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 GRB 211027A: Global MASTER-Net observations report
- GRB 211024A: Possible afterglow candidate from GIT
- GRB 211024A: Swift-XRT observations
- GRB 211027A: Fermi GBM Final Real-time Localization
- GRB 211024A: Fermi GBM detection
- GRB 211018A: Swift-XRT observations
- GRB 211025A: Optical Afterglow Detection
- GRB211023A: optical afterglow detection from Konkoly Observatory
- GRB 211024A: Swift ToO observations
- GRB 211024A: Swift/BAT-GUANO detection and candidate arcminute localization of a short burst
- GRB 211024B: Swift/UVOT detection
- GRB 211023A: Mondy optical observations
- GRB 211023B: Mondy optical afterglow confirmation
- GRB 211023B: Gemini-North Optical Observations
- Swift GRB 211025A: Global MASTER-Net observations report
- GRB 211023B: LDT Optical Afterglow Detection
- IceCube-211023A: Upper limits from a search for additional neutrino events in IceCube
- Correction to GCN 30965: GRB 211023A: Fermi GBM detection
- GRB 211025A: Swift-BAT refined analysis
- GRB 211025A: Swift-XRT refined Analysis
- GRB 211024B: CAHA 2.2m Detection; ultra-long GRB?
- GRB 211024B: Swift-XRT refined Analysis
- IPN Triangulation of GRB 211019A
- Possible Short GRB 211023B: CAHA 2.2m Detection
- GRB 211025A: Swift/UVOT Detection
- GRB 211023A: 1.5m OSN optical observation
- GRB 211024B: Swift-BAT refined analysis
- GRB 210610B: Sintesz-Newton/CrAO optical observations
- GRB 211025A: Enhanced Swift-XRT position
- GRB 211025A: Swift detection of a burst
- GECAM detection of a short burst probably from SGR J1555.2-5402
- GRB 211024B: Nanshan/NEXT optical afterglow detection
- GRB 210919A: FORS2/VLT observations
- GRB 211023A: OAJ Bright Afterglow Confirmation
- Swift GRB 211024B: Global MASTER-Net observations report
- GRB 211024B: Swift detection of a burst
- GRB 211023B: Swift-BAT refined analysis
- Fermi-LAT Gamma-ray Observations of IceCube-211023A
- GRB 211023A: MASTER OT J045237.07+851925.2 - optical counterpart discovery
- GRB 211023B: BOOTES-4/MET and 1.5m OSN optical upper limit
- GRB 211023B: Swift/UVOT Detection
- GRB 211024A: GECAM detection
- GRB 211023B: RATIR Optical and NIR Upper Limits
- GRB 211023B: TSHAO optical observation
- IceCube-211023A: No neutrino counterpart detected with ANTARES
- Fermi GRB 211023A: Global MASTER-Net observations report
- GRB 211023A: AGILE detection
- GRB 211022A: AstroSat CZTI detection
- GRB 211023B: Swift-XRT refined Analysis
- GRB 211023B: Enhanced Swift-XRT position
- GRB 211023A: Fermi GBM detection
- Swift GRB 211023B: Global MASTER-Net observations report
- Fermi GRB 211024A: Global MASTER-Net observations report
- GRB 211024A: Fermi GBM Final Real-time Localization
- GRB 211023A: Fermi-LAT detection
- GRB 211023B: Swift detection of a possibly short burst with an optical counterpart
- IceCube Alert 211023.36: Global MASTER-Net observations report
- GRB 211023A: Fermi GBM Final Real-time Localization
- IceCube-211023A - IceCube observation of a high-energy neutrino candidate track-like event
- IPN Triangulation of GRB 210927B
- GRB 211022A: GECAM detection
- AMON IC_HAWC NuEm-211020A: No neutrino counterpart detected with ANTARES
- GRB 211018A: Swift ToO observations
- GRB 211021A: BALROG localization (Fermi Trigger 656506979 / GRB 211021460)
- Fermi trigger No 656506979: Global MASTER-Net observations report
- AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-211020A
- BepiColombo MGNS joins the IPN
- Fermi trigger No 656268212: Global MASTER-Net observations report
- GRB 211018A: Fermi GBM observation
- GRB 211019A: Detection by GRBAlpha
- GRB 211018A: Detection by GRBAlpha
- Fermi GRB 211019A: Global MASTER-Net observations report
- GRB 211018A: Fermi-LAT detection
- GRB 211019A: BALROG localization (Fermi Trigger 656315976 / GRB 211019250)
- GRB 211019A: Fermi GBM Final Real-time Localization
- Fermi trigger No 656288898: Global MASTER-Net observations report
- Swift GRB211017.99: Global MASTER-Net observations report
- Integral GRB211016.42: Global MASTER-Net observations report
- IceCube-210922A: Hard X-ray flux limit for JCMT/SCUBA2 source from NuSTAR observations
- Swift trigger 1078701: MITSuME Akeno optical upper limits
- Fermi trigger No 655673024: Global MASTER-Net observations report
- GRB 210919A: LDT optical observations and candidate host galaxies
- IceCube-20210922A: No optical counterparts found by MITSuME observations
- Swift Trigger 1078701: Mondy, CrAO, AbAO observations, possible optical counterpart
- Fermi trigger No 655646385: Global MASTER-Net observations report
- Swift GRB211010.45: Global MASTER-Net observations report
- Swift Trigger 1078701 is probably not a GRB
- Fermi Gamma-ray Burst Monitor trigger 211008665/655401471 is not a GRB
- IceCube-20210922A: DESNU Optical counterpart candidate from 5 nights of DECam observations
- GRB 211008A: BALROG localization (Fermi Trigger 655401471 / GRB 211008665)
- Fermi trigger No 655401471: Global MASTER-Net observations report
- GRB 210928A: MeerKAT detection
- IceCube-210922A: DESI Observations
- GECAM observation of a burst from SGR J1555.2-5402
- Konus-Wind detection of GRB 210928A
- Fermi trigger No 654854799: Global MASTER-Net observations report
- Correction to GCN 30915: GRB 210928A: Swift-XRT analysis
- GRB 210928A: Kinder SLT-40cm optical limits
- GRB 210930A: Swift-BAT refined analysis
- SGR 1935+2154: Swift/BAT-GUANO detection and arcminute localization