GCN Circulars
GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.
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"
10363 results found.
- LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Final Epochs)
- Konus-Wind detection of GRB 250506A
- GRB 250507B: AstroSat CZTI detection
- EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
- EP250512a: Global MASTER-Net observations report
- GRB 250512B/EP250512a:SVOM/VT bright optical counterpart
- GRB 250512B: SVOM detection of a burst
- EP250512a: Einstein Probe detection of an X-ray transient
- EP250511a: Einstein Probe follow-up obsevation and refined analysis
- EP250511a: Global MASTER-Net observations report
- EP250511a: Einstein Probe detection of an X-ray transient
- Fermi GRB 250510C: Global MASTER-Net observations report
- GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
- GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 250509A: Swift-XRT refined Analysis
- GRB 250510A: SVOM possible detection of a burst
- Fermi GRB 250509A: Global MASTER-Net observations report
- GRB 250509A: Swift detection of a burst
- EP250508a: refined analysis of the EP-WXT and EP-FXT observations
- GRB 250506A: Swift-XRT afterglow detection
- EP250508a: Global MASTER-Net observations report
- EP250508a: Einstein Probe detection of an X-ray transient
- GRB 250507A: refined SVOM/MXT data analysis
- Fermi-LAT Gamma-ray Observations of IceCube-250506A
- IceCube Alert 250506.59: Global MASTER-Net observations report
- GRB 250430A: Konus-Wind detection and joint Konus-Wind+Swift-BAT spectral analysis
- GRB 250506A: REM optical/NIR upper limits
- GRB 250506A: Fermi GBM Observation
- GRB 250504A: Swift-BAT refined analysis
- GRB 250504A: REM optical/NIR observations
- GRB 250504A: MeerLICHT optical afterglow detection
- Fermi GRB 250504A: Global MASTER-Net observations report
- GRB 250504A: Swift detection of a burst
- GRB 250502A: Mondy and Tien-Shan Optical Observations
- GRB 250502A: Montarrenti Observatory optical detection
- GRB 250502A: Swift-XRT afterglow detection
- GRB 250502B: AstroSat CZTI detection
- GRB 250502A: LCO optical counterpart detection
- GRB 250502C: Fermi GBM Final Localization
- GRB 250407A: VZLUSAT-2 detection
- Fermi-LAT Gamma-ray Observations of IceCube-250429A
- GRB 250502B: DDOTI Optical Observations
- GRB 250430A: Swift-XRT refined Analysis
- GRB 250430A: Swift/UVOT Detection
- Fermi GRB 250502B: Global MASTER-Net observations report
- GRB 250430A: Swift detection of a burst with optical counterpart
- EP250428b: refined analysis of the EP-FXT follow-up observation
- EP250428b: SAO RAS optical upper limit
- EP250428b: Einstein Probe detection of a fast X-ray transient
- Fermi-LAT Gamma-ray Observations of IceCube-250426A
- EP250427a: REM optical/NIR afterglow detection
- EP250427a: Einstein Probe detection of a fast X-ray transient
- IceCube Alert 250426.74: Global MASTER-Net observations report
- IceCube-250421A: Upper limits from a search for additional neutrino events in IceCube
- Konus-Wind detection of GRB 250424A
- Fermi-LAT gamma-ray observations of IceCube-250421A
- GRB 250424A: Kilonova-Catcher optical afterglow detection
- GRB 250404A / EP250404a: GRBAlpha detection
- GRB 250424A: Swift-XRT refined Analysis
- GRB 250424A: AstroSat CZTI detection of a bright long burst
- GRB 250424A: DDOTI Afterglow Detection
- LIGO/Virgo/KAGRA S250328ae: Subaru/PFS Spectroscopic Follow up and Candidates
- SVOM/sb25042207: BOOTES-2 early optical upper limit
- SVOM/sb25042207: GOTO optical upper limits
- GRB 250421A: AstroSat CZTI detection
- GRB 250419A: Mephisto Multi-band Optical Detection
- GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
- IC-250421A: LAST optical observations of the IceCube neutrino candidate
- GRB 250419A: Mondy Continued Optical Observations
- Fermi GRB 250421A: Global MASTER-Net observations report
- GRB 250421B: AstroSat CZTI detection of a bright long burst
- IceCube Alert 250421.71: Global MASTER-Net observations report
- GRB 250419A: Liverpool Telescope observations
- GRB 250419A: JinShan optical observations
- GRB 250416C / EP250416a: SVOM/GRM observation of a burst
- GRB 250419A: LCO optical afterglow multi-band observations
- GRB 250419A: MASTER optical afterglow observation
- Fermi-LAT Gamma-ray Observations of IceCube-250416A
- GRB 250419A: Swift-XRT refined Analysis
- Konus-Wind detection of GRB 250416C (a counterpart of EP250416a)
- EP250416a: refined EP-WXT and EP-FXT analysis
- Konus-Wind detection of GRB 250403A
- IceCube-250416A: DDOTI Optical Observations
- EP250416a: GSP optical upper limit
- EP250416a: Global MASTER-Net observations report
- EP250416a: Einstein Probe detection of an X-ray transient
- IceCube-250416A: Global MASTER-Net observations report
- GRB 250413A: AstroSat CZTI detection
- GRB 250412A: AstroSat CZTI detection
- EP250404a: Nanshan 0.43m Telescope optical observatios
- Fermi trigger No 766148493: Global MASTER-Net observations report
- Fermi trigger No 766173972: Global MASTER-Net observations report
- Fermi GRB 250411A: Global MASTER-Net observations report
- GRB 250320B: cubesat Avion detection
- Fermi-LAT gamma-ray observations of IceCube-250406A
- Konus-Wind detection of GRB 250407A
- GRB 250407A: EP-WXT afterglow detection
- GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
- GRB 250407A: Fermi GBM Detection
- GRB 250407A: Swift-XRT afterglow detection