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"11511 results found.
- GRB 260705B: SVOM/GRM observation
- GRB 260708A: Fermi-GBM detection
- GRB 260706A: Further EP-FXT follow-up observation
- GRB 260706A: SVOM/VT optical upper limits
- Fermi GBM trigger 805087514/260707142 (GRB 260707A) is not a GRB
- GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
- GRB 260705C: Glowbug gamma-ray detection of a short burst
- GRB 260706A: SVOM/ECLAIRs refined analysis
- GRB 260706A: SVOM/GRM observation
- GRB 260706A: REM optical/NIR observations
- GRB 260706A: LCO optical upper limit
- GRB 260706A: EP-FXT follow-up observation
- GRB 260707A: Fermi GBM Final Real-time Localization
- GRB 260706A: Fermi GBM Observation
- GRB 260706A: SVOM detection of a burst
- GRB 260706A: Fermi GBM Final Real-time Localization
- GRB 260705C: Fermi GBM Final Localization
- GRB 260705B: Fermi GBM Final Real-time Localization
- Fermi GBM Sub-Threshold Detection of GRB 260705A
- 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 260703B: Fermi GBM Final Localization
- Fermi trigger No 804738310: Global MASTER-Net observations report
- Fermi GRB 260703A: Global MASTER-Net observations report
- GRB 260703A: Fermi GBM Final Localization
- GRB 260610B: VLA detection
- GRB 260623A: Glowbug gamma-ray detection
- GRB 260614B: ATCA Radio Upper Limits
- GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
- Fermi trigger No 804552016: Global MASTER-Net observations report
- GRB 260701A: Fermi GBM Final Real-time Localization
- Fermi GBM trigger 804552016/260630945 is not a GRB
- Fermi-LAT Gamma-ray Observations of IceCube-260622A
- GRB 260629A: Fermi GBM Final Real-time Localization
- Fermi GRB 260628A: Global MASTER-Net observations report
- GRB 260628A: Fermi GBM Final Real-time Localization
- GRB 260618A: Fermi GBM Observation
- MASS-Cube (GRID 2.0) detection of GRB 260616B
- Fermi GBM trigger 804010507/260624677 is not a GRB
- Konus-Wind detection of GRB 260618B
- GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
- GRB 260624A: Fermi GBM Final Real-time Localization
- GRB 260617A: Glowbug gamma-ray detection of a short burst
- GRB 260623A: Fermi GBM Final Real-time Localization
- GRB 260616B/EP260616a: Insight-HXMT/HE detection
- IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 260618B: LCO optical observations
- EP260618a: JinShan optical observations
- GRB 260616B/EP260616a: SVOM/GRM detection of a burst
- GRB 260618B: Fermi GBM Observation
- 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
- Fermi-LAT Gamma-ray Observations of IceCube-260610A
- GRB 260618B: SVOM/VT optical candidate
- GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
- 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
- EP260618a: EP-FXT follow-up observation
- 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 260618B: Fermi-LAT detection
- IPN triangulation of GRB 260617A (short)
- GRB 260610B/AT 2026owq: FTW optical and NIR observations
- GRB 260616A: Insight-HXMT detection
- GRB 260618B: Fermi GBM Final Real-time Localization
- EP260618a: EP-WXT detection of an X-ray transient
- GRB 260610B: AbAO optical observations
- GRB 260506B: cubesat Avion detection
- GRB 260618A: Fermi GBM Final Real-time Localization
- GRB 260617A: Fermi GBM Detection
- GRB 260616A: Fermi GBM Observation
- GRB 260617A: Fermi GBM Final Real-time Localization (Duplicate Submission)
- GRB 260617A: Fermi GBM Final Real-time Localization
- Konus-Wind detection of GRB 260616B/EP260616a
- Konus-Wind detection of GRB 260616A
- GRB 260616B: CALET Gamma-Ray Burst Monitor detection
- 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
- GRB 260610B / AT 2026owq: Possible re-brightening identified from Pan-STARRS observations
- GRB 260616B: Fermi GBM Detection
- GRB 260604C: GRANDMA late observations with CFHT/MegaCam
- GRB 260616B: BALROG localization (Fermi Trigger 803286321 / GRB 260616295)
- GRB 260616A: BALROG localization (Fermi Trigger 803272919 / GRB 260616140)