Saturday, August 31, 2019

Comets & Asteroids - Summary for July & August 2019

During the 2-month period July through August 2019, 7 new comets were discovered and there were 4 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

Jul 01 Discovery of C/2019 L3 (ATLAS)                  (CBET 4644)
Jul 02 Discovery of C/2019 K7 (SMITH)                  (CBET 4645)
Jul 02 Discovery of C/2019 K8 (ATLAS)                  (CBET 4646)
Jul 03 Discovery of C/2019 LB_7 (KLEYNA)           (CBET 4647)*
Jul 15 Discovery of C/2019 N1 (ATLAS)                  (CBET 4650)
Jul 17 Discovery of P/2019 M2 (ATLAS)                  (CBET 4651)**
Jul 18 Discovery of C/2019 M3 (ATLAS)                  (CBET 4653)

*The available astrometry for this very faint object was published on MPEC 2019-N20, where it was inadvertently given the minor-planet designation 2019 LB_7 by the Minor Planet Center.

**Following a private remark by the D. Green that the orbital elements of comets D/1884 O1 (Barnard) and P/2019 M2 are similar, Nakano has attempted an investigation into the possibility that the two designations might refer to the same comet. Nakano remarks that he is unable to link the two orbits, suggesting that (while possibly related) the two comets seem to be different objects. Additional astrometry for P/2019 M2 is urgently needed to extend the arc of observations at this return, before the comet fades rapidly in the coming weeks.(CBET 4657)

- Comet Recoveries

Jul 06 Recovery of P/2006 S1 (CHRISTENSEN) as P/2019 M1     (CBET 4649)
Jul 17 Recovery of 39P/OTERMA                                                   (CBET 4652)*
Jul 28 Recovery of P/2014 U2 (KOWALSKI) as P/2019 O1          (CBET 4654)
Aug 09 Recovery of P/2010 U2 (HILL) as P/2019 P1                    (CBET 4658)

*Recovery of comet 39P/Oterma (magnitude 24) on CCD images taken on July 3 UT with the 8.1-m "Gemini South" telescope, with confirmatory follow-up images being obtained on July 5 using both the 8.1-m "Gemini South" and the 6.5-m Magellan-Clay telescopes.  A point-source object was located within 1" of an ephemeris generated by the orbit given on MPC 75716.An upper bound of the nucleus radius -- based on photometry of the July 3 and 5 individual 100-s r' images and assuming a 4-percent albedo -- is between 2.1 and 2.5 km.  This upper bound is lower than what would be derived from 2001 photometry reported on MPCs 43260 and 43446 (2.5-3.5 km), suggesting that there might have been a compact coma in those observations and/or that 39P has an elongated nucleus.The comet was last seen in 2001 (cf. IAUC 7689). Comet 39P is currently inbound with perihelion in 2023. The comet was missed at its 1983 return.

- Other news

Jul 08 Zwicky Transient Facility (ZTF) spotted an unusual asteroid with the shortest "year" known for any asteroid. The rocky body, dubbed 2019 LF6, is about a kilometer in size and circles the sun roughly every 151 days. In its orbit, the asteroid swings out beyond Venus and, at times, comes closer in than Mercury, which circles the sun every 88 days. 2019 LF6 is one of only 20 known "Atira" asteroids, whose orbits fall entirely within Earth's. In the images below you can see an animation showing the asteroid as captured by ZTF on June 10 and how the orbit of 2019 LF6 (white) falls entirely within the orbit of Earth (blue).

Credit: ZTF/Caltech Optical Observatories

Credit: NASA/JPL-Caltech

Jul 12 ATel #12931 Disintegration of Comet C/2019 J2 (Palomar) - Quanzhi Ye et al. report the apparent disintegration of comet C/2019 J2 (Palomar), first detected by Soulier and Sárneczky on images taken on UT 2019 July 6-7. After receiving the reports from Soulier and Sárneczky, Ye examined the images taken with the Zwicky Transient Facility (ZTF) operated on the 1.2-m Oschin Schmidt telescope at Palomar Observatory. The ZTF image on July 9 shows that the comet has lost its central condensation. Although the disintegration only becomes apparent at some time between the ZTF observation on July 2 and the Maisoncelles/Konkoly observation on July 6, ZTF photometry suggests that the process likely started much earlier, possibly in early May. The brightness of the comet increased by ~0.6 mag from Apr. 27 to May 9, then decreased by an equal amount from May 9 to Jul. 2, while a typical comet would have brightened by 1.0 mag from Apr. 27 to Jul. 2.

Jul 29 Austrian filmmaker Christian Stangl combined some of the more than 400,000 images taken by @ESA's Rosetta mission into a stunning short film: "the Comet". Together the images show details of Comet 67P, which Rosetta followed and researched for 2 years.

Aug 07 On July 24, asteroid 2019 OK (60-130 meters in size; discovered by SONEAR team @CrisJacques)  approached Earth at about 65,000 km above the surface, one fifth the distance to the Moon. Largest Asteroid To Pass This Close To Earth in a Century

Credits: P. Chodas (NASA/JPL)

Aug 08 A possible impact on Jupiter recorded on 07 August 2019 at 04:07 UTC by E. Chappel. This is not the first time that we have seen something slam into Jupiter. It's actually the seventh event of its kind in recent years. More info about past recent events are available here

Credits: E. Chappel

Credits: E. Chappel

Aug 17 Fireball over Sardinia, Italy on the evening of August 16, 2019 via @ClaudioPorcu - More video available here  #meteor #meteora #astronomy #astronomia #Sardegna

Credits: C. Porcu

Below you can see a map showing the trajectory in the atmosphere projected to the ground of this bolide. The triangulation was done using 6 visual observations selected among the more than 80 arrived at the IMO.

(Credits: A. Carbognani)

by Ernesto Guido

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