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"16079 results found.
- GRB 251103A: Swift/UVOT Detection
- GRB 251103A: SVOM/GRM observation
- GRB 251103A: Swift-XRT afterglow detection
- GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
- EP251102a: Einstein Probe detection of a fast X-ray transient
- GRB 251025B: OHP/T193 optical upper limit
- GRB 251103A: LCO optical observation
- EP251102.890: COLIBRÍ optical counterpart candidate
- GRB 251103A: GOTO optical afterglow detection
- GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
- GRB 251103A: NOT spectroscopic redshift z = 0.76
- GRB 251103A: BOOTES-2/TELMA optical afterglow
- GRB 251103A: LCO optical afterglow detection
- GRB 251103A: NOT optical afterglow candidate (duplicate submission)
- GRB 251103A: NOT optical afterglow candidate
- GRB 251103A: SVOM detection of a bright burst
- GRB 251025C: SVOM/GRM observation
- GRB 251028A: SVOM/GRM observation
- GRB 251026B: SOAR Classification of GOTO25jgl/SN2025absf as a Type Ia supernova
- GRB 251026B: LBT near-infrared observations
- GRB 251026A/EP251026a: SVOM/VT optical counterpart
- GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
- GRB251026B: PRIME H-band upper limit
- GRB251025B: 3.6m DOT Optical Observations
- GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
- GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf
- GRB 251023B: Swift-UVOT Upper Limits
- EP251027.145: COLIBRÍ optical upper limits
- GRB 251022A: SVOM/GRM observation
- GRB 251027A: LCO optical upper limit
- GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 251017A: Mondy AZT-33IK and Koshka Zeiss-1000 optical observations
- GRB 251023B / EP251023b: Mondy optical upper limit
- GRB 251017A: INASAN-Kislovodsk optical observations
- GRB 251026A: Mondy optical upper limit
- GRB 251025B: Mondy optical observations
- GRB 251025B: Kilonova-Catcher optical afterglow detection
- GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
- GRB 251026B: Tentative GOTO optical counterpart candidate
- EP251023a: Mondy optical observations
- GRB 251025B: MAO/AZT-22 optical observations
- GRB 251025B: OHP/T193 optical detection
- GRB 251025B: J-band detection with WINTER
- IceCube-251025A: DDOTI Optical Upper Limit
- GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 251025B: SVOM/VT optical bump
- GRB 251025B: SVOM/COLIBRÍ (FM-GFT) strong rebrightening of the optical counterpart
- GRB 251023A: SVOM/GRM observation
- GRB 251025B: ULL-ASTRO-MASTER optical counterpart detection with IAC80 telescope at Teide Observatory
- GRB 251025B: GROWTH-India Telescope optical observations
- GRB 251024A: Swift/UVOT Upper Limits
- GRB 251025B: SVOM/VT optical observations with VHF data
- GRB 251025B: MASTER OT detection
- GRB 251025B: SVOM/C-GFT optical counterpart detection
- GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
- GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 251025A: SVOM/VT VHF optical upper limit
- GRB 251024A: LCOGT Optical Afterglow Detection
- GRB 251022A: KAIT optical observations
- GRB 251023B / EP251023b: COLIBRÍ Confirmation of the Fading Nature of the Optical Candidate
- GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
- EP251023a: MAO/AZT-22 optical observations
- GRB 251023B: OHP/T193 optical observations
- EP251023a: OHP/T193 optical observations
- EP251023b/GRB 251023B: JinShan optical observation
- GRB 251022A: Swift-XRT detection of GOTO25iym
- GRB 251022A: GROWTH-India Telescope optical observations
- EP251023a: GROWTH-India Telescope optical observations
- GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
- EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
- GRB 251023B / EP#01709247298: COLIBRÍ optical counterpart candidate
- EP251023a: COLIBRÍ optical observations
- GRB 251013C: further SAO RAS optical observations
- EP251023a: Keck/LRIS spectroscopic redshift z=2.232
- GRB 251022A: COLIBRÍ optical observations
- GRB 251013C: ISON-Castelgrande observatory optical observations
- GRB 251022A: MASTER OT detection
- GRB 251022A: DDOTI Optical Detection
- EP251021b/GRB 251021A: SVOM/VT optical candidate
- EP251023a: NOT optical counterpart detection
- EP251023a: GSP Optical Counterpart Detection
- EP251023a: Einstein Probe detection of an X-ray transient
- EP/WXT 01709247295: GOTO optical afterglow candidate.
- GRB 251022A: GOTO optical counterpart detection
- EP251021b: BOOTES-7 optical upper limit
- GRB 251017A: COLIBRÍ optical observations of a late plateau
- IceCube-251018A: DDOTI Optical Upper Limit
- GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
- GRB 251016A: Swift/UVOT Detection
- GRB 251017A: VLT/MUSE spectroscopic redshift z = 4.327
- GRB 251016A: VLT/FORS2 Optical Observation
- GRB 251018A: MASTER OT detection
- GRB 251018A: TRT optical afterglow detection
- GRB 251018A: Swift detection of a burst with an optical counterpart
- GRB 251017A: SVOM/VT optical observation
- GRB 251013C: OHP/T193 third epoch optical observations and detected rebrightening
- GRB 251017A: J-band detection with WINTER
- GRB 251013C: Liverpool Telescope observations
- GRB 251013C: Leavitt Observatory optical photometry
- GRB 251017A: JinShan observations of the optical afterglow