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ALPO Comet News for January 2019

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#1 Carl H.

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Posted 04 January 2019 - 07:25 PM

ALPO COMET NEWS FOR JANUARY 2019
 
2019-January-4
 
Happy New Year! and Welcome to 2019!

 

2018 was a great year for comet observers, especially the second half of the year. 2019 is looking to be a slower year for comet watchers. New discoveries may change that prediction and, in fact, the brightest comet of the year may be newly discovered C/2018 Y1 (Iwamoto) at 7-8th magnitude.

 

In addition to Iwamoto, January will see some of 2018’s bright comets remain visible including rapidly fading 46P/Wirtanen (starting the month at 5th magnitude) and brighter than expected 64P/Swift-Gehrels (starting January at 9th magnitude).

 

Bright Comets (magnitude < 10)
  
46P/Wirtanen - The comet event of 2018 was the historically close approach to Earth of short-period comet 46P/Wirtanen. While predictions based on previous apparitions had the comet getting up to magnitude 3.2 or so, most observers saw the comet peaking out at around magnitude 4.0. Additional analysis will be needed to determine if 46P was simply intrinsically fainter (i.e., less active) this time or a combination of a large low surface brightness coma and less than dark skies conspired to make the comet appear fainter than it really was.

 

46P is now a far northern object at declinations greater than +50 degrees as it traverses Lynx (Jan 1-12) and Ursa Major (12-31). CCD and visual magnitude estimates by J. J. Gonzalez, Carl Hergenrother and Raymond Ramlow found 46P to be around magnitude 4.9 to 5.2 over the past few nights. Depending on the asymmetry of 46P’s lightcurve relative to perihelion, it may fade rapidly as it moves away from the Earth this month. Starting at 5th magnitude, it could be up to 3 magnitudes fainter by the end of the month as it distance to Earth almost triples from 0.12 to 0.31 AU.

 

The ALPO Comet Section has received over 90 images of 46P/Wirtanen this apparition. We are always looking for observers to contribute their observations (whether visual magnitude estimates, sketches, photos, images, spectra, or just textual descriptions).

 

To see what the ALPO has received for 46P, please check our Comet Section Image Gallery at
http://www.alpo-astr...0P/46P-Wirtanen

 

Also check out the Comet Wirtanen Observing Campaign page at http://wirtanen.astro.umd.edu/ for recent findings. Radar observations from Arecibo found the nucleus to be larger than expected at 1.4 x 1.1 km in diameter. The rotation period of the nucleus has been measured at both 8.9 and 9.2 hours by different observers on different dates. As was seen with comet 41P, the difference in measured periods could be due to actual changes in the period, even on very short time scales of days.

 

46P/Wirtanen                                            
T = 2018-Dec-12  q = 1.06 AU   Short-Period comet  Period = 5.4 yr
    Date     Mag    R.A.   Decl.     r       d    Elong  const
2019-01-01   5.3   07 01  +57 20   1.086   0.122   145    Lyn
2019-01-06   5.9   07 51  +59 20   1.104   0.148   142    Lyn
2019-01-11   6.5   08 27  +59 32   1.125   0.176   140    Lyn
2019-01-16   7.1   08 51  +58 54   1.150   0.206   140    UMa
2019-01-21   7.6   09 06  +57 53   1.178   0.237   140    UMa
2019-01-26   8.2   09 16  +56 38   1.208   0.271   141    UMa
2019-01-31   8.7   09 23  +55 15   1.240   0.306   141    UMa
2019-02-05   9.2   09 27  +53 45   1.274   0.343   142    UMa

 

38P/Stephan-Oterma - Halley-family comet 38P/Stephan-Oterma has an orbital period of ~38 years and is making its first return since 1980. Now past perihelion (1.59 AU on November 10) and closest approach to Earth (0.77 AU on December 17), 38P is starting to fade. Estimates by  J. J. Gonzalez, Raymond Ramlow and Chris Wyatt over the past few nights have placed 38P between magnitude 9.7 and 10.2. It should fade by another magnitude or more by the end of January as it moves through Lynx. Stephan-Oterma won’t be back till 2056 though that return will be worse than the current one with it peaking at a fainter 11-12th magnitude.

 

38P/Stephan-Oterma                                    


T = 2018-Nov-10  q = 1.59 AU   Short-Period comet  Period = 38.0 yr
    Date     Mag    R.A.   Decl.     r       d    Elong  const
2019-01-01   9.9   08 35  +40 47   1.713   0.787   150    Lyn
2019-01-06  10.1   08 35  +42 25   1.737   0.803   152    Lyn
2019-01-11  10.4   08 35  +43 50   1.762   0.825   153    Lyn
2019-01-16  10.6   08 33  +45 02   1.790   0.852   154    Lyn
2019-01-21  10.9   08 32  +45 59   1.819   0.884   153    Lyn
2019-01-26  11.2   08 30  +46 42   1.849   0.920   152    Lyn
2019-01-31  11.5   08 28  +47 10   1.880   0.961   150    Lyn
2019-02-05  11.8   08 27  +47 25   1.913   1.007   147    Lyn

    
64P/Swift-Gehrels - Comet Swift-Gehrels is not an especially bright object intrinsically. This is its best known return with a minimum Earth-comet distance of 0.44 AU on October 28. In addition to the good apparition, 64P has been putting on quite a dynamic display. First there was a short lived outburst that saw it brighten by ~2-3 magnitudes to around 13th magnitude in mid-August. Since then it has been running brighter than expected. Now well past perihelion (November 3 at 1.39 AU) and closest approach to Earth (October 27 at 0.44 AU), it continues to remain bright with recent observations by J. J. Gonzalez, Raymond Ramlow and Chris Wyatt finding it between magnitude 9.1 and 9.3. Over the past few nights (Jan 2 and 3), CCD observers, including ALPO contributor Gianluca Masi, have detected a strong jet like feature emanating from the nucleus which may be evidence of another outburst.

 

This month the comet is an evening object moving across Aries (Jan 1-14) and Taurus (14-31). It should start to fade though how rapidly is TBD.

 

64P/Swift-Gehrels                                       
T = 2018-Nov-03  q = 1.39 AU   Short-Period comet  Period = 8.9 yr.
    Date     Mag    R.A.   Decl.     r       d    Elong  const
2019-01-01   9.2   02 57  +29 54   1.556   0.733   129    Ari 
2019-01-06   9.3   03 09  +29 16   1.582   0.781   127    Ari
2019-01-11   9.4   03 21  +28 42   1.610   0.833   124    Ari
2019-01-16   9.5   03 33  +28 10   1.640   0.889   122    Tau
2019-01-21   9.7   03 44  +27 42   1.670   0.949   119    Tau
2019-01-26   9.8   03 56  +27 16   1.702   1.011   116    Tau
2019-01-31  10.0   04 07  +26 53   1.734   1.077   114    Tau
2019-02-05  10.2   04 18  +26 32   1.768   1.147   111    Tau

 
C/2018 Y1 (Iwamoto) - Masayuki Iwamoto of Awa, Tokushima, Japan found a new 11th magnitude comet on Dec 18 on CCD images obtained with a 10-cm
f/4.0 Pentax SDUF II telephoto lens and Canon EOS 6D camera. This marks Iwamoto's 3rd comet discovery and second this year after C/2018 V1 (Machholz-Fujikawa-Iwamoto). With perihelion on February 6 at 1.28 AU and closest approach to Earth on February 12 at 0.30 AU, C/Iwamoto should brighten to become an easy object in large binoculars and small telescopes. How bright is still to be seen. As of early January, we still don’t know if this long-period comet is of the dynamically old variety (meaning it may brighten faster than the average long-period comet) or dynamically new (meaning it will brighten at a slower rate). Over the past few days, both Chris Wyatt (visual) and Raymond Ramlow (CCD) placed Iwamoto at magnitude 11.3 to 10.9. J. J. Gonzalez reported it even brighter at 9.2 on January 2. If we assume a brightening rate of 2.5n = 7.5 (typical for dynamically new comets), Iwamoto may brighten to around magnitude 7.3 in mid-February. A 2.5n = 10 rate results in a comet that is 0.1-0.2 magnitudes brighter. We’ll know more over the next few weeks as our baseline of magnitude measurements increase.

 

Currently, the comet is a morning object and visible from both hemispheres as it moves through Hydra (Jan 1-12) and Virgo (12-31).
 
C/2018 Y1 (Iwamoto)


T = 2019-Feb-06  q = 1.28 AU   Long-Period comet - dynamically ?


    Date     Mag    R.A.   Decl.     r       d    Elong  const
2019-01-01  11.1   14 15  -23 59   1.394   1.577    60    Hya
2019-01-06  10.8   14 12  -23 31   1.367   1.417    66    Hya
2019-01-11  10.5   14 08  -22 52   1.342   1.251    72    Hya
2019-01-16  10.1   14 01  -21 56   1.322   1.080    79    Vir
2019-01-21   9.7   13 51  -20 32   1.305   0.908    87    Vir
2019-01-26   9.2   13 36  -18 17   1.293   0.735    96    Vir
2019-01-31   8.6   13 10  -14 21   1.284   0.567   108    Vir
2019-02-05   7.9   12 25  -06 43   1.281   0.416   127    Vir

 

Faint Comets (between magnitude 10 and 13)
   
C/2016 M1 (PANSTARRS) - Comet C/2006 M1 (PANSTARRS) just keeps going and going. Now well past a rather distant (2.21 AU) August 10th perihelion, this dynamically old long-period comet has been very slow to fade. Chris Wyatt has been continuously monitoring it and found it to be between magnitude 10.4 and 10.8 over the last week. C/2016 M1 is located deep in the southern sky this month as it moves through Octans (Jan 1-17) and Hydrus (17-31).
 
C/2016 M1 (PANSTARRS)


T = 2018-Aug-10  q = 2.21 AU   Long-Period comet - dynamically old


    Date     Mag    R.A.   Decl.     r       d    Elong  const
2019-01-01  11.4   20 52  -86 11   2.746   3.036    63    Oct
2019-01-06  11.5   23 01  -85 42   2.779   3.043    65    Oct
2019-01-11  11.5   00 28  -84 18   2.812   3.051    66    Oct
2019-01-16  11.6   01 21  -82 25   2.846   3.060    68    Oct
2019-01-21  11.7   01 55  -80 19   2.880   3.072    69    Hyi
2019-01-26  11.8   02 18  -78 05   2.915   3.085    70    Hyi
2019-01-31  11.9   02 37  -75 47   2.950   3.101    72    Hyi
2019-02-05  11.9   02 51  -73 26   2.986   3.120    73    Hyi

 

C/2018 L2 (ATLAS) - This comet has been lurking low in the evening sky for the past few months. Considering its brightness of 9-10th magnitude, it has been poorly observed. J. J. Gonzalez has routinely placed the comet between magnitude 9.2 and 9.7 in December. Other observations submitted to COBS span between 9.8 to 11.8 since November. I know I tried to observe it on a couple of nights without success. Then again from my home, it was located deep in the light pollution of Tucson. Comet ATLAS is a dynamically old long-period comet which may explain the issue some have with seeing it as dynamically old LPCs are prone to possessing large, low surface brightness, gaseous comae.
 
Comet ATLAS passed perihelion on 2018 December 2 at a distance of 1.71 AU from the Sun. The magnitude predictions below are uncertain due to the large reported scatter and may be a magnitude too faint.  Complicating things further, C/2018 L2 will be moving against the dense Milky Way star field of Hercules (Jan 1), Sagitta (1-8) and Vulpecula (8-31).
 
C/2018 L2 (ATLAS)


T = 2018-Dec-02  q = 1.71 AU   Long-Period comet - dynamically old


    Date     Mag    R.A.   Decl.     r       d    Elong  const
2019-01-01  10.5   18 55  +18 45   1.754   2.358    41    Her
2019-01-06  10.6   19 10  +20 29   1.770   2.355    43    Sge
2019-01-11  10.7   19 26  +22 15   1.787   2.356    44    Vul
2019-01-16  10.9   19 42  +24 00   1.807   2.361    45    Vul
2019-01-21  11.0   19 58  +25 46   1.829   2.371    45    Vul
2019-01-26  11.2   20 15  +27 29   1.852   2.386    46    Vul
2019-01-31  11.4   20 32  +29 11   1.878   2.406    47    Vul
2019-02-05  11.7   20 49  +30 49   1.905   2.430    47    Cyg

 
Other Comets of Interest
  
(944) Hidalgo  - Large dormant comet (944) Hidalgo is still near its peak brightness this month. CCD observers are asked to look for any sign of comet activity. 

 

(944) Hidalgo


T = 2018-Oct-26  q = 1.95 AU   Extinct comet       Period = 13.8 yr


    Date     Mag    R.A.   Decl.     r       d    Elong  const
2019-01-01  14.4   13 27  +78 49   2.057   1.494   110    Cam
2019-01-06  14.4   13 30  +79 18   2.073   1.506   111    Cam
2019-01-11  14.5   13 29  +79 49   2.090   1.519   111    Cam
2019-01-16  14.5   13 22  +80 20   2.108   1.534   111    Cam
2019-01-21  14.5   13 08  +80 49   2.127   1.550   112    Cam
2019-01-26  14.6   12 48  +81 11   2.147   1.568   112    Cam
2019-01-31  14.6   12 21  +81 21   2.168   1.588   112    Cam
2019-02-05  14.6   11 49  +81 15   2.189   1.610   112    Cam

  
C/2018 W1 (Catalina) - As surmised in last month’s update, A/2018 W1 is actually an active comet. Observations taken on December 8 by Karen Meech and Jan Kleyna with the 3.5-m Canada-France-Hawaii Telescope on Mauna Kea found this object to possess a coma. Now designated C/2018 W1 (Catalina), this Halley-family comet will reach perihelion on 2019 May 11 at 1.36 AU from the Sun and 1.67 AU from Earth in late June. The comet should peak at 16th magnitude.

 

New Discoveries

 

P/2018 Y2 (Africano) - Brian Africano discovered this 19th magnitude comet on December 31 with the Mount Lemmon 1.5-m during the course of the Mount Lemmon Survey (which is part of the Catalina Sky Survey). This is the third comet named for Africano (the others being C/2018 V4 and C/2018 W2). Pre-Discovery observations by the Mount Lemmon Survey and the Purple Mountain Observatory were also found from earlier in December. The comet passed perihelion on December 20 at 3.87 AU. Its orbital period is 20.6 years. The comet should get no brighter this apparition.

 

C/2018 Y1 (Iwamoto) - See more on this bright amateur discovery above.

 

C/2018 X3 (PANSTARRS) - The Pan-STARRS2 telescope was used to discover this 20th magnitude comet on December 12. Pre-discovery observations by Pan-STARRS2 were also found from October and November. C?2018 X3 reached perihelion on December 30 at 2.70 AU. It is on a 43.8 year period orbit and will not get any brighter this return.

 

C/2018 X2 (Fitzsimmons) - Alan Fitzsimmons found C/2018 X2 on Nov. 8.5 UT with the "Asteroid Terrestrial-impact Last Alert System" (ATLAS) 0.5-m f/2 Schmidt reflector on Haleakala. At discovery the comet was 19th magnitude. This long-period comet should brighten to 17th magnitude as it approaches its 2019 July 8 perihelion at 2.13 AU from the Sun.

 

As always, the Comet Section is happy to receive all comet observations, whether images, drawings, magnitude estimates, and even spectra. Please send your observations via email to < carl.hergenrother @ alpo-astronomy.org >.
- Carl Hergenrother (ALPO Comet Section Coordinator)


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#2 Special Ed

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Posted 06 January 2019 - 09:09 AM

Thanks for all the info, Carl!  smile.gif 



#3 Cometman

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Posted 15 January 2019 - 09:55 PM

Carl came on The Observers Notebook Podcast to talk about Comets for 2019!

 

https://soundcloud.c...-comets-of-2019




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