GCN Circulars
GCN Circulars are rapid bulletins submitted by and distributed to the community. See the documentation for help with subscribing to or submitting Circulars.
Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
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"- Fermi trigger No 647365516: Global MASTER-Net observations report
- Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 6
- Fermi trigger No 647271699: Global MASTER-Net observations report
- Fermi GBM Observations of SGR J1935+2154
- Swift-BAT detection of a burst from SGR 1935+2154
- GRB 210706A: Fermi GBM observation
- GRB 210706A: optical upper limit of Sintesz-Newton/CrAO and AS-32/AbAO
- Konus-Wind detection of GRB 210706A
- GRB 210706A: GIT optical upper limits
- GRB 210704A: OAJ T80 multi-color detections
- GECAM detection of a bright short burst from SGR 1935+2154
- GRB 210706A: Swift-XRT afterglow detection
- Integral GRB210707.02: Global MASTER-Net observations report
- GRB 210706A: Swift ToO observations
- Fermi trigger No 647252274: Global MASTER-Net observations report
- INTEGRAL detection of a burst from SGR 1935+2154
- Integral GRB210706.72: Global MASTER-Net observations report
- GRB 210706A: Swift/BAT-GUANO detection and arcminute localization
- GRB 210704A: OSIRIS/GTC spectroscopy
- GRB 210704A: CAHA 2.2m Afterglow Detection
- GRB 210704A: RATIR optical upper limits
- GRB 210704A: Swift/UVOT Upper Limits
- Konus-Wind detection of GRB 210704A
- GRB 210704B: AstroSat CZTI detection
- GRB 210619B: ALMA detection
- GRB 210704A: TNG detection of the optical afterglow candidate
- GRB 210704A: Assy optical afterglow candidate
- GRB 210704A: DDOTI upper limit
- GRB 210704B: Fermi GBM detection
- GRB 210704A: possible local hosts
- GRB 210704A: Fermi GBM detection
- GRB 210704A: Swift-XRT afterglow detection
- GRB 210704A: AstroSat CZTI detection
- IceCube-210516A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- IceCube-210510A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- GRB 210704A: Fermi-LAT detection
- GRB 210704A: Swift ToO observations
- GRB 210705A: AGILE/MCAL detection of a burst
- GRB 210704A: AGILE/MCAL detection
- Fermi trigger No 647108723: Global MASTER-Net observations report
- Fermi trigger No 647120009: Global MASTER-Net observations report
- GRB 210704A: BALROG localization (Fermi Trigger 647120009 / GRB 210704815)
- GRB 210702A, Swift-BAT refined analysis
- GRB 210702A: BOOTES-3/YA optical counterpart observations
- Konus-Wind detection of GRB 210702A
- GRB 210702A: Chilescope optical observations
- GRB 210702A: iTelescope optical afterglow observations
- GRB 210702A: AGILE detection
- GRB 210702A: CALET Gamma-Ray Burst Monitor detection
- GRB 210619B: JCMT SCUBA-2 sub-mm observations
- GRB 210610B: JCMT SCUBA-2 sub-mm observations
- GRB 210610A: JCMT SCUBA-2 sub-mm observations
- GRB 210702A: Swift-XRT refined Analysis
- GRB 210702A: VLT/X-shooter redshift
- GRB 210702A: preliminary Swift/UVOT photometry
- GRB 210702A: Swift/UVOT redshift
- GRB210702A: MeerLICHT multi-colour photometry
- Swift GRB 210702A: Global MASTER-Net observations report
- Swift GRB210702.80: Global MASTER-Net OT detection
- GRB 210702A: Swift detection of a burst with a bright optical counterpart
- IceCube-210629A: Upper limits from a search for additional neutrino events in IceCube
- IceCube-210629A: One Candidate Counterpart from the Zwicky Transient Facility
- IceCube-210629A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- Fermi-LAT Gamma-ray Observations of IceCube-210629A
- IceCube-210629A: Upper limits from Fermi-GBM Observations
- GRB 210627B: GECAM detection
- IceCube Alert 210629.76: Global MASTER-Net observations report
- GRB 210619B: Sayan observatory 1.6-m telescope observations
- IceCube-210629A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 210626A: Swift/XRT afterglow confirmation
- GRB 210626A: Fermi GBM observation
- GRB 210626A: CAHA 2.2m telescope optical limit
- GRB 210619B: Deep CAHA 2.2m detection and late-time light curve behavior
- GRB 210626A: Ondrejov D50 optical limit
- GRB 210626A: GIT optical upper limit
- Fermi trigger No 646443989: Global MASTER-Net observations report
- Fermi GRB 210627B: Global MASTER-Net observations report
- GRB 210627B: BALROG localization (Fermi Trigger 646509445/ GRB 210627748)
- GRB 210627B: Fermi GBM Final Real-time Localization
- Fermi GRB 210627A: Global MASTER-Net observations report
- GRB 210627A: Fermi GBM Final Real-time Localization
- GRB 210626A: Swift-XRT afterglow detection
- Fermi trigger No 646322348: Global MASTER-Net observations report
- Fermi GRB 210626A: Global MASTER-Net observations report
- GRB 210626A: Swift ToO observations
- GRB 210626A: Swift/BAT-GUANO detection and arcminute localization
- GRB 150428A: late-time radio observations
- GRB 210626A: Fermi GBM Final Real-time Localization
- GRB 210618A: 1.5m OSN optical upper limit
- Fermi GRB 210625A: Global MASTER-Net observations report
- GRB210619B: optical afterglow detection from Konkoly Observatory
- GRB 210625A: Fermi GBM Final Real-time Localization
- IPN triangulation of GRB 210624A (short)
- GRB 210622A: Swift-XRT observations
- GRB 210610B: T-CAT optical observations
- GRB 210619B: ASIM observation
- Fermi trigger No 646189108: Global MASTER-Net observations report
- Fermi GBM observation of a bright burst in the direction of SGR 1935+2154
- GRB 210618A: Swift-XRT afterglow detection
- Fermi trigger No 646194855: Global MASTER-Net observations report