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"26303 results found.
- GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
- GRB 260706A: SVOM/GRM observation
- GRB 260706A: REM optical/NIR observations
- IceCube-260704A: No candidates from the Zwicky Transient Facility
- GRB 260706A: LCO optical upper limit
- GRB 260706A: EP-FXT follow-up observation
- GRB 260706A: Fermi GBM Observation
- IPN triangulation of GRB 260627A
- GRB 260705A: SVOM/ECLAIRs refined analysis
- GRB 260706A: SVOM detection of a burst
- IceCube260704A: OHP/T193 optical observations
- GRB 260705A: LCO optical upper limits
- GRB 260704A: NOT optical upper limits
- Fermi GBM Sub-Threshold Detection of GRB 260705A
- GRB 260705A: SVOM detection of a burst
- GRB 260704A: EP-FXT follow-up observation
- GRB 260629A: SVOM/GRM observation of a short burst
- GRB 260629A: GECAM-A observation of a short burst
- IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 260629A: AstroSat CZTI detection
- GRB 260704A: SVOM detection of a possible GRB
- EP260703a: EP-WXT detection of a fast X-ray transient
- EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
- GRB 260623A: Glowbug gamma-ray detection
- GRB 260614B: ATCA Radio Upper Limits
- Fermi-LAT Gamma-ray Observations of IceCube-260622A
- EP260628a: EP-WXT detection of a fast X-ray transient
- EP260626a: further Liverpool Telescope optical upper limits
- EP260626a: COLIBRÍ optical upper limit
- EP260626a: EP-WXT detection of a fast X-ray transient
- Konus-Wind detection of GRB 260623B / EP260623a
- EP260623a: TNG NIR afterglow detection
- GRB 260618A: Fermi GBM Observation
- MASS-Cube (GRID 2.0) detection of GRB 260616B
- GRB 260619A: SVOM/ECLAIRs refined analysis
- EP260623a: Liverpool Telescope optical observations
- Konus-Wind detection of GRB 260618B
- EP260623a:refined analysis of the EP-WXT and EP-FXT observation
- EP260623a: WINTER J-band observations
- GRB 260617A: Glowbug gamma-ray detection of a short burst
- IPN triangulation of GRB 260605A
- EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
- EP260623a: SVOM/VT optical observations
- EP260623a: TRT optical observations
- EP260623a: REM optical/NIR afterglow detection
- EP 260623a: COLIBRÍ optical observations
- GRB 260616B/EP260616a: Insight-HXMT/HE detection
- EP260623a: Las Cumbres discovery of the optical counterpart
- EP260623a: Einstein Probe detection of an X-ray transient
- GRB 260614B: EP-FXT follow-up observation
- IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
- EP260618a: Liverpool Telescope optical observations
- GRB 260619A: NOT optical observations
- GRB 260618B: LCO optical observations
- EP260618a: JinShan optical observations
- GRB 260616B/EP260616a: SVOM/GRM detection of a burst
- GRB 260618B: Fermi GBM Observation
- GRB 260619A: TRT optical counterpart confirmation
- GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
- GRB 260604B: 239Alferov CubeSat detection
- GRB 260604A: 239Alferov CubeSat detection
- GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
- GRB 260619A: SVOM/VT optical counterpart confirmation
- GRB 260618B: SVOM/VT optical candidate
- GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
- GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
- Konus-Wind detection of GRB 260617A
- GRB 260616B: AstroSat CZTI detection
- GRB 260616A: AstroSat CZTI detection
- GRB 260616A: SVOM/GRM observation
- EP260618a: OHP/T193 optical observations
- GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
- GRB 260619A: Kilonova-Catcher optical upper limit
- EP260618a: LCO optical counterpart confirmation
- GRB 260617A: CALET Gamma-Ray Burst Monitor detection
- EP260618a: COLIBRÍ optical counterpart candidate
- GRB 260616A: NuSTAR detection of prompt emission
- GRB 260614B: NuSTAR detection of prompt emission
- GRB 260619A: SVOM possible detection of a faint burst
- GRB 260618B: Fermi-LAT detection
- IPN triangulation of GRB 260617A (short)
- GRB 260616A: Insight-HXMT detection
- EP260618a: EP-WXT detection of an X-ray transient
- GRB 260506B: cubesat Avion detection
- GRB 260616C: GECAM-B observation of a burst
- GRB 260617A: Fermi GBM Detection
- GRB 260616A: Fermi GBM Observation
- Konus-Wind detection of GRB 260616B/EP260616a
- Konus-Wind detection of GRB 260616A
- GRB 260616B: CALET Gamma-Ray Burst Monitor detection
- EP260616a/GRB260616B: COLIBRÍ optical upper limit
- GRB 260616A: GECAM-B observation
- GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
- GRB 260429A: cubesat Avion detection
- GRB 260616A: Fermi-LAT detection
- GRB 260610B / AT 2026owq: Liverpool Telescope confirmation of continuing optical rebrightening
- GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
- GRB 260614A: AstroSat CZTI detection
- EP260616a: EP-WXT detection of a fast X-ray transient