Current comet magnitude parameters


Standard parameters:

Comet	 	Update	 H1	 K1	Period used
	  2P    170314	10.2	 9.6	1937 - 2017
	  4P    170914   8.5	 8.0	1932 - 2015
	  6P	211103	 9.5	[30]	2021		Linear
	  8P	220103	 7.5	 8.1	2021
	  9P	231214	 7.2	20.7	1972 - 2022
	 10P	180401	 6.8	16.6	1967 - 2016	Linear
	 11P	210105	13.3U	[20]
	 12P	241003	 5.2	 8.9			Poor fit due to outbursts
	 13P	241003	 2.6	21.9			Currently a mag brighter than mean curve
	 15P	170914	 8.1	14.3	1960 - 2015	Linear
	 16P	170914	 6.3	23.5	1932 - 2015
	 19P	231214	 8.0	13.9	1981 - 2022
	 21P	190204	 9.4U	14.6
	 22P    180401	 6.0	14.5	1945 - 2015
    	 24P	180301	 7.9U	21.9
	 26P	10208	11.9	12.1	1947 - 2013
	 32P	170914	 7.9	11.3	1969 - 2015
	 37P	181002	 7.3U	16.6
	 38P	190303	 9.4U	 [5]
	 40P	170914	 5.2	27.2	1992 - 2015
	 41P	170703	10.9U	26.0
	 43P	181204	 6.7	16.5	1951 - 2017
	 44P	180401	10.1	 7.6	1947 - 2015
	 45P	181204	11.3	13.6	1954 - 2017
	 46P	201003	 8.6	16.0	1986 - 2018
	 47P	120229	 5.3	[15]
	 48P	181031	 8.5U	[10]
	 51P	120229	10.4	[10]
	 52P	 	 6.8	[15]
	 53P	160831	 5.9U	15.2
	 55P	 	 8.5	26.7
	 56P	161115	 9.1U	[10]
	 58P	200902	 6.3U	[15]
	 59P	201003	11.0	[10]			Secular fade
	 60P	201003	11.3	 7.3	2012 - 2018	Linear
	 62P	240404	 7.9	22.0
	 63P	130801	 8.1U	[10]
	 64P	Linear
   	 65P	170801	 7.8U	 9.3
	 66P	180901	 7.9U	24.3
	 67P	180401	 9.8	 4.8	1982 - 2016	Linear
	 68P	200930	 6.8	18.8	1976 - 2019	
	 69P		 8.1 	 7.5
	 70P	170914	11.5	 7.5	1985 - 2015	Linear
	 71P	230502	 2.2	35.9
	 73P	221102	10.9U	18.2			Linear
	 74P	201003	 6.8	10.0	1992 - 2018
	 76P	200930	11.4	[21]	1975 - 2019	Secular fade
	 77P	181204	 5.7	17.1	1986 - 2016	
	 78P    200930	 4.6	17.1	1997 - 2020	Linear
	 81P	181204	 6.6	12.3	1978 - 2017
	 82P	120229	10.4	[10]
	 84P	170208	 7.3	18.5	1985 - 2014
	 88P    180401	 5.4	18.3	1987 - 2015	Linear
	 93P	071118	 8.7	18.5
	 94P	181204	 9.6	13.1	1984 - 2017
	 96P	161224	15.2	11.8	1986 - 2012
        102P    131128  11.9U   [10]
	103P	Linear
	104P	181204	 9.6	 9.9	1991 - 2017
	106P	000118	12.7U	 [5]
	108P	170914	 7.9	16.3	1985 - 2015
	110P	120229	 6.9	[10]
	110P	170914	 6.2	15.1	1988 - 2015
	114P    000411	 8.9U	28.9
	116P	181204	 5.6	13.4	1990 - 2016
	117P    220801	 3.3U	18.2
	118P	181204	 7.1	14.1	1996 - 2017
	123P	190603	 6.8	16.5
	124P	170914	14.1	 6.5	1991 - 2014
        128P		 6.3	[15]
        132P		10.3	[15]
	141P	180401	11.9	22.3	1994 - 2015
	144P	240404	 2.0	62.1			Linear
	154P	170208	 6.7	14.7	1992 - 2014
	161P	050731	 9.0	[10]
	162P	210105	14.1	[10]
	168P	130115	10.3U	 6.7
	177P	070102	 9.1	16.8
	185P	230731	12.0	[10]
	193P	120229	11.4	[10]
	201P	120229	12.7	[10]
	204P	120229	 9.9	[10]
	210P    090328	12.9U	 5.3
	216P	120229	12.4	[10]
	217P	171130	 9.9U	10.7
	218P	150517	13.9U	[10]
	222P	090928	16.4U	[15]
	226P	240102	11.9	[10]
	237P	230830	 5.2	23.5
	240P	180301	 5.4U	16.0
	246P	210703	 5.4U	15.0
	260P	191231	11.3U	[10]
	262P    130115	 9.4U	[15]
	263P	230403	17.9	[10]
	290P	140306	 1.0U	29.8
	315P	170404	 8.6U	[10]
	318P	151102	 4.6U	[20]
	332P	160301	12.4U	[15]
	333P	160602	10.7U	[20]
	364P	230601	15.6	17.4
	398P	210203	11.7U	[20]
	479P	240703	10.7	25.1
	3200	180109	16.3U	[5]
1995 O1		000411	-0.64	 7.53
1997 BA6	001003	 4.6U	 9.8
1997 D1			 8.0	[7.5]
1997 J2			 5.1	 5.8
1997 T1			 6.6	16.4		
1998 H1			11.0	 5.0
1998 J1			 6.2	 6.3
1998 M5		000411	 6.0U	10.2
1998 P1		991006	 6.7U	 9.9
1998 T1		990830	10.2U	 4.5
1998 U5		9905xx	 7.8U	19.6
1998 W1			11.7	[10]
1999 H1		000411	 6.7U	11.5
1999 H3		000630	 4.1U	12.5
1999 J2		011007	-1.2U	13.4
1999 J3		000411	 9.0U	11.8
1999 K5		001127	 6.7U	 8.2
1999 K8		001127	-2.8U 	20.8
1999 L3		000411	 2.7U	29.9
1999 N2		000401	 8.6U	 7.7
1999 S3		000401	 0.7U	39.8
1999 S4		000816	 8.6	 4.4
1999 T1		011007	 6.3U	 9.4
1999 T2		011007	 6.5U 	 8.2
1999 U4		020414	 6.9U	 4.6
1999 Y1		011219	 8.1U	 4.3
2000 SV74	020414	 8.0U	 3.9
2000 W1		010312	10.8U	12.7
2000 WM1	020601	 7.1U	10.6
2001 A2		011007	 7.3U	10.6
2001 HT50	040619	 6.5	 [5]
2001 K5		020619	 5.1 	 5.0
2001 MD7	020414	11.3U	[10]
2001 OG108	020414	10.2U	 5.9
2001 Q2		011202	10.7U	15.5
2001 Q4		050208	 5.7U	 6.6
2001 Q6		020414	 5.5U	41.0
2001 RX14       030519	 7.9U	 7.8
2002 C1		020601	 6.6U	 8.5
2002 E2		020414	 8.0U	[10]
2002 F1		020601	10.6U	18.1
2002 G3		020414	20.7U	22.1
2002 O7		040619	 8.9	 4.2
2002 T7		041213	 5.5U	 6.3
2002 V1		030407	 7.2	 9.5
2002 X5		030407	 7.2	 6.7
2002 Y1		040619	 6.5	 9.5
2003 H1		040619	 4.8	[15]
2003 K4		050420	 4.0U	11.1
2003 T3		040919	 6.6U	 6.9
2003 T4		050420	 7.8U	 6.6
2004 F4		040703	 8.0	 8.1
2004 H6		040718	 7.4	13.2
2004 Q1		050312	 1.5U	27.5
2004 Q2		050901	 5.2U	 9.3
2004 R2		040928	10.1U	 8.2
2005 A1		050731	 8.5U	10.2
2005 E2		060410	 6.8U	 8.5
2005 L3		090818	 5.9U	 [5]
2005 N1		050731	 8.5U	22.9
2006 A1		070102	 7.7	 8.3
2006 L1		070125	 6.7U	15.8
2006 L2		070102	 5.1	14.8
2006 M4		070102	 5.8U	 9.1
2006 OF2	090607	 6.7U	 6.3
2006 P1		071201	 4.4	 9.7
2006 Q1		090328	 4.8U	10.5
2006 S3		140401	 0.2U	12.1
2006 VZ13	071201	 8.2	11.1
2006 W3		101218	-0.7U	14.6
2007 E1		071201	 6.9	25.9
2007 E2		071201	 9.1	 7.6
2007 G1		080901	 0.3U	[20]
2007 H1		071201	 9.0	[10]
2007 N3		090607	 5.5U   10.5
2007 Q3		091205	 2.0U	13.2
2007 T1		080320	 7.4	13.4
2007 W1		081022	 8.6U	 9.6
2008 A1		090328	 5.9U	 8.7
2008 C1		080508	 6.9U	21.3
2008 Q3		090928	-1.1U	32.5
2008 J1		081124	 5.1U	17.6
2008 T2		091205	 6.5U	11.9
2009 F4		131114	 5.7U	 5.2
2009 F6		090928	 6.8U	[12]
2009 G1		090818	 7.6U	 9.3
2009 K5		101103	 6.5U	 6.3
2009 L2		090818	14.5U	[5]
2009 P1		130115	 4.4U	 6.8
2009 R1		100818	 6.7	 7.6
2009 Y1		101218	 3.3U	18.5
2010 G2		120719	 7.8U	 5.0
2010 S1		141001	-9.1U	22.7
2010 X1		110722	 8.1	 9.6
2011 A3		111223	-3.9U	28.6
2011 C1		111223	 9.4U	 4.3
2011 F1		131001	 6.0U	 6.9
2011 J2		131219	 5.1U	 9.5
2011 KP36	170202	-4.1U	19.5
2011 L4		130801	 5.4U	 9.5
2011 M1		111223	 9.5U	17.2
2011 R1		130630	 5.9U	10.5
2011 UF305	130115	-2.6U	34.2
2011 W3		130115	11.4U	17.5
2012 A2		131024	 2.1U	12.4
2012 B1		130630	 6.7U	[10]
2012 F3		150818	 5.0U	10.5
2012 F6		131016	 5.3U	 9.0
2012 J1		130115	 3.2U	[15]
2012 K1		150831	 6.2U	 6.9
2012 K5		130115	10.1U	 6.0
2012 L2		130430	 7.3U	 9.8
2012 S1		131219	 7.3	 6.3
2012 T5		130115	10.0	15.3
2012 V2		131219	 5.3U	10.2
2012 V4		130115	 9.5U	[15]
2012 X1		141216   5.0U	 9.0	Post March 1
2013 A1         150104	 8.7U	 4.8
2013 CU129	131001	15.2U	[10]
2013 E2		130801	 6.9U	15.0
2013 J2		131024	10.1U	[10]
2013 N4		131016	 7.4U	[10]
2013 R1		140629	 6.5U	10.9	Post perihelion
2013 UQ4	140802	11.7U	[10]
2013 US10	160602	 5.6U	 7.4
2013 V1		140116	 9.7U	 9.6
2013 V3		140306	 8.0U	13.4
2013 V5		150104	 8.8U	 5.8
2013 X1		160803	 4.7U	11.0
2014 E2		150104	 7.0U	10.3
2014 L2		141116	 9.1U	[10]
2014 Q1		150831	 7.6U	 9.0
2014 Q2		160301	 4.2U	 6.4	Post perihelion
2014 Q3		150117	 6.9U	[20]
2014 R1		150104	 8.4U	[10]
2014 S2		160803	 6.9U	 3.4
2014 W2		160831	 4.8U	12.2
2014 W11	150416	 7.2U	[10]
2015 C2		150517	 8.9U	[10]
2015 ER61	171130	 7.2U	11.1	Post perihelion
2015 F3		150517	 9.9U	13.5
2015 F4		151016	 5.6U	25.9
2015 F5		150517	11.4U	[10]
2015 G2		150802	 8.2U	 7.1
2015 O1		181201	 4.5U	 9.8
2015 P3		150831	11.8U	[10]
2015 V2		171019	 7.1U	 5.6
2015 VL62	171019	 8.8U	 7.1
2015 WZ		160702	 5.6U	32.9
2016 A8		161002	 7.8U	16.5
2016 M1		181031	 4.3U	10.6
2016 N4		171102	 9.4U	[5]
2016 N6		190204	 4.6U	11.7
2016 R2		190603	 7.8U	 3.6	Variable
2016 U1		170202	11.9U	10.9
2016 VZ18	170404	12.6U	[10]
2017 E1		170511	10.0U	[30]
2017 E4		170511	10.3U	[10]
2017 K2		231202	 5.7	 5.1
2017 M4		190603	 4.2U	12.4
2017 O1		180301	 8.1U	 8.6
2017 S3		181201	 8.7U	 6.3
2017 T1		180301	12.3U	 7.8
2017 T2		201002	 6.2U	 6.9
2017 T3		180801	 8.8	11.3
2018 EF9	180601	 8.6U	[10]
2018 F4		201002	 8.9U	 3.4
2018 L2		190204	 1.7U	25.8
2018 N1		181031	 9.9U	[10]
2018 N2		201002	 6.6U	 6.2
2018 R3		190731	 5.7U	21.7
2018 V1		190102	11.4U	[10]
2018 W1		190603	 8.0U	[15]
2018 W2		191201	 8.3U	11.9
2018 Y1		190402	 7.8U	10.9
2019 D1		190603	10.7U	[10]
2019 L3		230731	-0.9	13.1 currently brighter than mean curve
2019 N1		210304	 7.0U	10.1
2019 T4		230103	 1.3	12.6
2019 U5		230703	 4.1	10.6
2019 U6		201002	 7.5U	17.2
2020 A2		200401	11.2U	10.4
2020 F3		201002	 6.7U	11.6
2020 J1		220304	 7.8U	 5.5
2020 K1		230830	 6.2	 7.9
2020 K8		200902	12.9U	[10]
2020 M3		210202	 9.4U    9.4
2020 N1		210202	14.7U	 [5]
2020 P1		201101	14.2U	17.2
2020 Q1		201002	10.1U	 6.5
2020 R4		210502	 8.7U   18.4
2020 R7		220801	 8.0U	 7.6
2020 S3		210105	 9.1U	10.5
2020 T2		211103	 0.7U	27.3
2020 V2		230830	 4.7	 9.0
2021 A1		220204	 8.1U	11.7
2021 A2		210304	 9.2U	[20]
2021 A4		210304	14.7U	[10]
2021 D1		210501	 8.9U	16.1
2021 E3		220703	 6.2U	13.2
2021 F1		220703	 7.6U	26.6
2021 G2		240404	 5.0	 7.8
2021 O3		220601	13.9U	 3.3
2021 P4		220703	 8.4U	12.2
2021 Q5		211002	11.1U	[10]
2021 S3		240501	 8.5	 5.0
2021 T4		230830	 8.9	 8.0
2021 X1		230203	 9.7	 [5]
2021 Y1		230502	 8.8	10.1
2022 A2		231101	 4.5	15.2
2022 E2		241003	 4.9	 9.7
2022 E3		230703	 6.8	 9.4
2022 JK5	231101	 7.7	[10]
2022 L2		240501	10.7	 4.9
2022 P1		230103	-0.4	45.1
2022 R2		221102	14.2U	[10]
2022 U2		230203	 9.8	[20]
2023 A3		240905	 6.4	 7.8
2023 C2		240905	11.1	 2.1
2023 E1		231001	 7.5	17.3	Discordant observations
2023 H2		240102	10.3	 6.5
2023 P1		231001	 9.0	 8.1
2023 S2		231101	11.5	[10]
2023 S3		240302	12.6	27.0
2023 V4		240703	 8.0	21.4
2024 G3		240802	 8.7	[10]
2024 S1		241003	12.4	[15]
The magnitude of the comet can be obtained from : m = H1 + 5 log d + K1 log r
For periodic comets of multiple apparitions with stable behaviour, mean light curve parameters are given.  
For comets under observation up to 2022 November 30 a U after the H parameter indicates that the 
observed magnitudes have not been corrected for aperture. For comets currently under observation the
Magnitude parameters are calculated for an aperture of 30cm, with no aperture correction applied to
electronic observations.  K1 values in brackets are assumed.

Linear parameters

Comet		Update	H1	L1	dT
	  6P    220204   8.7U	 0.0522	-85	Secular trend
	  7P	210903	12.3U	 0.0320	-47.3	2021
	  8P    080421   6.8U    0.0429 -27.1
	 10P	180401	 8.6	 0.0231	-36.1	1967 - 2016
	 15P	170914	 8.0	 0.0478	-22.8	1960 - 2015
	 21P	201003	 8.7	 0.0283	-14.9	2018
	 38P	190204	10.3U	 0.0043	 29.1
	 41P    120229	 6.1     0.102   18
	 46P    021020   9.5U    0.0273 -31.7	Normal better
	 52P		10.9	 0.0299	 28.5
	 60P	201003	12.9	 0.0115	-55.3	1999 - 2018
	 64P	201003	 8.9	 0.0325	-57.3	1981 - 2018
	 67P	180401	10.1	 0.0157	-49.6	1982 - 2016
	 70P	170914	14.0	 0.0042	-139	1985 - 2015
	 71P	171102	10.5U	 0.0198	-41.2
	 73P	230103	10.3	 0.0285 -73.1
	 78P    200930	 9.4	 0.0113	-27.6	1997 - 2020
	 88P    180401	 7.6	 0.0231 -22.0	1987 - 2015
	 96P	130115	 9.7U	 0.0501	-16
	103P	111223	 9.0U	 0.0416	-26
	104P	220304	10.1U	 0.0640	-15
	141P	000118	11.8U	 0.0379 -21.2
	144P	240404	 9.8	 0.0685	-22.9
	156P	210304	10.1U	 0.0472	-39.7
	185P	130115	 9.8	 0.0375	-18
	217P	120229	 9.4	 0.0180 -32
	252P	181204	 9.2	 0.0895	-39.4
	260P	130115	13.2	 0.0145	-17
	273P	130219	 6.2	 0.0753	-15
1998 K5			16.5	 0.0201	-55.7
1998 U3			 9.8	 0.0151	 46.0
2007 F1		071201	 6.3	 0.0508	 10.3
2007 Q3		100610	 6.2	 0.0156	-44
2009 E1		090704	 7.0	 0.0719	-11.6
2009 K5		101218	 7.0U	 0.0172	-32
2014 S2		160503	 7.6U	 0.0081	-43
2016 R2		181031	 8.7U	 0.0028	196
2017 O1		180201	 8.8U    0.0233	 60
2019 U6		200702	 5.8U	 0.0711	 13.9
2019 Y1		200702	 6.9U	 0.0629	-18.7
2019 Y4		200603	 7.4U	 0.1125	 57.7
2020 F8		200603	 6.0U	 0.0931	 24.2
2020 M3		201202	10.0U	 0.0269	-13.1
2023 E1		230830	10.1	 0.0658	-12.0

The magnitude of the comet can be obtained from : m = H1 + 5 log d + L1 abs(t - T + dT)
if L1 is +ve the comet brightens towards perihelion, if dT is +ve the comet is brightest before perihelion.

Where there are insufficient observations to fully determine the r coefficient a value for K is assumed and given in [ ].