My archival search and the discovery of the Kracht group
I started my archival
search 2002 Feb 06 and found my first comet only after two days
Maik Meyer almost immediately suggested from his apparent motion that this comet could be a
member of his proposed comet group. This turned out to be true. The new group (found by Maik
Meyer) and another new group (found by Brian Marsden) were officially announced 2002 Feb 18
My new Feb 08 comet was added to the Meyer group Feb 21 (MPEC 2002-D16) as the seventh
member "as already suggested by M.Meyer on Feb 10 on the basis of preliminary measurements".
I found four more Meyer group comets and four Kreutz group comets from Feb 11 - 24.
On 2002 Feb 27 I found
a non-group comet in SOHO-images of 1999 Jun 30. I compared its
motion with that of the other known non-group comets and found that it moved similar to C/2000 O3.
I announced it as "a possible brother of C/2000 O3". I wrote to Brian Marsden about this and added
(a day later) that the perihelion direction for C/2000 O3 is close to the average value for the members
of the Marsden group. Brian confirmed my results and wrote "A more extended relationship among these
comets is therefore suggested" (MPEC 2002-E18).
I found four Marsden group comets from Mar 03 - 12 . Brian wrote about the first two comets:
"The other two comets, detected by Kracht, are members of the Marsden group, objects that could in fact
have orbits differing significantly from the assumed parabolas. Nevertheless, the objects clearly have orbits
that pass rather close to that of the earth (postperihelion), and D. A. J. Seargent has remarked
on the similarity to that of the Daytime Arietid meteor stream, with q = 0.09 AU and L = 104, B = +10
(degrees, J2000.0; cf. MPEC 2002-E18). Although q is still larger, and there are substantial differences in
the other orbital elements,the L and B values are also similar to those of both comet 96P/Machholz 1 and
the Quadrantid meteor stream". (MPEC 2002-E25)
On 2002 Mar 12 I found C/1999 N6 moving in an orbit similar to that of C/1999 M3 (the comet I had
found Feb 27). Brian wrote "C/1999 N6 [is] a likely member of the more extended population
(cf. MPEC 2002-E18, 2002-E25). Possibly C/1999 N6 is quite closely associated with C/1999 M3
(though not so much with C/2000 O3), but the orbit solution is not unique". (MPEC 2002-F03)
2002 Mar 19 turned out to be a very special day:
While working with the 1999 August SOHO images I found three new comets (one Meyer and a pair of Marsden
group comets) and later noticed that the apparent track of my first SOHO comet (C/2001 Q7, found in realtime
images of 2001 Aug 21) was close to the track of C/1999 M3.
I wrote about this to Maik the next day. He confirmed that C/2001 Q7 could have an orbit between C/1999 M3
and C/2000 O3. Maik gave some useful hints on how to derive an orbit and I could find a new orbit for my first
comet on Mar 21. I computed the new orbit, Brian Marsden accepted the orbit and wrote "Indeed, we could say
that these four comets belong to the Kracht group" (MPEC 2002-F43).
2002 Jul 16/17 I found three new members of the Kracht group C/2001 Q8, R8 and R9.
2002 Jul 22 Brian Marsden computed the orbital elements of C/2001 Q8, R8, R9 and wrote:
"Together with C/2001 Q7 (cf. the orbit on MPC 45182), C/2001 Q8, C/2001 R8 and C/2001 R9 above clearly form
the nucleus of a group (involving also C/1999 M3 and C/2000 O3) whose existence was proposed by R. Kracht
on MPEC 2002-E18; see also MPEC 2002-F03." (MPEC 2002-O35).
2002 Aug 10 The Kracht group is mentioned for the first time on the Circulars of the International Astronomical Union (IAUC 7952):
Further to IAUC 7951, D. Hammer reports measurements for comets
detected on C2 SOHO website images by R. Kracht (C/2001 K11 and V6, Meyer
group; C/2001 Q8, R8 and R9, Kracht group--see MPEC 2002-E18, 2002-E25,
2002-F03, 2002-O35), M. Oates (C/2001 L10, R7 and X10, Meyer group) and X.
Leprette (C/2001 L11, Kreutz group).
2002 Aug 13 I found a
new member of the Kracht group C/2002 N2.
2002 Aug 26 XingMing Zhou found the ninth member of the Kracht group C/2002 Q8
2002 Aug 27 I found the tenth member of the Kracht group C/2002 Q10
2002 Sep 17 Rob Matson found the eleventh member of the Kracht group C/2002 S4
2002 Sep 19 I found the twelfth member of the Kracht group C/2002 S5
2002 Sep 20 Rob Matson found the thirteenth member of the Kracht group C/2002 S7
2002 Sep 30 Toni Scarmato found the fourteenth member of the Kracht group C/2002 S11
It is the brightest Kracht group comet until now.
2003 No Kracht group comet was found.
2004 Jan 15 Tony
Hoffman found the 15th member of the Kracht group C/2004 A3.
2004 Jan 18 XingMing Zhou found the 16th member of the Kracht group C/2004 B3.
2004 May 07 I found the 17th member of the Kracht group C/2004 J4.
2004 May 12 I found the 18th member of the Kracht group C/2004 J12.
2004 May 13 I found the 19th member of the Kracht group C/2004 J13.
2004 May 14 I found the 20th member of the Kracht group C/2004 J15.
2004 May 14/15 Tony Hoffman found the 21th member of the Kracht group C/2004 J16.
2004 May 15 I found the 22th member of the Kracht group C/2004 J17.
2004 May 15 I found the 23th member of the Kracht group C/2004 J18.
2004 Jun 13 I found the 24th member of the Kracht group C/2004 L10.
2005 Nov 23 Bo Zhou found the 25th member of the Kracht group C/2005 W4
Brian Marsden could link it to C/2000 O3 with an orbital period of 5.3 years.
2005 Dec 29 I found two bright Kracht group comets in archival C2/C3 images of 1996 Dec 05/ 06.
These are the 26th and the 27th member of the Kracht group (C/1996 X4 and X5 ).
I found them in a search for the precursors of C/2002 S4/S5/S7/S11.
2006 Jan 02 I found a third Kracht group comet in archival C2 images of 1996 Dec 05/ 06.
This is the 28th member of the Kracht group (C/1996 X3 )
2007 Feb 13 Bo Zhou
found a Kracht group comet in archival C2 images of 2004 May 13.
This is the 29th member of the Kracht group (C/2004 J20).
2007 May 05 Bo Zhou found another Kracht group comet in archival C2 images of 2004 May 13.
It was not confirmed by Karl Battams.
2007 Oct 08 I have found numerous orbital links between the Kracht group comets of 1996 and 2002
and made predictions for their return in 2008. The predictions are at the bottom of this page.
2008 Mar 04 Hua Su
found a Kracht group comet in delayed C2 images of 2008 Mar 03.
This is the 30th member of the Kracht group (C/2008 E4).
I could link it to C/2002 Q8 with an orbital period of 5.5 years.
2008 Apr 13 Bo Zhou found a Kracht group comet in C2 images of April 12/13.
This is the 31th member of the Kracht group (C/2008 G).
I could link it to C/2002 S11 with an orbital period of 5.5 years.
2008 April 22-24 I could link C/1996 N6 with C/2004 J4 and C/1999 M3 with C/2004 J12/20/13/15/16/17/18.
2008 July 04 Tony Hoffman found the 32th Kracht group comet in C2 images (C/2008 N4).
2008 September 06 I found the 33th Kracht group comet in C3 images (C/2008 R7).
2009 May 04 The
nongravitational linkage of C/1996 X3 = 2002 S7 = 2008 N4 shows
that at least some of the Kracht comets are active.
2009 June 07 Tony Hoffman found the 34th Kracht group comet in C2 images of June 06/07 (C/2009 L8).
2009 June 09 I found the 35th Kracht group comet in C2 images of June 09 (C/2009 L13).
2009 October 09 Remeasurements of C/2001 Q7, 2001 Q8, 2002 Q8 and 2002 S5 are published (MPEC 2009-T26/T27)
together with linkages of C/2002 S5 with 1996 X5 and 2008 N4. The linkage of C/2002 S5 with 2008 N4 yields
T = 1996 Dec. 2.5 for the previous return. This is almost four days earlier than expected, so I will stay here with
C/1996 X3 = 2002 S7 = 2008 N4 (MPEC 2009-J14).
2009 December 24 I found the 36th Kracht group comet in delayed C2 images of December 20.
2010 April 30 Aldo
Vitagliano made a new version of EXORB, which allows to precisely
include STEREO observations.
I made 200 Monte Carlo runs with the SOHO and STEREO observations of C/2008 R7 and found an orbital period
of 7.5 ± 3.2 years (the linkage with C/2002 S11 has 5.93 years).
2010 October 23 Rob Matson found the 37th Kracht group comet, visible for 23 hours in C2 and C3. It belongs to the
subgroup of Kracht comets from 1999, 2004 and 2009.
2011 Mar 09 I found the 38th Kracht group comet in realtime C3 images. This is the return of C/2000 O3 = 2005 W4.
2012 Jan 18 Sergei Schmalz found the 39th Kracht group comet in realtime C2 images.
2013 Nov 09 Zhijian Xu found the 40th Kracht group comet in realtime C2 images.
2014 July 24 Arkadiusz
Kubczak found the 41th Kracht group comet in realtime C2 images
2014 August 26 Zhijian Xu found the 42th Kracht group comet in realtime C2 images.
2014 September 12 Zhijian Xu found the 43th Kracht group comet in realtime C3 images.
This is the return of C/2008 R7.
Orbital elements of the Kracht group comets:
|C/1996 X3||1996 12 06.12||0.0491||51.40||50.73||13.62||101.3||10.6||5.80||2450440.5||MPEC 2009-J14||2002 S7 = 2008 N4 = 1996 X3|
|C/1996 X4||1996 12 06.28||0.0491||51.26||50.86||13.65||101.3||10.6||5.79||2450440.5||Kracht||Elements from 1996 X4 = 2002 S4|
|C/1996 X5||1996 12 06.33||0.0490||50.97||51.11||13.66||101.3||10.6||5.79||2450440.5||MPEC 2009-T27||1996 X5 = 2002 S5|
|C/1999 M3||1999 06 30.68||0.0440||66.12||34.67||12.25||100.3||11.2||4.87||2451360.5||Kracht||Elements from 1999 M3 = 2004 J12|
|C/1999 N6||1999 07 12.34||0.0439||66.57||35.17||12.28||101.3||11.3||4.92||2451360.5||Kracht||Elements from 1999 N6 = 2004 L10|
|P/2000 O3||2000 07 30.95||0.0541||48.95||53.55||14.73||101.5||11.1||5.31||2451760.5||MPEC 2011-F14||2000 O3 = 2005 W4 = 2011 E1|
|C/2001 Q7||2001 08 21.84||0.0420||62.51||37.92||14.01||99.7||12.4||2452160.5||MPEC 2009-T26|
|C/2001 Q8||2001 08 24.83||0.0440||58.67||43.44||13.56||101.4||11.6||2452160.5||MPEC 2009-T26|
|C/2001 R8||2001 09 06.68||0.0436||59.60||42.35||13.61||101.2||11.7||5.17||2452160.5||Kracht||2011 R8 = 2012 B|
|C/2001 R9||2001 09 07.32||0.0472||53.31||48.90||12.47||101.6||10.0||2452160.5||MPEC 2002-O35|
|C/2002 N2||2002 07 11.92||0.0490||54.78||52.93||13.80||106.9||11.2||2452480.5||MPEC 2002-Q02|
|C/2002 Q8||2002 08 25.92||0.0492||50.29||52.37||13.40||101.9||10.3||5.52||2452520.5||MPEC 2009-T27||2002 Q8 = 2008 E4|
|C/2002 Q10||2002 08 27.51||0.0481||51.30||50.85||13.64||101.3||10.6||5.63||2452520.5||Kracht||Elements from 2002 Q10 = 2008 G6|
|C/2002 S4||2002 09 18.22||0.0483||51.45||50.70||13.62||101.4||10.6||5.78||2452520.5||Kracht||Elements from 1996 X4 = 2002 S4|
|C/2002 S5||2002 09 19.32||0.0482||51.15||50.95||13.63||101.3||10.6||5.78||2452520.5||MPEC 2009-T27||1996 X5 = 2002 S5|
|C/2002 S7||2002 09 21.07||0.0482||51.58||50.57||13.59||101.4||10.6||5.78||2452520.5||MPEC 2009-J14||2002 S7 = 2008 N4 = 1996 X3|
|C/2002 S11||2002 09 30.34||0.0481||51.66||50.71||13.76||101.6||10.8||5.93||2452560.5||Kracht||Elements from 2002 S11 = 2008 R7|
|C/2004 A3||2004 01 16.16||0.0433||58.54||44.75||14.75||102.4||12.5||2453040.5||MPEC 2004-M04|
|C/2004 B3||2004 01 18.27||0.0515||53.97||44.90||13.28||98.1||10.7||2453040.5||MPEC 2004-M04|
|C/2004 J4||2004 05 05.34||0.0438||67.17||34.56||12.24||101.3||11.3||4.84||2453120.5||Kracht||Elements from 1999 M3 = 2004 J4|
|C/2004 J12||2004 05 12.92||0.0438||66.64||34.12||12.20||100.3||11.2||4.86||2453120.5||Kracht||Elements from 1999 M3 = 2004 J12|
|C/2004 J20||2004 05 13.79||0.0438||67.12||34.48||12.24||101.1||11.3||4.87||2453120.5||Kracht||Elements from 1999 M3 = 2004 J20|
|C/2004 J13||2004 05 13.85||0.0439||66.48||34.34||12.20||100.3||11.2||4.87||2453120.5||Kracht||Elements from 1999 M3 = 2004 J13|
|C/2004 J15||2004 05 14.75||0.0437||67.69||34.88||12.30||102.1||11.4||4.87||2453160.5||Kracht||Elements from 1999 M3 = 2004 J15|
|C/2004 J16||2004 05 15.06||0.0438||67.16||34.55||12.25||101.2||11.3||4.87||2453160.5||Kracht||Elements from 1999 M3 = 2004 J16|
|C/2004 J17||2004 05 15.59||0.0438||67.20||34.57||12.25||101.3||11.3||4.87||2453160.5||Kracht||Elements from 1999 M3 = 2004 J17|
|C/2004 J18||2004 05 15.68||0.0438||66.96||34.43||12.23||100.9||11.2||4.87||2453160.5||Kracht||Elements from 1999 M3 = 2004 J18|
|C/2004 L10||2004 06 14.08||0.0438||67.11||34.61||12.23||101.2||11.3||4.92||2453160.5||Kracht||Elements from 1999 N6 = 2004 L10|
|P/2005 W4||2005 11 23.50||0.0546||49.37||53.11||14.63||101.5||11.1||5.32||2453680.5||MPEC 2011-F14||2000 O3 = 2005 W4 = 2011 E1|
|C/2008 E4||2008 03 03.02||0.0494||50.75||51.95||13.32||101.9||10.3||5.52||2454520.5||MPEC 2009-T27||2002 Q8 = 2008 E4|
|C/2008 G6||2008 04 13.48||0.0483||51.87||50.32||13.55||101.4||10.6||5.63||2454560.5||Kracht||2002 Q10 = 2008 G6|
|C/2008 N4||2008 07 04.38||0.0482||52.39||49.82||13.47||101.4||10.6||5.78||2454640.5||MPEC 2009-J14||2002 S7 = 2008 N4 = 1996 X3|
|C/2008 R7||2008 09 06.60||0.0477||52.78||49.67||13.60||101.7||10.8||5.93||2454720.5||Kracht||Elements from 2002 S11 = 2008 R7|
|C/2009 L8||2009 06 07.43||0.0414||78.17||25.27||11.95||103.2||11.7||2455000.5||MPEC 2009-O21|
|C/2009 L13||2009 06 09.16||0.0438||78.34||20.11||11.27||98.2||11.0||2455000.5||MPEC 2009-O22|
|C/2009 Y10||2009 12 20.37||0.0513||69.10||36.02||12.38||104.7||11.6||2455200.5||MPEC 2010-O30|
|C/2010 U11||2010 10 23.37||0.0442||77.48||24.58||11.80||101.8||11.5||2455492.5||Kracht||e=1|
|P/2010 E1||2011 03 09.84||0.0534||57.26||44.79||13.11||101.4||11.0||5.31||2455640.5||MPEC 2011-F14||2000 O3 = 2005 W4 = 2011 E1|
|C/2012 B||2012 01 19.06||0.0449||74.41||27.13||11.89||101.2||11.4||5.20||2455960.5||Kracht||2001 R8 = 2012 B|
The weights are the lengths of the observed arcs (last obs - first obs).
These identifications show three different subgroups of Kracht group comets. If we choose 2452520.5 as a common epoch, the orbital elements look like this:
|99M3 = 04J12||0.0437||66.46||34.30||12.21||100.3||11.1||4.87|
|99N6 = 04L10||0.0437||66.92||34.81||12.24||101.3||11.2||4.92|
This is the dynamically most evolved subgroup (q and incl decrease with time) with 12 apparitions, 1 C3 comet.
|96X3 = 02S7||0.0482||51.55||50.61||13.58||101.4||10.6||5.78|
|96X4 = 02S4||0.0483||51.45||50.70||13.62||101.4||10.6||5.78|
|96X5 = 02S5||0.0479||50.95||50.86||13.73||101.0||10.6||5.78|
|02Q8 = 08E4||0.0485||50.82||51.56||13.61||101.6||10.5||5.52|
|02Q10 = 08G6||0.0481||51.30||50.85||13.64||101.3||10.6||5.63|
|02S11 = 08R7||0.0481||51.65||50.72||13.76||101.6||10.8||5.93|
This is the middle or main subgroup with 12 apparitions and 8 C3 comets.
|00O3 = 05W4 = 11E1||0.0540||49.06||53.45||14.70||101.6||11.1||5.31|
This is the least evolved subgroup with one comet in 3 apparitions (all in C3).
Images of the Kracht group comets (close to their maximum brightness).
Family tree of the Kracht group comets (with images).
Orbital evolution of Kracht group comets
Are the Kracht/Marsden group comets active?
NEW (2010-07-17): A table of all Kracht group orbits (my linkages with residuals)