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"
16190 results found.
- EP250416a: Gemini South-GMOS optical counterpart
- SVOM/sb25041603 is not a GRB
- EP250416a: Einstein Probe detection of an X-ray transient
- IceCube-250416A: Global MASTER-Net observations report
- SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
- IceCube 250414.324: DDOTI Optical Observations
- EP250304a: ATCA radio observations
- EP250404a: Nanshan 0.43m Telescope optical observatios
- GRB 250411A: DDOTI Optical Observations
- GRB 250314A: e-MERLIN observations
- GRB 250407A: Mondy and AbAO Optical Observations
- EP250227a: Further NOT optical observations
- IceCube-250406A: Swift-XRT observations
- GRB 250407A: LCO detection of a fading optical counterpart
- GRB 250407A: SVOM/GRM observation of a bright long burst
- GRB 250407A: EP-WXT afterglow detection
- EP250407a: EP-WXT detection of a fast X-ray transient
- GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
- GRB 250407A: KAIT Optical Afterglow Candidate
- IceCube-250406A: No candidates from the Zwicky Transient Facility
- GRB 250407A: Swift-XRT afterglow detection
- IceCube 250406A: DDOTI Optical Observations of the Refined Position
- IPN triangulation of GRB 250406B (short/hard)
- IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
- IceCube 250406.951: DDOTI Optical Observations
- IceCube Alert 250406.95: Global MASTER-Net observations report
- EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
- GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
- EP250404a / GRB 250404A: Montarrenti Observatory optical observations
- GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
- EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
- Konus-Wind detection of GRB 250404A / EP250404a
- EP250404a: refined analysis of the EP-WXT and EP-FXT observations
- GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
- GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
- EP250402a: Optical upper limit with PD 1.3m observations
- GRB 250404A / EP250404a: NOT optical observations
- GRB 250331D: Swift-XRT afterglow detection
- EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
- EP250404a: REM optical/NIR observations
- EP250404a: Seimei/TriCCS optical counterpart detection
- EP250404A: COLIBRÍ/DDRAGO Optical Observations
- EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
- EP250404a: LCO optical counterpart detection
- EP250404a: Xinglong decaying optical counterpart
- GRB 250403A: Montarrenti Observatory optical detection
- GRB 250403A: KAIT optical observations
- EP250404a: AKO Optical Afterglow Detection
- EP250404a: LAST detection of optical counterpart
- GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
- GRB 250327B: VIRT Optical Upper Limit
- EP250404a: Mephisto multi-band optical detection
- EP250321A: J band upper limit by SYSU 80cm telescope
- EP250404a: Nanshan/HMT optical counterpart detection
- EP250404a: Einstein Probe detection of an X-ray transient
- GRB 250403A: Swift/UVOT Detection
- GRB 250402A: Swift/UVOT Upper Limits
- EP250402a: Optical upper limit with Kinder observations
- GRB 250403A: REM NIR afterglow detection
- GRB 250403A: LCO optical counterpart detection
- GRB 250403A: JinShan optical observations
- GRB 250402A: EP-FXT afterglow detection
- GRB 250403A: Optical counterpart detection by LCO.
- EP250402a: EP-FXT follow-up observations
- GRB 250403A: GMG Optical Observation
- GRB 250403A: 1.6m Mephisto multi-band optical detection
- GRB 250403A: SVOM/C-GFT optical observations
- GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
- GRB 250402A: REM optical/NIR upper limits
- GRB 250402A: LCO optical counterpart detection
- The EP-WXT trigger 01709133862 is a flaring star
- EP250402a: Einstein Probe detection of a fast X-ray transient
- GRB 250402A: SVOM/VT optical counterpart
- GRB 250402A: SVOM detection of a burst
- GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
- GRB 250329B: Swift/UVOT Upper Limit
- GRB 250329A: Swift/UVOT Upper Limit
- GRB 250327B: Swift/UVOT Detection
- GRB 250327A: Swift/UVOT Upper Limits
- GRB 250331E: SVOM/GRM observation
- GRB 250327B: Kilonova-Catcher Observations
- GRB 250331D: Fermi GBM observation
- GRB 250331C: Swift/UVOT Upper Limits
- GRB 250331B: Swift/UVOT Upper Limits
- GRB 250328A: AbAO AS-32 Optical Observations
- GRB 250219A: NOT candidate host galaxy detection
- GRB 250330B: SVOM/GRM observation of a short burst
- GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
- GRB 250331C: Enhanced Swift-XRT position
- GRB 250331B: Enhanced Swift-XRT position
- LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
- GRB 250330A: VLT/FORS2 Afterglow Detection
- GRB20250327B: 45th Parallel Observatory upper limit
- GRB 250328A: Swift/UVOT Detection
- GRB 250328A: Swift-XRT refined Analysis
- GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
- GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
- GRB 250331C: Swift detection of a burst
- GRB 250331B: Swift detection of a burst
- GRB 250330A: BOOTES-7 early optical upper limit