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').
18174 results found.
- GRB 250221A: AKO Optical Upper Limit
- GRB 250221A: Swift/UVOT Detection
- GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
- GRB 250221A: REM optical/NIR afterglow detection
- GRB 250221A: Enhanced Swift-XRT position
- GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
- GRB 250221A: Swift detection of a burst with an optical counterpart
- Swift GRB250221.15: Global MASTER-Net OT detection
- Swift GRB250221.15: Global MASTER-Net observations report
- GRB 250219A: Swift/UVOT Upper Limits
- GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
- GRB 250219A: 1.6m Mephisto optical upper limits
- GRB 250219A: SVOM/VT optical counterpart
- GRB 250219A: Swift-XRT observations
- GRB 250219A: Swift ToO observations
- GRB 250217C: Swift-XRT observations
- GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
- GRB 250217C: Tiled Swift observations
- IPN triangulation of GRB 250217C (short)
- Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
- SVOM/sb25021804: SVOM detection of a long X-ray transient
- GRB 250213A: Swift-XRT observations
- GRB 250215A / EP250215a: LCO detection of the afterglow
- GRB 250215A: Swift/UVOT Upper Limits
- GRB 250215A: Fermi GBM Observation
- GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
- GRB 250215A: Swift-XRT refined Analysis
- GRB 250213A: Swift ToO observations
- GRB 250211A: SVOM trigger sb25021103 is not a GRB
- GRB 250211A: Swift ToO observations
- GRB 250207A: Fermi GBM Observation
- Konus-Wind detection of GRB 250207A
- GRB 250207A: Skynet optical afterglow observations
- GRB 250207A: 1.3m DFOT Optical observations
- GRB 250206A: Swift-XRT observations
- GRB 250129A: GRANDMA Continued Afterglow Detection
- GRB 250207A: Swift-BAT refined analysis
- GRB 250205A: 1.3m DFOT optical upper limit
- GRB 250206A: Tiled Swift observations
- GRB 250206A: Fermi-LAT detection
- GRB 250207B: Swift-XRT observations
- EP250207a: EP-WXT detection and XRT follow-up observation
- GRB 250207A: Swift-XRT refined Analysis
- GRB 250207A: Enhanced Swift-XRT position
- GRB 250129A: ABObservatory SLOAN r’ afterglow detection
- GRB 250207A: REM IR afterglow detection
- GRB 250207A: FRAM-Auger optical detection
- GRB 250207B: Tiled Swift observations
- GRB 250207A: REM optical afterglow detection
- GRB 250207A: Swift/UVOT Detection
- GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
- GRB 250207A: Swift detection of a burst with optical counterpart
- GRB 250205A: Fermi GBM Observation
- GRB 250205A: Swift/UVOT Upper Limits
- GRB 250205A: Swift/XRT detection
- IPN triangulation of GRB 250201A
- GRB 250129A: Swift-BAT refined analysis
- IPN triangulation of GRB 250204B (short/hard)
- IPN triangulation of GRB 250202B
- GRB 250129A: LCO late afterglow detection
- GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
- GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
- GRB 250129A: SVOM/C-GFT optical observations
- Swift GRB250129A: MASTER 4 days observations report
- Konus-Wind detection of GRB 250129A
- GRB 250129A: 1.3m DFOT Optical observations
- GRB 250129A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations
- GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow
- GRB 250129A: COLIBRÍ Optical Observations
- GRB 250129A: TNG NIR afterglow detection
- GRB 250129A: GRANDMA/TAROT optical afterglow detection
- GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
- GRB 250128B: VLA radio upper limit
- Ep250125A: 1.3m DFOT optical upper limit
- GRB 250129A: Skynet optical observations
- GRB 250129A: KAIT optical observations of the rebrightening around 5.1 hours
- GRB 250129A: Swift-XRT refined Analysis
- GRB 250128B: TNG optical upper limit
- GRB 250129A: Swift/UVOT Detection
- GRB 250127A: CrAO and Terskol optical upper limits
- GRB 250129A: Enhanced Swift-XRT position
- GRB 250128B: NOT optical upper limit
- GRB 250129A: REM optical/NIR afterglow detection
- GRB 250129A: Early afterglow detection by LCO.
- Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
- GRB 250129A: LCO optical observations
- GRB 250129A: GOTO optical observations show brightening afterglow
- Swift GRB 250129A: Global MASTER-Net observations report
- GRB 250128B: Enhanced Swift-XRT position
- GRB 250129A: Swift detection of a burst with an optical counterpart
- Swift GRB 250129A: Global MASTER-Net OT detection
- GRB 250128B: Swift-XRT refined Analysis
- GRB 250128B: Fermi GBM Observation
- GRB 250128B: GOTO optical upper limit
- Swift GRB 250128B: Global MASTER-Net observations report
- EP250125a: Upper limits from Swift/BAT-GUANO
- GRB 250128B: LCO optical observations
- GRB 250128B: Swift detection of a short burst
- GRB 250127A: Swift-XRT observations
- GRB 250127A: EP-FXT afterglow detection