ALPO COMET SECTION NEWS FOR FEBRUARY 2016
2016-January-29
During January, the ALPO Comet Section received visual magnitude estimates of comets C/2013 US10 (Catalina), C/2013 X1 (PANSTARRS) and C/2014 S2 (PANSTARRS) from Salvador Aguirre, Carl Hergenrother and Gary Nowak. Images and drawings were submitted for comets 249P/LINEAR, C/2013 US10 (Catalina), C/2013 X1 (PANSTARRS), C/2015 G2 (MASTER) and C/2015 V2 (Johnson) from Salvador Aguirre, John Chumack, Carl Hergenrother, Eliot Herman, Manos Kardasis, Jean-Baptiste Kikwaya, John and Sabia. A major thanks to everyone who has contributed to the Section.
In past comet news, the Comet Section archive is being slowly digitized for uploading to the Section image gallery and magnitude databases. Additional thanks goes to John Sabia who has been rescanning some of his old comet photographs.
Evening Comets
C/2013 US10 (Catalina) [Perihelion on 2015-Nov-15 at 0.82 AU from the Sun]
The brightest comet of 2016 (so far) is C/2013 US10 (Catalina). Baring a new discovery or surprise outburst, it may end up holding on to that title. Comet Catalina has been between magnitude 6 and 7 going back as far as last August (though it was lost in the glare of the Sun for most of September, October and November). Now that the comet is quickly retreating from both the Sun (1.59 to 1.98 AU) and Earth (0.89 to 1.69 AU), it has started a rapid fade. ALPO contributor Salvador Aguirre has noted that the comet had faded to magnitude 6.8 on the 25th. At the start of February it may be around magnitude 7. It could fade to around 9th magnitude by the end of the month. Luckily, for northern observers, Catalina is visible all night long as it moves through Camelopardalis (declination falling from 81° to 58°).
The image below by ALPO contributor John Chumack from early January shows how photogenic Comet Catalina is with its multi-rayed ion tail and heavily curved dust tail.
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C/2013 X1 (PANSTARRS) [Perihelion on 2016-Apr-20 at 1.31 AU]
This month will be our last opportunity to observe C/2013 X1 (PANSTARRS) till April as it will be too close to the Sun for Earth-based observers. Luckily the comet may be visible in the FOV of the C3 coronagraph on the SOHO spacecraft for a few days in mid-March. Its brightness over the next few weeks is a little uncertain as the comet appears to be outburst prone with at least one outburst in early January that took it from magnitude 9.7 to 8.0. It has now faded back to around magnitude 8.8. Unless it experiences another outburst, PANSTARRS should be around 9th magnitude in February.
While C/2013 US10 (Catalina) holds the title of brightest comet of the young year, C/2013 X1 (PANSTARRS) may challenge that title. X1 is inbound to a April 20th perihelion at 1.31 AU from the Sun. The comet may brighten to 6th-7th magnitude as it comes within 0.64 AU of Earth in late June. While most recent comets discovered at large heliocentric distances have disappointed, X1 holds a bit more promise. Its original orbit suggests a dynamically old comet. Also its overall brightness behavior since discovery (not worrying about outbursts) has not shown many of the brightening stalls and fades that dynamically old comets show. So perhaps X1 will really get up to 6-7th magnitude as predicted.
This month, X1 is an evening object with an elongation dropping from 50° to 18° as it moves through Pegasus (Feb 1-20) and Pisces (20-29). Its distance from the Sun falls from 1.75 to 1.51 AU while its distance from Earth increases from 2.22 to 2.42 AU.
P/2010 V1 (Ikeya-Murakami) [Perihelion 2016-Mar-17 at 1.57 AU]
Not sure what to expect from this one. Back in 2010, Japanese amateur astronomers Kaoru Ikeya (of Ikeya-Seki fame) and Shigeki Murakami discovered this comet visually at 8th magnitude. Side note, this is the last comet to have been discovered visually thanks to the onslaught of CCD surveys (of which I’m guilty of making a contribution). After discovery it became apparent that it had experienced a large outburst and quickly faded. I-M is now back and though it is running very faint at 19th magnitude, it brought a surprise in that it came back as not one but at least four comets. While it is unlikely I-M will have another major outburst, those with CCDs might want to keep on eye on it. This month it moves through Lynx (Feb 1-25) and Cancer (25-29) as it moves closer to the Sun (1.63 to 1.58 AU) and makes its closest approach to Earth (0.65 AU).
252P/LINEAR [Perihelion 2016-Mar-15 at 1.00 AU]
252P will be making a very close approach to Earth on March 21 at 0.036 AU from the Earth (13.9 lunar distances). This is the closest predicted approach by a comet to Earth until 2109. Now some of you may be wondering why you are hearing about this now, well there is a catch… Comet 252P is a runt of a comet showing very little activity. Even at its closest it may not get much brighter than 10-11th magnitude. This is similar to what happened with 209P/LINEAR’s close approach a few years ago. Anyway, 252P may make an interesting visual target for large aperture observers and CCD target for any most apertures though it will be deep in the southern sky for much of March including the week of closest approach. I have been able to observe it with a 0.5-m telescope and CCD at magnitude 18.7 and 18.3 on January 11 and 18, respectively. This month the comet is an evening object in Lepus (Feb 1-21) and Columba (21-29) as its distance to the Sun falls from 1.16 to 1.02 AU and 0.28 to 0.13 AU for Earth.
Morning Comets
C/2014 S2 (PANSTARRS) [Perihelion on 2015-Dec-09 at 2.10 AU from the Sun]
Kind of a forgotten comet, few expected it to get bright enough for small telescopes and few seem to be observing it compared to much brighter US10 and X1. C/2014 S2 (PANSTARRS) passed perihelion on December 9th at 2.10 AU from the Sun. Even with the distant perihelion, it is now bright enough to be seen in binoculars and small telescopes under dark skies. As has been the case for the past few months, S2 is a northern circumpolar object moving through Draco (Feb 1-19) and Ursa Minor (19-29) at declinations between +65 and +71 degrees. It is observable all night long for northern observers though it is much better placed in the morning. The comet is slowly moving away from the Sun (2.19 to 2.31 AU) and a tad closer to Earth (1.86 to 1.83 AU) so its brightness should stay between magnitude 9 and 10 this month.
New Discoveries
Since the last Comet Section News posting, the recovery of one comet and discovery of ten have been reported.
P/2007 VA85 (LINEAR) was first observed back in 2007 when it was reported as and designated as a comet. H. Sato of Tokyo, Japan, first called attention to its cometary appearance on images taken on 2015 November 18 UT with an iTelescopes.net 0.51-m telescope located at Siding Spring, Australia. VA85 is on an orbit with a 8.7 year period and perihelion distance of 1.12 AU. The comet should get up to 14th magnitude in mid-February.
C/2015 VL62 has a rather convoluted discovery story. Pan-STARRS reported the discovery of a comet on images taken on January 23. They also found pre-discovery images from December 16. The 19th magnitude comet was then linked by the Minor Planet Center to two recently designated asteroids. 2015 VL62 was found at the Mount Lemmon 1.5-m by the Catalina Sky Survey on November 2 and 3. 2015 YY6 was found by Bill Yeung with a 0.7-m f/3 telescope near Mayhill, NM on December 18 and 19. Currently unnamed, the comet was designated after its first asteroid designation, C/2015 VL62. It is ~6 AU from the Sun now and many months out from its late August 2017 perihelion at 2.7 AU. The comet will probably not get very bright at perihelion due to its large perihelion and dynamically new orbit but it will be well observed by CCD observers at ~13-14th magnitude.
C/2016 A1 (PANSTARRS) is the first comet discovery of the year. Found with the Pan-STARR1 1.8-m telescope on the Hawaiian island of Maui, A1 was a faint 18th magnitude when found on January 1 UT. Its orbit is still rather uncertain but provisional predictions point towards a perihelion in late 2017 at 5.3 AU. If this orbit is correct, the comet should brighten a little to 16th magnitude at perihelion.
P/2016 A2 (Christensen) was found by Eric Christensen of the Catalina Sky Survey while using the Mount Lemmon 1.5-m reflector on January 2 UT. A2 is a short-period comet on an orbit with a 10 year period and 3.5 AU perihelion. With perihelion occurring last June, A2 is unlikely to get brighter than its current 19th magnitude.
P/2016 A3 (PANSTARRS) is also a short-period comet. It was 20th magnitude when discovered on January 4 UT with the Pan-STARRS1 1.8-m telescope. It is on a 21 year period orbit with perihelion out at 4.8 AU. It is unlikely to get any brighter.
333P/2016 A4 (NEAT) is a recovery of P/2001 F1 (NEAT) by two observing teams. K. Sarneczky of the Konkoly Observatory and S. Kurti of Nove Zamky, Slovakia, detected the comet on images taken by P. Szekely of the University of Szeged, Hungary, with the 0.60-m Schmidt telescope at the Piszkesteto Station of Konkoly Observatory on Jan. 7.9 UT. E. Schwab of Egelsbach, Germany, also recovered the comet on Jan. 10.1 UT by P. Ruiz with a 1.0-m f/4.4 reflector at the European Space Agency’s Optical Ground Station, Tenerife. 333P is a short-period comet on a 16 year orbit with perihelion at 4.2 AU. It was ~18th magnitude at recovery and not likely to get much brighter.
C/2016 A5 (PANSTARRS) is a long-period comet found by the Pan-STARRS1 telescope on January 9 UT at 20th magnitude. It will get no brighter as it is already well passed its June 2015 perihelion at 2.8 AU.
C/2016 A6 (PANSTARRS) is the 4th PANSTARRS find of the year. A6 was first seen on January 13 UT at 20th magnitude. Like most distant CCD discoveries, it was discovered near peak brightness. It preliminary orbit suggests a long-period comet with a perihelion at 2.4 AU last November.
P/2016 A7 (PANSTARRS) was discovered on January 14 UT at 20th magnitude. With an orbit that closely resembles that of a Phocaea family asteroid, A7 is another example of a Main Belt Comet or Activated Asteroid. Whether its cometary appearance is due to volatile outgassing or a recent impact is still not known. It only takes 3.8 years to orbit the Sun. Perihelion will occur in April at 2.0 AU.
C/2016 A8 (LINEAR) is a dynamically old comet found with the 3.5-m SST telescope by the LINEAR survey on January 14. It was 19-20th magnitude at discovery. At that time is was located 3.2 AU from the Sun. Perihelion will occur on August 30, 2016 when it will be 1.89 AU from the Sun and 1.05 AU from Earth and as bright as 14th magnitude. With an orbital period of ~220 years, A8 has been around the Sun quite a few times already. Such objects have a tendency to brighten faster than usual so perhaps A8 will be a few magnitudes brighter this summer.
C/2016 B1 (NEOWISE) was found by the NEOWISE spacecraft on January 17 UT at 19th magnitude. It may brighten another magnitude as it approaches its perihelion this September at 4.3 AU.
2016 BA14 is an asteroid on a comet-like orbit. While objects like these are discovered quite often and many may just be traditional asteroids on superficially cometary orbits, 2016 BA14 is one to keep an eye on because it will pass rather close to Earth. Even if it stays inactive it will brighten to 13th magnitude around the time of close approach on March 23 at 0.024 AU from Earth. This is also only a week past perihelion at 1.01 AU from the Sun.
As always, the Comet Section is happy to receive all comet observations, whether images, drawings or magnitude estimates.
- Carl Hergenrother (ALPO Comet Section Coordinator)
