra have been reported (see below for more about these news). "Current comet magnitudes" & "Daily updated asteroid flybys" pages are available at the top of this blog (or just click on the underline text here).

The dates below refer to the date of issuance of CBET (Central Bureau Electronic Telegram)  which reported the official news & designations.

- Comet Discoveries

Apr 05  Discovery of P/2016 G1 (PANSTARRS)
Apr 08  Discovery of P/2015 HG_16 (PANSTARRS)*

*G. V. Williams, Minor Planet Center, noted that the 2016 April 3 observations of  this comet appeared to belong to a supposedly asteroidal object found a year ago by Pan-STARRS1 on 2015 Apr. 20, 21, and 24 (and then given the minor-planet designation 2015 HG_16 on MPS 603395 and 603396)

- Cometary activity detected

Apr 24  Cometary activity detected in 2015 WZ = C/2015 WZ (PANSTARRS)

- Other news 

Apr 09  Pioneer comet observer Elizabeth (Pat) Roemer died on April 09. Astronomer Jim Scotti wrote this memory on Facebook: "With great sadness I must report the death of my friend and mentor Elizabeth (Pat) Roemer (1929-2016) this morning. She joined the Lunar and Planetary Lab in 1966. She led the world in the observation of faint comets and recovered 79 short period comets in an age where computing ephemerides and reducing astrometric observations were all done by hand. I learned so much from her beginning in Astronomy 400b which emphasized planetary astronomy and introductory celestial mechanics and was always a great help in later years in learning how to observe comets and asteroids".

Apr 23  CBET 4272 reports that minor planet (5674) Wolff is a binary system with an orbital period of 93.7 +/- 0.2 hr. Mutual eclipse/occultation events that are up to 0.70-magnitude deep indicate a lower limit on the secondary-to-primary mean-diameter ratio of 0.80.  

Apr 25  Astronomers have discovered a new satellite orbiting the main belt asteroid (130) Elektra (first announced via CBET 4036 on December 17, 2014). The team, led by Bin Yang (ESO, Santiago, Chile), imaged it using the extreme adaptive optics instrument, SPHERE, installed on the Unit Telescope 3 of ESO’s Very Large Telescope at Cerro Paranal, Chile. This new, second moonlet of (130) Elektra is about 2 kilometres across and has been provisionally named S/2014 (130) 1, making (130) Elektra a triple system. Exploiting the unprecedented sensitivity and spatial resolution of the instrument SPHERE, the team also observed another triple asteroid system in the main belt, (93) Minerva. Full paper now available here

Credit: Yang/ESO

Apr 26  NASA's Hubble Space Telescope has spotted a small, dark moon orbiting Makemake, the second brightest icy dwarf planet — after Pluto — in the Kuiper Belt. The moon — provisionally designated S/2015 (136472) 1 and nicknamed MK 2 — is more than 1,300 times fainter than Makemake. MK 2 was seen approximately 21,000 km (13,000 miles) from the dwarf planet, and its diameter is estimated to be 161 km (100 miles) across. Makemake is 1400 km (870 miles) wide. The dwarf planet, discovered in 2005, is named for a creation deity of the Rapa Nui people of Easter Island.

Credit: NASA, ESA, Parker & Buie (SRI), Grundy (Lowell Obs), K. Noll (NASA GSFC)

by Ernesto Guido