Tuesday, April 30, 2019

Comets & Asteroids - Summary for March & April 2019

During the 2-month period March through April 2019, 6 new comets were discovered and there were 3 comet recoveries. "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

Mar 21 Discovery of C/2019 D1 (FLEWELLING)                  (CBET 4614)
Mar 21 Discovery of C/2019 E3 (ATLAS)                                (CBET 4615)
Apr 10 Discovery of P/2019 G1 = P/2011 O2 (PANSTARRS) (CBET 4618)* 
Apr 10 Discovery of C/2019 F1 (ATLAS-AFRICANO)           (CBET 4619) 
Apr 22 Discovery of C/2019 F2 (ATLAS)                                (CBET 4620) 
Apr 23 Discovery of P/2019 GG_21 (PANSTARRS)               (CBET 4621)** 

* G. V. Williams, Minor Planet Center, then identified additional pre-discovery (apparently stellar) observations obtained at Kitt Peak by T. H. Bressi with the 1.8-m Spacewatch II on 2009 Feb. 26 and at the XuYi Station of  Purple Mountain Observatory with a 1.04-m Schmidt telescope on 2009 Mar. 25.

**  Initially designated as minor planet 2019 GG21, there was one prior report of cometary activity in this object. R. Weryk and R. Wainscoat (F51, Apr. 4) reported a ~1".9 FWHM ("seemingly" larger than the 1".4 +/- 0".2 FWHM of nearby stars) and a slight asymmetry to the northwest.  No other credible cometary reports were received.  A  report received today of a "new comet" (remarking that 2019 GG21 was predicted to be "nearby") from S. Sheppard  (807,Apr. 4 and 5) noted that the object had a 21" tail in P.A. 310.  The object is therefore being redesignated P/2019 GG21.

- Comet Recoveries

Mar 10 Recovery of P/2003 L1 (SCOTTI) as P/2019 E1     (CBET 4612)
Mar 18 Recovery of P/2005 Y2 (McNAUGHT) as P/2019 E2   (CBET 4613)
Apr 03 Recovery of P/2006 F4 (SPACEWATCH) as P/2019 D2 (CBET 4616)

- Other news

Mar 06 Image sequence captured by CAM-H during the touchdown of @haya2e_jaxa @haya2_jaxa spacecraft with  asteroid (162173) Ryugu last month. Also on youtube http://bit.ly/2VFTpfy  #astronomy #asteroids #ryugu

Credits: JAXA

Mar 12 New paper on Arxiv by D. Seligman, G. Laughlin & K. Batygin: "Implications of the Small Spin Changes Measured for Large Jupiter-Family Comet Nuclei". Long-form blog post up on http://oklo.org/2019/03/12/on-oumuamua/

Mar 19 OSIRIS-REx caught asteroid Bennu ejecting particles from its surface. NavCam 1 imager captured the first-ever close-up observations of material being released from an “active asteroid.” 

Credits: NASA/Goddard/University of Arizona/Lockheed Martin

Mar 27 The gigantic 170 ft (52 m) boulder on asteroid Bennu #Bennu #OSIRISREx #Asteroid via Roman Tkachenko

Credits: NASA/Goddard/University of Arizona/Lockheed Martin

Mar 28 Active asteroid (6478) Gault imaged by Hubble Space Telescope. Images from Hubble show two narrow, comet-like tails of dusty debris streaming from the asteroid (6478) Gault. Each tail represents an episode in which the asteroid gently shed its material.

Credits: NASA, ESA, Meech & Kleyna (University of Hawaii) and Hainaut (ESO)

Apr 05 The Hayabusa2 deployable camera, DCAM3, successfully photographed the ejector from when the SCI  (Small Carry-on Impactor) collided with Ryugu’s surface"This is the world’s first collision experiment with an asteroid! In the future, we will examine the crater formed and how the ejector dispersed".  (see image below. Image credits: JAXA, Kobe University, Chiba Institute of Technology, The University of Occupational and Environmental Health, Kochi University, Aichi Toho University, The University of Aizu, and Tokyo University of Science)

UPDATE Apr 25 Crater formation where the Small Carry-on Impactor collided with Ryugu has been confirmed! These images compare the surface before and after the SCI collision.

Credit: Hayabusa2 JAXA

Apr 05 (CBET 4617) P. Jenniskens, SETI Institute and NASA Ames Research Center; and J. W. Baggaley, University of Canterbury, Christchurch, report that an outburst of delta Pavonid meteors (IAU shower 120; code DPA) has been detected by the CAMS New Zealand stations operated by P. Aldous (Geraldine) and I. Crumpton (West Melton).The parent comet is presumed to be C/1907 G1 (Grigg-Mellish), which was poorly observed in 1907, with parabolic orbital elements q = 0.924 AU, i = 110.06 deg, Peri. = 328.76 deg, and Node = 190.417 deg (equinox 2000.0) -- in good agreement when allowing for the motion of the node due to planetary perturbations.

Credits: NASA Meteor Shower Portal; CAMS SETI

Apr 15 New paper on Arxiv by D. Jewitt et al.: "Episodically Active Asteroid 6478 Gault".

Credit: Jewitt et al.

Apr 23 New paper on Arxiv by Chandler et al.: "Six Years of Sustained Activity from Active Asteroid (6478) Gault".

Credits: Chandler et al.

Apr 24 Three months of surface temperature maps of #67P nucleus from Rosetta suggest that only the upper layers are affected by temporal effects, keeping the immediate interior pristine.

Credits: F. Tosi et al - Nature Astronomy 2019

by Ernesto Guido