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"- IceCube-211116A: not observable by Fermi-GBM
- IceCube-211023A: not observable by Fermi-GBM
- IPN triangulation of GRB 211124A (short)
- HAWC-211123A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- HAWC-211123A: not observable by Fermi-GBM
- GRB 211124A: Swift/BAT-GUANO detection of a short burst outside the coded FOV
- IceCube Alert 211123.60: Global MASTER-Net observations report
- HAWC-211123A: No neutrino counterpart detected with ANTARES
- IceCube-211123A - IceCube observation of a high-energy neutrino candidate track-like event
- Fermi trigger No 659413798: Global MASTER-Net observations report
- Trigger_21473: Tiled Swift observations
- GRB 211023B: LBT likely spectroscopic redshift of the host galaxy
- Alert from the HAWC Burst Monitor HAWC-211123A
- GRB 211120A: AGILE detection
- GRB 211120A: AstroSat CZTI detection
- Fermi trigger No 659183098: Global MASTER-Net observations report
- Fermi trigger No 659106591: Global MASTER-Net observations report
- GRB 211120B: Swift/BAT-GUANO detection outside the coded FOV
- GRB 211120A: GECAM detection
- GRB 211118A: AstroSat CZTI detection
- GRB 211023A: optical observations and photometric evidence of supernova
- Fermi-LAT Gamma-ray Observations of IceCube-211117A
- GRB211118A: Swift/BAT-GUANO detection outside the coded FOV
- Fermi trigger No 658971499: Global MASTER-Net observations report
- Search for counterpart to IceCube-211117A with ANTARES
- IceCube-211117A : IceCube observation of a high-energy neutrino candidate track-like event
- IceCube-211116A: Upper limits from a search for additional neutrino events in IceCube
- Fermi-LAT Gamma-ray Observations of IceCube-211116A
- IceCube-211116A: No neutrino counterpart detected with ANTARES
- IceCube Alert 211116.44: Global MASTER-Net observations report
- Fermi trigger No 658755664: Global MASTER-Net observations report
- Fermi trigger No 658764238: Global MASTER-Net observations report
- Konus-Wind detection of GRB 211107B
- IceCube-211116A : IceCube observation of a high-energy neutrino candidate track-like event
- GRB 211115A: CALET Gamma-Ray Burst Monitor detection
- Fermi trigger No 658686687: Global MASTER-Net observations report
- GRB 211115A: MAXI/GSC detection
- GRB 211023A: classification and SPI-ACS/INTEGRAL registration
- Fermi GRB 211112A: Global MASTER-Net observations report
- GRB 211106A: Swift/UVOT upper limits
- IPN triangulation of GRB 211106A (short)
- GRB 211112A: Fermi GBM Final Real-time Localization
- GRB 211110A: AstroSat CZTI detection
- Short GRB 211106A: spectroscopy of galaxies in the field
- GRB 211110A: GECAM detection
- Fermi trigger No 658214822: Global MASTER-Net observations report
- GRB 211107B: Swift-XRT afterglow detection
- GRB 211107A: GECAM detection
- GRB 211106A: VLT/FORS2 optical observations
- GRB 211106A, GROND observations
- GRB 211106A: Swift-XRT afterglow detection
- Fermi GRB 211109B: Global MASTER-Net observations report
- GRB 211023A: SAO RAS optical observations
- GRB 211107B: Swift-XRT observations
- MeerLICHT follow-up of GRB 211106A
- GRB 211109C: GECAM detection
- GRB 211107B: Swift ToO observations
- GRB 211109B: Fermi GBM Final Real-time Localization
- Fermi GRB 211109A: Global MASTER-Net observations report
- GRB 211109A: Fermi GBM Final Real-time Localization
- GRB 211107B: Swift/BAT detection
- GRB 211023A: A BdHN of type I
- Fermi GBM Sub-Threshold Detection of GRB 211106A
- Konus-Wind detection of GRB 211106A
- GRB 211023A: BTA spectroscopic redshift
- GRB 211107A: Fermi GBM Final Real-time Localization
- GRB 211106A: Swift-XRT observations
- GRB 211106A: Swift ToO observations
- GRB 211106A: Swift/BAT-GUANO candidate arcminute localization of a short burst
- GRB 211105A: MASTER optical inspection
- GRB 211105A: Swift/BAT-GUANO detection outside the coded FOV
- GRB 211105A: GECAM detection
- Swift Trigger 1082569 is probably not a GRB
- GRB 211105A: AGILE detection of a burst
- Fermi GBM trigger 657780594/211105201 is not a GRB
- GRB 211023A: optical detection by SBT in Ondrejov
- GRB 211023A: continued 1.3m DFOT Optical Observations and possible jet break
- Fermi trigger No 657742914: Global MASTER-Net observations report
- GRB 211104A: Fermi GBM Final Real-time Localization
- GRB 211023B: Subaru optical observation
- GRB 211024A: MITSuME Akeno optical observation
- GCN Viewer Now Available
- GRB 211102B: GECAM detection
- Fermi GRB 211102A: Global MASTER-Net observations report
- GRB 211102B: BALROG localization (Fermi Trigger 657554740 / GRB 211102587)
- GRB 211102B: Fermi GBM Final Real-time Localization
- GRB 211023B: MITSuME Akeno optical upper limits
- GRB 211102A: BALROG localization (Fermi Trigger 657533168 / GRB 211102338)
- GRB 211102A: Fermi GBM Final Real-time Localization
- GRB 211024B: Optical afterglow observation by Ondrejov D50
- GRB 211024A: 1.3m DFOT observations
- Fermi GRB 211031A: Global MASTER-Net observations report
- GRB 211031A: Fermi GBM Final Real-time Localization
- IPN triangulation of GRB 211022A
- GRB 211023A: 1.3m DFOT Optical Observations
- Konus-Wind detection of GRB 211023A
- GRB 2121023B: 6 GHz VLA radio upper limit
- GRB 211023A: Terskol optical observations
- AMON NuEm-211020A: No Candidate Counterparts from Swift-XRT follow up observations
- GRB 211023A: continued Mondy optical observations