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 211211B: GECAM detection
- Fermi GRB 211212B: Global MASTER-Net observations report
- GRB 211211A: Afterglow detection from CAFOS/2.2m CAHA
- GRB 211211A: MITSuME Akeno optical observation
- Swift GRB 211211A: Global MASTER-Net observations report
- GRB 211212B: Fermi GBM Final Real-time Localization
- GRB 211211A: LCO Optical Observations
- GRB 211211A: Nanshan/NEXT optical observations
- GRB 211211A: Swift-XRT refined Analysis
- GRB 211212A: Fermi GBM Final Real-time Localization
- GRB 211211A: Fermi GBM observation
- GRB 211211A: Swift-BAT refined analysis
- Fermi GRB 211211B: Global MASTER-Net observations report
- GRB 211211B: Fermi GBM Final Real-time Localization
- Fermi GRB 211211A: Global MASTER-Net observations report
- GRB 211211A: Enhanced Swift-XRT position
- GRB 211207A: Swift/UVOT Detection
- GRB 211211A: KAIT Optical Afterglow Candidate
- GRB 211211A: Swift detection of a bright burst
- GRB 211211A: Fermi GBM Final Real-time Localization
- Fermi trigger No 660868196: Global MASTER-Net observations report
- IceCube-211208A: No significant detection in HAWC
- AMON NuEm-211020A: No neutrino counterpart detected with ANTARES
- Fermi trigger No 660736561: Global MASTER-Net observations report
- GRB 211130A: MeerLICHT identification of possible afterglow candidate
- IceCube-211208A: Upper limits from a search for additional neutrino events in IceCube
- Fermi-LAT Gamma-ray Observations of IceCube-211208A
- IceCube-211208A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-211209A
- IceCube-211208A - IceCube observation of a high-energy neutrino candidate track-like event
- IceCube Alert 211208.84: Global MASTER-Net observations report
- GRB 211207A: Swift-BAT refined analysis
- GRB 211207A: VLT/X-shooter redshift
- Chandra observation of GW170817 at ~1573 days since merger (Epoch 1 of 4)
- GRB 211204C: Fermi GBM detection
- GRB 211207A: Swift-XRT refined Analysis
- GRB 211207A: Enhanced Swift-XRT position
- Swift GRB 211207A: Global MASTER-Net observations report
- GRB 211207A: Swift detection of a burst with an optical counterpart
- GRB 211206A: Not observable by Fermi-GBM
- GRB 211206A: AstroSat CZTI detection
- GRB 211206B: AstroSat CZTI detection
- GRB 211204C: AstroSat CZTI detection
- IPN triangulation of GRB 211204C
- GRB 211206A: Swift/BAT-GUANO detection outside the coded FOV
- GRB 211206A: AGILE/MCAL detection of a burst
- GRB 211204C: Swift/BAT-GUANO detection outside the coded FOV
- GRB 211204C: GECAM detection
- Fermi GRB 211204C: Global MASTER-Net observations report
- GRB 211204C: Fermi GBM Final Real-time Localization
- Fermi GRB 211204B: Global MASTER-Net observations report
- GRB 211204B: Fermi GBM Final Real-time Localization
- Fermi GRB 211204A: Global MASTER-Net observations report
- GRB 211204A: Fermi GBM Final Real-time Localization
- GRB 211124A: Fermi GBM Observation
- Swift Trigger 1086826 (possible GRB 211203A) is likely not an astrophysical event
- Swift GRB 211203A: Global MASTER-Net observations report
- Fermi GBM Upper limits for GRB 211203A
- Konus-Wind detection of GRB 211130A
- IPN triangulation of GRB 211130A
- GRB 211203A: Swift detection of a burst
- GRB 211201A: GECAM detection
- GRB 211201A: Swift/BAT-GUANO detection likely outside the coded FOV
- GRB 211106A: Second HST Observation
- Fermi GRB 211201A: Global MASTER-Net observations report
- GRB 211201A: Fermi GBM Final Real-time Localization
- Fermi GRB 211130A: Global MASTER-Net observations report
- IceCube-211125A: No significant detection in HAWC
- GRB 211130A: BALROG localization (Fermi Trigger 659978192 / GRB 211130636)
- GRB 211130A: Fermi GBM Final Real-time Localization
- GRB 211106A: GECAM detection
- GRB 211129A: Swift-BAT refined analysis
- GRB 211129A: Swift-XRT refined Analysis
- GRB 211129A: Swift/UVOT Upper Limits
- GRB 211106A: HST Observations
- GRB 211106A: Chandra Observations
- IceCube-Cascade 211128A: Upper limits from a search for additional neutrino events in IceCube
- IceCube-211125A: Upper limits from a search for additional neutrino events in IceCube
- GRB 211129A: Fermi GBM observation
- Swift GRB 211129A: Global MASTER-Net observations report
- GRB 211129A: Nanshan/NEXT optical upper limit
- GRB 211129A: Enhanced Swift-XRT position
- IPN triangulation of GRB 211118A
- GRB 211129A: MITSuME Akeno optical upper limits
- GRB 211129A: Swift detection of a burst
- IceCube-211125A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- GRB 211023A: Xinglong 2.16m optical observations
- GRB 211023A: Xinglong 2.16m optical observations
- Fermi-LAT Gamma-ray Observations of IceCube-211125A
- GRB 211120548: Fermi GBM observation
- Konus-Wind detection of GRB 211120A
- IPN triangulation of GRB 211120A
- IceCube-211125A: No neutrino counterpart detected with ANTARES
- Chandra observations of GRB 210905A
- IceCube-211125A: IceCube observation of a high-energy neutrino candidate track-like event
- GRB 211118A: Fermi GBM detection
- IceCube Alert 211125.27: Global MASTER-Net observations report
- Fermi-LAT Gamma-ray Observations of IceCube-211123A
- IceCube-211123A: Upper limits from a search for additional neutrino events in IceCube
- IceCube-211123A: INTEGRAL was inactive at the time of the event