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

Thursday, March 31, 2016

Comets & Asteroids - Summary for March 2016

During the month of March 2016,  3 new comets were discovered. On March 17, 2016 a new impact flash on Jupiter has been captured by amateur astronomers. Moreover, delay-doppler images of asteroid 2016 DV1 (on March 03, 2016) and of comet P/2016 BA14 (on March 22, 2016) have been obtained by Goldstone Solar System Radar.(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

Mar 11  Discovery of C/2016 E1 (PANSTARRS)
Mar 16  P/2015 B4 (LEMMON-PANSTARRS)
Mar 16  C/2016 E2 (KOWALSKI)


Scientists using the Goldstone Solar System Radar in California's Mojave Desert observed comet P/2016 BA14 during its historic flyby. Close approach of March 22, 2016 by P/2016 BA14 has been the third closest on record and the closest flyby of a comet in 246 years (for more info about P/2016 BA14 see our previous post). Radar images from the flyby indicate that the comet is about 1 kilometer in diameter. Moreover data collected by V. Reddy using the NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii indicate that the comet reflects less than 3 percent of the sunlight that falls on its surface. 

Radar images of comet P/2016 BA14 - Credit: NASA/JPL-Caltech/GSSR



Comet P/2016 BA14 - Credit: NASA/JPL-Caltech/GSSR



- Asteroid & Meteors news

On March 17, 2016 (at 00:18:35UT) a possible impact flash on Jupiter was imaged independently by 2 amateur astronomers: Gerrit Kernbauer (Mödling, Austria) & John McKeon (Dublin, Ireland). Both videos are on Youtube: bit.ly/1RwXOZb & bit.ly/1RwXOZc. If confirmed, this becomes the fifth such event in the past decade. For more info about old impact flashes see our previous post here. Click on the gif below to see a comparison side by side of the 2 videos with an apparent impact flash on the Jupiter's East limb. 
 

Credit: Kernbauer & McKeon


On March 03, 2016, delay-doppler images of asteroid 2016 DV1 were obtained using DSS-13 to transmit and GBT to receive. The images span ~1 rotation. Rotation period is about 304 +/-8 seconds.

Goldstone Radar Observations of 2016 DV1




















by Ernesto Guido

Wednesday, March 16, 2016

New Comet: C/2016 E2 (Kowalski)

CBET nr. 4266, issued on 2016, March 16, announces the discovery of a comet (magnitude ~18) by R. A. Kowalski on CCD images obtained with the 0.68-m Schmidt telescope in the course of the Catalina Sky Survey on Mar. 15.44-15.46 UT. The new comet has been designated C/2016 E2 (Kowalski).

We performed follow-up measurements of this object, while it was still on the neocp. Stacking of 65 unfiltered exposures, 15 seconds each, obtained remotely on 2016, March 16.3 from H06 (iTelescope network - New Mexico) through a 0.25-m f/3.4 reflector + CCD, shows that this object is a comet with a diffuse irregular coma nearly 10 arcsec in diameter.

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



M.P.E.C. 2016-F03  assigns the following preliminary parabolic orbital elements to comet C/2016 E2: T 2016 Feb. 6.70; e= 1.0; Peri. =  322.01; q = 1.07;  Incl.= 136.00

Credit: JPL

This comet will have a close approach with Earth at about 114 LD (Lunar Distances = ~384,000 kilometers) or 0.2920 AU (1 AU = ~150 million kilometers) on March 17, 2016 at 06:41 UT (it passed perihelion on Feb. 06, 2016 at 1.075 AU). Comet C/2016 E2 will fade in the coming days as its distance from both the Earth and Sun increase.


by Ernesto Guido & Nick Howes

Monday, February 29, 2016

Comets & Asteroids - Summary for February 2016

During the month of February 2016,  3 new comets were discovered, there were 2 recoveries and cometary activity was detected for 2 previously discovered objects (earlier designated as asteroids). New fragments of comet  P/2015 Y2 = P/2010 V1 (IKEYA-MURAKAMI) (see previous post) reported. According to a paper available on Arxiv, at least 17 fragments have been identified. Moreover the binary nature of asteroid (2535) Hämeenlinna and a previously unknown shower of naked-eye meteors, now known as the Volantids, 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

Feb 14  Discovery of C/2016 C1 (PANSTARRS)
Feb 15  Discovery of P/2016 BA14 (PANSTARRS)*
Feb 19  Discovery of C/2016 C2 (NEOWISE)


Comet P/2016 BA14 - M.Kelley/S.Protopapa/UMD


*The comet 252P/LINEAR will pass perihelion on 2016 Mar. 15 and make an historic close approach to the Earth on 2016 March 21 at 0.036 AU (or 13.9 LD), which is one of the closest cometary approaches to the Earth on record. In the meantime, on 2016 Jan 22, asteroid 2016 BA14 was discovered by the Pan-STARRS survey and it will have a close approach with Earth on 2016 March 22 at 0.0237 (or 9.2 LD). This asteroid and comet 252P have very similar orbital elements (a fact first noted by D. Denisenko on Comets Mailing List). This similarity prompted observers to image asteroid 2016 BA14 with the 4.3-m Lowell Observatory's Discovery Channel Telescope that led to the discovery of its cometary activity (new designation P/2016 BA14).  Close approach by P/2016 BA14 will be the third closest on record and the closest flyby of a comet in 246 years (since the 1770 passage by Comet D/1770 L1 -Lexell- at 5.9 LD). These objects are very probably related to one another, fragments from a past larger comet; observations in program (by the way also with the HST space telescope) will provide further confirmation.

Credit: http://neo.jpl.nasa.gov/ca/


- Comet Recoveries

Feb 06  Recovery of P/2008 Y2 (GIBBS) as P/2016 A9
Feb 15  Recovery of P/2006 G1 (McNAUGHT) as P/2016 B2

- Cometary activity detected

Feb 01  Cometary activity detected in 2015 ER61 = C/2015 ER61 (PANSTARRS)
Feb 02  Cometary activity detected in 2015 PD229 = P/2015 PD229 (ISON-Cameron) 


Comet P/2015 PD229 (ISON-Cameron) - NOAO DECam DECAL



- Asteroid & Meteor news

Feb 20  CBET 4261 reports that CAMS video camera surveillance of meteor showers in the Southern Hemisphere (CAMS New Zealand) detected a previously unknown shower of naked-eye meteors that peaked at the time of the local new year's eve celebrations. One out of three meteors that night came from this shower. The new shower is now known as the Volantids, named after the constellation Volans, the flying fish, from where the meteoroids appear to approach us. The parent body has not yet been identified. The source is a Jupiter-family comet that must now be in a relatively highly inclined orbit. A copy of the paper submitted to for publication in WGN, the Journal of the International Meteor Organization (JIMO) is available here.

Direction from which meteors approached us on December 31 (and next night). Credit: CAMS


Feb 25  CBET 4262 reports that minor planet (2535) Hämeenlinna is a binary system with an orbital period of 21.23 +/- 0.01 hr.  The primary shows a period of 3.23106 +/- 0.00006 hr and has a lightcurve amplitude of 0.10 mag at solar phases 2-8 degrees, suggesting a nearly spheroidal shape.

by Ernesto Guido

Sunday, January 31, 2016

Comets & Asteroids - Summary for January 2016

This post introduces a new monthly column that will serve as a summary of the most important news about comets & asteroids and an overview of the comets  discovered (and recovered) throughout the month just ended. During the month of January 2016,  8 new comets were discovered, there were 2 recoveries and cometary activity has been reported for 2 previously discovered objects (earlier designated as asteroids). Moreover, observations of a secondary companion for comet P/2015 Y2 = P/2010 V1 (IKEYA-MURAKAMI) and the discovery of the binary nature of asteroid (2242) BALATON have been reported. "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 07  Discovery of C/2016 A1 (PANSTARRS)
Jan 07  Discovery of P/2016 A2 (CHRISTENSEN)
Jan 07  Discovery of C/2016 A3 (PANSTARRS)  
Jan 16  Discovery of C/2016 A5 (PANSTARRS)  
Jan 20  Discovery of C/2016 A6 (PANSTARRS)  
Jan 23  Discovery of P/2016 A7 (PANSTARRS)
Jan 23  Discovery of C/2016 B1 (NEOWISE)
Jan 29  Discovery of C/2016 A8 (LINEAR)

Comet C/2016 B1 (NEOWISE) - J. Masiero / Gemini Observatory / AURA

- Comet Recoveries 

Jan 03  Recovery of P/2010 V1 (IKEYA-MURAKAMI) as P/2015 Y2 + secondary component
Jan 11  Recovery of P/2001 F1 (NEAT) as P/2016 A4

- Cometary activity detected

Jan 10  Cometary activity detected in 2007 VA85 = P/2007 VA_85 (LINEAR)
Jan 29  Discovery of 2015 VL62 = 2015 YY6 = C/2015 VL62 (LEMMON-YEUNG-PANSTARRS)


Comet P/2015 Y2 (IKEYA-MURAKAMI) - Credit: LCOGT/Man-To Hui

- Asteroid news

Near-Earth Objects (NEOs) discovered in January 2016:  155

Jan 23  CBET 4243 reports that minor planet (2242) BALATON is a binary system with an orbital period of 12.96 +/- 0.01 hr.  

Dictionary of Minor Planet Names by Lutz D. Schmadel

by Ernesto Guido

Tuesday, December 8, 2015

New Comet: C/2015 X4 (ELENIN)

CBET nr. 4216, issued on 2015, December 08, announces the discovery of a comet (magnitude ~18.2) by L. Elenin on three CCD images obtained with a 0.4-m f/3 reflector at the ISON-NM observatory near Mayhill, NM, USA on Dec. 3.5 UT. The new comet has been designated C/2015 X4 (ELENIN)

I performed follow-up measurements of this object, while it was still on the neocp. Stacking of 20 unfiltered exposures, 120 seconds each, obtained remotely on 2015, December 03.9 from I89 (iTelescope network - Nerpio) through a 0.32-m f/8.0 astrograph + CCD, shows that this object is a comet with a compact coma nearly 8 arcsec in diameter elongated toward PA 290.

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



M.P.E.C. 2015-X105 assigns the following preliminary elliptical orbital elements to comet C/2015 X4: T 2015 Nov. 2.64; e= 0.81; Peri. =  176.15; q = 3.39;  Incl.= 29.49


by Ernesto Guido

Thursday, November 12, 2015

WT1190F to hit Earth's atmosphere on Nov. 13, 2015

An object (probably space junk) discovered on October 3, 2015 by the Catalina Sky Survey and designated WT1190F will enter the Earth's atmosphere on 13 November 2015, making it one of the very few space impacting object observed prior to atmospheric entry (see old posts about asteroids 2008 TC3 & 2014 AA).  

This object will re-enter Earth's atmosphere in a few hours, around 06:20 UT on 13 November 2015 about 100 km off the southern coast of Sri Lanka (at 11:50am local time). It is quite small, probably about one or two meters across and so it is expected that most or all of WT1190F will burn up in the atmosphere before impacting, but will be possibly visible as a bright daytime fireball. 

Click on the images below to see the impact location. The magenta blob off the south coast of Sri Lanka is the nominally predicted impact area. According to Bill Gray: "nominally predicted impact area is the area within which we'd expect it to hit, assuming the object doesn't move in unexpected ways. Small objects such as this are pushed around a bit by sunlight. So I won't be surprised if it lands a couple of kilometers outside the predicted region". 


Credit: Bill Gray


Credit: Bill Gray


After collecting more observations and unearthing 2012 and 2013 obs from telescope archives, it has been possible to conclude that WT1190F is most probably a piece of discarded space junk. In fact WT1190 interacts with solar radiation pressure in a way that suggests it has low density (space junk is a lot lighter than a rock. It's so light that even sunlight can exert a very gentle push on it). Moreover it is in a very unusual and elongated orbit (eccentricity 0.96) taking it to within one Earth radius of the surface of the Earth at perigee but 1.65 Lunar Distances at apogee. It could be a spent rocket stage or panelling shed by a recent Moon mission. It is also possible that the debris dates back decades, perhaps even to the Apollo era.  Below a plot of the last three orbits of WT1190F. The small red circle is the earth. The big green circle is the orbit of the moon, just to give some scale to the chart (click on it for a bigger version).

Credit: Bill Gray


For more detailed info about the nature, size & history of this object please check the webpage maintained by Bill Gray at Project Pluto.

Astrometry obtained just before impact will help to pin down the trajectory and the impact location. So, I performed follow-up measurements of this object, about 22 hours before it entering Earth's atmosphere. Below you can see the image showing WT1190F at magnitude ~18.5, stacking of 30 unfiltered exposures, 30-sec each, obtained remotely on 2015, November 12.4 from H06 (iTelescope network - New Mexico) through a 0.43-m f/6.8 astrograph + CCD + f/4.5 focal reducer. Click on the image below for a bigger version. 




Below a short animation (spanning about 10 minutes) made out of my follow-up images. The first frame was obtained at 08:17UT while the second frame was obtained at 08:27UT of Nov, 12, 2015. (WT1190F is the star-like object at the centre while stars are trailed because the images were stacked on WT1190F motion)




UPDATE - November 13, 2015

First images of WT1190F reentry are available!! Images obtained by a team of researchers under the consortium "Rapid Response to a next TC3 asteroid impact". They were observing the event from an airborne sponsored by United Arab Emirates Space Agency & the International Astronomical Center (IAC) in Abu Dhabi.

Credit: IAC/UAE/NASA/ESA

Credit: IAC/UAE/NASA/ESA

Credit: IAC/UAE/NASA/ESA

Credit: IAC/UAE/NASA/ESA

See also the video below prepared by the expedition team, with photos of the re-entry and  of the cameras & instruments used on the airborne to follow the event: 



by Ernesto Guido