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"28879 results found.
- 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 260604C: SVOM/C-GFT upper limit
- 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
- GRB260603A: SVOM/ECLAIRs refined analysis
- EP260603a: COLIBRÍ optical upper limit
- GRB 260604A: Glowbug gamma-ray detection
- GRB 260604C: LCO optical upper limit
- GRB 260604C: Liverpool Telescope optical detection
- The EP-WXT trigger 01709267001 is likely a flaring star
- GRB 260527A/EP260527a: 6 GHz VLA observations
- GRB 260604C: GOTO detections of the optical afterglow
- GRB 260604C: Kilonova-Catcher optical afterglow detection
- GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
- The EP-WXT trigger 01709266798 is likely a flaring star
- GRB 260604C: Jinshan optical observations
- GRB 260604C: Fermi GBM Observation
- EP260602d: J-band upper limit with WINTER
- EP260602b: J-band upper limit with WINTER
- GRB 260604C: LAST detection of optical counterpart candidate
- Fermi GRB 260604C: Global MASTER-Net observations report
- Fermi GRB 260604C: Global MASTER-Net observations report
- SVOM GRB260604.85: Global MASTER-Net observations report
- GRB 260604C: SVOM detection of a long burst
- GRB 260604C: Fermi GBM Final Real-time Localization
- GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
- GRB 260603A: NOT optical observations
- GRB 260603A: Simeiz Zeiss-1000 optical upper limit
- GRB 260604B: Fermi GBM Final Real-time Localization
- GRB 260601A: CALET Gamma-Ray Burst Monitor detection
- EP260603a: Global MASTER-Net observations report
- GRB 260604A: Fermi GBM Final Real-time Localization
- EP260602b: Liverpool Telescope observations
- EP260602a: Liverpool Telescope optical upper limits
- GRB 260603B: Fermi GBM Final Localization
- GRB 260603A: EP-FXT follow-up observation
- EP260601a/GRB 260601B: EP-FXT follow-up observation
- GRB 260603A: SVOM/VT optical observations
- GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
- EP260602d: Einstein Probe detection of a fast X-ray transient
- Fermi trigger No 802141998: Global MASTER-Net observations report
- GRB 260601A: SVOM/GRM observation of a short burst
- EP260602c: Einstein Probe detection of a fast X-ray transient
- GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
- EP260602a: COLIBRÍ optical observations
- GRB260601B/EP260601a: NOT near-infrared observations
- SVOM GRB260603.23: Global MASTER-Net observations report
- GRB 260603A: SVOM detection of a burst
- Fermi GRB 260602B: Global MASTER-Net observations report
- Fermi GRB 260602B: Global MASTER-Net observations report
- EP260602a: SVOM/VT optical candidate
- EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
- GRB 260602B: Fermi GBM Final Localization
- GRB 260601A: GECAM-B observation of a short burst
- GRB 260601B/EP260601a: J-band upper limit with WINTER
- GRB 260602A: Fermi GBM Final Real-time Localization
- GRB 260601B: CALET Gamma-Ray Burst Monitor detection
- GRB 260601B / EP260601a: NuSTAR detection of prompt emission
- GRB 260601B/EP260601a: SVOM/VT optical observations
- GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
- EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
- EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
- GRB 260601A: Glowbug gamma-ray detection of a short burst
- GRB 260531B: Glowbug gamma-ray detection
- GRB 260516D: VLA radio detection
- GRB 260601A: Fermi GBM Observation
- GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
- Fermi GRB 260601A: Global MASTER-Net observations report
- GRB 260601A: Fermi GBM Final Real-time Localization