ALPO COMET NEWS for APRIL 2020 a Publication of the Comet Section of the Association of Lunar and Planetary Observers by Carl Hergenrother - 2020-April-1

ALPO COMET NEWS FOR APRIL 2020 A Publication of the Comet Section of the Association of Lunar and Planetary Observers By Carl Hergenrother - 2020-April-1

The monthly ALPO Comet News PDF can be found on the ALPO Comet Section website (http://www.alpo-astronomy.org/cometblog/). A shorter version of this report is posted on a dedicated Cloudy Nights forum (https://www.cloudynights.com/topic/700215-alpo-comet-news- for-april-2020/). All are encouraged to join the discussion over at Cloudy Nights. The ALPO Comet Section welcomes all comet related observations, whether textual descriptions, images, drawings, magnitude estimates, or spectra. You do not have to be a member of ALPO to submit material, though membership is encouraged. To learn more about the ALPO, please visit us @ http://www.alpo-astronomy.org.

A lot has changed since over the past month, not only with the state of the world, but with comets. C/2019 Y4 (ATLAS) has asserted itself as the comet of the moment. Currently between 7th and 8th magnitude as April begins, the comet may become a borderline naked eye object under dark skies by the end of the month. It will be interesting to watch how it develops.

C/2019 Y4 isn’t the only object of interest. Both C/2017 T2 (PANSTARRS) and C/2019 Y1 (ATLAS) are brighter than 10th magnitude and CCD and large aperture visual observers are encouraged to watch fainter comets 88P/Howell, 210P/Christensen, 249P/LINEAR, and C/2019 U6 (Lemmon).

Bright Comets (magnitude < 10.0)

C/2019 Y4 (ATLAS) – The Great Comet of 2020, a Great Disappointment, or something in between? For the first time since 2013, a comet has the potential to become something special. Some articles in the popular press are already hyping this comet as you can see from these example headlines.

“Comet Atlas could be the brightest comet in decades” “Comet ATLAS: Comet could be as bright as the MOON as it nears the Sun” “Comet of a generation set to light up the night sky”

When it was discovered at the end of 2019, C/2019 Y4 was a faint 19th magnitude object. Other than the fact that it shared an orbit and possibly a progenitor with the Great Comet of 1844, the

1 comet looked like it was destined to remain a faint object or even disintegrate as it neared perihelion. An extraordinary rapid brightening through early March brought the comet to around 8th magnitude. It was extrapolating this brightening trend through to perihelion that lead to the predictions that inspired the above headlines.

So, where does ATLAS stand as April begins? The comet possesses a large low surface brightness gas coma which is evident visually and in color CCD images (see the image below by Martin Mobberley from March 31). ALPO contributors measured the coma as large as 15’ visually and 22’ in images. Some reports to the COBS website have measured an even larger coma. A condensed inner dust coma and tail is also evident. Unfortunately, the large coma is complicating the measurement of its total brightness. The observation of such a large object is very sensitive to sky conditions, equipment, and observer experience.

CCD image of C/2019 Y4 (ATLAS) by Martin Mobberley on 2020 March 31.

Magnitude estimates submitted to the ALPO by Salvador Aguirre, Michel Deconinck, J. J. Gonzalez, and Carl Hergenrother over the past 2 weeks found ATLAS to be between magnitude 7.2 and 8.6 (March 14-31). Personally, I’ve used 30x125 and 10x50 binoculars to observe ATLAS. On most nights since March 15th, I placed the comet between 7.9 and 8.4. On the evening of March 28, the comet appeared brighter in both of my binoculars. In fact, it was the only night when it was a strong detection in my 10x50s. That night I placed the comet at magnitude 7.2 in the 10x50s and 7.6 in the 30x125s. I’m not sure if the comet was actually brighter, the night was more transparent than usual, or I was biased to the bright side that evening. The fact that most observers didn’t see

2 the comet brighter that night suggests the later reason is correct. Regardless, by the night of 30th, it was back to its usual recent brightness. If we ignore the anomalous night, the comet’s appearance (and brightness) didn’t seem to change much, if at all, over the past 2 weeks.

So now the big question, how bright will C/2019 Y4 (ATLAS) get? The prediction below assumes an n = 3 rate of increase which is the average for a long-period comet. If ATLAS brightens at this rate it could be a borderline naked eye comet from a dark site by the end of April and perhaps a 3rd-4th magnitude object before it is lost in the glow of twilight from the northern hemisphere. At perihelion, it could brighten to 1st magnitude. ATLAS’ large phase angle at perihelion may result in another magnitude of brightness due to forward scattering. Of course, at that time the comet will be very close to the Sun and even at 1st magnitude may not be visible to most observers. Now this is just a nominal prediction and the comet may be brighter or fainter. In fact, its recent brightness trend suggests that it is underperforming the n = 3 rate. There is still a possibility that the comet will disintegrate as it approaches perihelion just like C/2012 S1 (ISON), the last “Great Comet” that wasn’t. Alternately, those of a certain age may remember C/1989 X1 (Austin) which didn’t disintegrate but seemed to experience a slow fizzle as it experienced an intrinsic fading over much of its apparition.

Even if ATLAS does reach 0th or 1st magnitude at perihelion, the majority of observers (including probably most of the public) will see the comet as no brighter than 3rd magnitude. A nice comet, no doubt, and one I’m looking forward to seeing, but not a Great Comet. We’ll know more as April develops and the ALPO encourages all visual and CCD observers to keep an eye on ATLAS.

C/2019 Y4 (ATLAS) T = 2020-May-31 q = 0.25 au Max El Long-Period comet - dynamically old (deg) Date Mag R.A. Decl. r d Elong Const 40N 40S 2020-04-01 7.8 07 55 +68 31 1.475 1.045 92 Cam 61 0 2020-04-06 7.6 07 20 +68 01 1.383 1.029 85 Cam 59 0 2020-04-11 7.3 06 49 +67 03 1.288 1.012 79 Cam 56 0 2020-04-16 7.0 06 22 +65 44 1.191 0.995 73 Cam 51 0 2020-04-21 6.7 05 59 +64 08 1.090 0.974 66 Cam 46 0 2020-04-26 6.3 05 38 +62 16 0.986 0.951 60 Cam 41 0 2020-05-01 5.9 05 18 +60 06 0.879 0.922 53 Cam 35 0 2020-05-06 5.3 04 59 +57 28 0.768 0.890 47 Cam 28 0

C/2017 T2 (PANSTARRS) – With all the attention on C/2019 Y4, it might be easy to forget there are two other bright comets visible in the evening, C2017 T2 (PANSTARRS) and C/2019 Y1 (ATLAS). The former has been bright enough to be seen visually in small apertures since late last year. April brings the comet within a month of its May 4th perihelion at 1.62 au. During March, J. J. Gonzalez and Carl Hergenrother observed T2 to be between magnitude 8.4 and 8.7 with a coma diameter of 3-5’

This month should see more of the same as the comet slowly brightens another 0.3 magnitudes. The comet is well placed in the northern circumpolar sky as it moves through Cassiopeia (Apr 1- 10) and Camelopardalis (10-30). Southern observers will have to wait till late June or July to catch another glimpse of PANSTARRS. The comet should still be between 8-9th magnitude at that time.

Lightcurve of C/2017 T2 (PANSTARRS). Data consists of visual and CCD observations submitted to the ALPO Comet Section by Salvador Aguirre, Michel Deconinck, J. J. Gonzalez, Carl Hergenrother, Raymond Ramlow, and Chris Wyatt.

CCD image of C/2017 T2 (PANSTARRS) by John D. Sabia on 2020 March 16.

C/2017 T2 (PANSTARRS) T = 2020-May-04 q = 1.62 au Max El Long-Period comet - dynamically new (deg) Date Mag R.A. Decl. r d Elong Const 40N 40S 2020-04-01 8.5 03 03 +68 47 1.679 1.768 68 Cas 40 0 2020-04-06 8.5 03 19 +70 18 1.662 1.762 67 Cas 39 0 2020-04-11 8.4 03 41 +71 49 1.647 1.753 67 Cam 39 0 2020-04-16 8.4 04 09 +73 17 1.635 1.743 66 Cam 39 0 2020-04-21 8.3 04 43 +74 37 1.626 1.731 66 Cam 40 0 2020-04-26 8.3 05 26 +75 41 1.620 1.718 67 Cam 41 0 2020-05-01 8.2 06 17 +76 16 1.616 1.705 67 Cam 43 0 2020-05-06 8.2 07 13 +76 13 1.615 1.692 68 Cam 44 0

C/2019 Y1 (ATLAS) – It may seem a bit confusing but there is another C/2019 Y# (ATLAS) comet bright enough for small aperture observers. C/2019 Y1 (ATLAS) was discovered on 2019 December 16 with the Asteroid Terrestrial-Impact Last Alert System (ATLAS) 0.5-m f/2 astrograph at Haleakala on Maui, Hawaii. It is a long-period comet with perihelion on 2020 March 15 at 0.84 au. C/2019 Y1 (ATLAS) appears to be the 4th member of a comet family associated with C/1988 A1 (Liller). The other family members include C/1996 Q1 (Tabur) and C/2005 F3 (SWAN). Tabur peaked at 5th magnitude before experiencing a catastrophic disruption event a few weeks before perihelion resulting in a rapid fade. SWAN was discovered 12 days after its perihelion at around 10th magnitude. Though it rapidly faded as well, whether it also disintegrated is in question. Considering the fate of Tabur, it is a good idea to keep a close eye on C/2019 Y1 in case it also experiences a disintegration event.

Last month was tough for observing C/2019 Y1 as it hugged the western horizon after dusk. We received two visual magnitude estimates from J. J. Gonzalez and Carl Hergenrother who reported the comet between magnitude 8.2 and 8.4 on March 14 and 15. I (Hergenrother) made a few other attempts to observe this comet before and after the 15th without success due to the comet’s low altitude and the still bright sky. This month the comet will climb higher for northern observers as it moves through Cassiopeia (Apr 1-26) and Cepheus (27-30). It starts the month as both an evening and morning object, though it is best in the morning. By mid-month it becomes circumpolar and again best in the morning.

C/2019 Y1 (ATLAS) T = 2020-Mar-15 q = 0.83 au Max El Long-Period comet - dynamically old (deg) Date Mag R.A. Decl. r d Elong Const 40N 40S 2020-04-01 8.7 00 18 +46 55 0.886 1.305 42 Cas 16 0 2020-04-06 8.7 00 24 +52 28 0.922 1.254 46 Cas 20 0 2020-04-11 8.8 00 34 +58 23 0.965 1.205 50 Cas 24 0 2020-04-16 8.9 00 49 +64 39 1.013 1.162 55 Cas 28 0 2020-04-21 9.0 01 15 +71 13 1.066 1.126 59 Cas 30 0 2020-04-26 9.1 02 10 +77 42 1.123 1.101 64 Cas 32 0 2020-05-01 9.3 04 38 +82 28 1.182 1.089 68 Cep 39 0 2020-05-06 9.4 08 23 +80 55 1.244 1.091 72 Cep 46 0

5 Fainter Comets of Interest (fainter than magnitude 10.0)

C/2019 U6 (Lemmon) – This object was discovered on a long-period cometary orbit back on October 31 with the University of Arizona’s 1.5-m Mount Lemmon reflector. At the time the object was designated with the A/ prefix. Recently cometary activity has been recognized and the object was reclassified as comet C/2019 U6 (Lemmon).

At discovery, C/2019 U6 was 20th magnitude. As recently as February, CCD imagers were reporting the comet at 16-17th magnitude. Either the comet has recently become active or a faint coma was being missed because visual observer and ALPO contributor Chris Wyatt detected it between magnitude 12.3 and 13.5 on March 18, 19, 20, and 31.

If the comet continues to brighten at a normal rate (n~3-4), it may become an 8-9th magnitude object at perihelion this June. This month U6 should brighten from 12th to 10th magnitude as it moves through Eridanus (Apr 1-23) and Lepus (23-30). The comet is currently only visible from the southern hemisphere. Northern observers will have to wait till early July. While that is a few weeks after perihelion, the comet should still be close to its maximum brightness.

C/2019 U6 (Lemmon) T = 2020-Jun-18 q = 0.91 au Max El Dynamically old long period comet (deg) Date Mag R.A. Decl. r d Elong Const 40N 40S 2020-04-01 12.3 04 18 -23 40 1.612 1.865 59 Eri 3 42 2020-04-06 12.1 04 25 -23 23 1.549 1.824 58 Eri 0 40 2020-04-11 11.9 04 32 -23 07 1.487 1.777 56 Eri 0 39 2020-04-16 11.6 04 41 -22 52 1.425 1.725 55 Eri 0 38 2020-04-21 11.4 04 50 -22 39 1.365 1.669 54 Eri 0 38 2020-04-26 11.1 05 0 -22 27 1.306 1.607 54 Lep 0 37 2020-05-01 10.8 05 12 -22 16 1.249 1.542 53 Lep 0 36 2020-05-06 10.5 05 25 -22 04 1.194 1.472 53 Lep 0 36

88P/Howell – Short-period comet 88P/Howell is making its 9th observed return. 88P was discovered on photographic plates taken with the 0.46-m Palomar Schmidt in August 1981 by then Caltech student, and currently my fellow University of Arizona OSIRIS-REx team member, Ellen Howell. In addition to being found in pre-discovery observations from 1955, 88P has been observed at every return since 1981. The comet’s perihelion distance has gradually fallen from 1.92 au in 1955, to 1.62 au in 1981, to 1.41 au in 1993 to its current 1.35 au. As a result, comet Howell now often peaks brighter than 10th magnitude. Its brightest return was in 2009 when it peaked at 8th magnitude. This year it comes to perihelion on September 28 and should again peak around 8-9th magnitude.

This month, 88P will brighten from around magnitude 14.4 to 12.9 bringing it within range of large aperture visual observers. Its location in Virgo near the celestial equator makes it a good target for both hemispheres.

CCD image of 88P/Howell by John Maikner on 2020 March 14.

88P/Howell T = 2020-Sep-28 q = 1.35 au Max El Jupiter-family comet (deg) Date Mag R.A. Decl. r d Elong Const 40N 40S 2020-04-01 14.4 13 29 -03 55 2.236 1.248 168 Vir 46 54 2020-04-06 14.2 13 24 -03 30 2.202 1.205 173 Vir 46 54 2020-04-11 13.9 13 19 -03 04 2.169 1.169 174 Vir 47 53 2020-04-16 13.7 13 13 -02 39 2.136 1.140 170 Vir 47 53 2020-04-21 13.5 13 07 -02 15 2.102 1.116 164 Vir 48 52 2020-04-26 13.3 13 02 -01 54 2.069 1.099 158 Vir 48 52 2020-05-01 13.1 12 57 -01 36 2.036 1.088 152 Vir 48 52 2020-05-06 12.9 12 52 -01 23 2.002 1.082 146 Vir 49 51

210P/Christensen & 249P/LINEAR – These two objects are similar in that they are both short- period comets with perihelion distances of ~0.5 au and may not be comets in the traditional sense. While most comets originate in the Kuiper Belt or Oort Cloud, dynamical and spectral evidence suggests that some may originate closer to the inner solar system in the Main Belt. Both 210P and 249P have been flagged as possible escaped Main Belt comets. Unlike most comet nuclei which are red and resemble D-type asteroids. 249P’s nucleus is slightly blue and is classified as a B-type similar to the Geminid parent (3200) Phaethon and the OSIRIS-REx target (101955) Bennu.

Both objects are faint or inactive until they get within ~1-2 au of the Sun but can be borderline visual objects at perihelion. 210P was discovered by Eric Christensen of the Catalina Sky Survey in May 2003 with the 0.7-m Catalina Schmidt. A month prior, X.-m. Zhou had detected the comet in SOHO SWAN instrument data. Due to the poor resolution of the SWAN data, the object was lost until the Catalina Sky Survey observations. With a ~5.6-year period, 210P is now making its 4th observed return after past returns in 2003, 2008, and 2014. 249P/LINEAR is also making its 4th observed return after past returns in 2006, 2011, and 2015. It was discovered October 2006 by

7 the LINEAR (Lincoln Laboratory Near-Earth Asteroid Research) project with a 1-m telescope based outside of Socorro, New Mexico.

210P passes perihelion on the 12th of this month at 0.53 au. At that time, it will be located at a small elongation of ~20 degrees and 11-12th magnitude. As a result, we’ll need to wait till the later part of April before it moves far enough away from the Sun to be observed. By then it should still be 12-13th magnitude. In June/July, 249P may become a faint visual object at low elongation. At some point this month, 249P should become active and start to rapidly brighten. CCD imagers are requested to routinely monitor 249P to record the start of activity. This month 249P is visible from both hemispheres as it moves through Sextans (Apr 1-23) and Hydra (23-30).

210P/Christensen T = 2020-Apr-12 q = 0.53 au Max El Jupiter-family comet? / Active Asteroid? (deg) Date Mag R.A. Decl. r d Elong Const 40N 40S 2020-04-01 12.8 01 29 +06 03 0.582 1.523 11 Psc 0 0 2020-04-06 12.2 01 58 +09 39 0.546 1.452 14 Ari 0 0 2020-04-11 11.9 02 29 +13 21 0.529 1.382 17 Ari 0 0 2020-04-16 11.8 03 02 +17 02 0.533 1.315 21 Ari 2 0 2020-04-21 12.1 03 37 +20 33 0.559 1.255 25 Tau 6 0 2020-04-26 12.5 04 14 +23 42 0.602 1.203 29 Tau 10 0 2020-05-01 13.1 04 52 +26 21 0.657 1.165 34 Tau 14 0 2020-05-06 13.8 05 32 +28 20 0.720 1.142 38 Aur 17 2

249P/LINEAR T = 2020-Jun-26 q = 0.50 au Max El Jupiter-family comet? / Active Asteroid? (deg) Date Mag R.A. Decl. r d Elong Const 40N 40S 2020-04-01 18.3 10 49 -11 06 1.624 0.675 151 Sext 39 61 2020-04-06 18.3 10 34 -09 28 1.561 0.638 143 Sext 40 59 2020-04-11 18.3 10 19 -07 34 1.497 0.607 135 Sext 42 58 2020-04-16 18.3 10 04 -05 30 1.431 0.581 127 Sext 44 56 2020-04-21 18.3 09 49 -03 17 1.364 0.561 118 Sext 46 53 2020-04-26 18.4 09 35 -00 59 1.296 0.544 109 Hya 46 51 2020-05-01 18.4 09 22 +01 22 1.226 0.529 101 Hya 44 49 2020-05-06 18.5 09 09 +03 44 1.156 0.516 92 Hya 40 46

New Discoveries, Recoveries and Other Comets in the News

P/2020 F1 (Leonard) – Gregory Leonard found P/2020 F1 at 20th magnitude with the Mount Lemmon 1.5-m reflector on 2020 March 16. The comet is the fifth to bear the Leonard name. It has its perihelion on 2019 August 29 at 3.98 au and has likely already peaked in brightness.

Now 19-20th magnitude is faint, but that’s little problem for the professional near-Earth asteroid surveys. That and the fact that this comet had a large perihelion distance means that a number of past observations have been found going back to March 2002. CBET 4737 reports that orbital integrations by Syuichi Nakano found a close approach between P/Leonard and Saturn of 0.0074 au on 1936 May 7. Prior to that approach, the comet was on a more Centaur-like orbit with a perihelion of 9.02 au and period of 37.9 years. On its current orbit with an orbital period of 17.9 years, this comet will be next at perihelion in June 2037.

C/2019 S4 (Lemmon) – C/2019 U6 (Lemmon) wasn’t the only A/ object to be reclassified as a comet last month. The Mount Lemmon Survey discovered this object back on 2019 September 17 at 20th magnitude. A number of observers since late October reported cometary activity. C/2019 S4 is a dynamically old long-period comet with a perihelion on 2020 April 7 at 3.44 au. The comet will peak at 19th magnitude.

CBET 4738 has an interesting note on this object’s A/ designation. According to MPEC 2018- H54, “an A/ designation will be used for an object with an osculating hyperbolic orbit that has not been reported as cometary”. But, C/2019 S4 was designated with an A/ designation even though its orbit was elliptical and not hyperbolic.

C/2017 U7 (PANSTARRS) – This object was discovered with the Pan-STARRS1 telescope back on 2017 October 29. Because it was an asteroidal object on a hyperbolic orbit, it was given an A/ designation. Multiple observers going back to April 2018 reported the object as an active comet. The comet was a very faint 23rd magnitude in pre-discovery observations from August 2017, a still faint 20th magnitude at discovery, and is currently around 16th magnitude. It is a dynamically new long-period comet with perihelion back on 2019 September 11 at a distant 6.42 au.

As always, the Comet Section is happy to receive all comet observations, whether textual descriptions, images, drawings, magnitude estimates, or spectra. Please send your observations via email to < carl.hergenrother @ alpo-astronomy.org >.

Stay safe and enjoy the sky.

- Carl Hergenrother (ALPO Comet Section Coordinator)

9 Recent Magnitude Measurements Contributed to the ALPO Comet Section

Comet Des YYYY MM DD.DD Mag SC APER FL POW COMA TAIL ICQ CODE Observer Name (UT) T Dia DC LENG PA 2019Y4 2020 03 30.28 S 8.0 TK 5.0B 10 10 3 ICQ xx HER02 Carl Hergenrother 2019Y4 2020 03 29.23 Z 8.1 U4 10.6R 5a360 22.0 ICQ xx HER02 Carl Hergenrother 2019Y4 2020 03 29.23 k 9.3 U4 10.6R 5a360 10.0 ICQ xx HER02 Carl Hergenrother 2019Y4 2020 03 28.89 8.0 25.0T 10 12 5 ICQ xx DEC Michel Deconinck 2019Y4 2020 03 28.13 M 7.2 TK 5.0B 10 15 4 ICQ xx HER02 Carl Hergenrother 2019Y4 2020 03 28.12 M 7.6 TK 12.5B 30 9 5 ICQ xx HER02 Carl Hergenrother 2019Y4 2020 03 26.18 Z 8.2 U4 10.6R 5a360 22.0 ICQ xx HER02 Carl Hergenrother 2019Y4 2020 03 26.18 k 9.6 U4 10.6R 5a360 10.0 ICQ xx HER02 Carl Hergenrother 2019Y4 2020 03 25.16 M 8.0 TK 12.5B 30 8 4 ICQ xx HER02 Carl Hergenrother 2019Y4 2020 03 24.14 M 7.9 TK 12.5B 30 9 4 ICQ xx HER02 Carl Hergenrother 2019Y4 2020 03 22.13 M 7.9 TK 12.5B 30 9 4 ICQ xx HER02 Carl Hergenrother 2019Y4 2020 03 20.17 S 8.1 TK 12.5B 30 8 3 ICQ xx HER02 Carl Hergenrother 2019Y4 2020 03 18.76 8.6 25.0T 10 4 5 1 ICQ xx DEC Michel Deconinck 2019Y4 2020 03 15.12 S 8.4 TK 12.5B 30 9 4 ICQ xx HER02 Carl Hergenrother 2019Y4 2020 03 14.85 S 8.2 TK 5.0B 10 12 3 ICQ XX GON05 J. J. Gonzalez Suarez 2019Y4 2020 03 05.43 C 9.8 U4 10.6R 5a600 16.3 ICQ xx HER02 Carl Hergenrother 2019Y1 2020 03 15.11 S 8.2 TK 12.5B 30 2 3 ICQ xx HER02 Carl Hergenrother 2019Y1 2020 03 14.83 M 8.4 TK 10.0B 25 3 7 ICQ XX GON05 J. J. Gonzalez Suarez 2019U6 2020 03 31.38 xS 12.3 AQ 25.0L 5 74 2.5 2/ ICQ XX WYA Christopher Wyatt 2019U6 2020 03 20.42 xM 12.4 AQ 40.0L 4 108 2.2 3 ICQ XX WYA Christopher Wyatt 2019U6 2020 03 19.41 xM 12.8 AQ 40.0L 4 108 2.2 3/ ICQ XX WYA Christopher Wyatt 2019U6 2020 03 18.41 xS 13.5 AQ 40.0L 4 108 1.4 3 ICQ XX WYA Christopher Wyatt 2018F4 2020 03 20.41 xM 14.1 AQ 40.0L 4 108 1.0 3/ ICQ XX WYA Christopher Wyatt 2018F4 2020 03 19.40 xM 14.0 AQ 40.0L 4 108 1.0 4 ICQ XX WYA Christopher Wyatt 2018F4 2020 03 18.39 xM 14.0 AQ 40.0L 4 108 1.0 3/ ICQ XX WYA Christopher Wyatt 2017T2 2020 03 28.11 M 8.5 TK 12.5B 30 4 5 ICQ xx HER02 Carl Hergenrother 2017T2 2020 03 25.15 M 8.6 TK 12.5B 30 4 5 ICQ xx HER02 Carl Hergenrother 2017T2 2020 03 24.13 M 8.5 TK 12.5B 30 4 5 ICQ xx HER02 Carl Hergenrother 2017T2 2020 03 22.12 S 8.5 TK 12.5B 30 5 5 ICQ xx HER02 Carl Hergenrother 2017T2 2020 03 20.17 S 8.5 TK 12.5B 30 4 5 ICQ xx HER02 Carl Hergenrother 2017T2 2020 03 15.11 S 8.4 TK 12.5B 30 4 5 ICQ xx HER02 Carl Hergenrother 2017T2 2020 03 14.86 S 8.7 TK 10.0B 25 3 5 ICQ XX GON05 J. J. Gonzalez Suarez

10 Recent Select Images and Sketches Contributed to the ALPO Comet Section

CCD image of C/2020 B3 (Rankin) by John Maikner on 2020 March 16.

CCD image of C/2019 Y4 (ATLAS) by Martin Mobberley on 2020 March 29.

CCD image of C/2019 Y4 (ATLAS) by Chris Schur on 2020 March 29.

CCD image of C/2019 Y4 (ATLAS) by Tenho Tuomi on 2020 March 26.

Visual sketch image of C/2019 Y4 (ATLAS) by Michel Deconinck on 2020 March 28.

CCD image of C/2019 Y4 (ATLAS) by Dan Crowson on 2020 March 28.

CCD image of C/2019 Y4 (ATLAS) by John Chumack on 2020 March 26.

CCD image of C/2019 Y4 (ATLAS) by Martin Mobberley on 2020 March 26.

CCD image of C/2019 Y4 (ATLAS) by Gianluca Masi on 2020 March 24.

CCD image of C/2019 Y4 (ATLAS) by Martin Mobberley on 2020 March 22.

CCD image of C/2019 Y4 (ATLAS) by Chris Schur on 2020 March 21.

CCD image of C/2019 Y4 (ATLAS) by Martin Mobberley on 2020 March 20.

CCD image of C/2019 Y4 (ATLAS) by Carl Hergenrother on 2020 March 20.

CCD image of C/2019 Y4 (ATLAS) by Martin Mobberley on 2020 March 18.

CCD image of C/2019 Y4 (ATLAS) by Martin Mobberley on 2020 March 17.

Visual sketch of C/2019 Y4 (ATLAS) by Michel Deconinck on 2020 March 18.

CCD image of C/2019 Y4 (ATLAS) by John Maikner on 2020 March 16.

CCD image of C/2019 Y4 (ATLAS) by John D. Sabia on 2020 March 16.

CCD image of C/2019 Y4 (ATLAS) by John D. Sabia on 2020 March 14.

CCD image of C/2019 Y4 (ATLAS) by Efrain Morales Rivera on 2020 March 14.

Visual sketch of C/2019 Y4 (ATLAS) by Michel Deconinck on 2020 March 11.

CCD image of C/2019 Y4 (ATLAS) by Gianluca Masi on 2020 March 11.

CCD image of C/2019 Y4 (ATLAS) by Martin Mobberley on 2020 March 8.

CCD image of C/2017 T2 (PANSTARRS) by Martin Mobberley on 2020 March 16.

CCD image of C/2017 T2 (PANSTARRS) by Martin Mobberley on 2020 March 15.

CCD image of C/2017 T2 (PANSTARRS) by Efrain Morales Rivera on 2020 March 14.

CCD image of C/2017 T2 (PANSTARRS) by Martin Mobberley on 2020 March 13.

CCD image of C/2017 T2 (PANSTARRS) by John D. Sabia on 2020 March 8.