New Outburst of 174P/Echeclus

On December 08, 2017 B. Skiff reported on mpml mailing list, that the centaur 174P/Echeclus  (also known as 60558 Echeclus) "seems to be at least 4 mag brighter than expected, and indeed as it appeared at the start of last night's images.  The Dec 7 series shows the outburst in progress on images taken near 2:00 and 2:48 UT; it is much brighter now (Dec 8 about 3:30 UT)". Last observations before this outburst had this object at around magnitude 18.

Prompted by this alert, I perfomed some follow-up of 174P/Echeclus and I can confirm that this object is experiencing a bright phase. Unfiltered exposures, 30-seconds each, obtained  remotely from Q62 (iTelescope network) on 2017, December 08.57 (through a 0.50-m f/6.8 astrograph + CCD + f/4.5 focal reducer) reveal 174P as a bright featureless star-like object of magnitude ~14.1 N (click on the image below for a bigger version).

This very interesting object was discovered by Spacewatch in 2000 and initially classified as a minor planet with provisional designation 2000 EC98 (its final minor planet designation is 60558 Echeclus). The presence of coma around it was first detected by Choi and Weissman (2006) on 2005 December 30.50 UT with the Palomar 5m telescope. Soon after, the object was given the periodic comet designation 174P/Echeclus. During the years, it experienced many outbursts. You can find info and images on all these past bright phases on this blog.

by Ernesto Guido

Comets & Asteroids - Summary for July 2017

During the month of July 2017, 2 new comets were discovered and cometary activity was detected for 1 previously discovered object (earlier designated as an asteroid). "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/2017 M5 (TOTAS)

Jul 24 Discovery of C/2017 O1 *

* Note on CBET 4426 issued on August 26: After considerable discussion, the IAU "Working Group for Small Body Nomenclature" (formerly the IAU "Committee for Small Body Nomenclature" and the IAU "Small Bodies Names Committee") has decided to accept the name "ASASSN" for comet C/2017 O1 (cf. CBET 4414).

- Cometary activity detected

Jul 03 Cometary activity detected in Hilda-type minor planet (457175) 2008 GO_98 *

* The following permanent number has been assigned on CBET 4442 issued on October 09: 362P/(457175)P/2008 GO_98

- Other news

Jul 5 CBET 4412 reports that minor planet (7344) SUMMERFIELD is a binary system with an orbital period of 17.41 +/- 0.01 hr.  The primary shows a period of 2.58975 +/- 0.00003 hr and has a lightcurve amplitude of 0.17 mag at solar phases 9-15 degrees, suggesting a nearly spheroidal shape.  Mutual eclipse/occultation events that are 0.03- to 0.07-magnitude deep indicate a secondary-to-primary mean-diameter ratio of 0.18 +/- 0.03.  The mean absolute R magnitude in the Cousins system is H_R = 12.88 +/- 0.08, assuming the phase relation slope parameter G = 0.24 +/- 0.11.

Jul 07  New paper on Arxiv by Kokotanekova et al.: "Rotation of Cometary Nuclei: New Lightcurves and an Update of the Ensemble Properties of Jupiter-Family Comets"

Credit: Kokotanekova et al

Jul 12 CBET 4413 report the discovery of an apparent satellite (S/2017 (113) 1) of minor planet (113) Amalthea from observations made of the Tycho Catalogue star 1878-01081-1 (magnitude V = 10.0) during an occultation by the minor planet (which was at V = 12.9) on 2017 Mar. 14.167 UT.  A total of ten observation sites recorded seven positive events and three negative events for (113), two of which are attributed to the possible satellite.

Credit: IOTA / Brad Timerson

by Ernesto Guido                        

New Close Approach by Asteroid 2012 TC4

Asteroid 2012 TC4 was discovered by F51 Pan-STARRS 1, Haleakala on images taken on 2012, Oct. 04.4 with a 1.8-m Ritchey-Chretien + CCD. Just eight days after its discovery, on 2012 Oct. 12, this object passed at about 0.25 LD from Earth. 

After exactly 5 years, 2012 TC4 will have a new close approach with our planet that will provide astronomers with a valuable opportunity to learn more about its orbit and composition and to test the network of observatories and scientists who work with planetary defense. This asteroid was not observed since the week it was discovered in October 2012 and it has been recovered by astronomers using one of the European Southern Observatory's 8.2-meter telescopes at the Very Large Telescope (VLT) on July 27, 2017 at an apparent magnitude of 26.8 (making it the faintest Near Earth Asteroid so far measured).

Credit: ESO/ESA NEOCC/Hainaut (ESO), Micheli (ESA) & Koschny (ESA)

2012 TC4 has an estimated size of 12 m - 27 m (H=26.7) and it will have a close approach with Earth at about 0.13 LD (Lunar Distances = ~384,000 kilometers) or 0.00034 AU (1 AU = ~150 million kilometers) at 0542 UT on 12 Oct. 2017 and it will reach the peak magnitude ~13. (For comparison, the asteroid that hit Earth’s atmosphere near Chelyabinsk, Russia, in February 2013 was roughly 20 meters across). The rapid rotation and lightcurve amplitude (rotation period of 0.2038 hours with a brightness variation of 0.93 magnitude) suggest that the 2012 TC4 is an elongated, monolithic body (a rubble pile would have spun itself apart). Non-principal axis rotation suggests that it probably has a complex (non-ellipsoidal) shape. 2012 TC4 should be detectable at Goldstone from about Oct. 9 - 16, but not at the moment of closest approach, when it will be too far south for Goldstone to track.

Below you can see my image (single 120-second exposure) of 2012 TC4 obtained on 2017, Oct. 11.35, few hours before its close approach. At the moment of the shot, the asteroid was of magnitude ~15.9 and moving at ~24"/min. The asteroid is trailed in the image due to its fast speed. Click on the image below to see a bigger version. (North is up, East is to the left). 

The short animation below is showing the movement of 2012 TC4 (two consecutive 120-second exposure). Click on the thumbnail below to see the animation (North is up, East is to the left).

Thanks to the new observations following its 2017 recovery, it became clear that new orbit solution precludes a possible impact in 2050: "2012 TC4 would miss the keyhole that would lead to an impact with Earth in 2050. This plot shows the b-plane—the asymptotic location of TC4 relative to the Earth before the Earth's gravity starts bending the trajectory of TC4. The b-plane intersections for progressive orbit solutions is shown by the ellipses (dashed lines show 1-σ uncertainties, solid lines show 3-σ uncertainties), while the red dots show the b-plane coordinates that lead to an impact in 2050. Starting with the Sept 28 solution, the 3-σ uncertainites fall well clear of the red dots, indicating that the asteroid will miss the Earth in 2050. Future impacts beyond that date have not been ruled out."

Credit: The 2012 TC4 Observing Campaign

by Ernesto Guido

Comets & Asteroids - Summary for June 2017

During the month of June 2017, 6 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

Jun 01 Discovery of P/2017 K3 (GASPAROVIC)

Jun 01 Discovery of C/2017 K4 (ATLAS)

Jun 01 Discovery of C/2017 K5 (PANSTARRS)

Jun 01 Discovery of C/2017 K6 (JACQUES)

Jun 23 Discovery of C/2017 M3 (PANSTARRS)

Jun 23 Discovery of C/2017 M4 (ATLAS)

Comet C/2017 K4 (ATLAS) - E. Guido

- Comet Recoveries

Jun 06  Recovery of P/2000 S1 (SKIFF) as P/2017 L1

Jun 06  Recovery of P/2009 S2 (McNAUGHT) as P/2017 M1

Jun 06  Recovery of P/2010 A2 (LINEAR) as P/2017 B5

Jun 06  Recovery of P/2004 T1 (LINEAR-NEAT) as P/2017 M2

Comet P/2009 S2 (McNAUGHT) - Guido & Sostero

- Other news

Jun 5 CBET 4401 reports that minor planet (9972) MINORUODA is a binary system with an orbital period of 22.89 +/- 0.01 hr.  The primary shows a period of 3.4221 +/- 0.0002 hr and has a lightcurve amplitude of 0.11 mag at solar phases 10-14 degrees, suggesting a nearly spheroidal shape.  Mutual eclipse/occultation events that are 0.06- to 0.13-magnitude deep indicate a lower limit on the secondary-to-primary mean-diameter ratio of 0.24.

Jun 13 CBET 4403 provide the following update by Jenniskens & Lyytinen on expected meteor activity from long-period comet C/2015 D4, now that an improved comet orbit is available (cf. CBET 4127).  Based on an orbit for C/2015 D4 calculated by G. V. Williams from 43 observations spanning 2015 Feb. 23-Oct. 15 (cf. MPEC 2015-U54), the position of the one-revolution dust trail was calculated for the period 1996-2070.  Results show that the dust trail will be in the earth's path on 2017 July 29d00h22m UT (solar longitude 125.858 deg), when the earth passes the center of the trail at a relative distance of only r - Delta = +0.0006 AU; the earth will thus pass inside the comet's orbit at a time when the comet has just passed perihelion, both favorable circumstances for detecting meteors.  Meteors are expected from geocentric R.A. = 79 deg, Decl. = -32 deg, with geocentric velocity 45.9 km/s.

Jun 20 Images of asteroid 6 Hebe taken using SPHERE instrument on ESO ’s Very Large Telescope and related research paper http://bit.ly/2tnC9hR

Credit: ESO/M. Marsset 

Jun 21 New paper on Arxiv by C. Snodgrass et al.: "X-shooter search for outgassing from Main Belt Comet P/2012 T1 (Pan-STARRS)". 

Jun 22 New paper on Arxiv by D. Nesvorny et al.: "Origin and Evolution of Short-Period Comets". In the panel below, extracted from the paper, the orbital distribution of known SPCs. The thin lines show the division between between ECs and NICs (panel b; TJ = 2).

Credit: Nesvorny et al.

Jun 24 CBET 4409 reports that comet C/2015 ER61 (PANSTARRS)  has evidently experienced a splitting: a companion fragment (denoted 'B') was reported by E. Bryssinck (Kruibeke, Belgium) from CCD images taken by F.-J.Hambsch (Mol, Belgium) and himself on June 13, 15, and 16 remotely with a 0.4-m f/6.8 reflector (both unfiltered and with a Bessel R filter) at the private "ROAD Observatory" located at San Pedro de Atacama, Chile; Bryssinck noticed a change over a couple of days in the shape of the nuclear condensation, followed by the appearance of a possible nuclear fragment inside the coma and tail.  On June 13.41 UT, seven exposures show a very faint fragment located 12".3 from the main nuclear condensation in p.a. 243 degrees with a diameter of 8" (magnitude R = 16.5 in an aperture of diameter 5".4).  Seven images taken on June 15.42 show the very faint fragment 13".0 from the main condensation in the same direction and with magnitude R = 16.6 in the same-sized aperture.  Nine images taken on June 16.41 show component B at size 8".8 (with R = 16.6 in a 5".4 aperture) and located 13".4 from component A in p.a. 248 deg.  Component B is difficult to see due its small distance from component A and to its location within the tail.

Credit: ROAD Observatory - Hambsch & Bryssinck

by Ernesto Guido

Comets & Asteroids - Summary for May 2017

During the month of May 2017, 2 new comets were discovered and cometary activity was detected for 1 previously discovered object (earlier designated as an asteroid).  "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

May 24 Discovery of C/2017 K1 (PANSTARRS)

May 24 Discovery of C/2017 K2 (PANSTARRS)

- Cometary activity detected

May 28 Cometary activity detected in 2016 WM_48 = P/2016 WM_48 (LEMMON)

- Other news 

May 02 H. H. Hsieh reports on CBET 4388 that r'-band observations taken on Apr. 26 and 29 with the Gemini South Observatory (seven 100-s exposures per night; queue observer J. Chavez) show that comet 259P (cf. IAUC 8969; CBET 3115), which has been previously identified as an active minor planet and main-asteroid-belt comet candidate, is currently active. According to CBET 4388: "Including its previously observed active apparition in 2008 (IAUC 8969), these observations mark the second time that comet 259P has been seen to be active.  The fact that 259P exhibits regularly repeated periods of activity, interspersed with periods of quiescence, is a strong indicator that its activity is driven by the sublimation of volatile material, consistent with its initial identification as an ice-bearing main-asteroid-belt comet."

May 18 Hubble Spots Moon Around "2007 OR10", Third Largest Dwarf Planet in the Kuiper Belt. The team's results appeared in The Astrophysical Journal Letters: "2007 OR10 is currently the third largest known dwarf planet in the trans-Neptunian region, with an effective radiometric diameter of ∼1535 km. It has a slow rotation period of ∼45 hr that was suspected to be caused by tidal interactions with a satellite undetected at that time. Here, we report on the discovery of a likely moon of 2007 OR10, identified on archival Hubble Space Telescope WFC3/UVIS system images."

Credits: NASA, ESA, C. Kiss (Konkoly Observatory), and J. Stansberry (STScI)

May 24 CBET 4394 reports that minor planet (190166) 2005 UP156 is a fully-synchronous binary system with an orbital/rotational period of 40.542 +/- 0.008 hr.  The V magnitude was 16.0 on May 4, brightening to 15.2 on May 23.  The out-of-eclipse lightcurve shows an amplitude of about 0.5 magnitude with eclipse attenuations of about 0.6 mag.  The deeper event lasts about 2.8 hours.  The effective secondary-to-primary diameter ratio is estimated to be 0.8 +/- 0.1. 

May 26 A possible impact flash on #Jupiter was imaged by on May 26 by S. Pedranghelu with at least 2 independent confirmations. More info on see our blog post here

Credit: T. Riessler 

May 29 RIP Dr. Michael Francis A'Hearn (1940 - 2017). PI for the NASA Deep Impact; he introduced Afρ parameter for comets.

Credit: M. Mendelsohn

by Ernesto Guido

New Comet: C/2017 O1

CBET nr. 4414, issued on 2017, July 24, announces the discovery of a comet (magnitude ~15.3) in the course of the "All-Sky Automated Survey for Supernovae" (ASASSN) program, from images taken with the 14-cm "Cassius" survey telescope at Cerro Tololo on July 19.32 UT. The new comet has been designated C/2017 O1. 

I performed follow-up measurements of this object, while it was still on the neocp. Stacking of 10 unfiltered exposures, 60 seconds each, obtained remotely on 2017, July 23.7 from Q62 (iTelescope network) through 0.50-m f/6.8 astrograph + CCD + f/4.5 focal reducer, shows that this object is a comet with a sharp central condensation surrounded by diffuse coma about 3 arcmins in diameter

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

Below you can see the discovery image by ASASSN survey

Credit: ASASSN

M.P.E.C. 2017-O45 assigns the following preliminary parabolic orbital elements to comet C/2017 O1: T 2017 Oct. 14.3; e= 1.0; Peri. =  20.29; q = 1.51;  Incl.= 39.75

Below you can see a graph generated using the software Orbitas and showing the predicted magnitude for this comet (click on the image for a bigger version). Visual estimates have the comet at mag. ~10 on July 24, 2017. Syuichi Nakano, Sumoto, Japan, notes on CBET 4414 that this comet could reach total visual magnitude 7 during September-November. A word of caution: as always with comets, the future magnitudes reported here are only indicative.

UPDATE - August 26, 2017

According to CBET 4426: "After considerable discussion, the IAU "Working Group for Small Body Nomenclature" (formerly the IAU "Committee for Small Body Nomenclature" and the IAU "Small Bodies Names Committee") has decided to accept the name "ASASSN" for comet C/2017 O1 (cf. CBET 4414)."

by Ernesto Guido 

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

New Impact Flash on Jupiter

On May 26, 2017 (between 19:24.6 and 19:26.2 Universal Time) a new possible impact flash on Jupiter was imaged by Sauveur Pedranghelu, a French amateur astronomer from Corsica. According to a preliminar analysis by Marc Delcroix (who runs a Jovian impact flashes detection project) this flash, detected in the North polar area of Jupiter, seems shorter than the others (~0.7s vs 1-2s) and displayed two brightness peaks. (click on the images below for a bigger version).

The image by Pedranghelu was then posted online as a call for observations of Jupiter obtained in the same time interval to exclude the possibility that the flare might have been caused by an artefact or flashing satellite. Few hours after the posting, two other observers from Germany (Andre Fleckstein & Thomas Riessler) confirmed independently from one another the finding with their own images. 

Below you can see an animation made by Thomas Riessler using his Jupiter observations showing the impact flash on Jupiter. (click on it for a bigger version). The impact area imaged in the hours after the reported flash showed NO remnants of the impact.

Credit: T. Riessler 

This is not the first time that we have seen something slam into Jupiter, beginning with a fireball recorded by Voyager 1 as it flew past in 1979 (see image below) and the famous impact of Comet Shoemaker-Levy 9 in 1994. 

March 5, 1979 - Fireball in Jupiter's Atmosphere by Voyager 1

Credit: Cook & Duxbury

In this blog we reported about all the recent cases starting from the event of July 19, 2009 (a scar left on Jupiter by an unseen impact observed by Anthony Wesley), of June 03, 2010 (impact flash observed by Anthony Wesley and Christopher Go), of August 20, 2010 (impact flash observed by Masayuki Tachikawa & Aoki Kazuo), of September 10, 2012 (impact flash observed  by Dan Petersen and George Hall), of March 17, 2016 (impact flash observed by Gerrit Kernbauer and John McKeon).

The role of planet Jupiter as a shield protecting Earth from getting hit by such objects is still controversial and it has been discussed in depth in a series of articles by Jonathan Horner and Barrie Jones (Jupiter - friend or foe?).

by Ernesto Guido

Comets & Asteroids - Summary for March 2017

During the month of March 2017, 8 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

Mar 01 Discovery of P/2017 D1 (FULS)
Mar 01 Discovery of C/2017 D2 (BARROS)
Mar 01 Discovery of C/2017 D3 (ATLAS)
Mar 01 Discovery of P/2017 D4 (PANSTARRS)
Mar 04 Discovery of C/2017 E1 (BORISOV)
Mar 07 Discovery of C/2017 E2 (XUYI)
Mar 13 Discovery of C/2017 E3 (PANSTARRS)
Mar 13 Discovery of C/2017 E4 (LOVEJOY)

 Click on the images below for a bigger version

C/2017 E1 (BORISOV) - E. Guido

C/2017 E4 (LOVEJOY) - E. Guido

Discovery images of C/2017 D3 (ATLAS) - Credits: The ATLAS Project

- Other news 

Mar 02 New paper on arXiv by Z. Sekanina & R. Kracht: "Orbital Evolution, Activity, and Mass Loss of Comet C/1995 O1 (Hale-Bopp). I. Close Encounter with Jupiter in Third Millennium BCE and Effects of Outgassing on the Comet's Motion and Physical Properties"

Credits: Z. Sekanina & R. Kracht

Mar 03 A new, bright Sungrazing comet racing towards the Sun via @SungrazerComets

Credits: ESA/NASA/SOHO/LASCO C3

Mar 04 New paper on arXiv by Kiss et al.: "Discovery of a satellite of the large trans-Neptunian object (225088) 2007OR10"

Credits: Kiss et al.

Mar 09 CBET 4371 & CBET 4374 (Mar 19) report that the following minor planets are binaries systems: (2825) CROSBY & (1798) WATTS

Mar 09 PAN, the second-innermost moon of Saturn, imaged by @CassiniSaturn on March 07, 2017

Credits: NASA/JPL-Caltech/Space Science Institute

Mar 28 New paper on arXiv by Jewitt & al.: "Anatomy of an Asteroid Break-Up: The Case of P/2013 R3"

Credits: Jewitt & al.

Mar 29 CBET 4376 reports that the following names have been voted upon by the IAU Working Group on Small Body Nomenclature for recently discovered comets:

Designation (Name)                          Discovery Reference

P/2015 PD229 (Cameron-ISON)             CBET 4251

C/2014 HU195 (Valdes-TOTAS)             CBET 4294

Further to CBET 4343, the following permanent numbers have been assigned to short-period comets based upon their being securely observed at multiple returns to perihelion.

                                                                                               

Designation/Name         Provisional Designations              Discovery/Recovery Reference       

348P/PANSTARRS      P/2017 A2 = P/2011 A5                        CBET 4341

349P/Lemmon              P/2010 EY90 = P/2017 B1                    CBET 4349

350P/McNaught           P/2010 J5 = P/2017 B2                         CBET 4352

Mar 30 New paper on NATURE by Wiegert et al. about the first retrograde co-orbital asteroid: 2015 BZ509: "A retrograde co-orbital asteroid of Jupiter" (see animation below)

by Ernesto Guido

Comets & Asteroids - Summary for February 2017

During the month of February 2017, 4 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

Feb 04 Discovery of C/2017 B3 (LINEAR)

Feb 04 Discovery of P/2017 B4 (PANSTARRS)

Feb 12 Discovery of C/2017 C1 (NEOWISE)

Feb 20 Discovery of C/2017 C2 (PANSTARRS)

- Other news 

Feb 02 At this link, animation by L. Elenin showing the egress of near-earth asteroid 2017 BS32 from Earth's shadow. 

Feb 3 CBET 4353, CBET 4356 (Feb 09), CBET 4361 (Feb 14) report that the following minor planets are binaries systems: (226514) 2003 UX_34, (2486) METSAHOVI, (27675) 1981 CH.

Feb 09 & Feb 13 Two new papers on arXiv about active asteroid P/2016 J1 (PANSTARRS): "Split Active Asteroid P/2016 J1 (PANSTARRS)" & "The splitting of double-component active asteroid P/2016 J1 (PANSTARRS)". Click on the image below for a bigger version.

Credits: Man-To Hui, David Jewitt, Xinnan Du

Feb 09 New impact crater spotted on Mars: "This new crater, which formed explosively at the point of impact, has a diameter of roughly 8 meters (about 25 feet), but its surrounding blast zone and ejecta extend over a kilometer (about one mile) beyond the crater itself. This new impact was discovered using the lower-resolution Context Camera (CTX), also on board Mars Reconnaissance Orbiter. An older CTX image of this region from May 2012 shows a uniformly dust-covered surface, while a newer CTX image from September 2016 reveals the crater’s dark blast zone.". Click on the image below for a bigger version.

Credits: NASA/JPL/University of Arizona 

Feb 11 Unknown fragment from Comet 73P discovered in outburst by T. Noel. Click on the image below for a bigger version.

Feb 13 Radar images of asteroid 2017 BQ6 were obtained on Feb. 6 and 7 with NASA’s 70-meter antenna at GSSR. "They reveal an irregular, angular-appearing asteroid about 660 feet (200 meters) in size that rotates about once every three hours. The images have resolutions as fine as 12 feet (3.75 meters) per pixel.Asteroid 2017 BQ6 safely passed Earth on Feb. 6 at 10:36 p.m. PST (1:36 a.m. EST, Feb. 7) at about 6.6 times the distance between Earth and the moon (about 1.6 million miles, or 2.5 million kilometers). It was discovered on Jan. 26 by the NASA-funded Lincoln Near Earth Asteroid Research (LINEAR) Project, operated by MIT Lincoln Laboratory on the Air Force Space Command’s Space Surveillance Telescope at White Sands Missile Range, New Mexico." Click on the image below for a bigger version.

Credits: Credits: NASA/JPL-Caltech/GSSR

Feb 15 Arecibo Radar Observatory captures revealing images of Comet 45P/Honda-Mrkos-Pajdusakova :  "The comet’s shape is probably two lobes and is seen here to be about 1.3 km in size. Gif below composed of thirteen delay-Doppler images of Comet 45P/HMP after 2 hours of observation. The new radar observations have revealed Comet 45P/HMP to be somewhat larger than previously estimated. The radar images suggest a size of about 1.3 km (0.8 mi) and that it rotates about once every 7.6 hours."

Credits: Arecibo Observatory/NASA/NSF

Feb 15 On this day, 4 years ago  the Chelyabinsk meteor (15 FEBRUARY 2013). Click on the image below for a bigger version.

Credits: Alex Alishevskikh - CC BY-SA 2.0

by Ernesto Guido

Comets & Asteroids - Summary for January 2017

During the month of January 2017, 4 new comets were discovered, cometary activity was detected for 1 previously discovered object (earlier designated as an asteroid) and there was 1 comet recovery. "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

Jan 6  Discovery of C/2017 A1 (PANSTARRS)

Jan 07 Discovery of P/2017 A2 = P/2011 A5 (PANSTARRS)

Jan 11 Discovery of C/2017 A3 (ELENIN)

Jan 28 Discovery of P/2017 B1 = 2010 EY_90 (LEMMON)

- Cometary activity detected

Jan 29 Cometary activity detected in 2016 VZ_18 = C/2016 VZ_18 (PANSTARRS)

- Comet Recoveries

Jan 30  Recovery of P/2010 J5 (McNAUGHT) as P/2017 B2

- Other news

Jan 8 CBET 4342, CBET 4345 (Jan. 12), CBET 4346 (Jan. 14) & CBET 4347 (Jan. 28) report that the following minor planets are binaries systems: (4296) VAN WOERKOM, (12326) SHIRASAKI, (6186) ZENON, (163693) ATIRA. 

Credit: Arecibo Observatory

by Ernesto Guido

New Comet: C/2017 E4 (LOVEJOY)

CBET nr. 4373, issued on 2017, March 13, announces the discovery of a comet (magnitude ~15) by Terry James Lovejoy on three CCD 8-s exposures taken five minutes apart starting on Mar. 9.684 UT with a Celestron C14 reflector operating at f/1.9 (+ QHY9 camera). The new comet has been designated C/2017 E4 (LOVEJOY). 

I performed follow-up measurements of this object, while it was still on the neocp. Stacking of 10 unfiltered exposures, 30 seconds each, obtained remotely on 2017, March 10.7 from Q62 (iTelescope network) through a 0.50-m f/6.8 astrograph + CCD + focal reducer, shows that this object is a comet with a diffuse coma nearly 15 arcsec in diameter.

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

M.P.E.C. 2017-E86 assigns the following preliminary parabolic orbital elements to comet C/2017 E4: T 2017 Apr. 23.3; e= 1.0; Peri. =  87.21; q = 0.49;  Incl.= 88.23

 Discovery image set from March 9.68, 2017. Credit. T. Lovejoy

by Ernesto Guido

New Comet: C/2017 E1 (Borisov)

CBET nr. 4369, issued on 2017, March 04, announces the discovery of a comet (magnitude ~17) by Gennadii Vladimirovich Borisov on three unfiltered 120-s exposures obtained on Mar. 1.10 UT with a 0.4-m f/2.3 astrograph at the "Mobil Astronomical Robotics Genon" Observatory (MARGO) near Nauchnij. The new comet has been designated C/2017 E1 (Borisov). 

I performed follow-up measurements of this object, while it was still on the neocp. Stacking of 20 unfiltered exposures, 30 seconds each, obtained remotely on 2017, March 1.5 from H06 (iTelescope network) through a 0.43-m f/6.8 reflector + CCD + f/4.5 focal reducer, shows that this object is a comet with a diffuse coma nearly 30 arcsec in diameter.

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

M.P.E.C. 2017-E42 assigns the following preliminary parabolic orbital elements to comet C/2017 E1: T 2017 Apr. 9.8; e= 1.0; Peri. =  151.90; q = 0.90;  Incl.= 14.54

by Ernesto Guido