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ALPO Comet News for September 2019

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#1 Carl H.

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Posted 02 September 2019 - 04:08 AM

ALPO COMET NEWS FOR SEPTEMBER 2019
 


 

2019-September-2
 


 

Finally, a bright comet is easily observable. OK, bright is a relative term as the bright comet in question, C/2018 W2 (Africano), will only brighten to around magnitude 8.5. But that’s bright compared to the comets of the past few months. September will also see comet C/2017 T2 (PANSTARRS) reach 12th magnitude. PANSTARRS will become brighter and remain a small telescope target throughout much of 2020.

 

Bright Comets (magnitude < 10.0)
   


 

C/2018 W2 (Africano) - September sees comet C/2018 W2 (Africano) at its best. The comet was discovered back on 2018 November 27 by Brian Africano with the Mount Lemmon 1.5-m reflector. Over the next few weeks, it reaches perihelion (2019 September 5 at 1.45 au) and its minimum distance to Earth (September 27 at 0.49 au). In August, my magnitude predictions were about a magnitude too bright. J.J. Gonzalez and I observed Africano to be between magnitude 9.8 and 10.1 during the last week of August. We also both saw the comet to have a diffuse 4’-5’ coma with little central condensation. Looking at all the visual observations submitted to the COBS website over the last week of August, the range of magnitudes were between 9.8 and 11.2. Coma diameters ranged between 2’ and 9’. No one has yet to report a visually observable tail, though CCD observers have reported tails with lengths up to 2.3’ in length.

 

The comet should brighten from around magnitude 10.0 on the 1st to 9.0 at mid-month and peak around 8.5 at the time of closest approach. Northern observers have the best view for most of the month. The brightening is mainly due to the rapidly decreasing Earth-comet distance (0.97 au on the 1st to 0.49 au on the 27th). After the 27th, the comet should start a rapid fade as it moves away from both the Sun and Earth. Southern hemisphere observers will get there first glimpse of the comet towards the second half of September. By the end of the month, it should be an easy object for both hemispheres. The comet can be seen moving through the constellations of Perseus (Sep 1-8), Andromeda (8-20), Pisces (20-21), Andromeda (21-25), Pegasus (25-29), and Pisces (29-30).

 

C/2018 W2 (Africano)


T = 2019-Sep-05  q = 1.45 au                                     Max El
Long-Period comet - dynamically old                               (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S


2019-09-01   9.9   03 16  +55 08   1.456   0.974    94    Per    73    0
2019-09-06   9.6   02 48  +52 54   1.455   0.846   102    Per    77    0
2019-09-11   9.2   02 14  +49 08   1.457   0.725   113    And    81    1
2019-09-16   8.9   01 33  +42 49   1.462   0.619   126    And    87    7
2019-09-21   8.6   00 50  +32 47   1.471   0.537   143    Psc    83   17
2019-09-26   8.5   00 07  +18 52   1.483   0.496   162    Peg    66   34
2019-10-01   8.6   23 28  +03 23   1.498   0.508   165    Psc    51   49
2019-10-06   9.0   22 57  -10 09   1.517   0.569   149    Aqr    38   62

 

Faint Comets (between magnitude 10.0 and 13.0)

29P/Schwassmann-Wachmann - Outbursting comet 29P/Schwassmann-Wachmann has been between magnitude 11 and 14 since May. 29P is dynamically a Centaur object (defined as an object with an orbit entirely between Jupiter and Neptune). This month it is slowly moving through Pisces as it approaches its October opposition.

 

29P/Schwassmann-Wachmann


T = 2019-Mar-07  q = 5.77 au                                     Max El
Centaur comet - 14.8 yr orbital period                            (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S


2019-09-01  11-13? 00 56  +16 19   5.773   4.986   137    Psc    66   34
2019-09-06  11-13? 00 55  +16 18   5.773   4.938   142    Psc    66   34
2019-09-11  11-13? 00 53  +16 15   5.773   4.897   147    Psc    66   34
2019-09-16  11-13? 00 51  +16 09   5.774   4.862   152    Psc    66   34
2019-09-21  11-13? 00 49  +16 03   5.774   4.833   157    Psc    66   34
2019-09-26  11-13? 00 47  +15 54   5.775   4.811   162    Psc    66   34
2019-10-01  11-13? 00 44  +15 44   5.775   4.797   166    Psc    66   34
2019-10-06  11-13? 00 42  +15 33   5.775   4.790   169    Psc    66   34

 

260P/McNaught - Rob McNaught discovered 260P/McNaught on 2012 May 20 with the 0.5-m Uppsala Schmidt during the course of the Siding Spring Survey. With an orbital period of ~7 years (currently 6.9 years), the comet is making its 3rd observed return. It peaked between magnitude 11 and 12 during its last return in 2012. This year’s return is very similar with a slightly smaller minimum Earth-comet distance (0.56 vs 0.58 au) and smaller perihelion distance (1.42 vs 1.50 au). A recent observation on August 28 by Chris Wyatt placed 260P at magnitude 12.6. The comet may brighten by a further ~0.5 magnitudes by the end of the month as it passes perihelion on September 9 and approaches its minimum distance to Earth on October 3. September sees the comet in the morning sky as it moves through Aries (Sep 1-17), Triangulum (17-22), and Perseus (17-30). Since it will be traveling north it may become a difficult object for southern observers as the month progresses.

 

260P/McNaught


T = 2019-Sep-09  q = 1.42 au                                     Max El
Short-Period comet - 6.9 year period                              (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S


2019-09-01  12.5   02 18  +21 06   1.420   0.628   118    Ari    71   29
2019-09-06  12.3   02 26  +24 14   1.417   0.610   120    Ari    74   26
2019-09-11  12.2   02 32  +27 22   1.417   0.594   122    Ari    78   22
2019-09-16  12.1   02 38  +30 27   1.418   0.582   124    Ari    81   19
2019-09-21  12.1   02 43  +33 28   1.422   0.572   126    Tri    84   16
2019-09-26  12.0   02 47  +36 21   1.428   0.566   128    Per    86   14
2019-10-01  12.0   02 50  +39 03   1.436   0.563   131    Per    89   11
2019-10-06  12.1   02 51  +41 32   1.447   0.562   133    Per    88    8

 

C/2017 T2 (PANSTARRS) - C/2017 T2 (PANSTARRS) will be a common sight in the ALPO Comet News for the rest of the year and most of 2020. C/2017 T2 (PANSTARRS) was discovered on 2017 October 7 with the Pan-STARR1 telescope on Haleakala, Maui, Hawaii. At discovery the comet was 20th magnitude and 9.3 au from the Sun which is close to the distance of Saturn. Perihelion happens on 2020 May 4 at 1.62 au. Unfortunately, it never gets very close to Earth. Closest approach occurs on 2019 December at 1.52 au. By the time of perihelion, the comet will be 1.69 au from Earth.

 

Over the past 2 weeks, most observers have the comet between magnitude 13.5 and 14.0. This month the comet starts around 3.4-3.5 au from the Earth and Sun. By the end of the month, it will be 3.15 au from the Sun and 2.78 au from Earth. The decreasing heliocentric and geocentric distances should cause C/2017 T2 to brighten from magnitude ~13.3 to ~12.5. Looking forward, this object should reach magnitude 8 or 9 next summer.

 

Note, a few observers have been reporting this comet to be much brighter, in some cases as bright as magnitude 8.7. I’m not sure what to make of these estimates. Such a bright comet should be easily visible to more observers. The bright estimates may have lead to predictions of this comet peaking at 3rd magnitude next summer. Until the bright estimates are confirmed by others, I’ll be sticking with the predicted magnitudes shown below.

 

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


2019-09-01  13.3   05 19  +22 41   3.440   3.518    77    Tau    51   23
2019-09-06  13.2   05 23  +23 22   3.392   3.396    81    Tau    55   23
2019-09-11  13.0   05 26  +24 06   3.344   3.272    85    Tau    60   23
2019-09-16  12.9   05 29  +24 52   3.297   3.149    89    Tau    64   22
2019-09-21  12.8   05 32  +25 41   3.249   3.026    93    Tau    68   22
2019-09-26  12.7   05 34  +26 34   3.201   2.904    97    Tau    72   22
2019-10-01  12.5   05 36  +27 31   3.153   2.783   102    Tau    76   21
2019-10-06  12.4   05 38  +28 32   3.105   2.664   106    Tau    78   21

 

C/2018 N2 (ASASSN) - Comet C/2018 N2 (ASASSN) was discovered over ~1 year ago on 2018 July 7 by the All-Sky Automated Survey for Supernovae (ASAS-SN) program. Since discovery, ASASSN has brightened at a very slow rate and that’s unlikely to change. ASASSN is still inbound towards a November 11 perihelion at a rather distant 3.12 au. During the last week of August reports to COBS ranged between magnitude 11.5 and 12.4 with most being fainter than 12.0.  Chris Wyatt estimated its brightness at magnitude 12.3 on August 28. This month, C/2018 N2 is a morning object in Aries (Sep 1-15) and Triangulum (15-30).

 

C/2018 N2 (ASASSN)


T = 2019-Nov-11  q = 3.12 au                                     Max El
Long-Period comet - dynamically old                               (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S


2019-09-01  12.3   02 33  +23 29   3.200   2.650   114    Ari    74   26
2019-09-06  12.2   02 29  +24 57   3.190   2.572   119    Ari    75   25
2019-09-11  12.1   02 24  +26 25   3.180   2.500   124    Ari    77   23
2019-09-16  12.0   02 18  +27 54   3.172   2.434   129    Tri    78   22
2019-09-21  12.0   02 11  +29 22   3.164   2.375   134    Tri    79   21
2019-09-26  11.9   02 02  +30 48   3.156   2.324   139    Tri    81   19
2019-10-01  11.9   01 53  +32 11   3.150   2.282   144    Tri    82   18
2019-10-06  11.8   01 43  +33 29   3.144   2.250   148    Tri    84   16

 

C/2019 A9 (PANSTARRS) - Every once in awhile we get surprised and a comet becomes quite a bit brighter than originally predicted. C/2019 A9 (PANSTARRS) is just such a comet. This comet has an orbital period of ~240 years and passed perihelion back on July 26 at 1.43 au. Closest approach to Earth is on September 3 but at a distant 1.92 au. A few observers have been keeping an eye on C/2019 A9 and reporting a brightness between magnitude 10.8 and 12.3 in August. The comet should fade this month as it is past perihelion and soon to be moving away from Earth as well. Only southern observers will be able to see C/2019 A9 as moves through Vela (Sep 1-25) and Centaurus (25-30).

 

C/2019 A9 (PANSTARRS)


T = 2019-Jul-26  q = 1.43 au                                     Max El
Long-Period comet - dynamically old                               (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S


2019-09-01  12.5   09 08  -38 42   1.516   1.918    51    Vel     0   28
2019-09-06  12.7   09 28  -42 28   1.541   1.917    53    Vel     0   28
2019-09-11  12.9   09 49  -46 06   1.568   1.924    54    Vel     0   29
2019-09-16  13.1   10 13  -49 32   1.598   1.941    55    Vel     0   29
2019-09-21  13.4   10 39  -52 41   1.630   1.968    55    Vel     0   28
2019-09-26  13.7   11 08  -55 28   1.664   2.004    55    Cen     0   27
2019-10-01  14.0   11 39  -57 48   1.699   2.049    55    Cen     0   26
2019-10-06  14.3   12 12  -59 41   1.737   2.101    55    Cru     0   25

 

Fainter Comets of Interest (probably fainter than magnitude 13.0)

 


P/2008 Y12 = P/2014 K3 (SOHO) - P/2008 Y12 has a very small perihelion distance of 0.065 AU. Since it has only been seen when at its closest to the Sun (in fact only within a day or two of its 2008 and 2014 perihelia), we have no idea how bright it is when further from the Sun. Quite a few sites are showing this comet as currently bright and observable. I believe that many are using the MPC magnitude parameters which are probably not valid. The predictions published by Astro-Vanbuitenen (http://astro.vanbuitenen.nl/comets) are probably much closer to reality.

 

I am not aware of any successful observations of this comet in 2019. Still this is a good apparition and P/SOHO may be bright enough to be seen in a large telescope + CCD. Since its brightness is such a big unknown it may be worth trying to image it this month in the hopes that it is brighter than anticipated. It will be a much better placed object for southern hemisphere observers as it moves through Scorpius (Sep 1-4), Libra (4-25), and Virgo (25-30) in the evening sky. Near perihelion it will be too close to the Sun to be seen from the ground, but we may be able to watch with the SOHO coronagraphs around the time of perihelion on October 9-10.

 

P/2008 Y12 is a member of the 'Machholz Complex' named after comet 96P/Machholz (yes, as in Don Machholz, former ALPO Comet Section coordinator). This complex is made up of related objects that most likely originated from a single progenitor some time in the past. In addition to P/2008 Y12, the Machholz complex also consists of an asteroid (now 2003 EH1, but may have been observed as comet C/1490 Y1), lots of meteor showers (Quadrantids, daytime Arietids, Northern δ-Aquariids, Southern δ-Aquariids, November ι-Draconids, December α-Draconids, daytime λ-Taurids, θ-Carinids, κ-Velids) and other comets (96P/Machholz and all of the Marsden and Kracht comet groups). P/2008 Y12 has an orbit that closely matches the Southern δ-Aquariids meteors and may be that shower’s parent comet.
 
P/2008 Y12 (SOHO)


T = 2019-Oct-10  q = 0.065 au                                    Max El
Short-Period comet                                                (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S


2019-09-01   ???   16 10  -27 29   1.184   0.660    87    Sco    13   65 
2019-09-06   ???   15 48  -24 54   1.085   0.674    77    Lib    11   56 
2019-09-11   ???   15 28  -22 16   0.980   0.690    67    Lib     9   46 
2019-09-16   ???   15 09  -19 37   0.868   0.706    57    Lib     6   36 
2019-09-21   ???   14 51  -16 53   0.748   0.723    48    Lib     4   26 
2019-09-26   ???   14 32  -13 59   0.617   0.739    37    Vir     0   16 
2019-10-01   ???   14 09  -10 46   0.470   0.760    26    Vir     0    4 
2019-10-06   ???   13 40  -07 07   0.298   0.798    14    Vir     0    0

 

New Discoveries, Recoveries and Other Comets in the News

 

P/2019 O1 = P/2014 U4 (Kowalski) Recovery - Hirohisa Sato used a iTelescope.net 0.51-m at Siding Spring to recover this comet on July 27 and 28 UT. The comet was magnitude 20 with a stellar appearance. Perihelion occurs on 2019 October 11 at 1.12 au. At that time, it may be as bright as magnitude 17. This is P/Kowalski’s first return since its 2014 discovery apparition.

 

P/2019 P1 = P/2010 U2 (Hill) Recovery - Krisztian Sarneczky used the Konkoly Observatory 0.60-m Schmidt telescope to recover this 20th magnitude comet on August 2 and 7 UT. Comet Hill was discovered by ALPO Solar Section Coordinator Rik Hill back in November of 2010 with the Catalina Sky Survey Schmidt telescope. This apparition the comet arrives at perihelion on 2019 September 14 at 2.57 au. It reached 18th magnitude during its discovery apparition, it is expected to reach a similar peak brightness this time around.

 

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 >.


- Carl Hergenrother (ALPO Comet Section Coordinator)


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#2 Rich (RLTYS)

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Posted 04 September 2019 - 06:38 PM

Thanks again for your comet news. waytogo.gif



#3 Zorbathegeek

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Posted 04 September 2019 - 07:04 PM

Thanks for another great update Carl. I've noticed that a lot of the estimated magnitudes submitted to COBS over the past week have had C/2018 W2 (Africano) around half to a full magnitude fainter than your last submission. Obviously, I'm hoping your estimate is closer to the mark. 

 

Also, I know it's a long way off, but to my amateur analysis of the data I've looked at, it appears that 2017 K2 (Panstarrs) is currently running almost 2 magnitude brighter than estimates. 

 

Cheers, Ray.



#4 Carl H.

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Posted 05 September 2019 - 06:08 AM

Ray, good observation. Jacob Cerny has provided the only visual magnitude estimates for C/2017 K2 and they are ~1-2 magnitudes brighter than the CCD measurements. It'll be interesting to see if other visual observers start seeing it as bright.

 

There is still a large scatter for C/2018 W2. Since 9/1, visual observations have ranged from 9.5 to 10.9. While my prediction is contained within that range, I'm wondering if it is still too optimistic.



#5 Carl H.

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Posted 11 September 2019 - 03:52 PM

New interstellar comet discovery!!!

 

C/2019 Q4 (Borisov) is a 17th magnitude comet discovered by Gennady Borisov with an eccentricity of ~3. This makes it the second interstellar object, after 1I'Oumuamua, and the first definite interstellar comet. Discovery announcement at https://minorplanetc...K19/K19RA6.html . Not quite sure why this comet gets a C/ designation and not an I/ designation.

 

Image by Gennady Borisov posted by Artyom Novichonok on comets-ml

https://astronomy.ru...h=1205630;image

 

The comet has already been extensively discussed on both the comets-ml and MPML lists:

 

MPML thread

https://groups.yahoo...35229?reverse=1

 

comets-ml thread

https://groups.yahoo...27945?reverse=1


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#6 goodricke1

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Posted 12 September 2019 - 05:53 AM

It seems amazing that the first true interstellar comet was discovered by a backyard amateur with a home-made telescope, rather than by the major surveys.


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#7 Carl H.

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Posted 12 September 2019 - 03:47 PM

But what a home-made telescope! 0.65-m f/1.5 astrograph!

 

See picture of his setup at

 

https://www.skyandte...headed-our-way/

 

Perihelion is on December 10 at 1.94 au. Looks like this comet will peak at magnitude 14.5 to 15 around the time of perihelion.


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#8 goodricke1

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Posted 12 September 2019 - 06:15 PM

Yes it's an impressive piece of kit admittedly!



#9 Rich (RLTYS)

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Posted 13 September 2019 - 06:51 AM

An amazing looking telescope. drool5.gif



#10 Carl H.

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Posted 13 September 2019 - 11:07 AM

Here's an ephemeris for C/2019 Q4 (Borisov) through the end of the year. For the magnitudes, I'm using the brightness parameters suggested by Dan Green on CBET 4666 (H = 11.0, 2.5n = 8.0) which have it brightening to magnitude 14.8 in December. The comet's actual rate of brightening may be different.

 

Northern hemisphere observers can see the comet already though it will start to get towards the end of the year. Southern observers will be able to start seeing the comet in late October, early November.

 

C/2019 Q4 (Borisov)
T = 2019-Dec-09  q = 1.97 au                                     Max El
Interstellar comet                                                (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S


2019-09-11   17.2  08 49  +30 14   2.768   3.423    42    Cnc    25    0
2019-09-16   17.0  08 58  +28 38   2.694   3.313    44    Cnc    27    0
2019-09-21   16.9  09 07  +26 56   2.622   3.204    46    Cnc    29    0
2019-09-26   16.7  09 17  +25 06   2.553   3.096    48    Cnc    31    0
2019-10-01   16.5  09 26  +23 09   2.486   2.990    51    Leo    33    0
2019-10-06   16.4  09 35  +21 04   2.421   2.886    53    Leo    34    0
2019-10-11   16.2  09 44  +18 50   2.360   2.785    55    Leo    36    2
2019-10-16   16.0  09 54  +16 28   2.303   2.686    57    Leo    38    4
2019-10-21   15.9  10 03  +13 56   2.249   2.591    59    Leo    39    6
2019-10-26   15.7  10 12  +11 14   2.198   2.501    61    Leo    40    8
2019-10-31   15.6  10 21  +08 23   2.152   2.414    62    Leo    41   10
2019-11-05   15.4  10 30  +05 22   2.111   2.333    64    Sxt    41   13
2019-11-10   15.3  10 39  +02 10   2.074   2.258    66    Sxt    41   15
2019-11-15   15.2  10 48  -01 10   2.043   2.189    68    Sxt    40   18
2019-11-20   15.1  10 56  -04 40   2.017   2.126    70    Leo    39   21
2019-11-25   15.0  11 05  -08 18   1.997   2.071    71    Crt    37   25
2019-11-30   14.9  11 14  -12 03   1.982   2.023    73    
Crt    35   28
2019-12-05   14.8  11 22  -15 53   1.974   1.983    75    
Crt    32   32
2019-12-10   14.8  11 31  -19 47   1.972   1.951    76    
Crt    29   36
2019-12-15   14.8  11 39  -23 42   1.975   1.927    78    
Crt    26   41
2019-12-20   14.8  11 48  -27 36   1.985   1.911    79    Hya    22   45
2019-12-25   14.8  11 56  -31 27   2.001   1.903    81    Hya    18   50
2019-12-30   14.8  12 04  -35 13   2.023   1.901    82    Hya    14   54
2020-01-04   14.9  12 11  -38 52   2.050   1.907    83    Cen    11   59



#11 Zorbathegeek

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Posted 29 September 2019 - 10:34 PM

According to my daily look at the COBS home page, it looks as though someone has recovered c/2008 Y12 (SOHO) at 9.5 magnitude. It would be great if someone has detected this from the ground. 



#12 Carl H.

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Posted 30 September 2019 - 10:53 AM

Zorba, I see two non-detections listed on COBS for C/2008 Y12. The '[' before the magnitude means the given brightness is an upper limit. So no C/2008 Y12 down to magnitude 9.5 on September 29.93. Guess we'll have to wait till it shows up in the SOHO coronagraphs. 



#13 Zorbathegeek

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Posted 30 September 2019 - 09:09 PM

Thanks Carl. I've learnt something new. I just thought there was an unusual number of bad typists submitting to COBS! 

 

Ray.


Edited by Zorbathegeek, 30 September 2019 - 09:10 PM.


#14 Stu Todd

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Posted 02 October 2019 - 06:03 AM

I was using a fresh ephemerides download for comets in CdC today and I have my limit set to 12th mag. 

Africano showed up, as well as 289P/Blanpain, curving its way through Aquarius at 8th magnitude!

 

I had a look elsewhere and 289P is nowhere near 12th magnitude at the moment. 

 

Does the MPC sometimes produce duff data or perhaps a typo at their end. I haven't come across this before.

 

Stu



#15 Carl H.

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Posted 02 October 2019 - 06:37 PM

Yes, the MPC magnitude parameters can be off sometimes. 289P has experienced some major outbursts in the past and I think that's skewing some of the parameters. 

 

The most recent observations on COBS (https://www.cobs.si/recent, Kevin Hill on Sept. 27.96 UT) has the comet at magnitude 17.7.


  • Stu Todd likes this

#16 Stu Todd

Stu Todd

    Sputnik

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  • Posts: 42
  • Joined: 14 Feb 2016
  • Loc: Southern New Zealand

Posted 03 October 2019 - 03:46 AM

Thanks Carl, great link too!




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