Comets & Asteroids - Summary for April 2017

During the month of April 2017, 7 new comets were discovered. "Current comet magnitudes" & "Daily updated asteroid flybys" pages are available at the top of this blog (or just click on the underline text here). See below for the "Other news" section.

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

- Comet Discoveries

Apr 02 Discovery of C/2017 D5 (PANSTARRS)

Apr 02 Discovery of C/2017 E5 (LEMMON)

Apr 02 Discovery of C/2017 F1 (LEMMON)

Apr 06 Discovery of C/2017 F2 (PANSTARRS)

Apr 06 Discovery of P/2017 G1 (PANSTARRS)

Apr 21 Discovery of P/2017 G2 (PANSTARRS)

Apr 21 Discovery of C/2017 G3 (PANSTARRS)

- Other news 

Apr 04 More #Rosetta #OpenAccess papers in special issue of Monthly Notices of the Royal Astronomical Society.

Apr 06 New extreme TNO, 2013 SY99, from @OSSOSurvey: a=730±40 au, q=50.0 au, i=4.2°, e=0.93, H=6.8. 

Credit: Michele Bannister

Apr 14 Closest images ever taken of Saturn's moon, Atlas, imaged on April 12, 2017, by @CassiniSaturn

Credit: NASA/JPL-Caltech/Space Science Institute

Apr 18 New paper on Arxiv by Julio A. Fernández et al.: "Physical and dynamical properties of the anomalous comet 249P/LINEAR"

Apr 20 Radar images of 2014 JO25 from @NAICobservatory reveal shadows, possible boulders, and more on this 650+ m (twice as big as previously estimated) asteroid rotating in ~4.5 hours: "Arecibo radar observations revealed the asteroid to have a lumpy, two-lobed shape very reminiscent of Comet 67P/Churyumov–Gerasimenko recently visited by the European Space Agency's Rosetta mission."

Credit: Arecibo Obs./NASA/NSF

Apr 29 CBET 4387 reports that minor planet (2881) is a binary system with an orbital period of 20.42 +/- 0.01 hr.  Mutual eclipse/occultation events that are 0.09- to 0.15-magnitude deep indicate a secondary-to-primary mean-diameter ratio of 0.29 +/- 0.02. 

by Ernesto Guido

New Comet: C/2017 K4 (ATLAS)

CBET nr. 4397, issued on 2017, June 01, announces the discovery of a comet (magnitude ~17) by the "Asteroid Terrestrial-impact Last Alert System" (ATLAS) Team on CCD exposures taken on May 26.5 with the ATLAS 0.5-m f/2.0 Schmidt telescope at Haleakala. The new comet has been designated C/2017 K4 (ATLAS). 

I performed follow-up measurements of this object, while it was still on the neocp. Stacking of 10 unfiltered exposures, 120 seconds each, obtained remotely on 2017, May 29.4 from Q62 (iTelescope network) through 0.43-m f/6.8 reflector + CCD, shows that this object is a comet with a diffuse coma nearly 10 arcsec in diameter

My confirmation image (click on it for a bigger version)

Discovery animation by ATLAS Survey

Credit: The ATLAS Project

M.P.E.C. 2017-L04 assigns the following preliminary parabolic orbital elements to comet C/2017 K4 (ATLAS): T 2018 Jan. 13.3; e= 1.0; Peri. =  20.42; q = 2.54;  Incl.= 17.19

by Ernesto Guido