Comets « Comet Section

ALPO COMET SECTION NEWS – APRIL 2016

2016-April-4

The two brightest (observable) comets in March were both surprises. The continued brightness of C/2014 S2 (PANSTARRS) may not be a surprise anymore, but I know I’m always happy to see this comet month after month considering it was not expected to get very bright. Then there’s the case of 252P/LINEAR. Making one of the closest approaches to Earth of the modern era, it was expected to be an exciting CCD target. While that was still true, the comet brightened more than expected and was even a naked eye object for a lucky few.

Evening Comets

C/2014 S2 (PANSTARRS) [Perihelion on 2015-Dec-09 at 2.10 AU from the Sun]

As mentioned above, C/2014 S2 has outperformed expectations. It has held steady near its peak brightness of magnitude 9.0 to 9.5 since November. I was able to easily observe it in 30×125 binoculars at magnitude 9.4 last night (April 3 UT). The comet will be easy to find this month as it slowly crosses the bowl of the Big Dipper from north to south. Its location also makes it a circumpolar object for most northern hemisphere observers. The comet starts the month 2.48 AU from the Sun and 1.95 AU from Earth and ends the month at distances of 2.67 and 2.30 AU from the Sun and Earth. If its current brightness behavior holds, the comet will start to fade this month from between ~9.4 to ~9.7.

The image below from Bob Lunsford gives a good indication of the appearance of C/2014 S2 in small telescopes.

C/2013 US10 (Catalina) [Perihelion on 2015-Nov-15 at 0.82 AU from the Sun]

Comet Catalina is rapidly moving away from the Sun and Earth and is no longer an easy object for small telescopes. In fact, the Comet Section has not received a positive report for this comet since the end of February. I tried to observe it a few times in March with 30×125s and was not successful. Observations submitted to the COBS (Comet Observation Database) site show the comet to still be between 10th and 11th magnitude. Located in Perseus, not too far from the star Capella, US10 is still a good target for large aperture visual observers and CCD imagers. This month it continues to move away from the Sun (2.38 to 2.75 AU) and Earth (2.63 to 3.41 AU).

Morning Comets

252P/LINEAR [Perihelion 2016-Mar-15 at 1.00 AU]

Comet 252P/LINEAR was not forecast to get brighter than ~10th magnitude even though it was making the 6th closest observed comet approach to Earth. Observers down south (close approach occurred at very far south declinations) reported numerous naked eye observations to the COBS site for a few days leading up to its March 21 flyby at 0.036 AU. The brightest estimates put the comet at magnitude 3.8. More naked eye sightings would have been possible if not for a near Full Moon washing out the view.

Luis Mansilla and Willian Souza both reside in the southern hemisphere observers and contributed observations of 252P to the Comet Section. Northern observers started looking for the comet as it rapidly cleared the southern horizon starting on March 24 though the first positive northern Section observation didn’t occur till the 26th due to the bright Moon. The comet was a barely visible ghost with the bright Moon interfering. Now that the comet can be observed in a Moon-less sky, it is large (~1/2 deg) and easily seen in 10×50s. Reports from Salvador Aguirre and Carl Hergenrother have placed the comet between magnitude 5.5 and 6.5 over the past week.

252P should fade this month as it moves away from the Sun (1.02 to 1.19 AU) and Earth (0.07 to 0.24 AU). The rate of its fading is uncertain as the comet does not seem to be intrinsically fading even though it is past perihelion. The comet is easily observable in the morning sky from both hemispheres as it moves northward through Serpens (1-2) and Ophiuchus (2-30).

If you are wondering about 252P’s possible sibling, P/2016 BA14 (PANSTARRS) passed even closer to Earth but never showed much activity other than a short dust tail. Even at its brightest it was relatively faint at magnitude 12.5-13.0. The close approach did allow NASA JPL’s Goldstone radar to image the roughly 1 km in diameter nucleus of BA14 as seen below.

These radar images of comet P/2016 BA14 were taken on March 22, 2016, by scientists using an antenna of NASA's Deep Space Network at Goldstone, California. At the time, the comet was about 2.2 million miles (3.6 million kilometers) from Earth. Credits: NASA/JPL-Caltech/GSSR.

C/2013 X1 (PANSTARRS) [Perihelion on 2016-Apr-20 at 1.31 AU]

C/2013 X1 (PANSTARRS) has been too close to the Sun to be observed from Earth since February. This will change in April as PANSTARRS slowly moves away from the glare of the Sun in the morning sky. On April 1st, X1 is located at a small elongation of 17°. Elongation grows to 30° by April 14, 40° by April 23 and 49° by May 1. The comet spends all of April in Pisces as it moves from 1.35 AU from the Sun on the 1st, passes through perihelion at 1.31 AU on the 20th and only recedes to a heliocentric distance of 1.32 AU at April’s end. Its geocentric distance rapidly decreases from 2.27 AU to 1.74 AU over the course of the month. This distance will continue to drop to a minimum of 0.64 AU in late June. Since it hasn’t been seen in nearly two months, its brightness in April is uncertain but should be between 7th and 8th magnitude.

New Discoveries

Since the last Comet Section News posting, only three comet discoveries were reported.

C/2016 E2 (Kowalski) was found on March 15 with the 0.68-m Catalina Schmidt by Rich Kowalski. The comet is a long-period comet that assed perihelion February 6 UT at 1.08 AU. It passed within 0.30 AU of Earth two days after discovery. The comet is intrinsically faint and only got as bright as 17th magnitude.

C/2016 E1 (PANSTARRS) is a high perihelion distance object (8.0 AU) that doesn’t pass perihelion till August of 2017. It was found by Pan-STARRS on March 3 at 20th magnitude. The large perihelion distance will keep it from getting much brighter.

C/2015 B4 (Lemmon-PANSTARRS) was seen by the Pan-STARRS project as a comet in images taken on 2016 March 13. The Minor Planet Center’s Gareth Williams than identified many other observations of the comet taken over the past year or more with the first on 2015 January 16 by the Mount Lemmon Survey. Now named Comet Lemmon-PANSTARRS, C/2015 B4 is on a 25 year orbit and passed perihelion back in February of 2015 at 3.75 AU from the Sun. It never got brighter than ~20th magnitude.

As always, the Comet Section is happy to receive all comet observations, whether images, drawings or magnitude estimates.
- Carl Hergenrother (ALPO Comet Section Coordinator)

UPDATE ON TWO CLOSE-APPROACHING COMETS

2016-Mar-23

Just a quick update on comets 252P/LINEAR and P/2016 BA14 (PANSTARRS). Both comets have now passed the point of closest approach to Earth. 252P passed within 0.036 AU of Earth on 21st while P/2016 BA14 passed within 0.024 AU on the 22nd.

P/2016 BA14 peaked at 12th magnitude and still shows only the most tenuous hint of cometary activity. For the most part, this comet was an imaging target and it looks like it’ll never get bright enough for easy visual observation. 252P, on the other hand, has definitely surprised. Based on its observed apparitions in 2000 and 2010, the prediction was for 252P to only get up to 10th magnitude. The caveat in that prediction is that it was never observed at perihelion so we really had no idea how bright it could get. The most recent magnitude estimates reported to the Comet Section from Luis Mansilla and Willian Souza showed the comet brightening from magnitude 7.0 on the 16th to 4.9 on the 20th. The observation from the 20th also reported a coma diameter of 1°.

P/2016 BA14 is a northern hemisphere object and will remain so. For the rest of the month it will travel through the constellations of Ursa Major (23-24), Canes Venectica (24-25), Ursa Major (25-26), Bootes (26-31), Hercules (31) as it fades from magnitude ~13 to ~15 at the end of the month.

252P took a far southern route and was invisible to northern observers. That is now changing as it moves northward through Ara (21-24), Scorpius (24-26), Ophiuchus (26-30) and Serpens (30-31). Though its recent brightness suggests a naked eye object, a near Full Moon and large coma will probably conspire to keep it a binocular or small telescope object. Since this is the first time 252P has been observed around perihelion, it may rapidly fade. The only way to know is to get out and observe it.

Frank Melillo submitted this video of P/2016 BA14 racing across the sky on March 22 over a span on 10 minutes.

As always, the Comet Section solicits all types of comet observations.

- Carl Hergenrother (ALPO Comet Section Coordinator)

ALPO COMET SECTION NEWS – MARCH 2016

2016-March-7

March’s big story is the very close approach of not one, but two comets at the end of the month. Comets 252P/LINEAR and P/2016 BA14 (PANSTARRS) are both passing within 0.04 AU of Earth on March 21/22. 252P is already bright enough for visual observation. P/2016 BA14, on the other hand, may remain faint.

This will probably be your last month to visually observe C/2013 US10 (Catalina) as it is rapidly fading as it moves away from the Earth and Sun. Our other bright comet, C/2013 X1 (PANSTARRS), is too close to the Sun to be seen. It will reappear next month and be a nice binocular object for the next few months.

The Close Approachers

252P/LINEAR [Perihelion 2016-Mar-15 at 1.00 AU] and P/2016 BA14 (PANSTARRS) [Perihelion 2016-Mar-15 at 1.01 AU]

Both of these comets will be making the closest predicted return by a comet to Earth until 2109. 252P will be the first to flyby by making a very close approach to Earth on March 21 (13:15 UT) at 0.036 AU from the Earth (13.9 lunar distances). P/2016 BA14 will follow even more closely on the next day (March 22 at 15:31 UT) at 0.024 AU or 9.2 lunar distances. If it seems quite a coincidence that the 3rd and 6th closest observed comet approaches (at least for objects we have good orbits for) are occurring within 27 hours of each, it is possible that these two comets are actually related to each other. Their orbits are similar though a difference in inclination of ~9° does call their relationship into question.

Both comets are expected to be low activity objects. 252P is the more active of the two and has already been reported as bright as 9-10th magnitude. It may brighten a little more by the time of close approach though it will not be an easy object as it appears to be a large, diffuse, low surface brightness object. It also helps if you live down south as 252P will be making a very rapid visit to the southern sky passing though the following constellations: Columba (Mar 1-9), Pictor (9-15), Dorado (15-16), Mensa (16-18), Octans (18-20), Apus (20-21), Ara (21-24), Scorpius (24-26), Ophiuchus (26-30) and Serpens (30-31).

P/2016 BA14 (PANSTARRS) will be taking a different path across the sky as it moves through Columba (Mar 1-11), Canis Major (11-18), Monoceros (18-20), Cancer (20-22), Leo Minor (22-23), Ursa Major (23-24), Canes Venectica (24-25), Ursa Major (25-26), Bootes (26-31), Hercules (31). Originally reported as an inactive comet, a faint tail was seen on images taken on Feb. 10 and 13 with the 4.3-m Discovery Channel Telescope in northern Arizona by University of Maryland astronomers. Unlike 252P, P/2016 BA14 is not brightening very fast and remains around 18th magnitude in images I obtained with a Sierra Stars Observatory Network telescope in Australia on Mar. 2 UT. It is questionable if the comet will ever get bright enough for visual observation. Both objects will be nice targets for CCD observers.

Efrain Morales Rivera observed both comets a few nights ago. His image show the contrast in their appearances and brightness.

Evening Comets

C/2013 US10 (Catalina) [Perihelion on 2015-Nov-15 at 0.82 AU from the Sun]

Comet Catalina is rapidly fading. After spends some months around 6th magnitude, it has now faded to 9-10th magnitude and will continue to rapidly fade as it moves away from the Sun (1.98 to 2.38 AU) and Earth (1.69 to 2.63 AU). It is a evening object located in the northern sky as it moves through Camelopardalis (Mar 1-16) and Perseus (16-31).

C/2013 X1 (PANSTARRS) [Perihelion on 2016-Apr-20 at 1.31 AU]

C/2013 X1 is too close to the Sun to be observed from Earth as its elongation drops from 18° to a minimum of 7° on March 17 then back up to 17°. Luckily we might be able to catch some glimpses of it for a few days around March 17 when it will pass within the FOV of the C3 coronagraph on the SOHO spacecraft. Next month, X1 will again be visible to Earth-based observers as it moves out of the Sun’s glare. With perihelion on April 20 at 1.31 AU from the Sun and a close approach to Earth of 0.64 AU in late June, X1 may be as bright as 6-7th magnitude from April through July.

Morning Comets

C/2014 S2 (PANSTARRS) [Perihelion on 2015-Dec-09 at 2.10 AU from the Sun]

The little comet that could, C/2014 S2 is still being reported as bright as 9th magnitude. C/2014 S2 (PANSTARRS) passed perihelion on December 9th at 2.10 AU from the Sun. As has been the case for the past few months, S2 is a northern circumpolar object moving through Ursa Minor (Mar 1-17), Draco (17-29) and Ursa Major (29-31) at declinations between +71 and +64 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 (2.31 to 2.48 AU) and Earth (1.83 to 1.95 AU) so its brightness should fade from 9-10th magnitude to 10-11th magnitude..

New Discoveries

Since the last Comet Section News posting, two comet recoveries and two discoveries were reported.

335P/Gibbs = P/2016 A9 = P/2008 Y2 was recovered by E. Schwab of Egelsbach, Germany. He used a 1-meter reflector at the ESA’s Optical Ground Station on Tenerife island. The comet was 20th magnitude when recovered on January 10. It passed perihelion last November at 1.63 AU. Alex Gibbs discovered this comet during the course of the Catalina Sky Survey on the last day of 2008. Comet 335P is a short period with a period of 6.8 years.

336P/McNaught = P/2016 B2 = P/2006 G1 is the second return of a comet discovered by Rob McNaught in April 2006. Gareth Williams of the Minor Planet Center recovered 336P on images taken by the PanSTARRS survey on January 18 and February 14. The comet was 21st magnitude. The comet has a 11.3 year period and will reach perihelion on 2017 February 3 at 2.78 AU. It should reach a peak brightness of 18th magnitude.

C/2016 C1 (PANSTARRS) was found with the Pan-STARR1 telescope on Maui on February 12 at 19th magnitude. The long-period comet passed perihelion in January at a very distant 8.5 AU. It is likely to have gotten as bright as it will get.

C/2016 C2 (NEOWISE) was first seen on February 8 by the NEOWISE IR survey spacecraft at 19th magnitude. It has a period of 500-600 years and will reach perihelion at 1.56 AU on April 19 of this year. NEOWISE should brighten to 17th magnitude.

As always, the Comet Section is happy to receive all comet observations, whether images, drawings or magnitude estimates.
- Carl Hergenrother (ALPO Comet Section Coordinator)

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.

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)

ALPO COMET SECTION NEWS FOR JANUARY 2016

2016-January-02

Happy New Year and Welcome to 2016!

Before looking at the comets visible this month, let’s recap 2015. The Comet Section received 252 positive magnitude estimates of 19 different comets. A total of 555 images and drawings of 67 different comets were also submitted this past year though this number includes observations taken prior to 2015 but only recently archived with the ALPO. The brightest observed comet was C/2014 Q2 (Lovejoy) at magnitude 3.7 with C/2015 G2 (MASTER) and C/2013 US10 (Catalina) tied for second place at magnitude ~6.0-6.1.

Evening Comets

10P/Tempel 2 [Perihelion on 2015-Nov-14 at 1.42 AU from the Sun]

Comet 10P/Tempel 2 has a long observational history stretching back to its discovery from Milan, Italy in 1873. The current apparition marks its 23rd observed return since then. This month 10P is an evening object moving through Capricornus (Jan 1-6) and Aquarius (6-31). It will be a tough object as its elongation decreases from 41° to 34°. Now ~2 months past perihelion and moving away from the Sun (1.50 to 1.64 AU) and Earth (2.10 to 2.36 AU), 10P should see its brightness fade from its current 10-11th magnitude.

C/2014 S2 (PANSTARRS) [Perihelion on 2015-Dec-09 at 2.10 AU from the Sun]

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 located in Draco at declinations between +61 and +66 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 (2.12 to 2.19 AU) and a little closer to Earth (1.92 to 1.86AU) so its brightness should stay around magnitude 9.0 this month.

C/2013 X1 (PANSTARRS) [Perihelion on 2016-Apr-20 at 1.31 AU]

While C/2013 US10 (Catalina) is the brightest comet this January, C/2013 X1 (PANSTARRS) will probably hold that title within the next month or two. X1 is inbound to a April 20th perihelion at 1.31 AU from the Sun. The comet will get even brighter as it comes within 0.64 AU of Earth in late June. Already visible in small telescopes and binoculars at ~9th magnitude, X1 should be a good comet to observe between now and late February when it gets too close to the Sun. We should pick it up again in April as it brightens to ~6-7th magnitude in June (though it may be too far south for some for a few weeks around close approach).

This month, X1 is an evening object with an elongation dropping from 90° to 50° as it moves through Pegasus. Its distance from the Sun falls from 2.06 to 1.75 AU while its distance from Earth increases from 1.80 to 2.22 AU.

Morning Comets

C/2013 US10 (Catalina) [Perihelion on 2015-Nov-15 at 0.82 AU from the Sun]

Comet Catalina is a nice 6th magnitude double tailed comet (see the image below by Manos Kardasis). At the start of January, it is located a few degrees north of Arcturus. If you are out watching the Quadrantids, remember to take a look for this comet. While US10 doesn’t rise till around 1am at the start of the month, its northern motion makes it circumpolar for most northern observers by mid-month as it moves through Bootes (Jan 1-8), Canes Venatici (8-14), Ursa Major (14-20), Draco (20-22), Ursa Minor (22-23), Draco (23-25), Camelopardalis (25-28), Draco (28-30) and Camelopardalis (30-31).

Comet Catalina starts the month at 1.18 AU from the Sun and recedes to 1.59 AU. It is still rather far from Earth though this distance will greatly shrink from 0.89 AU to 0.72 to 0.89 AU.

New Discoveries

Since the last Comet Section News posting, nine comets were discovered. While it may seem that PANSTARRS is finding most of the comets these days, December did see a nice variety in discovery teams.

P/2015 X3 (PANSTARRS) was first seen on December 1 with the 1.8-m Pan-STARRS 1 telescope on Haleakala. It was 20th magnitude at discovery and will probably not get much brighter. A short period comet with a 11.3 year period, X3 passed perihelion back in August at 2.82 AU.

C/2015 X4 (Elenin) was found by Leonid Elenin of Russia with the 0.4-m ISON-NM astrograph in Mayhill, NM, USA on December 3. Discovered at 18th magnitude, it was reported as bright as 16th magnitude in the weeks after discovery. The latest Elenin is a Halley-type comet with a period of 77 years and perihelion of 3.40 AU on November 3, 2015.

C/2015 XY1 (Lemmon) was first seen as an asteroidal object by J. A. Johnson on December 4 with the Mount Lemmon 1.5-m located north of Tucson, AZ, USA. Follow-up observations with the same telescope found the object to be cometary. XY1 is a long-period comet with a perihelion distance of 8.1 AU (T = 2018 March). Currently around 19th magnitude it will only brighten by another magnitude or so by 2018.

C/2015 X5 (PANSTARRS) was surprisingly found over 2 years after perihelion. Perhaps this shouldn’t be too surprising since X5 has spent the past few years at far southern declinations where there are no active large aperture professional asteroid surveys (though there are many smaller aperture surveys trying to fill the gap). First seen on December 6th with the 1.8-m Pan-STARRS1 telescope, the comet was ~20th magnitude. It may have been as bright as 16th magnitude when it was near perihelion in September 2013 at 3.9 AU.

P/2015 X6 (PANSTARRS) has a typical Main Belt asteroid orbit and is probably another example of a Main Belt Comet, also referred to as an Activated Asteroid. Whether its ‘cometary’ activity is due to a recent impact or true ice-driven cometary activity is still TBD. The object was first seen on December 7 with the same telescope that found the other PANSTARRS objects. Perihelion will be on 2016 March 10 at 2.30 AU. It has an orbital period of 4.5 years and aphelion of only 3.2 AU. It was a faint 21st magnitude at discovery and probably won’t get brighter.

C/2015 X7 (ATLAS) is the first comet discovery by the Asteroid Terrestrial-impact Last Alert System (ATLAS) team. ATLAS is a new survey to detect small asteroids prior to impact. This project will undoubtably uncover many more new comets during the course of its search for small asteroid impactors. X7 was 17th magnitude when found with the ATLAS 0.5-m f/2 telescope at Haleakala, Maui, Hawaii, USA on December 12. Perihelion will be on 2016 July 28 at 3.67 AU from the Sun when it should still be around 17th magnitude.

C/2015 X8 (NEOWISE) is a space-based find with the NEOWISE (formally just WISE) satellite in low Earth orbit. X8 is another Halley-type object with a period of 77 years and perihelion distance of 1.19 AU (T = 2015 October 22). Visual observers have seen the comet as bright as 11-12th magnitude. It will quickly fade as it recedes from the Sun.

C/2015 Y1 (LINEAR) was found with the 3.5-m Space Surveillance Telescope operated by the LINEAR team on Atom Peak at White Sands, NM, USA. Found on December 16 at 18th magnitude, Y1 is a long-period comet that will brighten a little before passing perihelion on 2016 May 15 at 2.5 AU.

C/2015 YG1 (NEOWISE) is another NEOWISE find and yet another Halley-type object. It has a period of 78 years and passed perihelion in late September at 2.07 AU at ~16th magnitude.

As always, the Comet Section is happy to receive all comet observations, whether images, drawings or magnitude estimates.
- Carl Hergenrother (ALPO Comet Section Coordinator)

ALPO COMET SECTION NEWS FOR DECEMBER 2015

2015-December-06

Evening Comets

10P/Tempel 2 [Perihelion on 2015-Nov-14 at 1.42 AU from the Sun]

Ernst Wilhelm Liebrecht Tempel, a German astronomer, discovered comet 10P/Tempel 2 in 1873 from Milan, Italy. 2015 marks the comet’s 27th return since discovery and 23rd observed return. The comet has been observed at every return since 1946. This time around, 10P is an evening object moving through Sagittarius (Dec 1-5) and Capricornus (6-31). Recent observations suggest a brightness between magnitude 9.5 and 10.0.

C/2014 S2 (PANSTARRS) [Perihelion on 2015-Dec-09 at 2.10 AU from the Sun]

C/2014 S2 (PANSTARRS) is at perihelion on the 9th at 2.10 AU from the Sun. This comet has been an easy object in my 30×125 binoculars with a strongly condensed coma and a hint of a tail. Located in Draco at declinations between +65 and +61 degrees, it is a circumpolar object for northern observers and observable throughout the night. With little change in its distance from the Sun (2.10 to 2.12 AU) and Earth (1.91 to 1.92 AU), its brightness should stay around magnitude 9.0 for the remainder of December.

C/2013 X1 (PANSTARRS) [Perihelion on 2016-Apr-20 at 1.31 AU]

Yet another Comet PANSTARRS, C/2013 X1 is fainter than S2 but may become much brighter as it approaches its April perihelion. Recent visual reports place it between magnitude 10.0 to 10.5. Its rate of apparent brightening may slow down a bit this month as a decrease in distance to the Sun (2.38 to 2.06 AU) is countered by an increase in distance to Earth (1.53 to 1.80 AU). Still, the comet should be between magnitude 9.5 and 10.0 this month. The comet is nicely placed in the evening as it moves through through Andromeda (Dec 1-9), Pisces (9-13), Andromeda again (13-29) and Pegasus (29-31).

Unlike C/2013 US10 (Catalina) (more on it below), C/2013 X1 may be a dynamically old comet. Its orbit suggests that possibility as does its brightening trend since discovery. Unlike dynamically new comets which brighten in fits and starts and can even fade though still moving closer to the Sun, X1 has held a steady and healthy rate of brightening for the past two years. If this continues then X1 may become a nice binocular comet at ~6th magnitude between the time of perihelion in late April (1.31 AU from the Sun) and closest approach to Earth in late June (0.64 AU from Earth).

CCD images show a very asymmetrical coma with a northward pointing fan curving into an eastward pointing tail.

Morning Comets

C/2013 US10 (Catalina) [Perihelion on 2015-Nov-15 at 0.82 AU from the Sun]

Comet Catalina currently holds the title of brightest comet in the sky.

The brightest comet in the sky is currently behind the Sun and invisible. This state of affairs will change by the end of the month as C/2013 US10 (Catalina) races north through Virgo (Dec 1-24) and Bootes (24-31). Although its distance from the Sun has been decreasing, the comet has stayed steady at around magnitude 6.5 for the past 3 months. Intrinsically this means the comet has actually faded. What this means for the future is unknown though it is possible the comet experienced an outburst in late July or August and has spent the last few months fading back to “normal”.

Comet Catalina starts the month at 0.87 AU from the Sun and recedes to 1.18 AU. It is still rather far from Earth though this distance will greatly shrink from 1.53 AU to 0.89 AU. Elongation will also improve from 32 to 78 degrees. It you are outside on the morning of the 7th to watch the nice conjunction of Venus and the Moon, take a peak at the comet which is only ~4-5 degrees or so to the left (northeast) of Venus.

CCD images show a two tailed comet. Its gas tail has shown intricate, rapidly changing structure while its dust tail appears to be lagging the comet along its orbit. The position of the dust tail is suggestive of larger particles having been released some months prior to perihelion.

New Discoveries

C/2015 T5 (Sheppard-Tholen) is a Halley-type comet with a 149 year period and rather distant perihelion of 9.3 AU (Feb. 5, 2016), Sheppard-Tholen is very faint and should not get much brighter than its current magnitude 21.6. Befitting such a faint comet, the Subaru 8.2-m telescope in Hawaii was used to find it.

C/2015 V1 (PANSTARRS) is a long period comet coming to perihelion at 4.3 AU in December 2017. Discovered on Nov. 2 at ~19-20th magnitude, it will only brighten up to ~15-16th magnitude near perihelion.

C/2015 V2 (Johnson) is an object to keep on your radar as it may become a nice binocular object in 2017. First seen by J. A. Johnson of the Catalina Sky Survey at 17th magnitude, Comet Johnson will reach perihelion on 2017 June 14 at 1.64 AU and pass within 0.83 AU of Earth within a few weeks of perihelion. A peak brightness of 6-7th magnitude is possible.

C/2015 V3 (PANSTARRS) was first detected by the Pan-STARRS survey on Nov. 2 at 21st magnitude. Within weeks of discovery, the comet experienced an apparent outburst to 18th magnitude. V3 is a long period comet that passed perihelion on Nov. 22 at 4.2 AU from the Sun. It shouldn’t get much brighter but all bets are off if more outbursts occur.

C/2015 V4 (PANSTARRS) is on a ~80 year period orbit. Perihelion is in July of 2016 at 5.6 AU. The comet is unlikely to get much brighter than its current brightness of ~19th magnitude.

C/2015 W1 (Gibbs) is a Catalina Sky Survey find by Alex Gibbs with the 0.68-m Catalina Schmidt telescope. W1 was 18-19th magnitude at discovery on Nov. 18. Perihelion is on May 16 at 2.2 AU. It may brighten another magnitude or two in the coming months.

P/2015 W2 (Catalina) is another Catalina find, this time by J. A. Johnson and G. J. Leonard on Nov. 21. W2 is a short-period comet with a period of ~20 years and passed perihelion at 2.6 AU last September. It is unlikely to get brighter than its current 18-19th magnitude.

P/2015 X1 (PANSTARRS) was first recognized as a comet by Pan-STARRS on images taken on Dec. 1 at 20th magnitude. Pre-discovery observations by Pan-STARRS were found going back to August when the comet was 21-22nd magnitude. On a 6.9-year orbit, this Jupiter-family comet passed perihelion back in October at 2.1 AU.

C/2015 X2 (Catalina) is a runt of a long-period comet. Only a 2-3 weeks from perihelion (Dec. 19 at 1.9 AU) at discovery (Dec. 2), X2 is very faint at 19th magnitude. It is unlikely to get much brighter.

As always, the Comet Section is happy to receive all comet observations, whether images, drawings or magnitude estimates.
- Carl Hergenrother (ALPO Comet Section Coordinator)

ALPO COMET SECTION NEWS FOR NOVEMBER 2015

2015-November-03

Evening Comets

C/2014 S2 (PANSTARRS) [Perihelion on 2015-Dec-09 at 2.10 AU from the Sun]

October’s brightest comet, for those of us at northern latitudes, was C/2014 S2 (PANSTARRS). At around magnitude 9.5-10.0, it is located in the northern circumpolar sky as it moves from Ursa Minor (Nov 1-15) into Draco (15-30). The comet is still inbound as it gets closer to the Sun (2.15 to 2.10 AU) and Earth (1.87 to 1.91 AU) and may brighten another 0.5 magnitudes as it reaches its early December perihelion.

22P/Kopff [Perihelion on 2015-Oct-25 at 1.56 AU from the Sun]

Comet Kopff’s 2015 perihelion passage is its 16th since its discovery in 1919. This month Kopff is around 10th magnitude as it moves through Ophiuchus (Nov 1-6) and Sagittarius (6-30). It will move slowly away from the Sun (1.56 to 1.61 AU) and Earth (2.12 to 2.29 AU) as it is over a month past its late October perihelion.

C/2014 Q2 (Lovejoy) [Perihelion on 2015-Jan-30 at 1.29 AU from the Sun]

A year ago comet C/2014 Q2 (Lovejoy) was rapidly brightening on its way to being a naked eye object. Amazingly Lovejoy is still visible in reasonably sized backyard telescopes even at large distances from the Sun (3.78 to 4.09 AU) and Earth (4.28 to 4.72 AU). It can be seen at ~11-12th magnitude as it moves through Hercules (Nov 1-30).

Morning Comets

C/2013 US10 (Catalina) [Perihelion on 2015-Nov-15 at 0.82 AU from the Sun]

The brightest comet in the sky is currently behind the Sun and invisible. This state of affairs will change by the end of the month as C/2013 US10 (Catalina) races north through Hydra (Nov 1), Libra (1-15) and Virgo (15-30). Although its distance from the Sun has been decreasing, the comet has stayed steady at around magnitude 6.5 for the past 3 months. Intrinsically this means the comet has actually faded. What this means for the future is unknown though it is possible the comet experienced an outburst in late July or August and has spent the last few months fading back to “normal”.

Comet Catalina starts the month at 0.87 AU from the Sun, reaches perihelion at 0.82 AU from the Sun on the 15th and ends the month again at 0.87 AU. It is still rather far from Earth though this distance will shrink from 1.82 AU to 1.51 AU. Visibility will be difficult till the end of the month when it rapidly gains elevation in the morning sky. Observers south of the equator will still have a difficult time observing Comet Catalina.

C/2013 X1 (PANSTARRS) [Perihelion on 2016-Apr-20 at 1.31 AU]

C/2013 X1 may be brightening fast. Recent visual reports place it between magnitude 10.5 to 11.5. This month the comet should brighten another half to full magnitude as it cruises through Perseus (Nov 1-20) and Andromeda (20-30) and moves closer to the Sun (2.70 to 2.37 AU) and Earth (1.85 to 1.53AU). Discovered back in December of 2013, X1 is still over 5 months from perihelion and 7 months from its closest approach to Earth (0.64 AU in late June). This comet should be a nice small telescope object as it stays brighter than magnitude 10 for much of 2016. Peak brightness may be around magnitude 6 or 7 next June.

67P/Churyumov-Gerasimenko [Perihelion on 2015-Aug-13 at 1.24 AU]

The Rosetta mission target is now well past perihelion and will move from 1.57 to 1.79 AU from the Sun while moving slightly closer to Earth (1.80 to 1.74 AU). It is still around magnitude 12 as it moves through Leo.

New Discoveries

C/2015 T2 (PANSTARRS) is faint and far away. Perihelion for this long-period comet will not occur until the Spring of 2017 at 7.1 AU. It will not get much brighter than its current 20th magnitude.

P/2015 T3 (PANSTARRS) is a short-period comet with a period of 9.0 years. Perihelion occurred last December at 2.12 AU. Currently at 20th magnitude it may have been only a magnitude brighter a year ago.

C/2015 T4 (PANSTARRS) is yet another Pan-STARRS find from the past month. T4 is a long-period comet but appears to be dynamically old suggesting it may get a little brighter than predicted say 14th-15th magnitude versus 16th magnitude. Perihelion happens next June at 2.30 AU.

P/2015 TO19 (Lemmon-PANSTARRS) was found by both D. C. Fuls of the Mount Lemmon Survey and Pan-STARRS. It has probably already hit its peak at 19th magnitude. A short-period comet, TO19 is on a 9.75 year orbit with perihelion next March at 2.93 AU.

C/2015 TQ209 (LINEAR)… they’re baaack! For about 10 years starting in the late 90’s, it seemed like every other bright comet was a comet LINEAR. Back then they used a number of 1.0-m telescopes. Now LINEAR is back and using the 3.5-m Space Surveillance Telescope (SST). Their first find with the SST is 19th magnitude but may reach 13th magnitude around its August 2016 perihelion (1.41 AU). Its orbit has a low inclination so there is a chance it is actually a short-period comet with a larger perihelion distance.

As always, the Comet Section is happy to receive all comet observations, whether images, drawings or magnitude estimates.
- Carl Hergenrother (ALPO Comet Section Coordinator)

ALPO COMET SECTION NEWS FOR OCTOBER 2015

2015-October-03

C/2013 US10 (Catalina) still holds the top spot as brightest comet in the sky, albeit only for southern observers. Even they will lose sight of the comet by mid-month as its elongation decreases. The next brightest comet is 10th magnitude C/2014 S2 (PANSTARRS) which is located in the northern circumpolar sky. While pickings are slim for small aperture observers, large aperture owners have a number of faint 10th-12th magnitude comets to visually observe or image. They include C/2013 X1 (PANSTARRS), a faint ~11th magnitude object that will be a nice small telescope/binocular object for much of 2016.

Evening Comets

C/2013 US10 (Catalina) [Perihelion on 2015-Nov-15 at 0.82 AU from the Sun]

Comet C/2013 US10 (Catalina) continues as the brightest comet in the sky though its visibility is limited to the southern hemisphere. October will bring more of the same but even southern observers will lose sight of the comet as its elongation decreases from 47° to 11°. ALPO contributor Willian Souza of Brazil continues to find C/2013 US10 around magnitude 6.5. Last month, it may have experienced a small outburst which would explain why it brightened so quickly to magnitude 6.5. Since then the comet hasn’t shown much change in brightness even though it is still approaching perihelion.

This month Catalina moves through Centaurus (Oct 1-19) and Hydra (19-31) as its heliocentric distance decreases from 1.17 to 0.87 AU and geocentric distance increases from 1.61 AU to 1.82 AU. The comet should be a faint naked eye object from November through January when it will be well placed for northern comet watchers. It is already a nice photogenic object as seen in the below image from Minos Kardasis.

C/2014 S2 (PANSTARRS) [Perihelion on 2015-Dec-09 at 2.10 AU from the Sun]

A bit of a surprise comet, C/2014 S2 is around magnitude 10.0-10.5. It is located in the northern circumpolar sky as it moves from Cepheus (Oct 1-4) into Ursa Minor (4-31) and gets closer to the Sun (2.25 to 2.15 AU) and Earth (1.92 to 1.87 AU). This PANSTARRS comet may still have another magnitude of brightening before it peaks late this year.

22P/Kopff [Perihelion on 2015-Oct-25 at 1.56 AU from the Sun]

Comet Kopff’s 2015 perihelion passage is its 16th since its discovery in 1919. In fact it has never been missed at an apparition since discovery. This month Kopff is around 10th magnitude as it moves through Libra (Oct 1-5), Scorpius (5-12) and Ophiuchus (12-31). It reaches perihelion on October 25 at 1.56 AU. Though its heliocentric distance doesn’t change much this month, it will slowly move away from Earth (1.99 to 2.12 AU).

C/2014 Q1 (PANSTARRS) [Perihelion on 2015-Jul-06 at 0.31 AU from the Sun]

Back in July, C/2014 Q1 peaked at around 4th magnitude. Unfortunately it was never an easy comet to see visually from the northern hemisphere. The latest magnitude estimates from mid-August placed the comet at magnitude 12 and steadily fading. This month PANSTARRS should fade from 12th to 14th magnitude as it moves away from both Sun (1.89 to 2.37 AU) and Earth (2.39 to 3.02 AU) against the stars of Centaurus (Oct 1-2), Lupus (2-26) and Norma (26-31). Due to its far southern location in the sky, views of the comet are limited to southern observers.

C/2014 Q2 (Lovejoy) [Perihelion on 2015-Jan-30 at 1.29 AU from the Sun]

The other bright ‘Q’ comet of the past year is C/2014 Q2 (Lovejoy). Much fainter than at its 4th magnitude peak, Lovejoy is still holding on at ~11-12th magnitude as it moves through Corona Borealis (Oct 1-9) and Hercules (9-31). Its distance from the Sun (3.46 to 3.78 AU) and Earth (3.76 to 4.28 AU) continues to increase as it retreats into the outer solar system.

Morning Comets

C/2013 X1 (PANSTARRS) [Perihelion on 2016-Apr-20 at 1.31 AU]

I was able to observe C/2013 X1 visually on September 25 at magnitude 12.8. This month the comet will brighten another half to full magnitude as it cruises through Auriga (Oct 1-22) and Perseus (22-31) and moves closer to the Sun (3.02 to 2.70 AU) and Earth (2.65 to 1.85 AU). Discovered back in December of 2013, X1 is still over 6 months from perihelion and 8 months from its closest approach to Earth (0.64 AU in late June). This comet should be a nice small telescope object as it stays brighter than magnitude 10 for much of 2016. Peak brightness may be around magnitude 6 or 7 next June.

67P/Churyumov-Gerasimenko [Perihelion on 2015-Aug-13 at 1.24 AU]

Comet 67P/Churyumov-Gerasimenko is the target of ESA’s Rosetta mission. Earth-based observers can watch 67P as it moves through Leo this month. The comet is now past perihelion and will move from 1.38 to 1.57 AU from the Sun while holding steady at around 1.80 AU from Earth. I was able to observe 67P visually on September 25 at magnitude 11.5.

141P/Machholz [Perihelion on 2015-Aug-25 at 0.76 AU from the Sun]

141P is one of many discoveries by former ALPO Comet Section Coordinator Don Machholz. A short-period comet with a 5.25 year period, 141P is making its 5th perihelion passage since its 1994 discovery. During 1994 the comet was actually a multiple comet with 5 components (component D was even observed to split during the apparition). This year the primary (A) has been seen as well as another component provisionally designated component H but may, in fact, be a reappearance of components B, C or D. Hopefully additional astrometry will confirm H as one of the older components or a brand new one.

The comet was predicted to get as bright as 10th magnitude this year but had been severely lagging that prediction. Component A is now around 12th magnitude with component H a few magnitudes fainter. Comet Machholz is already past perihelion and will be moving away from the Sun (0.98 to 1.31 AU) and Earth (1.38 to 1.58 AU) this month. Though the comet(s) should fade rapidly, split comets are notorious for exhibiting erratic behavior so close attention is warranted. It is a morning object as it moves through Leo (Oct 1-8) and Sextens (8-31).

New Discoveries

P/2015 Q2 (Pimental) is a short period comet with a 19 year period. Perihelion occurred on September 15 at 1.82 AU for this 17th magnitude comet. It was discovered by Eduardo Pimental on August 24 as part of the SONEAR survey with a 0.45-m f/2.9 reflector located in Oliveira, Brazil. P/2015 Q2 will not get any brighter this apparition.

P/2015 R1 (PANSTARRS) is a short-period comet found by the Pan-STARRS survey on September 8 at 18th magnitude. It has a 14 year period and passed perihelion back on June 25 at 2.17 AU. It will also not get much brighter.

P/2015 R2 (PANSTARRS) was found by Pan-STARRS a night after they found P/2015 R1. Perihelion was on June 8 at 2.47 AU. The comet is on a 9.5 year orbit and will not get brighter than its current 20th magnitude.

C/2015 R3 (PANSTARRS) is yet another Pan-STARRS find. It was found on September 12 at 20th magnitude. R3 is well passed its 2014 February 12 perihelion which occurred at 5.24 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)

ALPO COMET SECTION NEWS FOR SEPTEMBER 2015

2015-September-01

Southern hemisphere observers will continue to hold a monopoly on viewing September’s brightest comet, C/2013 US10 (Catalina). At 6th magnitude, it is the only comet expected to get brighter than ~10th magnitude this month. Due to the small number of bright comets, this report will dig deeper and highlight some fainter, but interesting comets.

Evening Comets

C/2013 US10 (Catalina) [Perihelion on 2015-Nov-15 at 0.82 AU from the Sun]

The brightest comet in the sky, C/2013 US10 (Catalina) is now magnitude 6.5 and should brighten by another half magnitude or more by the end of the month. It will only be visible to southern observers as it moves through Norma (Sep 1), Circinus (1-6), Lupus (6-23) and Centaurus (23-30). Catalina sees its heliocentric distance decrease from 1.56 to 1.17 AU but its geocentric distance increase from 1.21 AU to 1.61 AU during September. If the comet continues to brighten at its current rate it may be a faint naked eye object from November through January. By late November, it will once again be visible to northern comet watchers.

C/2014 Q1 (PANSTARRS) [Perihelion on 2015-Jul-06 at 0.31 AU from the Sun]

Back in July, C/2014 Q1 peaked at around 4th magnitude. Unfortunately it was never an easy comet to see visually from the northern hemisphere. The latest magnitude estimates from mid-August placed the comet at magnitude 9.5 and steadily fading. This month PANSTARRS should fade from 10th to 12th magnitude as it moves away from both Sun (1.38 to 1.89 AU) and Earth (1.76 to 2.39 AU) against the stars of Centaurus. Due to its far southern location in the sky, views of the comet are still limited to southern observers.

C/2014 Q2 (Lovejoy) [Perihelion on 2015-Jan-30 at 1.29 AU from the Sun]

The other bright ‘Q’ comet of the past year is C/2014 Q2 (Lovejoy). Much fainter than at its 4th magnitude peak, Lovejoy will be around 11th magnitude this month as it slowly moves south through Boötes (Sep 1-6), Hercules (6-12) and Corona Borealis (12-30). Its distance from the Sun (3.15 to 3.46 AU) and Earth (3.27 to 3.76 AU) continues to increase as it retreats into the outer solar system.

22P/Kopff [Perihelion on 2015-Oct-25 at 1.56 AU from the Sun]

Comet Kopff’s 2015 perihelion passage is its 16th since its discovery in 1919. In fact it has never been missed at an apparition since discovery. This month Kopff should reach 10th-11th magnitude as it moves through Libra and approaches the Sun (1.65 to 1.58 AU) while moving away from Earth (1.89 to 1.99 AU).

Morning Comets

67P/Churyumov-Gerasimenko [Perihelion on 2015-Aug-13 at 1.24 AU]

A little fainter than most comets in this report at 12th magnitude, 67P is definitely a comet of interest. As the target of ESA’s Rosetta mission, we know more about this comet than any other. Rosetta’s ring-side seat has witnessed an outbursting jet and an ejected boulder just in the past few weeks. Ground-based observers can watch 67P from a safe distance of 1.8 AU as the comet glides through Gemini (Sep 1-5), Cancer (5-29) and Leo (29-30).

141P/Machholz [Perihelion on 2015-Aug-25 at 0.76 AU from the Sun]

141P is one of many discoveries by former ALPO Comet Section Coordinator Don Machholz. A short-period comet with a 5.25 year period, 141P is making its 5th perihelion passage since its 1994 discovery. During 1994 the comet was actually a multiple comet with 5 components (component D was even observed to split during the apparition). The two brightest components (the primary A and secondary D) made a visually striking double comet in small telescopes. Components A and D were re-observed in 1999 but by 2005 only component A was visible. Due to poor observing conditions, no components were seen in 2010. This year the primary (A) has been seen as well as another component (no orbit has been published yet for this object so whether it is component D or a new component is still TBD).

141P’s split personalities didn’t begin in 1994. Research by Zdenek Sekanina found that components B through E split from the primary during the period of 1987 to 1991. Other research suggests 141P (or its progenitor) may have been breaking up for some time as it is related to both the Alpha Capricornid meteor shower and comet 169P/NEAT (a weakly active comet on an orbit with a 4.2 year period).

The comet was predicted to get as bright as 10th magnitude this year but had been severely lagging that prediction. Over the past few weeks the component A rapidly brightened and is now around 11th magnitude. The new (currently undesignated) component is a few magnitudes fainter at ~14. Comet Machholz is already past perihelion and will be moving away from the Sun (0.77 to 0.98 AU) and Earth (1.06 to 1.38 AU) this month. Though the comet(s) should fade, split comets are notorious for exhibiting erratic behavior so close attention is warranted. It is a morning object as it moves through Gemini (Sep 1-3), Cancer (4-26) and Leo (26-30).

New Discoveries

C/2015 O1 (PANSTARRS) was mentioned in last month’s report. Its initial orbit suggested it might become a nice bright object though there were suspicions that its orbit was incorrect. As it turns out, those suspicions were correct as C/2015 O1 will reach perihelion at a rather distant 3.73 AU in early 2018. The comet is currently located at over 8 AU from the Sun. It may become as bright as 13th magnitude in 2018.

C/2015 P3 (SWAN) is the fourth comet discovered in data taken with the SWAN instrument on the SOHO spacecraft. Michael Mattiazzo of Australia detected the comet in images taken on July 28. Similar to the other 2015 SWAN finds, C/2015 P3 has a perihelion distance of less than 1 AU (0.72 AU on July 27). The brightest magnitude estimates placed it around 10th magnitude. The comet is rapidly fading and is already fainter than 12th magnitude.

P/2015 P4 (PANSTARRS) was discovered on August 14 at 21st magnitude. It is a short period comet with a period of 15 years. Perihelion will occur next year on January 19 at 2.5 AU from the Sun. The comet will remain faint and may not get brighter than 19th-20th magnitude.

P/2015 Q1 (Scotti) was found by former ALPO Comet Section Assistant Coordinator Jim Scotti on August 18 with the Spacewatch 0.9-m on Kitt Peak. Discovered at 19th magnitude the intrinsically faint comet will not get much brighter as it passes perihelion on September 7 at 1.73 AU. It is also a short period comet with a 5.4 year period.

As always, the Comet Section is happy to receive all comet observations, whether images, drawings or magnitude estimates.
- Carl Hergenrother (ALPO Comet Section Coordinator)

ALPO COMET SECTION NEWS FOR AUGUST 2015

2015-August-02

The southern hemisphere holds a monopoly on bright comets this August. Both C/2013 US10 (Catalina) and C/2014 Q1 (PANSTARRS) will be invisible for northern mid-latitude observers while well placed for those down south. Last month, Comet C/2014 Q1 (PANSTARRS) vied for the title of brightest comet of 2015 as it brightened to around 4th magnitude.

Evening Comets

C/2014 Q1 (PANSTARRS) [Perihelion on 2015-Jul-06 at 0.31 AU from the Sun]

After peaking around magnitude 4.0 near its early July perihelion, the comet has rapidly faded as expected. ALPO contributor Willian Souza of Brazil has been following C/2014 Q1 over the past few weeks and reported it fading from magnitude 5.2 on the 17th to 6.5 on the 27th. August will see it continue to fade from around magnitude 7.0 to 9.5 as it moves away from both the Sun (0.77 to 1.38 AU) and Earth (1.25 to 1.76 AU). The comet spends the month moving through the following constellations: Sextans (Aug 1-3), Hydra (3-4), Crater (4-17), Hydra (17-29) and Centaurus (29-31).

The comet is currently rather photogenic. In addition to the Willian Souza image shown below, see the spectacular image on Spaceweather.com taken by master comet imager Michael Jager (observing from Namibia).

Recent ALPO images and observations of C/2014 Q1 (PANSTARRS) can be found in the Comet Section Image Gallery and Magnitude Database. Finder charts can be found at the ALPO Comet Finder Chart page.

C/2014 Q2 (Lovejoy) [Perihelion on 2015-Jan-30 at 1.29 AU from the Sun]

Comet Lovejoy is still with us at it slowly fades. The brightest northern comet, Lovejoy is still around 10th magnitude though over 6 months past its January perihelion. It is located in the far northern sky as it slowly moves south through Draco (Aug 1-6), Boötes (6-7), Draco (7-11), Boötes (11-31). Its distance from the Sun (2.82 to 3.15 AU) and Earth (2.84 to 3.27 AU) continues to increase resulting in continued slow fading. Below image taken by ALPO member John Sabia on July 25.

Recent ALPO images and observations of C/2014 Q2 (Lovejoy) can be found in the Comet Section Image Gallery and Magnitude Database. Finder charts can be found at the ALPO Comet Finder Chart page.

C/2013 US10 (Catalina) [Perihelion on 2015-Nov-15 at 0.82 AU from the Sun]

The second brightest comet in the sky is still inbound towards a mid-November perihelion at 0.82 AU from the Sun. C/2013 US10 (Catalina) will only be visible to southern observers this month as it moves through Tucana (Aug 1-3), Indus (3-7), Pavo (7-17), Apus (17-21), Triangulum Australe (21-31) and Norma (31). Willian Souza has also been following this comet and reported it at magnitude 8.2 on the 27th.
Catalina sees its heliocentric distance decrease from 1.97 to 1.56 AU. Its geocentric distance starts at 1.16 AU, reaches a minimum of 1.09 AU at mid-month and increase to 1.21 AU by month’s end. It should brighten from its current brightness of magnitude 8.0 to 8.5 to around magnitude 7.0 to 7.5 by September 1. If the comet continues to brighten at its current rate it may reach 5th to 6th magnitude in November to January. By late November, it will once again be visible to northern comet watchers.

Recent ALPO images and observations of C/2013 US10 (Catalina) can be found in the Comet Section Image Gallery and Magnitude Database. Finder charts can be found at the ALPO Comet Finder Chart page.

New Discoveries

P/2015 M2 (PANSTARRS) is technically a Centaur comet as its perihelion distance of 5.93 AU is outside of Jupiter’s orbit while its aphelion distance of 8.48 AU is well within the orbit of Neptune and is actually much closer to Saturn. It’s orbital period is ~19 years. P/2015 M2 was discovered on June 28 at 19th magnitude and should not get much brighter.

C/2015 M3 (PANSTARRS) is on a ~1500 year orbit with a late August 2015 perihelion distance of 3.55 AU. Found on June 29 at 19th magnitude, M3 is another comet that will not get much brighter.

C/2015 O1 (PANSTARRS) could be a nice comet in late 2016-early 2017. Could. be. The original orbit has it reaching perihelion in early February 2017 at 1.04 AU from the Sun and ~1 AU from Earth. The problem is the orbit is highly uncertain and there is a possibility the comet’s perihelion will be at a much larger distance so we’ll have to wait for a revised orbit. C/2015 O1 was found at 18th magnitude on July 19.

As always, the Comet Section is happy to receive all comet observations, whether images, drawings or magnitude estimates.
- Carl Hergenrother (ALPO Comet Section Coordinator)

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