GCN Circulars
GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search
To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.
Advanced Search Examples (click to copy):
subject:"Swift"body:"GRB"submitter:"Judith Racusin"4055 results found.
- LIGO/Virgo S230606d: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S230606d: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S230605o: Updated Sky localization
- IceCube-230603A: Upper limits from a search for additional neutrino events in IceCube
- LIGO/Virgo/KAGRA S230601bf: Updated Sky localization
- LIGO/Virgo/KAGRA S230605o: Identification of a GW compact binary merger candidate
- LIGO/Virgo S230605o: Global MASTER-Net observations report
- LIGO/Virgo S230604z: Global MASTER-Net observations report
- LIGO/Virgo S230603aa: Global MASTER-Net observations report
- LIGO/Virgo S230602ap: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S230518h: Upper limits from a two-week IceCube neutrino search
- LIGO/Virgo S230601bf: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S230601bf: Identification of a GW compact binary merger candidate
- LIGO/Virgo S230531f: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S230529ay: Zwicky Transient Facility observations
- LIGO/Virgo/KAGRA S230528a: Zwicky Transient Facility observations
- LIGO/Virgo/KAGRA S230527ch: Zwicky Transient Facility observations
- LIGO/Virgo/KAGRA S230529ay: Upper limits from CALET observations.
- LIGO/Virgo/KAGRA S230529ay: AstroSat CZTI non-detection and upper limits
- LIGO/Virgo S230529ay: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S230529ay: upper limits from AGILE/MCAL
- LIGO/Virgo/KAGRA S230529ay: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S230529ay: Upper limits from Fermi-GBM Observations
- LIGO/Virgo/KAGRA S230529ay: Updated Sky localization and EM Bright Classification
- LIGO/Virgo/KAGRA S230529ay: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- LIGO/Virgo/KAGRA S230529ay: Identification of a GW compact binary merger candidate
- LIGO/Virgo S230529p: Global MASTER-Net observations report
- LIGO/Virgo S230525a: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S230518h: Updated Sky localization
- LIGO/Virgo/KAGRA S230520ae: Updated Sky localization
- LIGO/Virgo/KAGRA S230518h: Upper limits from Glowbug gamma-ray observations
- LIGO/Virgo/KAGRA S230518h: TESS observations of the localization region
- LIGO/Virgo/KAGRA S230518h: No transient candidates in CALET observations
- LIGO/Virgo/KAGRA S230524x: Retraction of GW compact binary merger candidate
- LIGO/Virgo S230524b: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S230521k: MASTER new OT discovery
- LIGO/Virgo/KAGRA S230521k: Additional candidates from Zwicky Transient Facility
- LIGO/Virgo S230522n: Global MASTER-Net observations report
- LIGO/Virgo S230522a: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S230522n: Upper limits from IceCube neutrino search
- LIGO/Virgo/KAGRA S230518h: Swift/UVOT Upper Limits for MeerLICHT candidates: AT2023ixg and AT2023iyb
- LIGO/Virgo/KAGRA S230522a: 2 counterpart neutrino candidates from IceCube neutrino searches
- LIGO/Virgo S230521k: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S230521k: Zwicky Transient Facility observations
- LIGO/Virgo S230520ae: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S230520ae: Identification of a GW compact binary merger candidate: End-to-End Test
- LIGO/Virgo/KAGRA S230520ae: Upper limits from IceCube neutrino search
- LIGO/Virgo/KAGRA S230518h: ATCA follow-up of candidate counterparts
- LIGO/Virgo/KAGRA S230518h: GECKO tiling observations with KMTNet
- LIGO/Virgo/KAGRA S230518h: Swift/UVOT Upper Limits for Swope candidates: SSS23a, SSS23b and SSS23c
- LIGO/Virgo/KAGRA S230518h: ATLAS observations of the skymap
- LIGO/Virgo/KAGRA S230518h: Swope Search and Candidate Counterpart Identification
- LIGO/Virgo/KAGRA S230518h: Upper limits from Konus-Wind observations
- LIGO/Virgo S230518h: AGILE/MCAL observations
- LIGO/Virgo S230518h: Swift XRT observations, 8 X-ray sources
- LIGO/Virgo/KAGRA S230518h: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/Kagra S230518h: NED Galaxies in the Localization Volume
- LIGO/Virgo/KAGRA S230518h: AstroSat CZTI non-detection and upper limits
- LIGO/Virgo/KAGRA S230518h: Upper limits from Fermi-GBM Observations
- LIGO/Virgo S230518h: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S230518h: Updated Sky localization and EM Bright Classification
- LIGO/Virgo S230518h: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- LIGO/Virgo S230518h: Upper limits from IceCube neutrino search
- LIGO/Virgo/KAGRA S230518h: Identification of a GW compact binary merger candidate
- IceCube-230511A: Upper limits from a search for additional neutrino events in IceCube
- IceCube-230506A: Upper limits from a search for additional neutrino events in IceCube
- GRB 230423A: Swift/UVOT Upper Limits
- New GCN Circulars Portal for Rapid Communications on Astronomical Transients is Online
- GRB 221231A: Swift/BAT-GUANO arcminute localization of a possibly short burst
- GRB 221215A: Swift/BAT-GUANO arcminute localization
- GRB 221206B: Swift/BAT-GUANO candidate arcminute localization
- LIGO-Virgo-KAGRA and GEO600 statement on GRB 221009A
- IPN triangulation of GRB 220927A (long)
- GRB 220909A: Swift/BAT-GUANO candidate arcminute localization
- IPN triangulation of GRB 220903A (long)
- GRB 220831A: Swift/BAT-GUANO localization of a short burst
- Introducing new GCN Kafka broker and web site for transient alerts, https://gcn.nasa.gov
- GRB 220710A: Swift/BAT-GUANO arcminute localization
- IPN triangulation of GRB 220711C (short)
- GRB 220708B: Swift/BAT-GUANO arcminute localization
- GRB 220606B: Swift/BAT-GUANO candidate arcminute localization of a short burst
- IPN triangulation of GRB 220601A (long)
- Fermi-GBM will trial new SAA regions from Tuesday June 7th
- IPN triangulation of GRB 220524B
- IPN triangulation of GRB 220524A
- IPN triangulation of GRB 220521B
- IPN triangulation of GRB 220519A
- GRB 220514A: MITSuME Akeno optical observation
- GRB 220511A: Swift/BAT-GUANO arcminute localization
- IPN triangulation of GRB 220411A
- IPN triangulation of short/soft GRB 220406A
- GRB 220310C: Swift/BAT-GUANO candidate arcminute localization
- IPN triangulation of GRB 220308A (long / very bright)
- IPN triangulation of GRB 220222A
- GCN Circ.draft on GRB 220222A
- ZTF22aabjpxh/AT2022cva: NICER X-ray detection is consistent with a GRB afterglow
- IPN triangulation of GRB 220219B (consistent with ZTF22aabjpxh/AT2022cva)
- ZTF22aaajecp/AT2022cmc: NICER X-ray detection
- IPN triangulation of GRB 220211A (short)
- IPN triangulation of a bright burst from SGR 1935+2154