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"- GRB 210606A: Fermi GBM detection
- GRB 210605B: Fermi GBM detection
- GRB 210610B: Swift-XRT refined Analysis
- GRB 210610B: Swift-BAT refined analysis
- GRB 210610B: Zwicky Transient Facility afterglow detection
- GRB 210610B: optical afterglow observations
- GRB 210610B: KAIT Optical Detection
- GRB 210610A: KAIT Optical Detection
- GRB 210607C: Insight-HXMT/HE detection
- GRB 210610B: Spectroscopy and redshift confirmation with the Himalayan Chandra Telescope
- GRB 210610A: Spectroscopy and redshift confirmation with the Himalayan Chandra Telescope
- GRB 210610B: Fermi GBM detection
- GRB 210610B: University of Siena Observatory optical photometry of the afterglow
- Konus-Wind detection of GRB 210610A
- Konus-Wind detection of GRB 210610B
- GRB 210610B: AGILE detection
- GRB 210610B: Redshift confirmation from GTC
- GRB 210610B: GOTO confirmation of afterglow detection
- GRB 210610A: Swift-XRT refined Analysis
- GRB 210610A: RATIR Optical and NIR Detection
- GRB 210610B: RATIR Optical and NIR Observations
- GRB 210610B: Enhanced Swift-XRT position
- GRB 210610B: Photometry and phot-redshift from Legacy Survey, PanSTAR, and SDSS
- GRB 210610B: SAO RAS optical observations
- GRB 210610A: Swift-BAT refined analysis
- GRB 210610A: 1.5m OSN optical observation
- GRB 210610B: correction to GCN 30181
- HAWC Transient Monitoring Alert: Significant Spot after 3 transits
- GRB 210610B: NOT optical observations and tentative redshift
- GRB 210610B: iTelescope optical afterglow observations
- GRB210610B: MeerLICHT multi-colour photometry
- Fermi trigger No 645047470: Global MASTER-Net observations report
- GRB 210610B: CrAO/ZTSh optical afterglow photometry
- GRB 210610B: BOOTES-2/TELMA optical observation
- Swift GRB 210610B: Global MASTER-Net observations report
- GRB 210610B: CrAO/ZTSh optical observations
- GRB 210610B: GIT optical detection
- Swift GRB210610.83: Global MASTER-Net OT detection
- GRB 210606A: Swift-XRT afterglow detection
- GRB 210610B: BALROG localization (Fermi Trigger 645047470 / GRB 210610827)
- GRB 210610B: Swift detection of a burst with bright optical afterglow
- GRB 210610A: MITSuME Ishigaki optical observation
- GRB210610A: MeerLICHT multi-colour photometry
- Swift GRB 210610A: Global MASTER-Net observations report
- Swift GRB 210610A: MASTER optical counterpart observation
- GRB 210610A: Enhanced Swift-XRT position
- GRB 210610A: Xinglong-2.16m redshift
- GRB 210610A: GIT optical detection
- GRB 210610A: Xinglong-2.16m optical afterglow observations
- GRB 210610A: MITSuME Akeno optical observation
- GRB 210610A: Swift detection of a burst with an optical counterpart
- GRB 210607B: Insight-HXMT/HE detection
- GRB 210605A: CALET Gamma-Ray Burst Monitor detection
- Konus-Wind detection of GRB 210606B
- Fermi-LAT Gamma-ray Observations of IceCube-210608A
- IceCube-210608A: not observable by Fermi-GBM
- IPN triangulation of GRB 210606B
- IceCube-210608A: IceCube observation of a high-energy neutrino candidate track-like event
- IceCube Alert 210608.15: Global MASTER-Net observations report
- Fermi Gamma-ray Burst Monitor trigger 644793834 / 210607892 is not a GRB
- GRB 210607A/MAXI J1733-222: MAXI/GSC detection
- MAXI GRB210607.82: Global MASTER-Net observations report
- Fermi trigger No 644793834: Global MASTER-Net observations report
- GRB 210606B: Fermi GBM detection
- GRB 210605B: Swift-XRT observations
- Konus-Wind detection of GRB 210602A
- Konus-Wind detection of GRB 210605A (short/hard)
- IPN triangulation of GRB 210605A (short)
- GRB 210606B: AGILE detection
- GRB 210606A: 1.5m OSN optical upper limit
- GECAM Sub-Threshold Detection of new magnetar Swift SGR J1555.2-5402
- GRB 210606B: BALROG localization (Fermi Trigger 644712030 / GRB 210606945)
- GRB 210606B: GECAM detection
- Fermi trigger No 644712030: Global MASTER-Net observations report
- GRB 210606A: Swift ToO observations
- Fermi GRB 210606A: DDOTI Upper Limits on the Afterglow
- GRB 210606A: Swift/BAT-GUANO detection and arcminute localization
- GRB 210605B: Swift ToO observations
- Fermi GRB 210606A: Global MASTER-Net observations report
- GRB 210606A: Fermi GBM Final Real-time Localization
- GRB 210605B: Swift/BAT-GUANO detection and arcminute localization
- GRB 210605B: Fermi GBM Final Real-time Localization
- Fermi GRB 210605A: Global MASTER-Net observations report
- GRB 210605A: Fermi GBM Final Real-time Localization
- Initial results of a NICER X-ray monitoring of the magnetar, Swift J1555.2-5402
- Fermi GBM Sub-Threshold Detection of new Swift SGR J1555.2-5402
- SGR J1555.2-5402: Swift-BAT refined analysis
- Fermi trigger No 644449593: Global MASTER-Net observations report
- Swift J1555.2-5402: Swift XRT refined analysis of the new SGR
- NICER discovery of 3.86 s pulsations from a new magnetar: SGR J1555.2-5402
- Swift Detection of probable new Swift SGR J1555.2-5402
- MAXI GRB210602.50: Global MASTER-Net observations report
- Swift GRB210603.41: Global MASTER-Net observations report
- GRB 210602A: CALET Gamma-Ray Burst Monitor detection
- GRB 210602B: GECAM detection
- GRB 210529A: GECAM detection
- Fermi trigger No 644359567: Global MASTER-Net observations report
- GRB 210602A: MAXI/GSC detection
- Fermi GRB 210601A: Global MASTER-Net observations report
- GRB 210601A: Fermi GBM Final Real-time Localization