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.
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"27916 results found.
- EP250416a: GSP optical upper limit
- EP250416a: Einstein Probe detection of an X-ray transient
- IceCube-250416A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 250416B: Fermi GBM Final Real-time Localization
- GRB 250416A: Fermi GBM Final Real-time Localization
- SVOM/sb25041603: SVOM detection of an X-ray transient
- GRB 250413A: AstroSat CZTI detection
- GRB 250412A: AstroSat CZTI detection
- GRB 250411A: Fermi GBM Final Real-time Localization
- GRB 250407A: Mondy and AbAO Optical Observations
- GRB 250320B: cubesat Avion detection
- IceCube-250406A: Swift-XRT observations
- IPN triangulation of GRB 250407A
- GRB 250407A: LCO detection of a fading optical counterpart
- EP250407a: Swift-XRT observations
- Konus-Wind detection of GRB 250407A
- 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: Fermi GBM Detection
- GRB 250407A: Swift-XRT afterglow detection
- GRB 250407A: Swift ToO observations
- GRB 250407A: SRG/ART-XC afterglow detection
- LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
- Konus-Wind detection of GRB 250406B (short/hard)
- IPN triangulation of GRB 250406B (short/hard)
- GRB 250407A: Fermi GBM Final Real-time Localization
- IceCube-250406A - IceCube observation of a high-energy neutrino candidate track-like event
- IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
- GRB 250406A: AstroSat CZTI detection
- GRB 250406A: Fermi GBM Final Real-time Localization
- Konus-Wind detection of GRB 250404A / EP250404a
- GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
- GRB 250331D: Swift-XRT afterglow detection
- GRB 250404B: AstroSat CZTI detection of a short burst
- GRB 250403A: AstroSat CZTI detection
- EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
- EP250404a: Seimei/TriCCS optical counterpart detection
- EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
- EP250404a: LCO optical counterpart detection
- GRB 250403A: Montarrenti Observatory optical detection
- GRB 250404A: Fermi GBM Detection
- EP250404a: AKO Optical Afterglow Detection
- EP250404a: LAST detection of optical counterpart
- GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
- EP250404a: Xinglong-2.16m spectroscopic redshift
- GRB 250327B: VIRT Optical Upper Limit
- EP250404a: Mephisto multi-band optical detection
- GRB 250331C Swift-BAT refined analysis
- GRB 250331B Swift-BAT refined analysis
- GRB 250330A Swift-BAT refined analysis
- EP250321A: J band upper limit by SYSU 80cm telescope
- EP250404a: BOOTES-4/JGT optical afterglow detection
- EP250404a: Nanshan/HMT optical counterpart detection
- EP250404a: Einstein Probe detection of an X-ray transient
- GRB 250404A: Fermi GBM Final Real-time Localization
- GRB 250403A: Swift/UVOT Detection
- GRB 250402A: Swift/UVOT Upper Limits
- GRB 250403A: REM NIR afterglow detection
- GRB 250403A: LCO optical counterpart detection
- IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
- GRB 250402A: EP-FXT afterglow detection
- GRB 250403A: Optical counterpart detection by LCO.
- GRB 250403A: Swift-XRT observations
- GRB 250322A: 10 GHz VLA radio upper limits
- GRB 250403A: 1.6m Mephisto multi-band optical detection
- GRB 250403A: GOTO detection of the optical afterglow
- GRB 250402A: Swift-XRT observations
- GRB 250403A : SVOM detection of a burst
- GRB 250403A: Fermi GBM Final Real-time Localization
- GRB 250225B: VLT host galaxy redshift z = 0.950
- GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
- GRB 250402A: VLT/FORS2 spectroscopic redshift z = 2.823
- GRB 250402A: LCO optical counterpart detection
- EP250402a: Einstein Probe detection of a fast X-ray transient
- GRB 250402B: AstroSat CZTI detection of a short burst
- GRB 250402A: SVOM detection of a burst
- GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
- GRB 250314A: ALMA detection
- GRB 250329B: Swift/UVOT Upper Limit
- GRB 250329A: Swift/UVOT Upper Limit
- GRB 250327B: Swift/UVOT Detection
- GRB 250327A: Swift/UVOT Upper Limits
- GRB250331D: AbAO optical observations
- GRB 250331D: Fermi GBM observation
- GRB 250331C: Swift/UVOT Upper Limits
- GRB 250331B: Swift/UVOT Upper Limits
- GRB 250219A: NOT candidate host galaxy detection
- GRB 250322B: GRBAlpha detection
- GRB 250331D: Swift-XRT observations
- GRB 250331C: Swift-XRT refined Analysis
- GRB 250331B: Swift-XRT refined Analysis
- GRB 250331B: Swift-XRT refined Analysis
- GRB 250322B possible detection by the AstroSat Satellite
- LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 2)
- GRB 250330B: EIRSAT-1 GMOD Detection
- GRB 250331E: Fermi GBM Final Real-time Localization
- GRB 250327A Swift-BAT refined analysis
- GRB 250329B: CAHA 2.2m telescope optical limit