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"18332 results found.
- The EP-WXT trigger 01709269176 is likely a flaring star
- EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
- GRB 260610B / AT 2026owq: COLIBRÍ optical 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
- 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
- EP260610a: COLIBRÍ optical upper limits
- EP260610a: Einstein Probe detection of a fast X-ray transient
- GRB 260604C: further SAO RAS optical observations
- 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
- EP260605a: EP-FXT follow-up observation
- GRB 260607A: TRT optical observations
- GRB 260604A: SVOM/GRM detection
- GRB 260604C: Mondy optical observations: evidence of a possible brightening
- 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
- EP260605a: Einstein Probe detection of a fast X-ray transient
- EP260603a: COLIBRÍ optical upper limit
- GRB 260604C: LCO optical upper limit
- The EP-WXT trigger 01709267001 is likely a flaring star
- 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
- The EP-WXT trigger 01709266798 is likely a flaring star
- 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 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
- GRB 260603A: EP-FXT follow-up observation
- EP260601a/GRB 260601B: EP-FXT follow-up observation
- 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
- SVOM GRB260603.23: Global MASTER-Net observations report
- 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
- 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
- The EP-WXT trigger 01709266272 is likely a flaring star
- 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
- EP260526a: SVOM/VT optical upper limits
- EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
- EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
- EP260527a/GRB 260527A: EP-FXT follow-up observation
- EP260526a: EP-FXT follow-up observation
- EP260527a: SVOM/VT optical observation
- EP260527a: COLIBRÍ optical detection
- EP260527a: Einstein Probe detection of a fast X-ray transient
- The EP-WXT trigger 01709266172 is likely a flaring star
- The EP-WXT trigger 01709266147 is likely a flaring star
- EP260526a: LCO optical upper limits
- EP260526a: Einstein Probe detection of a fast X-ray transient
- EP260526.405: COLIBRÍ optical upper limits
- The EP-WXT trigger 01709266106 is not a real source
- EP01709266106 (EP260526a?): Liverpool Telescope upper limits