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 260616A: Fermi GBM Final Real-time Localization
- GRB 260614B: SVOM/ECLAIRs refined analysis
- GRB 260610B: Terskol optical observations
- GRB 260614B: GECAM-B observation
- GRB 260610B: SVOM/GRM observation
- GRB 260614B: SVOM/VT optical afterglow confirmation
- GRB 260614B: Fermi GBM Observation
- GRB 260610B: ALMA detection
- GRB 260614A: GECAM-B observation
- GRB 260614B: SVOM detection of a burst
- GRB 260614B: Fermi GBM Final Real-time Localization
- GRB 260611B: SVOM/GRM detection
- GRB 260614A: Fermi GBM Final Localization
- GRB 260610B: further Liverpool Telescope optical observations
- GRB 260610B: Fermi GBM Observation
- GRB 260610B / AT2026owq: GRANDMA optical observations
- GRB 260610B / AT2026owq: further SAO RAS optical observations
- GRB 260611B: CALET Gamma-Ray Burst Monitor detection
- GRB 260610B / AT2026owq: SVOM/VT optical observations
- GRB 260610B / AT2026owq: OASDG optical observations
- GRB 260610B: IAC-80 Optical observations
- GRB 260610B / AT2026owq: SAO RAS optical observations
- GRB 260611B: Fermi GBM Final Real-time Localization
- GRB 260610B: optical counterpart shows spectroscopic redshift of z=0.473
- GRB 260610B / AT 2026owq: COLIBRÍ optical observations
- GRB 260610B / AT2026owq: Early ATLAS observations
- GRB 260610B: TRT optical observation
- GRB 260611A: Fermi GBM Final Real-time Localization
- GRB 260610B: DDOTI optical observations
- GRB 260610B: GOTO optical counterpart candidate
- GRB 260610B: Fermi GBM Final Localization
- IceCube-260610A - IceCube observation of a high-energy neutrino candidate track-like event
- Konus-Wind detection of GRB 260601A
- IPN triangulation of GRB 260601A (short/hard)
- GRB 260610A: Fermi GBM Final Real-time Localization (duplicate submission)
- GRB 260610A: Fermi GBM Final Real-time Localization
- GRB 260609A: Fermi GBM Final Localization
- Konus-Wind detection of GRB 260604C
- GRB 260608A: Fermi GRB Observation
- GRB 260604C: AstroSat CZTI detection
- IPN triangulation of GRB 260601B / EP260601a
- GRB 260604C: SVOM/ECLAIRs refined analysis
- GRB 260608A: SVOM/ECLAIRs refined analysis
- Konus-Wind detection of GRB 260607B
- GRB 260607B: GECAM-B observation
- GRB 260608C: Fermi GBM Final Real-time Localization (duplicate submission)
- GRB 260608C: Fermi GBM Final Real-time Localization
- GRB 260604C: further SAO RAS optical observations
- GRB 260607A: AT2026ong (GOTO26fqf) is a type-Ia SN
- GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
- GRB 260608B: Fermi GBM Final Localization
- GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
- GRB 260607B: AstroSat CZTI detection
- GRB 260608A: SVOM detection of a burst
- GRB 260608A: Fermi GBM Final Real-time Localization (duplicate submission)
- GRB 260608A: Fermi GBM Final Real-time Localization
- GRB 260607A: TRT optical observations
- GRB 260604C: GRANDMA further observations
- GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
- GRB 260604A: SVOM/GRM detection
- GRB 260604C: Mondy optical observations: evidence of a possible brightening
- GRB 260607B: Fermi GBM Observation
- GRB 260607B: Fermi-LAT detection
- GRB 260607B: Fermi GBM Final Localization Correction
- GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
- GRB 260604C: OPD1.6m - GRANDMA observations - detection
- GRB 260607A: Fermi GBM Final Real-time Localization (duplicate submission)
- GRB 260607A: Fermi GBM Final Real-time Localization
- GRB 260604C: GECAM-B observation
- GRB 260604C: 6 GHz VLA observations
- GRB 260604C: SAO RAS optical observations
- GRB 260604C: GRANDMA observations
- GRB 260604B: SVOM/GRM detection
- GRB 260604A: Glowbug gamma-ray detection
- GRB 260604C: LCO optical upper limit
- GRB 260604C: Liverpool Telescope optical detection
- GRB 260604C: GOTO detections of the optical afterglow
- GRB 260604C: Kilonova-Catcher optical afterglow detection
- GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
- GRB 260604C: Jinshan optical observations
- GRB 260604C: Fermi GBM Observation
- GRB 260604C: LAST detection of optical counterpart candidate
- Fermi GRB 260604C: Global MASTER-Net observations report
- Fermi GRB 260604C: Global MASTER-Net observations report
- GRB 260604C: SVOM detection of a long burst
- GRB 260604C: Fermi GBM Final Real-time Localization
- GRB 260604B: Fermi GBM Final Real-time Localization
- GRB 260601A: CALET Gamma-Ray Burst Monitor detection
- GRB 260604A: Fermi GBM Final Real-time Localization
- GRB 260603B: Fermi GBM Final Localization
- Konus-Wind detection of GRB 260601B/EP260601a
- Fermi trigger No 802141998: Global MASTER-Net observations report
- GRB 260601A: SVOM/GRM observation of a short burst
- Fermi GRB 260602B: Global MASTER-Net observations report
- Fermi GRB 260602B: Global MASTER-Net observations report
- GRB 260602B: Fermi GBM Final Localization
- GRB 260601A: GECAM-B observation of a short burst
- GRB 260602A: Fermi GBM Final Real-time Localization
- GRB 260601B / EP260601a: NuSTAR detection of prompt emission
- GRB 260601A: Glowbug gamma-ray detection of a short burst