List of gravitational wave observations

This page contains a list of observed/candidate gravitational wave events.

The first measurement of a gravitational wave event

Origin and nomenclature

Direct observation of gravitational waves, which commenced with the detection of an event by LIGO in 2015,^[1] plays a key role in gravitational wave astronomy. LIGO has been involved in all subsequent detections to date, with Virgo joining in August 2017.^[2]

Joint observation runs of LIGO and VIRGO, designated "O1, O2, etc." span many months, with months of maintenance and upgrades in-between designed to increase the instruments sensitivity and range. Within these run periods, the instruments are capable of detecting gravitational waves.

The first run, O1, ran from September 12, 2015, to January 19, 2016, and succeeded in its first gravitational wave detection. O2 ran for a greater duration, from November 30, 2016, to August 25, 2017.^[3] O3 began on April 1, 2019, which was briefly suspended on September 30, 2019, for maintenance and upgrades, thus O3a. O3b marks resuming of the run and began on November 1, 2019. Due to the COVID-19 pandemic^[4] O3 was forced to end prematurely.^[5] O4 began on May 24, 2023; initially planned for March, the project needed more time to stabilize the instruments.

The O4 observing run has been extended from one year to 18 months, following plans to make further upgrades for the O5 run.^[2][6] Updated observing plans are published on the official website, containing the latest information on these runs.^[6] There is a two month commissioning break planned from January to March 2024, after which observations will resume for the remainder of O4.^[7]

Gravitational wave events are named starting with the prefix GW, while observations that trigger an event alert but have not (yet) been confirmed are named starting with the prefix S.^[8] Six digits then indicate the date of the event, with the two first digits representing the year, the two middle digits the month and two final digits the day of observation. This is similar to the systematic naming for other kinds of astronomical event observations, such as those of gamma-ray bursts.

Probable detections that are not confidently identified as gravitational wave events are designated LVT ("LIGO-Virgo trigger"). Known gravitational wave events come from the merger of two black holes (BH), two neutron stars (NS), or a black hole and a neutron star (BHNS).^[9][10] Some objects are in the mass gap between the largest predicted neutron star masses (Tolman–Oppenheimer–Volkoff limit) and the smallest known black holes.

List of gravitational wave events

Events from LIGO & Virgo

 

O1 & O2/2015-2017 events

 

Distance and mass for events up to O4 in 2023

Confirmed events by distance

4 8 12 16 20 24 28 32 36 40 <100 Mpc 100-200 Mpc 200-500 Mpc 500-1000 Mpc 1-2 Gpc 2-5 Gpc 5+ Gpc   BNS mergers   NS-BH mergers   mass gap   BBH mergers

Initial objects by mass

5 10 15 20 25 30 35 40 45 50 1-2 M☉ 2-3 M☉ 3-5 M☉ 5-10 M☉ 10-20 M☉ 20-30 M☉ 30-40 M☉ 40-50 M☉ 50-60 M☉ 60-70 M☉ 70-80 M☉ 80-90 M☉ 90-100 M☉ 100-110 M☉   neutron star   mass gap   black hole

List of binary merger events^[11][12]

GW event and time (UTC)^[n 1]	Date published	Location area^[n 2] (deg^2)	Signal to Noise Ratio (SNR)	Luminosity distance (Mpc)^[n 3]	Energy radiated/c^2 (M☉) ^[n 4]	Chirp mass (M☉) ^[n 5]	Effective spin^[n 6]	Primary		Secondary		Remnant			Notes	Ref.
								Type	Mass (M☉)	Type	Mass (M☉)	Type	Mass (M☉)	Spin^[n 7]
GW150914 09:50:45	2016-02-11	179; mostly to the south	24.4+0.8 −0.8	430+150 −170	3.1+0.4 −0.4	28.6+1.6 −1.5	−0.01+0.12 −0.13	BH ^[n 8]	35.6+4.8 −3.0	BH ^[n 9]	30.6+3.0 −4.4	BH	63.1+3.3 −3.0	0.69+0.05 −0.04	First GW detection; first BH merger observed	^[18]^[19]^[17]
GW151012 [fr] 09:54:43	2016-06-15	1555	10.0+0.5 −0.5	1060+540 −480	1.5+0.5 −0.5	15.2+2.0 −1.1	0.04+0.28 −0.19	BH	23.3+14.0 −5.5	BH	13.6+4.1 −4.8	BH	35.7+9.9 −3.8	0.67+0.13 −0.11	Formerly candidate LVT151012; accepted as astrophysical since February 2019	^[20]^[12]^[11]
GW151226 03:38:53	2016-06-15	1033	13.1+0.0 −1.2	440+180 −190	1.0+0.1 −0.2	8.9+0.3 −0.3	0.18+0.20 −0.12	BH	13.7+8.8 −3.2	BH	7.7+2.2 −2.6	BH	20.5+6.4 −1.5	0.74+0.07 −0.05		^[21]^[22]
GW170104 10:11:58	2017-06-01	924	13.0+0.0 −0.0	960+430 −410	2.2+0.5 −0.5	21.5+2.1 −1.7	−0.04+0.17 −0.20	BH	31.0+7.2 −5.6	BH	20.1+4.9 −4.5	BH	49.1+5.2 −3.5	0.66+0.08 −0.10		^[13]^[23]
GW170608 02:01:16	2017-11-16	396; to the north	14.9+0.5 −0.8	320+120 −110	0.9+0.0 −0.1	7.9+0.2 −0.2	0.03+0.19 −0.07	BH	10.9+5.3 −1.7	BH	7.6+1.3 −2.1	BH	17.8+3.2 −0.7	0.69+0.04 −0.04	Smallest BH progenitor masses to date	^[24]
GW170729 18:56:29	2018-11-30	1033	10.2+0.6 −0.4	2750+1350 −1320	4.8+1.7 −1.7	35.7+6.5 −4.7	0.36+0.21 −0.25	BH	50.6+16.6 −10.2	BH	34.3+9.1 −10.1	BH	80.3+14.6 −10.2	0.81+0.07 −0.13	Largest progenitor masses until GW190521	^[12]
GW170809 08:28:21	2018-11-30	340; towards Cetus	12.4+0.0 −0.2	990+320 −380	2.7+0.6 −0.6	25.0+2.1 −1.6	0.07+0.16 −0.16	BH	35.2+8.3 −6.0	BH	23.8+5.2 −5.1	BH	56.4+5.2 −3.7	0.70+0.08 −0.09		^[12]
GW170814 10:30:43	2017-09-27	87; towards Eridanus	16.3+0.9 −0.4	580+160 −210	2.7+0.4 −0.3	24.2+1.4 −1.1	0.07+0.12 −0.11	BH	30.7+5.7 −3.0	BH	25.3+2.9 −4.1	BH	53.4+3.2 −2.4	0.72+0.07 −0.05	First announced detection by three observatories; first polarization measurement	^[25]^[26]
GW170817 12:41:04	2017-10-16	16; NGC 4993	33.0+0.0 −2.1	40±10	≥ 0.04	1.186+0.001 −0.001	0.00+0.02 −0.01	NS	1.46+0.12 −0.10	NS	1.27+0.09 −0.09	NS ^[n 10]	≤ 2.8^[n 11]	≤ 0.89	First NS merger observed in GW; first detection of EM counterpart (GRB 170817A; AT 2017gfo); nearest event to date	^[16]^[29]^[30]
GW170818 02:25:09	2018-11-30	39; towards Pegasus	11.3+0.0 −0.0	1020+430 −360	2.7+0.5 −0.5	26.7+2.1 −1.7	−0.09+0.18 −0.21	BH	35.5+7.5 −4.7	BH	26.8+4.3 −5.2	BH	59.8+4.8 −3.8	0.67+0.07 −0.08		^[12]
GW170823 13:13:58	2018-11-30	1651	11.1+0.4 −0.3	1850±840	3.3+0.9 −0.8	29.3+4.2 −3.2	0.08+0.20 −0.22	BH	39.6+10.0 −6.6	BH	29.4+6.3 −7.1	BH	65.6+9.4 −6.6	0.71+0.08 −0.10		^[12]
GW190403_051519 2019-04-03 05:15:19	2022-05-11	3900	7.6+0.6 −1.1	8300+6700 −4300		34.0+15.1 −8.4	0.68+0.16 −0.43	BH	85.0+6.7 −4.3	BH	20.0+26.3 −8.4	BH	102+26 −24	0.91+0.05 −0.17		^[31]
GW190408_181802 2019-04-08 18:18:02	2020-10-27	140	15.3+0.2 −0.3	1580+400 −590		18.3+1.4 −1.2	−0.03+0.13 −0.19	BH	24.5+5.1 −3.4	BH	18.3+3.2 −3.5	BH	41.0+3.8 −2.7	0.67+0.06 −0.07	Originally designated S190408an.	^[32]
GW190412 2019-04-12 05:30:44	2020-04-17	156; towards Virgo or Boötes	18.9+0.2 −0.3	730+140 −170		13.3+0.4 −0.3	0.25+0.08 −0.11	BH	29.7+5.0 −5.3	BH	8.4+1.8 −1.0	BH	37.0+4.1 −3.9	0.67+0.05 −0.07	First possible observation of a merger of two black holes of very different masses. Originally designated S190412m.	^[33]^[34]
GW190413_052954 2019-04-13	2020-10-27	1400	8.9+0.4 −0.7	4100+2410 −1890		24.0+5.4 −3.7	0.01+0.29 −0.33	BH	33.4+12.4 −7.4	BH	23.4+6.7 −6.3	BH	54.3+12.4 −8.4	0.69+0.12 −0.13		^[32]
GW190413_134308 2019-04-13	2020-10-27	520	10.0+0.4 −0.5	5150+2440 −2340		31.9+7.3 −4.6	−0.01+0.24 −0.28	BH	45.4+13.6 −9.6	BH	30.9+10.2 −9.6	BH	72.8+15.2 −10.3	0.69+0.10 −0.12		^[32]
GW190421_213856 2019-04-21	2020-10-27	1000	10.7+0.2 −0.4	3150+1370 −1420		30.7+5.5 −6.6	−0.05+0.23 −0.26	BH	40.6+10.4 −6.6	BH	31.4+7.5 −8.2	BH	68.6+11.7 −8.1	0.68+0.10 −0.11	Originally designated S190421ar.	^[32]
GW190424_180648 2019-04-24 18:06:48	2020-10-27	26000	10.4+0.2 −0.4	2550+1560 −1330		30.3+5.7 −4.2	0.15+0.22 −0.22	BH	39.5+10.9 −6.9	BH	31.0+7.4 −7.3	BH	67.1+12.5 −9.2	0.75+0.08 −0.09		^[32]
GW190425 2019-04-25 08:18:05	2020-01-06	430; towards Hercules^[35]	12.4+0.3 −0.4	159+69 −72		1.44+0.02 −0.02	0.012+0.01 −0.01	NS	1.60 - 1.87	NS	1.46 - 1.69	?			Originally designated S190425z (z:26th trigger|UTC day), this trigger was detected by a single LIGO instrument (of three LVC stations), and is considered by some scientists to have been confirmed as a binary neutron star merger.^[36] It was published in 2020 that a gamma-ray burst was detected (GRB 190425) ~0.5 seconds after the LIGO trigger, lasting 6 seconds and bearing similarities to GRB170817 (such as weakness [most power in sub-100 keV, or soft X-rays) bands], elevated energetic photon background levels [signal exceeding background by less than a factor of 2], and similar differences from other transients classified as short GRBs). Confidence was established for interpretation of a set of peaks through a control interval of only 2 days prior to the LIGO-Livingston trigger in INTEGRAL Electronic anticoincidence, could not be corroborated by other instruments and wasn't initially noted as a significant event. Non-detection in other instruments may be a consequence of an Earth-occulted source as the Fermi telescope attempted follow-up.^[35]	^[37]^[38]
GW190426_152155 2019-04-26 15:21:55	2020-10-27	1300	8.7+0.5 −0.6	370+180 −160		2.41+0.08 −0.08	−0.03+0.32 −0.30	BH?	5.7+3.9 −2.3	NS	1.5+0.8 −0.5	BH?			The primary object, being between 3.4 and 9.6 solar masses, is either a black hole or an object in the mass gap. Originally designated S230426c.	^[32]
GW190426_190642 2019-04-26 19:06:42	2022-05-11	4600	8.7+0.4 −0.6	4600+3400 −2300		76.0+19.1 −17.4	0.23+0.42 −0.41	BH	106+45 −24	BH	76+26 −36	BH	173+38 −34	0.77+0.14 −0.16		^[31]
GW190503_185404 2019-05-03 18:54:04	2020-10-27	94; towards Columba, Pictor, or Puppis	12.4+0.2 −0.3	1450+690 −630		30.2+4.2 −4.2	−0.03+0.20 −0.26	BH	43.3+9.1 −8.2	BH	28.4+7.7 −8.0	BH	68.6+8.8 −7.7	0.66+0.09 −0.12	Originally designated S230503bf.	^[32]
GW190512_180714 2019-05-12 18:07:14	2020-10-27	220; towards Scorpius or Ophiuchus	12.2+0.2 −0.4	1430+550 −550		14.6+1.3 −1.0	0.03+0.12 −0.13	BH	23.3+5.3 −3.8	BH	12.6+3.6 −2.5	BH	34.5+3.8 −3.5	0.65+0.07 −0.07	Originally designated S230512at.	^[32]
GW190513_205428 2019-05-13 20:54:28	2020-10-27	520; towards Sagittarius, Capricornus, Perseus, or Camelopardalis	12.9+0.3 −0.4	2060+880 −800		21.6+3.8 −1.9	0.11+0.28 −0.17	BH	35.7+9.5 −9.2	BH	18.0+7.7 −4.2	BH	51.6+8.2 −5.8	0.68+0.14 −0.12	Originally designated S230513bm.	^[32]
GW190514_065416 2019-05-14 06:54:16	2020-10-27	3000	8.2+0.3 −0.6	4100+2700 −2200		28.5+7.9 −4.8	−0.19+0.29 −0.32	BH	39.0+14.7 −8.2	BH	28.4+9.3 −8.8	BH	65+18 −10	0.63+0.11 −0.15		^[32]
GW190517_055101 2019-05-17 06:54:16	2020-10-27	470	10.7+0.4 −0.6	1860+1620 −840		26.6+4.0 −4.0	0.52+0.19 −0.19	BH	37.4+11.7 −7.6	BH	25.3+7.0 −7.3	BH	59.3+9.1 −8.9	0.87+0.05 −0.07	Originally designated S190517h.	^[32]
GW190519_153544 2019-05-19 15:35:44	2020-10-27	860	15.6+0.2 −0.3	2530+1830 −920		44.5+6.4 −7.1	0.31+0.20 −0.22	BH	66+11 −12	BH	41+11 −11	BH	101+12 −14	0.79+0.07 −0.13	Originally designated S190519bj.	^[32]
GW190521 2019-05-21 03:02:29	2020-09-02	765; towards Coma Berenices, Canes Venatici, or Phoenix	14.2+0.3 −0.3	5300+2400 −2600	7.6+2.2 −1.9	64+13 −8	0.08+0.27 −0.36	BH	85+21 −14	BH	66+17 −18	BH	142+28 −16	0.72+0.09 −0.12	Originally designated S190521g. Largest progenitor masses to date.	^[39]^[40]
GW190521_074359 2019-05-21 07:43:59	2020-10-27	550	25.8+0.1 −0.2	1240+400 −570		32.1+3.2 −2.5	0.09+0.10 −0.13	BH	42.2+5.9 −4.8	BH	32.8+5.4 −6.4	BH	71.0+6.5 −4.4	0.72+0.05 −0.07	Originally designated S190521r.	^[32]
GW190527_092055 2019-05-27 09:20:55	2020-10-27	3700	8.1+0.3 −0.9	2500+2500 −1200		24.3+9.2 −4.1	0.11+0.28 −0.28	BH	36.5+16.4 −9.0	BH	22.6+10.5 −8.1	BH	56.4+20.2 −9.3	0.71+0.12 −0.16		^[32]
GW190602_175927 2019-06-02 17:59:27	2020-10-27	690	12.8+0.2 −0.3	2700+1800 −1100		49.1+9.1 −8.5	0.07+0.25 −0.24	BH	69+16 −13	BH	48+14 −17	BH	111+18 −15	0.70+0.10 −0.14	Originally designated S190602aq.	^[32]
GW190620_030421 2019-06-20 03:04:21	2020-10-27	7200	12.1+0.3 −0.4	2800+1700 −1300		38.3+8.3 −6.5	0.33+0.22 −0.25	BH	57+16 −13	BH	36+12 −12	BH	87+17 −12	0.79+0.08 −0.15		^[32]
GW190630_185205 2019-06-30 18:52:05	2020-10-27	1200	15.6+0.2 −0.3	890+560 −370		24.9+2.1 −2.1	0.10+0.12 −0.13	BH	35.1+6.9 −5.6	BH	23.7+5.2 −5.1	BH	56.4+4.4 −4.6	0.70+0.05 −0.07	Originally designated S190630ag.	^[32]
GW190701_203306 2019-07-01 20:33:06	2020-10-27	46; towards Eridanus or Cetus	11.3+0.2 −0.3	2060+760 −730		40.3+5.4 −4.9	−0.07+0.23 −0.29	BH	53.9+11.8 −8.0	BH	40.8+8.7 −12.0	BH	90.2+11.3 −8.9	0.66+0.09 −0.13	Originally designated S190701ah.	^[32]
GW190706_222641 2019-07-06 22:26:41	2020-10-27	650	12.6+0.2 −0.4	4400+2600 −1900		42.7+10.0 −7.0	0.28+0.26 −0.29	BH	67+15 −16	BH	38+15 −13	BH	99+18 −14	0.78+0.09 −0.18	Originally designated S190706ai.	^[32]
GW190707_093326 2019-07-07 09:33:26	2020-10-27	1300	13.3+0.2 −0.4	770+380 −270		8.5+0.7 −0.6	−0.05+0.10 −0.08	BH	11.6+3.3 −1.7	BH	8.4+1.4 −1.7	BH	19.2+1.9 −1.3	0.66+0.03 −0.04	Originally designated S190707q.	^[32]
GW190708_232457 2019-07-08 23:24:57	2020-10-27	14000	13.1+0.2 −0.3	880+330 −390		13.2+0.9 −0.6	0.02+0.08 −0.10	BH	17.6+4.7 −2.3	BH	13.2+2.0 −2.7	BH	29.5+2.5 −1.8	0.69+0.04 −0.04		^[32]
GW190719_215514 2019-07-09 21:55:14	2020-10-27	2900	8.3+0.3 −0.8	3900+2600 −2000		23.5+6.5 −4.0	0.32+0.29 −0.31	BH	37+18 −10	BH	20.8+9.0 −7.2	BH	55+17 −10	0.78+0.11 −0.17		^[32]
GW190720_000836 2019-07-20 00:08:36	2020-10-27	460; mostly towards Cygnus	11.0+0.3 −0.7	790+690 −320		8.9+0.5 −0.8	0.18+0.14 −0.12	BH	13.4+6.7 −3.0	BH	7.8+2.3 −2.2	BH	20.4+4.5 −2.2	0.72+0.06 −0.05	Originally designated S190720a.	^[32]
GW190725_174728 2019-07-25 17:47:28	2022-05-11	2200	9.1+0.4 −0.7	1030+520 −430		7.4±0.5	−0.04+0.36 −0.16	BH	11.8+10.1 −3.0	BH?	6.3+2.1 −2.5	BH	17.6+7.7 −1.8	0.65+0.09 −0.07		^[31]
GW190727_060333 2019-07-27 06:03:33	2020-10-27	830	11.9+0.3 −0.5	790+690 −320		28.6+5.3 −3.7	0.11+0.26 −0.25	BH	38.0+9.5 −6.2	BH	29.4+7.1 −8.4	BH	63.8+10.9 −7.5	0.73+0.10 −0.10	Originally designated S190727h.	^[32]
GW190728_064510 2019-07-28 06:45:10	2020-10-27	400	13.0+0.2 −0.4	870+260 −370		8.6+0.5 −0.3	0.12+0.20 −0.07	BH	12.3+7.2 −2.2	BH	8.1+1.7 −2.6	BH	19.6+4.7 −1.3	0.71+0.04 −0.04	Originally designated S190728q.	^[32]
GW190731_140936 2019-07-31 14:09:36	2020-10-27	3400	8.7+0.2 −0.5	3300+2400 −1700		29.5+7.1 −5.2	0.06+0.24 −0.24	BH	41.5+12.2 −9.0	BH	28.8+9.7 −9.5	BH	67+15 −11	0.70+0.10 −0.13		^[32]
GW190803_022701 2019-08-03 02:27:01	2020-10-27	1500	8.6+0.3 −0.5	3300+2000 −1600		27.3+5.7 −4.1	−0.03+0.24 −0.27	BH	37.3+10.6 −7.0	BH	27.3+7.8 −8.2	BH	61.7+11.8 −8.5	0.68+0.10 −0.11		^[32]
GW190805_211137 2019-08-05 21:11:37	2022-05-11	1600	8.1+0.5 −0.7	6100+3700 −3100		31.9+8.8 −6.3	0.37+0.29 −0.39	BH	46+15 −11	BH	31+12 −11	BH	72+18 −13	0.82+0.09 −0.16		^[31]
GW190814 2019-08-14 21:11:18	2020-06-23	18.5; towards Cetus or Sculptor^[citation needed]	24.9+0.1 −0.2	241+41 −45		6.09+0.06 −0.06	−0.002+0.06 −0.061	BH	23.2+1.1 −1.0	MG	2.59+0.08 −0.09	BH	25.6+1.1 −0.9	0.28+0.02 −0.02	No optical counterpart was discovered despite an extensive search of the probability region. The mass of the lighter component is estimated to be 2.6 times the mass of the Sun, placing it in the mass gap between neutron stars and black holes.^[41]	^[42]^[43]^[44]^[45]^[46] ^[47]^[48]^[49]^[50]
GW190828_063405 2019-08-28 06:34:05	2020-10-27	520	16.2+0.2 −0.3	2130+660 −930		25.0+3.4 −2.1	0.19+0.15 −0.16	BH	32.1+5.8 −4.0	BH	26.2+4.6 −4.8	BH	54.9+7.2 −4.3	0.75+0.06 −0.07	Originally designated S190828j.	^[32]
GW190828_065509 2019-08-28 06:55:09	2020-10-27	660	10.0+0.3 −0.5	1600+620 −600		13.3+1.2 −1.0	0.08+0.16 −0.16	BH	24.1+7.0 −7.2	BH	10.2+3.6 −2.1	BH	33.1+5.5 −4.5	0.65+0.08 −0.08	Originally designated S190828l.	^[32]
GW190909_114149 2019-09-09 11:41:49	2020-10-27	4700	8.1+0.4 −0.6	3800+3300 −2200		30.9+17.2 −7.5	−0.06+0.37 −0.37	BH	46+53 −13	BH	28+13 −13	BH	72+55 −17	0.66+0.15 −0.20		^[32]
GW190910_112807 2019-09-10 11:28:07	2020-10-27	11000	14.1+0.2 −0.3	1460+1030 −580		34.3+4.1 −4.1	0.02+0.18 −0.18	BH	43.9+7.6 −6.1	BH	35.6+6.3 −7.2	BH	75.8+8.5 −8.6	0.70+0.08 −0.07		^[32]
GW190915_235702 2019-09-15 23:57:02	2020-10-27	400; towards Coma Berenices, Canes Venatici, or Ursa Major	13.6+0.2 −0.3	1620+710 −610		25.3+3.2 −2.7	0.02+0.20 −0.25	BH	35.3+9.5 −6.4	BH	24.4+5.6 −6.1	BH	57.2+7.1 −6.0	0.70+0.09 −0.11	Originally designated S230915ak.	^[32]
GW190916_200658 2019-09-16 20:06:58	2022-05-11	2400	8.1+0.3 −0.5	4900+3700 −2400		26.9+8.2 −5.4	0.20+0.33 −0.31	BH	44+20 −13	BH	23+13 −11	BH	65+17 −13	0.74+0.13 −0.24		^[31]
GW190917_114630 2019-09-17 11:46:30	2022-05-11	1700	8.3+0.5 −0.8	720+300 −310		3.7±0.2	−0.08+0.21 −0.43	BH	9.7+3.4 −3.9	MG?	2.1+1.1 −0.4	BH	11.6+3.1 −2.9	0.42+0.14 −0.05		^[31]
GW190924_021846 2019-09-24 02:18:46	2020-10-27	360; towards Hydra or Cancer	11.5+0.3 −0.4	570+220 −220		5.8+0.2 −0.2	0.03+0.30 −0.09	BH	8.9+7.0 −2.0	BH?	5.0+1.4 −1.9	BH	13.3+5.2 −1.0	0.67+0.05 −0.05	The secondary component, being between 3.1 and 6.4 solar masses, is either a black hole or an object in the mass gap. Originally designated S230924h.	^[32]
GW190925_232845 2019-09-25 23:28:45	2022-05-11	2900	9.7+0.3 −0.6	930+460 −350		15.6±1.1	0.09+0.16 −0.15	BH	20.8+6.5 −2.9	BH	15.5+2.5 −3.6	BH	34.9+3.5 −2.6	0.71±0.06		^[31]
GW190926_050336 2019-09-26 05:03:36	2022-05-11	2000	8.1+0.6 −0.8	3300+3400 −1700		24.4+9.0 −4.9	−0.02+0.25 −0.32	BH	41+21 −13	BH	20.4+11.4 −8.2	BH	60+22 −12	0.64+0.14 −0.20		^[31]
GW190929_012149 2019-09-29 01:21:49	2020-10-27	2200	10.1+0.6 −0.8	2100+3700 −1100		35.8+14.9 −8.2	0.01+0.34 −0.33	BH	81+33 −33	BH	24+19 −11	BH	102+34 −25	0.66+0.20 −0.31		^[32]
GW190930_133541 2019-09-30 13:35:41	2020-10-27	1700	9.5+0.3 −0.5	760+360 −320		8.5+0.5 −0.5	0.14+0.31 −0.15	BH	12.3+12.4 −2.3	BH?	7.8+1.7 −3.3	BH	19.4+9.2 −1.5	0.72+0.07 −0.06	The secondary component, being between 4.5 and 9.5 solar masses, is either a black hole or an object in the mass gap. Originally designated S190930s.	^[32]
GW191103 2019-11-03 01:25:49	2021-11-17	2500	8.9+0.3 −0.5	990+500 −470		8.34+0.66 −0.57	0.21+0.16 −0.10	BH	11.8+6.2 −2.2	BH	7.9+1.7 −2.4	BH	19.0+3.8 −1.7	0.75+0.06 −0.05		^[51]
GW191105 2019-11-05 14:35:21	2021-11-17	640	9.7+0.3 −0.5	1150+430 −480		7.82+0.61 −0.45	−0.02+0.13 −0.09	BH	10.7+3.7 −1.6	BH	7.7+1.4 −1.9	BH	17.6+2.1 −1.2	0.67+0.04 −0.05	Originally designated S191105e.	^[51]
GW191109 2019-11-09 01:07:17	2021-11-17	1600	17.3+0.5 −0.5	1290+1130 −650		47.5+9.6 −7.5	−0.29+0.42 −0.31	BH	65+11 −11	BH	47+15 −13	BH	107+18 −15	0.61+0.18 −0.19	Originally designated S191109d.	^[51]
GW191113 2019-11-13 07:17:53	2021-11-17	3600	7.9+0.5 −1.1	1290+1130 −650		10.7+1.1 −1.0	0.00+0.37 −0.29	BH	29+12 −14	BH	5.9+4.4 −1.3	BH	34+11 −10	0.45+0.33 −0.11		^[51]
GW191126 2019-11-26 11:52:59	2021-11-17	1400	8.3+0.2 −0.5	1620+740 −740		8.65+0.95 −0.71	0.21+0.15 −0.11	BH	12.1+5.5 −2.2	BH	8.3+1.9 −2.4	BH	19.6+3.5 −2.0	0.75+0.06 −0.05		^[51]
GW191127 2019-11-27 05:02:27	2021-11-17	980	9.2+0.7 −0.6	3400+3100 −1900		29.9+11.7 −9.1	0.18+0.34 −0.36	BH	53+47 −20	BH	24+17 −14	BH	76+31 −29	0.75+0.13 −0.29		^[51]
GW191129 2019-11-29 13:40:29	2021-11-17	850	13.1+0.2 −0.3	790+260 −330		7.31+0.43 −0.28	0.06+0.18 −0.06	BH	10.7+4.1 −2.1	BH	6.7+1.5 −1.7	BH	16.8+2.5 −1.2	0.69+0.03 −0.05	Originally designated S191129u.	^[51]
GW191204_110529 2019-12-04 11:05:29	2021-11-17	3700	8.8+0.4 −0.6	1800+1700 −1100		19.8+3.6 −3.3	0.05+0.26 −0.27	BH	27.3+11.0 −6.0	BH	19.3+5.6 −6.0	BH	45.0+8.6 −7.6	0.71+0.12 −0.11		^[51]
GW191204_171526 2019-12-04 17:15:26	2021-11-17	350; towards Pictor, Caelum, or Eridanus	17.5+0.2 −0.2	650+190 −250		8.55+0.38 −0.27	0.16+0.08 −0.05	BH	11.9+3.3 −1.8	BH	8.2+1.4 −1.6	BH	19.21+1.79 −0.95	0.73+0.03 −0.03	Originally designated S191204r.	^[51]
GW191215 2019-12-15 22:30:52	2021-11-17	530	11.2+0.3 −0.4	1930+890 −860		18.4+2.2 −1.7	−0.04+0.17 −0.21	BH	24.9+7.1 −4.1	BH	18.1+3.8 −4.1	BH	41.4+5.1 −4.1	0.68+0.07 −0.07	Originally designated S191215w.	^[51]
GW191216 2019-12-16 21:33:38	2021-11-17	490	18.6+0.2 −0.2	340+120 −130		8.33+0.22 −0.19	0.11+0.13 −0.06	BH	12.1+4.6 −2.3	BH	7.7+1.6 −1.9	BH	18.87+2.80 −0.94	0.70+0.03 −0.04	Originally designated S191216ap.	^[51]
GW191219 2019-12-19 16:31:20	2021-11-17	1500	9.1+0.5 −0.8	550+250 −160		4.32+0.12 −0.17	0.00+0.07 −0.09	BH	31.1+2.2 −2.8	NS	1.17+0.07 −0.06	BH	32.2+2.2 −2.7	0.14+0.06 −0.06	The event is unconfirmed due to difficulty accurately modelling the extreme mass ratio.	^[51]
GW191222 2019-12-22 03:35:37	2021-11-17	2000	12.5+0.2 −0.3	3000+1700 −1700		33.8+7.1 −5.0	−0.04+0.20 −0.25	BH	45.1+10.9 −8.0	BH	34.7+9.3 −10.5	BH	75.5+15.3 −9.9	0.67+0.08 −0.11	Originally designated S191222n.	^[51]
GW191230 2019-12-30 18:04:58	2021-11-17	1100	10.4+0.3 −0.4	4300+2100 −1900		36.5+8.2 −5.6	−0.05+0.26 −0.31	BH	49.4+14.0 −9.6	BH	37+11 −12	BH	82+17 −11	0.68+0.11 −0.13		^[51]
GW200105 2020-01-05 16:24:26	2021-06-29	7200	13.7+0.2 −0.4	280±110		3.41+0.08 −0.07	−0.01+0.11 −0.15	BH	8.9+1.2 −1.5	NS	1.9+0.3 −0.2	BH	10.4+2.7 −2.0	0.43+0.04 −0.03	First event confirmed to be a black hole and neutron star merger. Originally designated S200105ae.	^[52]^[53]
GW200112 2020-01-12 15:58:38	2021-11-17	4300	19.8+0.1 −0.2	1250+430 −460		27.4+2.6 −2.1	0.06+0.15 −0.15	BH	35.6+6.7 −4.5	BH	28.3+4.4 −5.9	BH	60.8+5.3 −4.3	0.71+0.06 −0.06	Originally designated S200112r.	^[51]
GW200114 2020-01-14 02:08:08	2022-08-18	403; towards Gemini, Orion, or Eridanus		1250+1500 −400		68+6 −4	−0.75+0.50 −0.15	BH	78+10 −10	BH	70+10 −10	BH	140+15 −15		Originally designated S200114f. The event was initially published as an unmodeled gravitational wave burst, and different studies have offered conflicting interpretations. One study suggested it was a nearby high-mass black hole merger with component masses of 118+10 −12 and 89+18 −8 Msun which was poorly modeled because of its high mass.^[54] Another study interpreted it as a somewhat smaller black hole merger taking place at the same time as a detector glitch.^[55] Both studies conclude the signal is most likely a real event, and the latter model is included in the table.	^[54]^[55]
GW200115 2020-01-15 04:23:09	2021-06-29	600	11.3+0.3 −0.5	300+150 −100		2.42+0.05 −0.07	−0.19+0.23 −0.35	BH	5.7+1.8 −2.1	NS	1.5+0.7 −0.3	BH	7.8+1.4 −1.6	0.38+0.04 −0.03	Second event confirmed to be a black hole and neutron star merger. Originally designated S200115j.	^[52]^[56]
GW200128 2020-01-28 02:20:11	2021-11-17	2600	10.6+0.3 −0.4	3400+2100 −1800		32.0+7.5 −5.5	0.12+0.24 −0.25	BH	42.2+11.6 −8.1	BH	32.6+9.5 −9.2	BH	71+16 −11	0.74+0.10 −0.10	Originally designated S200128d.	^[51]
GW200129 2020-01-29 06:54:58	2021-11-17	130; towards Equuleus, Delphinus, or Vulpecula	26.8+0.2 −0.2	900+290 −380		27.2+2.1 −2.3	0.11+0.11 −0.16	BH	34.5+9.9 −3.2	BH	28.9+3.4 −9.3	BH	60.3+4.0 −3.3	0.73+0.06 −0.05	Originally designated S200129m.	^[51]
GW200202 2020-02-02 15:43:12	2021-11-17	170	10.8+0.2 −0.4	410+150 −160		7.49+0.24 −0.20	0.04+0.13 −0.06	BH	10.1+3.5 −1.4	BH	7.3+1.1 −1.7	BH	16.76+1.87 −0.66	0.69+0.03 −0.04		^[51]
GW200208_130117 2020-02-08 13:01:17	2021-11-17	30; towards Pyxis or Antlia	10.8+0.3 −0.4	2230+1000 −850		27.7+3.6 −3.1	−0.07+0.22 −0.27	BH	37.8+9.2 −8.2	BH	27.5+6.1 −7.4	BH	62.5+7.3 −6.4	0.66+0.09 −0.13	Originally designated S200208q.	^[51]
GW200208_222617 2020-02-08 22:26:17	2021-11-17	2000	7.4+1.4 −1.2	4100+4400 −1900		19.6+10.7 −5.1	0.45+0.43 −0.44	BH	51+104 −30	BH	12.3+9.0 −5.7	BH	61+100 −25	0.83+0.14 −0.27		^[51]
GW200209 2020-02-09 08:54:52	2021-11-17	730	9.6+0.4 −0.5	3400+1900 −1800		26.7+6.0 −4.2	−0.12+0.24 −0.30	BH	35.6+10.5 −6.8	BH	27.1+7.8 −7.8	BH	59.9+13.1 −8.9	0.66+0.10 −0.12		^[51]
GW200210 2020-02-10 09:22:54	2021-11-17	1800	8.4+0.5 −0.7	940+430 −340		6.56+0.38 −0.40	0.02+0.22 −0.21	BH	24.1+7.5 −4.6	MG	2.83+0.47 −0.42	BH	26.7+7.2 −4.3	0.34+0.13 −0.08	The secondary component, being between 2.41 and 3.30 solar masses, is an object in the mass gap.	^[51]
GW200216 2020-02-16 22:08:04	2021-11-17	2900	8.1+0.4 −0.5	3800+3000 −2000		32.9+9.3 −8.5	0.10+0.34 −0.36	BH	51+22 −13	BH	30+14 −16	BH	78+19 −13	0.70+0.14 −0.24		^[51]
GW200219 2020-02-19 09:44:15	2021-11-17	700	10.7+0.3 −0.5	3400+1700 −1500		27.6+5.6 −3.8	−0.08+0.23 −0.29	BH	37.5+10.1 −6.9	BH	27.9+7.4 −8.4	BH	62.2+11.7 −7.8	0.66+0.10 −0.13	Originally designated S200219ac.	^[51]
GW200220_061928 2020-02-20 06:19:28	2021-11-17	3000	7.2+0.4 −0.7	6000+4800 −3100		62+23 −15	0.06+0.40 −0.38	BH	87+40 −23	BH	61+26 −25	BH	141+51 −31	0.71+0.15 −0.17		^[51]
GW200220_124850 2020-02-20 12:48:50	2021-11-17	3200	8.5+0.3 −0.5	4000+2800 −2200		28.2+7.3 −5.1	−0.07+0.27 −0.33	BH	38.9+14.1 −8.6	BH	27.9+9.2 −9.0	BH	64+16 −11	0.67+0.11 −0.14		^[51]
GW200224 2020-02-24 22:22:34	2021-11-17	50; towards Virgo or Crater	20.0+0.2 −0.2	1710+490 −640		31.1+3.2 −2.6	0.10+0.15 −0.15	BH	40.0+6.9 −4.5	BH	32.5+5.0 −7.2	BH	68.6+6.6 −4.7	0.73+0.07 −0.07	Originally designated S200224ca.	^[51]
GW200225 2020-02-25 06:04:21	2021-11-17	370; towards Ursa Minor or Cepheus	12.5+0.3 −0.4	1150+510 −530		14.2+1.5 −1.4	−0.12+0.17 −0.28	BH	19.3+5.0 −3.0	BH	14.0+2.8 −3.5	BH	32.1+3.5 −2.8	0.66+0.07 −0.13	Originally designated S200225q.	^[51]
GW200302 2020-03-02 01:58:11	2021-11-17	6000	10.8+0.3 −0.4	1480+1020 −700		23.4+4.7 −3.0	0.01+0.25 −0.26	BH	37.8+8.7 −8.5	BH	20.0+8.1 −5.7	BH	55.5+8.9 −8.6	0.66+0.13 −0.15	Originally designated S200302c.	^[51]
GW200306 2020-03-06 09:37:14	2021-11-17	4600	7.8+0.4 −0.6	2100+1700 −1100		17.5+3.5 −3.0	0.32+0.28 −0.46	BH	28.3+17.1 −7.7	BH	14.8+6.5 −6.4	BH	41.7+12.3 −6.9	0.78+0.11 −0.26		^[51]
GW200308 2020-03-08 17:36:09	2021-11-17	2000	7.1+0.5 −0.5	5400+2700 −2600		19.0+4.8 −2.8	0.65+0.21 −0.17	BH	36.4+11.2 −9.6	BH	13.8+7.2 −3.3	BH	47.4+11.1 −7.7	0.91+0.03 −0.08		^[51]
GW200311 2020-03-11 11:58:53	2021-11-17	35; towards Cetus	17.8+0.2 −0.2	1170+280 −400		26.6+2.4 −2.0	−0.02+0.16 −0.20	BH	34.2+6.4 −3.8	BH	27.7+4.1 −5.9	BH	59.0+4.8 −3.9	0.69+0.07 −0.08	Originally designated S200311bg.	^[51]
GW200316 2020-03-16 21:57:56	2021-11-17	190	10.3+0.4 −0.7	1120+470 −440		8.75+0.62 −0.55	0.13+0.27 −0.10	BH	13.1+10.2 −2.9	BH	7.8+1.9 −2.9	BH	20.2+7.4 −1.9	0.70+0.04 −0.04	Originally designated S200316bj.	^[51]
GW200322 2020-03-22 09:11:33	2021-11-17	6500	6.0+1.7 −1.2	3600+7000 −2000		15.5+15.7 −3.7	0.24+0.45 −0.51	BH	34+48 −18	BH	14.0+16.8 −8.7	BH	53+38 −26	0.78+0.16 −0.17		^[51]
GW230529 2023-05-29 18:15:00	2024-04-05	25600	11.4+0.2 −0.1	201+102 −96		1.94+0.04 −0.04	−0.1+0.12 −0.17	MG	3.6+0.8 −1.2	NS	1.4+0.6 −0.2	?			Originally designated S230529ay. Was detected using only the LIGO Livingston detector. It provides strong support for the primary object to be within the mass gap.	^[57]

 

Gravitational Wave Transient Catalog 1. Credit:LIGO Scientific Collaboration and Virgo Collaboration/Georgia Tech/S. Ghonge & K. Jani

Candidate events and marginal detections

There is possible detection of nanohertz waves by observation of the timing of pulsars, but they have not been confirmed at the 5 sigma level of confidence, as of 2023^[update].^[58]

Marginal detections from O1 and O2

In addition to well-constrained detections listed above, a number of low-significance detections of possible signals were made by LIGO and Virgo. Their characteristics are listed below, only including detections with a <50% chance of being noise:

Marginal event detections

Candidate event	Detection time (UTC)	Date published	Luminosity distance (Mpc)^[n 12]	Detector ^[n 13]	False alarm rate (year)	Effective spin	Primary		Secondary		Probability of terrestrial noise	Notes	Ref
							Type	Mass (M☉)	Type	Mass (M☉)
151205	2015-12-05 19:55:25	2019-10-11	3000+2400 −1600	H,L	0.61	0.14+0.40 −0.38	BH	67+28 −17	BH	42+16 −19	0.47		^[59]
170121	2017-01-21 21:25:36	2019-04-15		H,L		−0.3±0.3	BH	29+4 −3	BH		<0.01		^[60]
170304	2017-03-04 16:37:53	2019-10-11	2300+1600 −1200	H,L	2.5	0.11+0.29 −0.27	BH	44.9+17.6 −9.4	BH	31.8+9.5 −11.6	0.30		^[59]
170402	2017-04-02 21:51:50	2019-10-21		H,L							0.32		^[61]
170727	2017-07-27 01:04:30	2019-10-11	2200+1500 −1100	H,L	180	−0.05+0.25 −0.30	BH	41.6+12.8 −7.9	BH	30.4+7.9 −8.2	0.006		^[59]
170817A	2017-08-17 03:02:46	2019-10-21		H,L,V	11.5	0.5±0.2	BH	56+16 −10	BH	40+10 −11	0.14		^[61]

Observation candidates from O3/2019

From observation run O3/2019 on, observations are published as Open Public Alerts to facilitate multi-messenger observations of events.^[62][63][64] Candidate event records can be directly accessed at the Gravitational-Wave Candidate Event Database (GraceDB).^[65] On 1 April 2019, the start of the third observation run was announced with a circular published in the public alerts tracker.^[66] The first O3/2019 binary black hole detection alert was broadcast on 8 April 2019. A significant percentage of O3 candidate events detected by LIGO are accompanied by corresponding triggers at Virgo.

False alarm rates are mixed, with more than half of events assigned false alarm rates greater than 1 per 20 years, contingent on presence of glitches around signal, foreground electromagnetic instability, seismic activity, and operational status of any one of the three LIGO-Virgo instruments. For instance, events S190421ar and S190425z weren't detected by Virgo and LIGO's Hanford site, respectively.

The LIGO/Virgo collaboration took a short break from observing during the month of October 2019 to improve performance and prepare for future plans, with no signals detected in that month as a result.^[67]

The Kamioka Gravitational Wave Detector (KAGRA) in Japan became operational on 25 February 2020,^[68] likely improving the detection and localization of future gravitational wave signals.^[69] However, KAGRA does not report their signals in real-time on GraceDB as LIGO and Virgo do, so the results of their observation run will likely not be published until the end of O3.

The LIGO-Virgo collaboration ended the O3 run early on March 27, 2020, due to health concerns from the COVID-19 pandemic.^[5][70]

Candidate detections from O3 by month

1 2 3 4 5 6 7 8 9 10 19/04 19/05 19/06 19/07 19/08 19/09 19/10 19/11 19/12 20/01 20/02 20/03   BNS mergers   NS-BH mergers   mass gap   BBH mergers   terrestrial noise   false positives   unidentified

O3 detections by distance

2 4 6 8 10 12 14 16 18 20 <100 Mpc 100-200 Mpc 200-500 Mpc 500-1000 Mpc 1-2 Gpc 2-5 Gpc 5+ Gpc   BNS mergers   NS-BH mergers   mass gap   BBH mergers

List of unconfirmed O3 event alerts^[11][12]

GW event	Detection time (UTC)	Location area^[n 14] (deg^2)	Luminosity distance (Mpc)^[n 15]	Detector ^[n 16]	False alarm Rate (Hz)	False alarm chance in O3^[n 17]	Classification					Notes	Ref
							NS / NS ^[n 18]	NS / BH ^[n 19]	BH / BH ^[n 20]	Mass gap ^[n 21]	Terrestrial ^[n 22]
S190901ap	2019-09-01 23:31:01	14753	241±79	L,V	7.0 10^−9	0.181	0.861	0.0	0.0	0.0	0.139		^[71]
S190910d	2019-09-10 01:26:19	2482	632±186	H,L	3.7 10^−9	0.100	0.0	0.976	0.0	0.0	0.024		^[72]
S190910h	2019-09-10 08:29:58	24264	230±88	L	3.6 10^−8	0.642	0.612	0.0	0.0	0.0	0.388	Detected by only the Livingston detector, resulting in a bad sky localization.	^[73]
S190923y	2019-09-23 12:55:59	2107	438±133	H,L	4.8 10^−8	0.746	0.0	0.677	0.0	0.0	0.322		^[74]
S190930t	2019-09-30 14:34:07	24220	108±38	L	1.5 10^−8	0.348	0.0	0.743	0.0	0.0	0.257	Detected by only the Livingston detector, resulting in a bad sky localization; last detection of the O3a run.	^[75]
S191205ah	2019-12-05 21:52:08	6378	385±164	H,L,V	1.2 10^−8	0.290	0.0	0.932	0.0	0.0	0.068		^[76]
S191213g	2019-12-13 04:34:08	4480	201±81	H,L,V	3.5 10^−8	0.631	0.768	0.0	0.0	0.0	0.232		^[77]
S200213t	2020-02-13 04:10:40	2326	201±80	H,L,V	1.8 10^−8	0.401	0.629	0.0	0.0	0.0	0.371		^[78]

Observation candidates from O4/2023

On 15 June 2022, LIGO announced to start the O4 observing run in March 2023.^[79] As the date got closer, engineering challenges delayed the observing run to May 2023.^[80] An engineering run to assess the sensitivity of LIGO, Virgo, and KAGRA began in April, with the Hanford detector's first operations beginning on April 29,^[81] and the Livingston and Virgo detectors' first operations beginning on May 5.^[82]

On March 7, 2023, a gamma-ray burst compatible with a neutron star merger was detected by the Fermi telescope and named GRB 230307A. The burst, identified as being from a host galaxy approximately 296 Mpc away, would likely have only been marginally detected at best by LIGO if it had been operating at the time, as the detectors would only later achieve a sensitivity of 160 Mpc for neutron star mergers by O4's beginning, 3 months later.

Near the end of the engineering run on 15 May 2023, LIGO announced that O4 would be beginning on 24 May 2023, running for 20 months with up to 2 months of maintenance. The LIGO detectors failed to achieve the hoped for 160-190 Mpc sensitivity for neutron star mergers, but did achieve an improved 130-150 Mpc sensitivity over O3's 100-140 Mpc, later improving to nearly 160 Mpc for both detectors by late 2023. Virgo was found to have both a damaged mirror and other new, unknown noise sources, limiting its sensitivity to just 31-35 Mpc (similar to its performance during O2 in 2017, and lower than O3's 40-50 Mpc.) As a result, Virgo spent most of 2023 in commissioning, with a deadline of March 2024 to improve its sensitivity before joining O4. KAGRA achieved its planned 1 Mpc sensitivity before returning to commissioning in July, with plans to rejoin at an improved 10 Mpc sensitivity by early 2024. However, the M_w7.5 2024 Noto earthquake occurred on 1 January 2024 only 103 kilometres (64 mi) from KAGRA, damaging the detector's sensitive instruments and delaying its development by at least several months.

On 18 May 2023, near the end of the engineering run and shortly before O4 proper, the first candidate gravitational wave event was detected. Four more were detected before the official beginning of the run. In October, LIGO announced a planned pause between January and March 2024, for a mid-run commissioning break intended to reduce noise and improve the uptime of the detectors.

Candidate detections from O4 by month

5 10 15 20 23/05 23/06 23/07 23/08 23/09 23/10 23/11 23/12 24/01 24/02 24/03 24/04 24/05   BNS mergers   NS-BH mergers   mass gap   BBH mergers   unidentified

O4 detections by distance

6 12 18 24 30 36 42 48 54 60 <100 Mpc 100-200 Mpc 200-500 Mpc 500-1000 Mpc 1-2 Gpc 2-5 Gpc 5-10 Gpc 10+ Gpc   BNS mergers   NS-BH mergers   mass gap   BBH mergers

List of O4 event alerts

GW event	Detection time (UTC)	Location area^[n 23] (deg^2)	Luminosity distance (Mpc)^[n 24]	Detector ^[n 25]	False Alarm Rate (Hz)	False Alarm chance in O4^[n 26] ^[n 27]	Classification					Notes	Ref
							NS / NS ^[n 28]	NS / BH ^[n 29]	BH / BH ^[n 30]	Mass gap ^[n 31]	Terrestrial ^[n 32]
S230518h	2023-05-18 12:59:07	460; near the galactic plane	204±57	H,L	3.2 10^−10	0.015	0.0	0.864	0.037	0.0	0.099	Detected during the engineering phase, before the official start of O4.	^[83]
S230520ae	2023-05-20 22:48:41	1702	2014±663	H,L	3.1 10^−9	0.133	0.0	0.0	~1.0	0.0	1.4e-7		^[84]
S230522a	2023-05-22 09:38:04	24219	3102±1032	L	1.0 10^−8	0.383	0.0	0.0	0.99973	0.00071	0.00027		^[85]
S230522n	2023-05-22 15:30:32	29021	2221±870	L	6.5 10^−9	0.261	0.0	0.0	0.993	0.0041	0.0069		^[86]
S230601bf	2023-06-01 22:41:34	2531	3565±1260	H,L	1.7 10^−15	7.8 10^−8	0.0	0.0	~1.0	0.0022	6.4e-9		^[87]
S230605o	2023-06-05 06:53:43	1077	1067±333	H,L	4.5 10^−9	0.190	0.0	0.0	0.988	0.0	0.012		^[88]
S230606d	2023-06-06 00:43:05	1221	2545±874	H,L	1.1 10^−8	0.412	0.0	0.0	0.99928	0.0	0.00072		^[89]
S230608as	2023-06-08 20:50:47	1694	3447±1079	H,L	1.4 10^−10	0.0064	0.0	0.0	0.99981	0.0	0.00019		^[90]
S230609u	2023-06-09 06:49:58	1287	3390±1125	H,L	1.0 10^−8	0.374	0.0	0.0	0.961	0.0	0.038		^[91]
S230624av	2023-06-24 11:31:03	1718	2556±787	H,L	1.3 10^−8	0.455	0.0	0.0	0.953	0.0	0.047		^[92]
S230627c	2023-06-27 01:53:37	90; towards Leo, Leo Minor, Ursa Major, or Draco	278±68	H,L	3.2 10^−10	0.015	0.0	0.365	0.354	0.251	0.030		^[93]
S230628ax	2023-06-28 23:12:00	705	2047±585	H,L	3.2 10^−10	0.015	0.0	0.0	~1.0	0.0	2.4e-5		^[94]
S230630am	2023-06-30 12:58:06	3642	8710±2735	H,L	2.4 10^−8	0.676	0.0	0.0	0.941	0.042	0.017		^[95]
S230630bq	2023-06-30 23:45:32	1975	1150±360	H,L	7.7 10^−9	0.303	0.0	0.00076	0.890	0.079	0.031		^[96]
S230702an	2023-07-02 18:54:53	2267	2428±849	H,L	1.5 10^−12	7.2 10^−5	0.0	0.0	~1.0	0.0	2.8e-5		^[97]
S230704f	2023-07-04 02:12:11	1948	2965±978	H,L	2.8 10^−9	0.123	0.0	0.0	0.997	0.0	0.0026		^[98]
S230706ah	2023-07-06 10:43:33	1553	2143±684	H,L	4.3 10^−8	0.863	0.0	0.0	0.939	0.035	0.027		^[99]
S230707ai	2023-07-07 12:40:47	2714	3766±1135	H,L	1.4 10^−8	0.474	0.0	0.0	0.951	0.0	0.049		^[100]
S230708t	2023-07-08 05:37:05	1227	3010±988	H,L	4.3 10^−8	0.867	0.0	0.0	0.973	0.0041	0.027		^[101]
S230708z	2023-07-08 07:18:59	3373	4647±1696	H,L	7.0 10^−8	0.962	0.0	0.0	0.954	0.0041	0.046		^[102]
S230708cf	2023-07-08 23:09:35	2525	2056±608	H,L	1.6 10^−8	0.515	0.0	0.0	0.989	0.0	0.011		^[103]
S230709bi	2023-07-09 12:27:27	2644	4364±1585	H,L	3.1 10^−9	0.133	0.0	0.0	0.997	0.0	0.0028		^[104]
S230723ac	2023-07-23 10:18:23	1117	1551±436	H,L	5.3 10^−8	0.917	0.0	0.0	0.867	0.0	0.133		^[105]
S230726a	2023-07-26 00:29:40	27774	2132±714	L	3.8 10^−14	1.8 10^−6	0.0	0.0	~1.0	0.0	1.4e-7	Detected by only the Livingston detector, resulting in a bad sky localization.	^[106]
S230729z	2023-07-29 08:23:17	1945	1495±444	H,L	3.4 10^−9	0.158	0.0	0.0	0.942	0.055	0.0030		^[107]
S230731an	2023-07-31 21:53:07	599	1001±242	H,L	3.2 10^−10	0.015	0.0	0.174	0.771	0.053	0.0022		^[108]
S230802aq	2023-08-02 11:33:59	25885	576±246	H	2.2 10^−8	0.646	0.0	0.020	0.289	0.657	0.035	The other component is a black hole. Detected by only the Hanford detector, resulting in a bad sky localization.	^[109]
S230805x	2023-08-05 03:42:49	2235	3852±1193	H,L	9.2 10^−9	0.349	0.0	0.0	0.99975	0.0	0.00025		^[110]
S230806ak	2023-08-06 20:40:41	3715	5423±1862	H,L	3.0 10^−9	0.129	0.0	0.0	0.997	0.0	0.0026		^[111]
S230807f	2023-08-07 20:50:45	5436	5272±1900	H,L	7.1 10^−8	0.964	0.0	0.0	0.913	0.041	0.047		^[112]
S230811n	2023-08-11 03:21:16	810	1905±672	H,L	3.2 10^−10	0.015	0.0	0.0	~1.0	0.0	2.2e-5		^[113]
S230814r	2023-08-14 06:19:20	3389	3788±1416	H,L	4.8 10^−8	0.894	0.0	0.0	0.932	0.0	0.068		^[114]
S230814ah	2023-08-14 23:09:01	25259	330±105	L	1.7 10^−21	8.6 10^−14	0.0	0.0	~1.0	0.0	2.0e-14	Detected by only the Livingston detector, resulting in a bad sky localization.	^[115]
S230819ax	2023-08-19 17:19:10	4044	4216±1645	H,L	8.8 10^−9	0.338	0.0	0.0	0.993	0.0	0.0072		^[116]
S230820bq	2023-08-20 21:25:15	1373	3600±1437	H,L	4.2 10^−8	0.861	0.0	0.0	0.958	0.0	0.042		^[117]
S230822bm	2023-08-22 23:03:37	3974	5154±1771	H,L	2.6 10^−8	0.700	0.0	0.0	0.939	0.042	0.019		^[118]
S230824r	2023-08-24 03:30:47	3279	4701±1563	H,L	1.6 10^−11	0.00076	0.0	0.0	~1.0	0.0	2.9e-5		^[119]
S230825k	2023-08-25 04:13:34	3012	5283±2117	H,L	2.4 10^−9	0.105	0.0	0.0	0.939	0.059	0.0022		^[120]
S230831e	2023-08-31 01:54:14	3803	4900±2126	H,L	2.0 10^−8	0.603	0.0	0.0	0.985	0.0073	0.015		^[121]
S230904n	2023-09-04 05:10:13	2015	1095±327	H,L	2.2 10^−9	0.100	0.0	0.0007	0.927	0.064	0.009		^[122]
S230911ae	2023-09-11 19:53:24	27759	1623±584	H	1.9 10^−12	8.8 10^−5	0.0	0.0	~1.0	0.0	3.6e-6	Detected by only the Hanford detector, resulting in a bad sky localization.	^[123]
S230914ak	2023-09-14 11:14:01	1532	2676±827	H,L	9.0 10^−10	0.041	0.0	0.0	0.992	0.0	0.0083		^[124]
S230919bj	2023-09-19 21:57:12	708	1491±402	H,L	3.2 10^−10	0.015	0.0	0.0	0.99965	0.0	0.00035		^[125]
S230920al	2023-09-20 07:11:24	2180	3139±1003	H,L	3.2 10^−10	0.015	0.0	0.0	~1.0	0.0	1.1e-5		^[126]
S230922g	2023-09-22 02:03:44	324; towards Pisces Austrinus or Aquarius	1491±443	H,L	1.9 10^−24	0.0	0.0	0.0	~1.0	0.0	0.0		^[127]
S230922q	2023-09-22 04:06:58	4658	6653±2348	H,L	3.6 10^−10	0.017	0.0	0.0	~1.0	0.0	2.2e-5		^[128]
S230924an	2023-09-24 12:44:53	835	2358±596	H,L	3.2 10^−10	0.015	0.0	0.0	~1.0	0.0	1.9e-5		^[129]
S230927l	2023-09-27 04:37:29	1177	2966±1041	H,L	1.1 10^−8	0.394	0.0	0.0	0.976	0.0	0.024		^[130]
S230927be	2023-09-27 15:38:32	298	1059±289	H,L	3.2 10^−10	0.015	0.0	0.0	0.99966	0.0	0.00034		^[131]
S230928cb	2023-09-28 21:58:27	3093	5604±1692	H,L	9.5 10^−10	0.043	0.0	0.0	~1.0	0.0	2.8e-5		^[132]
S230930al	2023-09-30 11:07:30	2799	5123±1615	H,L	7.4 10^−9	0.291	0.0	0.0	0.994	0.0041	0.0061		^[133]
S231001aq	2023-10-01 14:02:20	3181	4425±1946	H,L	5.0 10^−9	0.207	0.0	0.0	0.996	0.0044	0.0040		^[134]
S231005j	2023-10-05 02:10:30	5480	6417±2246	H,L	3.2 10^−8	0.777	0.0	0.0	0.978	0.0	0.022		^[135]
S231005ah	2023-10-05 09:15:49	2497	3707±1335	H,L	2.0 10^−9	0.091	0.0	0.0	0.998	0.0041	0.0015		^[136]
S231008ap	2023-10-08 14:25:21	3102	3531±1320	H,L	1.5 10^−9	0.069	0.0	0.0	0.9986	0.0	0.0014		^[137]
S231014r	2023-10-14 04:05:48	1807	2857±903	H,L	1.0 10^−8	0.382	0.0	0.0	0.992	0.0	0.0080		^[138]
S231020ba	2023-10-20 14:29:47	1339	1168±361	H,L	1.3 10^−9	0.057	0.0	0.076	0.851	0.066	0.0070		^[139]
S231020bw	2023-10-20 18:05:09	386	2620±694	H,L	3.5 10^−10	0.016	0.0	0.0	0.99965	0.0	0.00035		^[140]
S231028bg	2023-10-28 15:30:06	1207	4221±923	H,L	7.6 10^−31	0.0	0.0	0.0	~1.0	0.0	0.0		^[141]
S231029y	2023-10-29 11:15:08	29972	3292±1313	L	2.2 10^−10	0.010	0.0	0.0	0.99977	0.0	0.00023	Detected by only the Livingston detector, resulting in a bad sky localization.	^[142]
S231102w	2023-11-02 07:17:36	2343	3493±1015	H,L	5.8 10^−23	0.0	0.0	0.0	~1.0	0.0	3.3e-16		^[143]
S231104ac	2023-11-04 13:34:18	759	1357±321	H,L	3.2 10^−10	0.015	0.0	0.0020	0.988	0.0088	0.0018		^[144]
S231108u	2023-11-08 12:51:42	949	1986±494	H,L	3.2 10^−10	0.015	0.0	0.0	0.99969	0.0	0.00032		^[145]
S231110g	2023-11-10 04:03:20	636	1849±533	H,L	1.9 10^−8	0.593	0.0	0.0	0.968	0.0	0.032		^[146]
S231113bb	2023-11-13 12:26:23	2172	3260±1181	H,L	5.6 10^−8	0.927	0.0	0.0	0.965	0.0041	0.035		^[147]
S231113bw	2023-11-13 20:04:17	1713	1186±376	H,L	1.4 10^−8	0.470	0.0	0.161	0.743	0.056	0.040		^[148]
S231114n	2023-11-14 04:32:11	1267	1317±407	H,L	3.2 10^−10	0.015	0.0	0.0	0.99985	0.0095	0.00015		^[149]
S231118d	2023-11-18 00:56:26	1063	2352±681	H,L	3.2 10^−10	0.015	0.0	0.0	0.99981	0.0	0.00019		^[150]
S231118ab	2023-11-18 07:14:02	3197	4531±1498	H,L	1.9 10^−8	0.587	0.0	0.0	0.985	0.0	0.015		^[151]
S231118an	2023-11-18 09:06:02	1048	1396±377	H,L	7.5 10^−8	0.969	0.0	0.015	0.726	0.017	0.242		^[152]
S231119u	2023-11-19 07:52:48	5211	6597±2556	H,L	7.4 10^−8	0.969	0.0	0.015	0.914	0.041	0.045		^[153]
S231123cg	2023-11-23 13:54:30	2714	1148±338	H,L	3.2 10^−10	0.015	0.0	0.015	0.99999	0.041	7.6e-6		^[154]
S231127cg	2023-11-27 16:53:00	3450	4425±1718	H,L	5.8 10^−9	0.237	0.0	0.0	0.996	0.0063	0.0044		^[155]
S231129ac	2023-11-29 08:17:45	3089	3964±1513	H,L	1.8 10^−8	0.561	0.0	0.0	0.986	0.0041	0.014		^[156]
S231206ca	2023-12-06 23:31:34	2335	3230±1141	H,L	3.2 10^−10	0.015	0.0	0.0	0.99998	0.0	0.000018		^[157]
S231206cc	2023-12-06 23:39:01	342	1467±264	H,L	1.9 10^−35	0.0	0.0	0.0	~1.0	0.0	0.0		^[158]
S231213ap	2023-12-13 11:14:17	1469	3861±1257	H,L	6.3 10^−10	0.029	0.0	0.0	0.99998	0.0	0.000022		^[159]
S231223j	2023-12-23 03:28:36	3520	4468±1602	H,L	1.1 10^−9	0.051	0.0	0.0	0.99905	0.000023	0.00095		^[160]
S231224e	2023-12-24 02:43:21	394	863±213	H,L	1.5 10^−9	0.069	0.0	0.00019	0.880	0.117	0.0034		^[161]
S231226av	2023-12-26 10:15:20	199	1218±171	H,L	1.1 10^−50	0.0	0.0	0.0	~1.0	0.0	0.0		^[162]
S231231ag	2023-12-31 15:40:16	27061	1066±339	H	8.4 10^−15	3.9 10^−7	0.0	0.0	~1.0	0.0	2.9e-8	Detected by only the Hanford detector, resulting in a bad sky localization.	^[163]
S240104bl	2024-01-04 16:49:32	27948	1978±615	H	3.6 10^−17	6.8 10^−10	0.0	0.0	~1.0	0.0	2.2e-10	Detected by only the Hanford detector, resulting in a bad sky localization.	^[164]
S240107b	2024-01-07 01:32:15	3961	3890±1212	H,L	5.8 10^−8	0.934	0.0	0.0	0.966	0.0	0.034		^[165]
S240109a	2024-01-09 05:04:31	28048	1594±567	H	7.3 10^−9	0.290	0.0	0.0	0.995	0.0	0.0053	Detected by only the Hanford detector, resulting in a bad sky localization.	^[166]
S240406aj	2024-04-06 06:28:47	1724	2449±692	H,L	1.6 10^−15	7.3 10^−8	0.0	0.0	~1.0	0.0	9.2e-9		^[167]
S240413p	2024-04-13 02:20:19	34; towards Leo or Sextans	526±101	H,L,V	3.2 10^−10	0.015	0.0	0.0	0.584	0.400	0.020		^[168]
S240420ax	2024-04-20 04:21:16	6423	?	H,L	5.7 10^−8	0.929	0.0	0.0	0.0	0.0	?	Unidentified gravitational wave "burst" lasting 33 milliseconds at a frequency of 219 Hertz.	^[169]
S240422ed	2024-04-22 21:35:13	259; towards Puppis, Pyxis, or Hydra	188±43	H,L,V	3.1 10^−13	1.4 10^-5	0.0	0.541	0.0	0.459	1.3e-5		^[170]
S240426s	2024-04-26 03:14:51	3832	454±143	H,L	7.6 10^−9	0.299	0.0	0.0	0.968	0.030	0.00191		^[171]
S240428dr	2024-04-28 22:54:40	286	765±177	H,V	2.1 10^−14	9.8 10^−7	0.0	0.0	~1.0	0.0	7.4e-8		^[172]
S240430ca	2024-04-30 09:35:17	4045	5705±2109	H,L	7.5 10^−8	0.969	0.0	0.0	0.920	0.041	0.039		^[173]
S240501an	2024-05-01 03:35:34	1458	4812±1338	H,L,V	4.2 10^−10	0.019	0.0	0.0	0.99999	0.0	1.3e-5		^[174]

See also

• GRB 150101B, a weak gamma-ray burst trigger observed prior to aLIGO O1 (beginning September 12, 2015), with claimed similarities to model-supported possible neutron star merger GW170817/GRB 170817A/AT2017gfo.

Notes

1. The detection date of a GW event is indicated by its designation; i.e., event GW150914 was detected on 2015-09-14.
2. The relatively large and distant area of the sky within which it is claimed to be possible to localize the source.
3. 1 Mpc is approximately 3.26 Mly.
4. c²M_☉ is about 1.8×10³ foe; 1.8×10⁴⁷ J; 1.8×10⁵⁴ erg; 4.3×10⁴⁶ cal; 1.7×10⁴⁴ BTU; 5.0×10⁴⁰ kWh, or 4.3×10³⁷ tonnes of TNT.
5. The chirp mass is the binary parameter most relevant to the evolution of the inspiral gravitational waveform, and thus is the mass that can be measured most accurately. It is related to, but less than, the geometric mean ${\displaystyle (m_{geo})}$  of the binary masses, according to ${\displaystyle m_{geo}\left({\frac {m_{geo}}{m_{1}+m_{2}}}\right)^{1/5}}$ , thus ranging from ~87% of ${\displaystyle m_{geo}}$  when the masses are the same to ~78% when they differ by an order of magnitude.
6. The dimensionless effective inspiral spin parameter is: ${\displaystyle {\frac {m_{1}a_{1}cos\theta _{LS_{1}}+m_{2}a_{2}cos\theta _{LS_{2}}}{m_{1}+m_{2}}},}$ ^[13] where ${\displaystyle m}$  is the mass of a black hole, ${\displaystyle a}$  is its spin, and ${\displaystyle \theta _{LS}}$  is the angle between the orbital angular momentum and a merging black hole's spin (ranging from ${\displaystyle 0}$  when aligned to ${\displaystyle \pi }$

May 02, 2024