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"21760 results found.
- GRB 260610b: Liverpool Telescope optical observations
- EP260610b: Liverpool Telescope optical upper limits
- The EP-WXT trigger 01709269176: SVOM/C-GFT confirmation of a stellar flare
- GRB 260610B / AT2026owq: SAO RAS optical observations
- EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
- GRB 260610B / AT 2026owq: COLIBRÍ optical observations
- GRB 260610B / AT2026owq: Early ATLAS observations
- GRB 260610B: TRT optical observation
- EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
- EP260610b: COLIBRÍ optical observations
- GRB 260610B: DDOTI optical observations
- EP260610b: MAO/AZT-22 optical observations
- GRB 260610B: GOTO optical counterpart candidate
- EP260610b: NOT optical observation
- EP260610b: SVOM/VT optical confirmation with blue color
- GRB 260515A: SOAR optical observations
- EP260610a: SVOM/VT optical upper limits
- EP260610b: Einstein Probe detection of an X-ray transient
- Konus-Wind detection of GRB 260601A
- EP260610a: COLIBRÍ optical upper limits
- EP260610a: Einstein Probe detection of a fast X-ray transient
- Konus-Wind detection of GRB 260604C
- GRB 260604C: SVOM/ECLAIRs refined analysis
- GRB 260608A: SVOM/ECLAIRs refined analysis
- Konus-Wind detection of GRB 260607B
- GRB 260604C: further SAO RAS optical observations
- GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
- 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
- EP260605a: EP-FXT follow-up observation
- GRB 260607A: TRT optical 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-LAT detection
- GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
- GRB 260604C: OPD1.6m - GRANDMA observations - detection
- GRB 260604C: 6 GHz VLA observations
- GRB 260604C: SAO RAS optical observations
- GRB 260604B: SVOM/GRM detection
- GRB260603A: SVOM/ECLAIRs refined analysis
- EP260605a: Einstein Probe detection of a fast X-ray transient
- EP260603a: COLIBRÍ optical upper limit
- GRB 260604C: LCO optical upper limit
- GRB 260604C: Liverpool Telescope optical detection
- EP260602d: EP-FXT follow-up observation
- EP260602c: EP-FXT follow-up observation
- GRB 260527A/EP260527a: 6 GHz VLA observations
- GRB 260604C: Kilonova-Catcher optical afterglow detection
- GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
- GRB 260604C: Jinshan optical observations
- EP260602d: J-band upper limit with WINTER
- EP260602b: J-band upper limit with WINTER
- GRB 260604C: LAST detection of optical counterpart candidate
- GRB 260604C: SVOM detection of a long burst
- GRB 260603A: Simeiz Zeiss-1000 optical upper limit
- EP260602a: EP-FXT follow-up observation
- EP260603a: Einstein Probe detection of a fast X-ray transient
- EP260602d: Optical Upper limits with kinder observations
- EP260602b: Liverpool Telescope observations
- EP260602a: Liverpool Telescope optical upper limits
- EP260602b: Liverpool Telescope and LCO observations
- EP260602a: GTC and Liverpool Telescope optical observations
- Konus-Wind detection of GRB 260601B/EP260601a
- GRB 260601B / EP260601a: Mondy optical upper limit
- EP260602b: EP-FXT follow-up observation
- GRB 260603A: Kilonova-Catcher optical upper limit
- GRB 260603A: SVOM/VT optical observations
- EP260602a: NOT NIR J-band observations
- GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
- EP260602d: Einstein Probe detection of a fast X-ray transient
- 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
- GRB 260603A: SVOM detection of a burst
- EP260602b: Einstein Probe detection of a fast X-ray transient
- EP260602a: SVOM/VT optical candidate
- EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
- GRB 260601B/EP260601a: J-band upper limit with WINTER
- EP260530a/AT 2026nwl: COLIBRÍ optical follow up
- EP260530a/AT 2026nwl: KAIT optical observations
- EP260602a: Optical upper limits with Kinder observations
- EP260602a: Einstein Probe detection of a fast X-ray transient
- GRB 260601B/EP260601a: SVOM/VT optical observations
- GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
- EP260601a: Einstein Probe detection of an X-ray transient
- EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
- EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
- EP260530a/AT 2026nwl: COLIBRÍ optical observations
- GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
- GRB 260531B: GECAM-B observation
- GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
- AT2026nik: EP-FXT X-ray counterpart
- AT 2026nuz: COLIBRÍ optical observations
- EP260527a/GRB 260527A: optical upper limit with Kinder observations
- GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
- GRB 260527A/EP260527a: VLT/X-shooter tentative redshift