Comet Section

ALPO COMET NEWS FOR FEB 2017

2017-February-11

Sorry for the late update. The big story this month is the extreme close approach of comet 45P/Honda-Mrkos-Pajdusakova to Earth on February 11 at 0.08 au. A few other comets, including frequent visitor 2P/Encke, will be visible in small telescopes.

Evening Comets

2P/Encke [Perihelion on 2017 March 10 at 0.34 au]

Comet Encke is making its 63rd observed apparition since it was first seen in 1786. Encke will become a visual object this February as it brightens from 10th to 7th magnitude in Pisces. Its elongation drops from 46 to 24 degrees. as its distance from the Sun decreases from 0.91 to 0.42 au and geocentric distance decreases from 1.27 to 0.81 au.

41P/Tuttle-Giacobini-Kresak [Perihelion on 2017 Apr 12 at 1.05 au]

This comet was discovered on three separate occasions: in 1858 by Horace Tuttle, 1907 by Michel Giacobini and 1951 by Lubor Kresak. 2017 marks 41P’s 11th observed apparition. Nominally 41P should become 6th magnitude by late March. I say nominally because this comet is prone to outbursts. In 1973, T-G-K experienced two 10-magnitude outbursts. Smaller outbursts also occurred in 1995 and 2001. If T-G-K were to experience an outburst during this return it could become a naked eye object. Perihelion is on April 13 at 1.05 au and close approach to Earth is on March 27 at 0.14 au. During February, T-G-K will brighten from 13th to 9th magnitude as it moves from 1.40 to 1.19 au from the Sun and 0.42 to 0.22 au from Earth. It will be located in Leo near opposition all month.

Morning Comets

45P/Honda-Mrkos-Pajdusakova [Perihelion on 2016 December 31 at 0.53 au]

Comet 45P/H-M-P brightened up to 6th magnitude before it was lost in the glow of dusk in early January. At that time is was highly condensed and displayed a hint of bluish-green in my 30×125 binoculars. The comet is currently racing higher into the eastern sky at dawn. Salvador Aguirre spotted it on Feb 10 at magnitude 6.5. A night earlier, I spotted it in 10×50s as a large diffuse glow over 1/2 degree across. Its appearance was very similar to that of 252P/LINEAR which made a close approach last year. Unfortunately, the best for this comet is probably over as large, diffuse, low surface brightness objects usually don’t fare well against a bright Moon. The comet will still be visible to small telescope and binocular observers throughout the month but will be fading (probably no brighter than 9th magnitude by the end of the month). This month, its heliocentric distance increases from 0.83 to 1.23 au while its geocentric distance initially decreases from 0.16 au to February 11’s close approach at 0.08 au and back to 0.25 au as it moves through Aquila (Feb 1-7), Hercules (7-11), Corona Borealis (11-13), Bootes (13-15), Canes Venatici (15-20), Coma Berenices (20-21), Ursa Major (21-25) and Leo (25-28). Elongation climbs from a still too low 17 degrees on the 1st to 45 deg on the 7th, 90 deg on the 12th, and a close to opposition 159 deg at the end of the month.

C/2015 ER61 (PANSTARRS) [Perihelion on 2017 May 9 at 1.04 au]

C/2015 ER61 (PANSTARRS) will reach perihelion on May 9 at 1.04 au from the Sun but never gets closer to Earth than 1.18 au. As a result, ER61 may only brighten to 8th magnitude at is brightest in May. For northern observers, it will be located low in the morning sky. It will be better placed for southern observers. This month its distance from the Sun increases from 1.86 au to 1.54 au. Its geocentric distance grows from 2.08 to 1.58 au as it travels through Ophiuchus (Feb 1-23) and Sagittarius (23-28). It is currently 10-11th magnitude and may brighten to 9th magnitude by the end of the month.

C/2015 V2 (Johnson) [Perihelion on 2017 June 12 at 1.64 au]

Comet Johnson is inbound with a perihelion of 1.64 au and close approach to Earth at 0.81 au this summer. It is well placed for northern observers through perihelion. Now is a good time for CCD imagers and large aperture visual observers to watch C/Johnson brighten from its current 10th magnitude to a peak of 6-7th magnitude. This month, it is a morning object in Bootes (Feb 1-9) and Hercules (9-28) at an elongation that increases from 96 to 101 degrees. It starts the month 2.36 au from the Sun and 2.05 au from Earth. At the end of the month, these values decrease to 2.13 au from the Sun and 1.70 au from Earth.

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 NEWS FOR JAN 2017

2017-January-1

Happy New Year! 2017 promises to be a busy year for comet observers as no less than 7 comets are predicted to become brighter than 10th magnitude: 2P/Encke, 41P/Tuttle-Giacobini-Kresak, 45P/Honda-Mrkos-Pajdusakova, 96P/Machholz, C/2015 ER61 (PANSTARRS), C/2015 V2 (Johnson), C/2016 U1 (NEOWISE). Of course there are the comets yet to be discovered as well as the dozens of fainter comets within reach of CCDs.

The last month of 2016 was a productive one for the ALPO Comet Section. CCD imagers continued to monitor a number of comets, both bright and faint, while visual observations were reported for the month’s two brightest comets. While January will see a slow down in visual observations as we lose our two bright comets to the glare of the Sun, the action will pick up again in February.

During December, CCD observers Denis Buczynski, Carl Hergenrother, Efrain Rivera Morales, Richard Owens and John D. Sabia contributed images of the following comets: 2P/Encke, 41P/Tuttle-Giacobini-Kresak, 43P/Wolf-Harrington, 45P/Honda-Mrkos-Pajdusakova, 56P/Slaughter-Burnham, 74P/Smirnova-Cherynkh, 93P/Lovas, 174P/Echeclus, 226P/Pigott-LINEAR-Kowalski, 315P/LONEOS, C/2010 U3 (Boattini), C/2013 US10 (Catalina), C/2015 VL62 (Lemmon-Yeung-PANSTARRS), C/2015 V2 (Johnson), C/2015 X7 (ATLAS), C/2016 N4 (MASTER), and C/2016 T2 (Matheny). Visual comet magnitude estimates were submitted by Carl Hergenrother, John D. Sabia and Willian Souza for 45P/Honda-Mrkos-Pajdusakova and C/2016 U1 (NEOWISE).

The effort to digitize the archives of the Comet Section and place them online continues. Currently the Section Gallery contains over 2300 images and drawings of 215 different comets.

Evening Comets

45P/Honda-Mrkos-Pajdusakova [Perihelion on 2016 December 31 at 0.53 au]

Comet 45P/H-M-P has been brightening as predicted with visual observers placing it at magnitude 7.2-7.3 at the end of December. After passing perihelion on New Year’s Eve, its orbit will carry 45P between the Sun and Earth. As a result, we will lose sight of the comet during the first week of January. Not to worry, the best is yet to come as 45P will become an easily observable object (up to 6th-7th magnitude) in the morning sky starting in early February as it passes within 0.08 au of Earth. This month, its heliocentric distance increases from 0.53 to 0.84 au while its geocentric distance crashes from 0.68 to 0.16 au as it moves through Capricornus (Jan 1-15) and Aquarius (15-31) in the evening sky.

The image below was taken by Richard Owens on December 27.

2P/Encke [Perihelion on 2017 March 10 at 0.34 au]

Comet Encke is back again and making its 63rd observed apparition since it was first seen in 1786. Encke will become a visual object this February as it brightens to 7th magnitude. This month, the comet rapidly brightens from ~13th to 10th magnitude. The Section asks that CCD imagers monitor Encke as it approaches perihelion. Note, that Encke’s appearance depends on what filter is used. The comet may still appear asteroidal in the red while a large gas coma is already detectable in the blue. This month Encke is an evening object moving through Pisces as its elongation drops from 97 to 68 degrees. Its distance from the Sun decreases from 1.39 to 0.91 au while its geocentric distance decreases from 1.42 to 1.26 au.

Morning Comets

C/2015 V2 (Johnson) [Perihelion on 2017 June 12 at 1.64 au]

Jess Johnson of the Catalina Sky Survey discovered this long period comet on November 3, 2015 with the 0.68-m Catalina Schmidt. The comet is inbound with a perihelion of 1.64 au and close approach to Earth at 0.81 au this summer. It is well placed for northern observers through perihelion. Now is a good time for CCD imagers and large aperture visual observers to watch C/Johnson brighten from its current 12th magnitude to a peak of 6-7th magnitude. This month, it is a morning object in Bootes at an elongation that increases from 89 to 96 degrees. It starts the month 2.64 au from the Sun and 2.47 au from Earth. At the end of the month, these values decrease to 2.36 au from the Sun and 2.05 au from Earth.

C/2016 U1 (NEOWISE) [Perihelion on 2017 January 14 at 0.32 au]

Comet NEOWISE is a surprise comet. Only 19th magnitude when discovered in late October, the comet rapidly brightened and was approaching magnitude 8.0 at the end of December. The comet will be lost to most observers during the first week of the month as it moves too close to the Sun. At that time it may be as bright as 7th magnitude. Southern hemisphere observers may be able to pick the comet up again in February though it may already be too faint for visual observation. Northern observers won’t get another shot at NEOWISE till August when it may be too faint even for CCD imagers. This month its distance from the Sun drops from 0.49 au to a perihelion on January 14 of 0.32 au. The distance grows to 0.61 au at the end of the month. Its geocentric distance grows from 0.89 to 1.48 au. Though mostly unseen, C/NEOWISE will travel through Ophiuchus (Jan 1-7), Serpens (7-10), Scutum (10-11), Sagittarius (11-26) and Microscopium (26-31).

New Discoveries

Only one comet discovery was reported in the past month. Yet another interesting asteroid on a very cometary orbit was announced.

C/2016 X1 (Lemmon) is a long-period comet with a large perihelion distance of 7.6 au. It was found by G. J. Leonard with the Mount Lemmon 1.5-m reflector. Even though perihelion will not occur till May of 2019, the comet shouldn’t get much brighter than its current 20th magnitude.

Last month we reported on 2016 VY17, an apparently asteroidal object on a Halley-type orbit. A similar object has been recently announced. 2016 VZ18 is on a long-period comet orbit with a period of ~2700 years. Perihelion will occur in early March at 0.91 au. in early April it will approach to within 0.53 au of Earth. If it remains inactive, VZ18 will not get any brighter than magnitude 20. If it does ‘turn on’, it could become much brighter. CCD observers are encouraged to monitor this object and send your images and photometry to the Comet Section. Who knows, maybe you will be the first to notice VZ18 as an active comet.

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 NEWS FOR DECEMBER 2016

2016-December-2

With 2016 drawing to a close, it is a good time to look back on the comet year that was. The brightest comets of 2016 were 252P/LINEAR (mag 4), C/2013 US10 (Catalina) (mag 6), C/2013 X1 (PANSTARRS) (mag 6), and C/2014 S2 (PANSTARRS) (mag 8). Before the year ends, two more comets may work their way onto the list. Though comet 45P/Honda-Mrkos-Pajdusakova will be a much easier target to observe in February, observers with a good southwestern horizon may peak a glimpse of it rapidly brightening this month. C/2016 U1 (NEOWISE) is surrounded by some uncertainty, but recent observations suggest this comet will become bright enough for visual observers this month as well.

During November, CCD observers Denis Buczynski and Gianluca Masi contributed images of 56P/Slaughter-Burnham, 74P/Smirnova-Cherynkh, 117P/Helin-Roman-Alu, 128P/Shoemaker-Holt, 226P/Pigott-LINEAR-Kowalski, C/2010 U3 (Boattini), C/2013 US10 (Catalina), C/2013 V4 (Catalina), P/2015 TP200 (LINEAR), C/2015 V1 (PANSTARRS), C/2015 V2 (Johnson), C/2015 VL62 (Lemmon-Yeung-PANSTARRS), and C/2016 T3 (PANSTARRS). Also, visual observer Per-Jonny Bremseth has been contributing his extensive collection of excellent comet drawings going back to C/1969 Y1 (Bennett).

Evening Comets

45P/Honda-Mrkos-Pajdusakova [Perihelion on 2016 December 31 at 0.53 AU]

Comet 45P/Honda-Mrkos-Pajdusakova… Honestly, that is the kind of name a comet should have. When 45P was discovered back in 1948, comets were routinely named after three discoverers. That practice has fallen out of favor. In fact, no new discoveries in 2016 even share two names. The two tri-named comets mentioned above (Lemmon-Yeung-PANSTARRS and Pigott-LINEAR-Kowalski) represent the only comets named after three discoverers since 2003.

Comet 45P/Honda-Mrkos-Pajdusakova is out best bet to break our recent bright comet drought. 2016 will be the 12th observed apparition for 45P as it rounds the Sun once every ~5.3 years. It is one of a class of Jupiter-family comets that have small perihelion distances but are only active (and bright) when close to the Sun. As December begins, the comet is around 11th to 12th magnitude. It will be around 9th magnitude by the middle of the month and 7th magnitude by the end. Observing this comet will still be difficult as it is usually very diffuse (as is typical for a gaseous comet) and located low in the southwestern sky during the evening as it traverses Sagittarius (Dec 1-14) and Capricornus (14-31). For observers at 40N, the comet will only be located at an elevation of ~10 degrees at the end of astronomical twilight all month long. After solar conjunction in early February, 45P will rapidly climb into the morning sky as a 7th-8th magnitude object as it passes within 0.08 AU of Earth. This month, its heliocentric and geocentric distances decrease from 0.81 to 0.53 AU and 1.27 to 0.68 AU, respectively.

2P/Encke [Perihelion on 2017 March 10 at 0.34 AU]

Comet Encke is back again and making its 63rd observed apparition since it was first seen in 1786. Encke will be a visual object this February as it brightens to 7th magnitude. This month, the comet is only of interest to CCD imagers as it rapidly brightens from ~17th to 14th magnitude. The Section asks that CCD imagers start following Encke now so we can watch it brighten and develop as it travels towards perihelion. An interesting imaging activity is to monitor the development of its coma in different colors. In the past, the gas coma has developed faster than the dust coma so Encke appeared to have a large coma in a blue filter while still appearing inactive in a red filter. This month Encke is an evening object moving through Pisces at an elongation that drops from 97 to 68 degrees. It distance from the Sun decreases from 1.79 to 1.39 AU while its geocentric distance increases slightly from 1.37 to 1.42 AU.

Morning Comets

C/2015 V2 (Johnson) [Perihelion on 2017 June 12 at 1.64 AU]

Jess Johnson of the Catalina Sky Survey discovered this long period comet on November 3, 2015 with the 0.68-m Catalina Schmidt. The comet is inbound with a perihelion of 1.64 AU and close approach to Earth at 0.81 AU this summer. It is well placed for northern observers through perihelion. Now is a good time for CCD imagers and large aperture visual observers to watch C/Johnson brighten from its current 12th magnitude to a peak of 6-7th magnitude. This month, it is a morning object in Canes Venatici (Dec 1-19) and Bootes (19-31) at an elongation that increases from 79 to 89 degrees. It starts the month 2.93 AU from the Sun and 2.96 AU from Earth. At the end of the month, these values decrease to 2.64 AU from the Sun and 2.47 AU from Earth.

C/2016 U1 (NEOWISE) [Perihelion on 2017 January 14 at 0.32 AU]

The discovery of this comet was announced in the previous ALPO Comet News. Initially reported as very faint by most CCD astrometrists, recent CCD and visual observations show it to be much brighter than originally thought. At the end of November, C/NEOWISE is around 11-12th magnitude. With perihelion on January 14 at a very small distance of 0.32 AU, the comet may brighten to 7-8th magnitude before getting too close to the Sun in early January. This month, C/NEOWISE travels through Canes Venatici (Dec 1-3), Bootes (3-12), Corona Borealis (12-16), Serpens (16-17), Hercules (17-24), and Ophiuchus (24-31) in the morning sky as its heliocentric distance drops from 1.13 to 0.49 AU and its geocentric distance from 0.77 to a minimum of 0.71 on Dec 12/13 before growing to 0.71 AU at the end of the month.

New Discoveries

Amazingly since the last Comet Section News posting, no comet discoveries have been officially reported. That said, an asteroid on a very cometary orbit was announced.

2016 VY17 is on Halley-type orbit with a retrograde inclination of 148 deg and period of 37.5 years. Perihelion will occur in early July at 1.66 au and closest approach to Earth follows in mid-August at 0.89 au. If the object is truly inactive it will brighten to 17th magnitude in mid-August. It is very possible that VY17 will become active and if so, it could become bright enough for visual observation. CCD observers are encouraged to monitor this object and send your images and photometry to the Comet Section. Who knows, maybe you will be the first to notice VY17 as an active comet.

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 NEWS FOR NOVEMBER 2016

2016-November-7

We are still in the midst of a bright comet drought this month. While there have been no visual magnitude estimates submitted to the ALPO Comet Section since July, CCD observers have been busy imaging some of the fainter comets. During October, Richard Owens and Gianluca Masi contributed images of 2P/Encke, 53P/Van Biesbroeck, 93P/Lovas, 174P/Echeclus, C/2014 A4 (SONEAR), C/2016 A8 (LINEAR), and C/2016 M1 (PANSTARRS). Though no comets are expected to be brighter than magnitude 11-12 in November, there are some comets that will become bright during the coming months that would benefit from CCD imaging now as they brighten.

Evening Comets

45P/Honda-Mrkos-Pajdušáková [Perihelion on 2016 December 31 at 0.53 AU]

2016 will be the 12th observed apparition for Comet Honda-Mrkos-Pajdušáková as it rounds the Sun once every ~5.3 years. As November begins, there have been no reported observations of this comet. Historically, 45P brightens rapidly when close to the Sun and should be ~17th magnitude. The lack of observations may be its location very low in the evening sky as it traverses Sagittarius. CCD users imaging Venus and Mars can try to go a bit deeper for 45P as it should brighten to 12th magnitude by the end of the month. Visual observers will be able to observe 45P very low in the evening sky starting in December through early January as it brightens to 7th magnitude. After solar conjunction in early February, 45P will rapidly climb into the morning sky as a 7th-8th magnitude object as it passes within 0.08 AU of Earth. This month, its heliocentric and geocentric distances decrease from 1.23 to 0.81 AU and 1.57 to 1.27 AU, respectively.

2P/Encke [Perihelion on 2017 March 10 at 0.34 AU]

Comet Encke is back again. In fact, it never really ‘leaves’ in that it is visible even at aphelion if one can image down to ~20th magnitude. 2017 will mark Encke’s 63rd observed apparition since it was first seen in 1786. The high number of returns is due not only to Encke’s long observational history but also due to it having the shortest known cometary orbital period at 3.3 years. Encke will be a visual object this February as it brightens to 7th magnitude. This month, the comet is only of interest to CCD imagers as it will be ~17th magnitude. The Section asks that CCD imagers start following Encke now so we can watch it brighten and develop as it heads towards perihelion. An interesting imaging activity is to monitor the development of its coma in different colors. In the past, the gas coma has developed faster than the dust coma so Encke appeared to have a large coma in a blue filter while still appearing inactive in a red filter. This month Encke is an evening object moving through Pegasus (Nov 1-7) and Pisces (7-30) at an elongation that drops from 134 to 97 degrees. It distance from the Sun decreases from 2.12 to 1.79 AU while its geocentric distance increases slightly from 1.30 to 1.37 AU.

Morning Comets

C/2015 V2 (Johnson) [Perihelion on 2017 June 12 at 1.64 AU]

Jess Johnson of the Catalina Sky Survey discovered this long period comet on November 3, 2015 with the 0.68-m Catalina Schmidt. The comet is inbound to a perihelion of 1.64 AU and close approach to Earth of 0.81 AU this summer. It is well placed for northern observers through perihelion. As a result, now is a good time for CCD imagers and large aperture visual observers to watch C/Johnson brighten from its current 13th magnitude to a peak of 6-7th magnitude. This month, it is a morning object in Canes Venatici at an elongation that increases from 67 to 79 degrees. It starts the month 3.21 AU from the Sun and 3.47 AU from Earth. At the end of the month, these values decrease to 2.93 AU from the Sun and 2.96 AU from Earth.

C/2016 U1 (NEOWISE) [Perihelion on 2017 January 14 at 0.32 AU]

This will be an interesting comet to watch over the coming few months. With perihelion on January 14 at a very small distance of 0.32 AU, there are hopes that this comet could become bright. Dampening those hopes is the fact that the comet is currently 1.6 AU from the Sun and still only 20th magnitude. This suggests that C/NEOWISE is intrinsically very faint. While it may brighten significantly as it approaches perihelion, it may not become bright enough for visual observation. While currently out of range for most CCD imagers, I’ll send out a mid-month Comet Section news update if the comet does brighten enough to warrant additional attention. This month, C/NEOWISE travels through Ursa Major into Canes Venatici in the morning sky as its heliocentric distance drops from 1.67 to 1.13 AU and its geocentric distance from 1.32 to 0.77 AU.

New Discoveries

Since the last Comet Section News posting, a number of new comets were discovered in addition to the already mentioned C/2016 U1 (NEOWISE).

C/2016 T3 (PANSTARRS) is one of three dynamically old long period comets (meaning this is not their first trip through the inner Solar System) discovered since the last Comet Section news update. C/2016 T3 was found by the Pan-STARRS program at 20th magnitude. With perihelion occurring on September 8, 2017 at 2.67 AU from the Sun, it may brighten by a few magnitudes to ~17.

C/2016 T2 (Matheny) is also a dynamically old long period comet with a perihelion distance of 1.92 AU and inclination of 81 degrees. It was 18th magnitude when Rose Matheny of the Catalina Sky Survey used the 1.5-m Mount Lemmon reflector first saw it on October 10. Perihelion occurs this December 27 when the comet will peak at 17-18th magnitude.

C/2016 T1 (Matheny) was also found by Rose Matheny with the Catalina Sky Survey 1.5-m Mount Lemmon reflector. This comet was found 4 days before C/2016 T2. The two comets are Matheny’s only comet discoveries. Similar to C/2016 T2, C/2016 T1 is a dynamically old long period comet but with a perihelion distance of 2.30 AU, perihelion date of February 2, 2017, and inclination of 129 degrees. It was 18th magnitude at discovery and may brighten another magnitude.

P/2016 S1 (PANSTARRS) is a short period comet first seen by Pan-STARRS on September 21. It is on a 24 year period orbit with a 94 degree inclination and a March 16, 2017 perihelion at 2.41 AU from the Sun. The comet may brighten to 17th magnitude from its discovery brightness of 19th magnitude.

P/2016 SV (PANSTARRS) is another short period comet with a 6.9 year period. It reaches perihelion on September 11, 2016 at 2.22 AU from the Sun. It was 19th magnitude when discovered by Pan-STARRS on September 19. Pre-discovery observations by Pan-STARRS from June 20 and the Catalina Sky Survey from 2009 were identified after discovery. It is unlikely this comet will get much brighter than 19th magnitude.

P/2016 R4 (Gibbs) was found by Alex Gibbs of the Catalina Sky Survey with the Mount Lemmon 1.5-m reflector. P/2016 R4 was first seen on September 10 at 18th magnitude. It has a 12.3 year period and passed perihelion on July 16, 2016 at q = 2.80 AU.

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 NEWS FOR SEPTEMBER/OCTOBER 2016

2016-September-17

We are in the midst of a bright comet drought. August and the first half of September saw no comets brighter than ~10th magnitude and it looks like the rest of September and October will see the same unless there is a new bright discovery or outburst. Currently the next comet predicted to brighten above 10th magnitude will be short-period 45P/Honda-Mrkos-Pajdušáková in late December.

Just a bit fainter than 10th magnitude are a number of comets that are viable targets for large aperture visual observers and CCD imagers. Images of a few fainter comets have been submitted to the Comet Section, including 29P/Schwassmann-Wachmann, 53P/Van Biesbroeck, C/2016 A8 (LINEAR) by Charles Bell, Manos Kardasis and John Sabia. The table below is from the main Comet Section webpage and lists comets 12th magnitude or brighter.

New Discoveries

Since the last Comet Section News posting, a number of comets have been discovered. Most are faint though the most recent find comes with an interesting story.

C/2016 R3 (Borisov) – Gennady Borisov found this comet on September 11 with a 0.3-m f/1.5 Genon astrograph + CCD at the MARGO Observatory in the Crimea. It is his 6th comet discovery since 2013. While Gennady and other CCD observers reported the comet at 16th magnitude, experienced observer Alan Hale was able to observe it visually at 13th magnitude. Perihelion will occur on October 10 at 0.45 AU. Unfortunately, C/2016 R3’s elongation is ~30° and dropping fast in the morning sky. It is possible this comet will only be observable for another week since it will be too close to the Sun to be observed when bright.

Interestingly, the orbit of C/2016 R3 (Borisov) is very similar to that of C/1915 R1 (Mellish). The 1915 comet was discovered by John E. Mellish, purported early observer of craters on Mars and namesake of the Martian crater Mellish. It was one of five comets discovered by Mellish and his second of 1915. With perihelion in 1915 being on October 13, it had almost the exact same, and poor, observing circumstances as in 2016. So far orbit computers have not been able to positively link the 1915 and 2016 observations for orbit periods of ~100, 50, 25 and 20 years. There is no doubt that the 1915 and 2016 comets are related though they may be separate components of a splitting event. The faintness of the 2016 comet relative to the 1915 comet also suggests that the two may be different.

C/2016 R2 (PANSTARRS) – The Pan-STARRS survey found this 19th magnitude comet with their 1.8-m Pan-STARRS1 telescope in Hawaii on September 7. It is a long-period comet with an inclination of 58° and perihelion at 2.64 AU from the Sun in May of 2018. It could brighten to 13th magnitude in 2018.

C/2016 Q4 (Kowalski) – Richard Kowalski discovered this 18th magnitude comet on August 30 with the Mount Lemmon 1.5-m. It is a Centaur-type comet with an inclination of 7°, period of 69 years and perihelion in January of 2018 at 7.1 AU from the Sun. It could brighten by another magnitude between now and perihelion.

C/2016 Q2 (PANSTARRS) – Discovered on 2016 August 26 at 21st magnitude by Pan-STARRS. It is a long-period comet with an inclination of 63° and perihelion is not till 2020 January 3 at 3.43 AU from the Sun. It could brighten to 12-13th magnitude in 2019/2020.

C/2016 P4 (PANSTARRS) – Discovered on August 7 at 22nd magnitude by Pan-STARRS. It is a long-period comet with an inclination of 30° and perihelion on October 16 at 5.89 AU from the Sun. Magnitude 22 is as bright as this comet will get.

P/2016 P2 (PANSTARRS) – Discovered on August 8 at 21st magnitude by Pan-STARRS. It is a short-period comet with a period of 9.3 years. Perihelion was back in November of 2015 at 3.12 AU. This comet will not get any brighter.

P/2016 P1 (PANSTARRS) – Discovered on August 1 at 22nd magnitude by Pan-STARRS. It is a short-period comet with a period of 5.8 years. Perihelion was back in September of 2015 at 2.28 AU. This comet will also not get any brighter.

C/2016 N6 (PANSTARRS) – Discovered on July 14 at 20th magnitude by Pan-STARRS. It is a long-period comet with an inclination of 106° and perihelion on 2018 July 18 at 2.67 AU from the Sun. It may reach 14th magnitude during 2018.

Also the following periodic comets were recovered and numbered.

343P/NEAT-LONEOS = P/2016 P3 = P/2003 SQ205 [T = 2017 Jan 27, q = 2.28 AU, P = 12.8 yrs, expected peak mag = 17]

342P/SOHO = P/2016 N5 = P/2011 E1 = P/2005 W4 = P/2000 O3 – [T = 2016 Jul 1, q = 0.05 AU, P = 5.3 yrs, expected peak mag = very faint outside of SOHO FOV]

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 NEWS FOR AUGUST 2016

2016-August-7

The past months have been rather slow with only a single comet brighter than 10th magnitude. Barring a surprise discovery or outburst, August will see more of the same with no comets brighter than 9th magnitude. As bad as the summer has been for comet observers, this Fall will be worse as it is very possible that no comets will be brighter than 10th magnitude from September till late December when short-period 45P/Honda-Mrkos-Pajdušáková makes its 12th observed apparition.

Evening Comets

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

Comet PANSTARRS is now outbound and fading as its distance from the Sun (1.98 to 2.30 AU) and Earth (1.60 to 2.56 AU) increases. It is located low in the southwest as it moves through Centaurus (Aug 1-13) and Hydra (13-31). Low declination (-32° to -27°) and low elongation (96° to 64°) will make it a difficult object for far northern observers. It’s an “easier” target the further south one is located. Having peaked at 6th magnitude in June, X1 is now 9th magnitude and should fade to 10-11th magnitude by the end of August.

New Discoveries

Since the last Comet Section News posting, one comet was discovered.

The MASTER (Mobile Astronomical System of the Telescope-Robots) survey discovered its 3rd comet, C/2016 N4 (MASTER), on July 15. MASTER utilizes a world-wide network of small telescopes to scan the sky for transient objects (mainly supernovae and variable stars; and the occasional comet and near-Earth asteroid). C/2016 N4 was 16th magnitude when first seen by a team consisting of O. Gress, V. Lipunov, and eleven others with a 0.4-m f/2.5 telescope on the island of Tenerife. It is a dynamically old long-period comet with a period of ~1100 years. Perihelion occurs on Sept. 10, 2017 at 3.2 AU from the Sun. It will be ~14th magnitude at that time.

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 NEWS FOR JULY 2016

2016-July-3

June was a slow month for comet watchers. C/2013 X1 (PANSTARRS) was bright enough at 6th magnitude but spent much of June at far southern declinations. This month, X1 is slowly returning to the northern sky though it may still be too far south for many northern observers. Unfortunately, no other comets are expected to be brighter than 10th magnitude this month.

The Comet Section image gallery ( https://alpo-astronomy.org/gallery/main.php?g2_itemId=4491 ) is only a few images shy of 2000 images! Please take a look at our extensive collection of comet images. If you have images that are missing from the archive, please submit them for inclusion by contacting me (chergen @ lpl . arizona . edu). The Comet Section would like all types of comet submissions (CCD images, photographic images, drawings, magnitude estimates, textual descriptions) for all comets, past and present. CCD data can be sent as FITS and/or GIF, JPEG, PNG images.

Evening Comets

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

C/2013 X1 (PANSTARRS) is now well past its April perihelion and also its closest approach to Earth on June 21. It peaked at magnitude 6.0 to 6.5 as it passed within 0.64 AU of Earth. The comet has since faded to magnitude 7.0.

During most of June it was located far south. This month X1 is moving slowly north in the evening sky as it travels through Ara (Jul 1-3), Norma (3-8), Lupus (8-16), and Centaurus (16-31). Its declination will increase from -48° to -32° as its elongation drops from 148° to 96°. At the beginning of the month, PANSTARRS will be 1.68 AU from the Sun and 0.73 AU from the Earth. By the end of the month, the distances will increase to 1.98 and 1.60 AU from the Sun and Earth, respectively. As a result of these increases, the comet will fade from 7th to 9th magnitude.

New Discoveries

Since the last Comet Section News posting, only one comet was discovered.

C/2016 M1 (PANSTARRS) was discovered on June 22 with the 1.8-m Pan-STARRS1 telescope on Maui. C/2016 M1 is a long-period comet and was 7.7 AU from the Sun at discovery. Its perihelion won’t occur till August of 2018 at a much closer heliocentric distance of 2.2 AU. Though currently 18th magnitude, it may get as bright as 10th magnitude during the summer of 2018. Northern CCD observers will be able to follow the comet before perihelion when its 91° inclination orbit takes it south and makes it well placed for southern CCD observers post-perihelion.

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 NEWS FOR JUNE 2016

2016-June-5

For most of 2016, there have been 2 or 3 comets bright enough for visual observers using small telescopes and binoculars. That changes this month as only a single comet is easily visible. Previously bright comets 252P/LINEAR and C/2014 S2 have now faded to fainter than magnitude 10.5. That’s still plenty bright enough for CCD observing but would require relatively large telescopes for visual observation. Luckily, C/2013 X1 (PANSTARRS) is bright at ~6th-7th magnitude this month.

Morning Comet (Jun 1-25), Evening Comet (Jun 25-30)

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

C/2013 X1 (PANSTARRS) passed perihelion back on April 20 at 1.31 AU from the Sun. At the time, the comet was located on the far side of the Sun. During May the comet slowly moved away from the Sun though this was more than countered by a rapidly decreasing Earth-comet distance. Between May 6 and June 5, ALPO contributors have observed PANSTARRS to be between magnitude 6.8 and 7.2. PANSTARRS starts the month in Aquarius (Jun 1-7). As it passes Earth (0.95 AU on the 1st, 0.64 AU at its closest on the 21st, and then back out to a distance of 0.73 AU at the end of the month), the comet will rapidly move through the southern constellations of Aquarius (Jun 1-7), Pisces Austrinus (7-13), Microscopium (13-18), Sagittarius (18-20), Telescopium (20-26) and Ara (27-30). Furthest southern declination will be reached on the 28th at -49°. Currently at magnitude ~7.0, X1 may brighten another 0.5 to 1 magnitude at the time of closest approach.

Manos Kardasis took this image of C/2013 X1 back on May 6 showing a thin straight gas tail and a broad sweeping dust tail.

New Discoveries

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

P/2016 J1 (PANSTARRS) is not one but two comets. A single comet (component A) was discovered with the University of Hawaii 1.8-m Pan-STARRS1 telescope on May 5 UT at 21st magnitude. Follow-up observations taken the next night with the 3.6-m Canada-France-Hawaii Telescope found a second 21st magnitude comet (component B) moving with identical motion to component A. Both comets are likely related though there is some question as to whether they are comets in the traditional sense. Its orbit is very asteroidal orbit and located in the Main Belt (q = 2.33 AU, e = 0.25, i = 13, P = 5.5 yrs) so P/2016 J1 may be a case of an asteroid that recently split into two (or more fainter pieces) due to its rapid rotation. Alternately, it could be a volatile rich object that split after a recent outburst. Hopefully future large telescope observations will shed more light on this interesting object’s true nature.

C/2016 J2 (Denneau) was found by Larry Denneau as part of the ATLAS survey at the University of Hawaii. The 0.5-m ATLAS telescope was used to discover C/2016 J2 on May 6 UT at 18th magnitude. At discovery, J2 was located at 0.8 AU from the Earth. Unfortunately, J2 was already past perihelion (T = 2016 April 11, q = 1.52 AU) and past its closest approach to Earth so it has been rapidly fading. It is a long-period comet with an inclination of 130 degrees.

P/2016 J3 (STEREO) is a new low perihelion short-period comet. Scott Ferguson first spotted it in images taken on May 11 UT with the STEREO-A spacecraft located on the far side of the Sun from Earth. The comet was surprisingly bright at 8th magnitude though it appeared to rapidly fade to magnitude 13 over the course of a few days. The sharp spike in brightness is likely due to forward scattering by the comet’s dust, a condition that can greatly enhance the brightness of a comet when the phase angle (Sun-comet-observer angle) is very large. A similar event occurred to comet C/2014 C2 (STEREO) which was observed at magnitude 4 by STEREO at high phase angles but was in truth a fairly faint, no brighter than 14th magnitude, comet at normal phase angles. This new comet STEREO passed perihelion on May 21 UT at 0.47 AU from the Sun. It is a short-period comet with an inclination of 25 degrees and period of 7.7 years. Earth-based observers will have a chance to observe it this month as it moves away from the Sun in the evening sky though its brightness is very uncertain and it may be very faint, even for CCD imagers.

C/2016 KA (Catalina) was reported as an asteroidal object by Catalina Sky Survey observer R. G. Matheny. It was first observed on May 16 UT at 19th magnitude with the University of Arizona 0.68-m Catalina schmidt. Follow-up observations uncovered its cometary nature. KA is a long-period comet (T = 2016 Feb. 8 UT, q = 5.41 AU, e = 1.0, i = 104.6 degrees) and will not get brighter.

C/2016 K1 (LINEAR) was discovered on May 31 UT by the LINEAR program with the 3.5-m SST telescope near White Sands, NM, USA. It is currently an 18th magnitude comet on a long-period orbit (T = 2016 July 14 UT, q = 2.29 AU, e = 1.0, i = 90.9 degrees) and may only get a few magnitudes 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 NEWS FOR May 2016

2016-May-2

Evening Comets

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

Now 5 months past perihelion, this relatively large perihelion long-period comet is still bright enough for visual observation. I was able to observe it last night (May 2.3 UT) in 30×125 binoculars at magnitude 10.2. This May its range from the Sun and Earth increases from 2.67 to 2.89 AU and 2.30 to 2.85 AU, respectively. As a result it should fade by another 0.5 magnitude by the end of the month. It elongation in the evening sky falls from 100° to 82° degrees as its moves southward through Ursa Major (from a declination of +49° to +34°.

Morning Comets

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

252P/LINEAR has been a pleasant surprise this year. Not expected to get much brighter than 10th magnitude even while making an extremely close approach to Earth in late March (0.036 AU), the comet became a naked eye object for southern observers. The comet faded much slower than expected in April. Observations submitted to the Comet Section by Salvador Aguirre, Carl Hergenrother, John Sabia and Willian Souza showed the comet fading from magnitude ~6 to ~7 over the course of April. It remains a nice tailless weakly condensed fuzzball, but should continue to fade as its moves away from the Sun (1.19 to 1.44 AU) and Earth (0.24 to 0.47 AU) as it moves through Ophiuchus (May 1-25) and Hercules (25-31). Though technically a morning object, it is approaching opposition and can be observed late in the evening.

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

Until the past week or so, C/2013 X1 (PANSTARRS) had been too close to the Sun to be observed since February. This month PANSTARRS will move away from the glare of the Sun in the morning sky (elongation grows from 49° to 95° degrees). The comet spends May moving among the stars of Pisces (May 1-5) and Aquarius (5-31). Unfortunately, the comet is moving south of the Sun’s declination (-2° to -17°) making it an increasingly tough object for northern observers. Perihelion occurred back on April 20th. An increasing heliocentric distance (1.32 AU to 1.45 AU) will be countered by a decreasing geocentric distance (1.74 AU to 0.95 AU). Though the Section has not received any observations of this comet, recent observations submitted to the COBS website show the comet to be around magnitude 7.5. The decreasing Earth-comet range should help PANSTARRS brighten during May to magnitude 6.5 to 7.0. The comet will continue to brighten to perhaps magnitude 6.0 as it passes within 0.0.64 AU of Earth in late June.

New Discoveries

Since the last Comet Section News posting, three comet discoveries were reported though two of them were first seen in 2015.

C/2015 WZ (PANSTARRS) was discovered back on 2015 October 25 by the Pan-STARRS1 survey at a faint 21st magnitude. Further observations were made last November but due to a lack of obvious cometary activity it was designated as asteroid 2015 WZ. Artyom Novichonok of Russia reported cometary activity on April 17 on images taken with a 0.5-m f/2 telescope. At that time the comet was a much brighter magnitude 13. Since then, there have a been a handful of CCD and visual brightness measurements suggesting the comet may be as bright as magnitude 10.5 to 12.0. C/2015 WZ is a dynamically old long-period comet with a period of 2700 years. Perihelion occurred on April 15 at 1.38 AU.

P/2015 HG16 (PANSTARRS) is another example of a comet discovered last year (seen in March and April 2015) and designated as an asteroid. On 2016 April 4, Pan-STARRS1 rediscovered the object as a comet. With a peak brightness of magnitude 20-21, HG16 will not be getting very bright. It is a short-period object with a period of 10.5 years and perihelion of 3.13 AU.

P/2016 G1 (PANSTARRS) is a Main Belt comet or activated asteroid. Its orbit is very non-cometary with a perihelion of 2.05 AU, semi-major axis of 2.58 AU, eccentricity of 0.21 and inclination of 11°. It was discovered by the Pan-STARRS1 telescope on April 1 at 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)

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)

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