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"27015 results found.
- GRB 251105A: Fermi GBM Final Real-time Localization
- Fermi Gamma-ray Burst Monitor trigger 783986701/251104920 is not a GRB
- GRB 251103B: Fermi GBM observation
- GRB 251104A: SVOM detection of a burst
- EP251102a: FTW optical and NIR observations
- GRB 251103A: WFST optical observations
- EP251102a: update of EP-FXT follow-up observation
- GRB 251103A: Xinglong 2.16m optical detection
- GRB 251103B: Nanshan/HMT optical upper limit
- GRB 251103A: Swift/BAT-GUANO arcminute localization of a burst
- GRB 251103B: MITSuME Akeno optical upper limits
- GRB 251103B: Swift-XRT refined Analysis
- Fermi GRB 251103A: Global MASTER-Net observations report
- EP251102a: NIR observations with WINTER
- GRB 251103A: J-band detection with WINTER
- Swift GRB 251103B: Global MASTER-Net observations report
- GRB 251103B: GROWTH-India Telescope optical upper limits
- GRB 251103A: Kilonova-Catcher optical afterglow detection
- GRB 251103B: Swift detection of a burst
- GRB 251103B: Fermi GBM Final Real-time Localization
- GRB 251103A: Swift/UVOT Detection
- GRB 251103A: Fermi GBM Observation
- GRB 251103A: SVOM/GRM observation
- GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
- EP251102a: Einstein Probe detection of a fast X-ray transient
- EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
- 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: BOOTES-2/TELMA optical afterglow
- GRB 251103A: LCO optical afterglow detection
- GRB 251103A: Fermi GBM Final Localization
- GRB 251103A: NOT optical afterglow candidate
- GRB 251103A: SVOM detection of a bright burst
- GRB 251102B: Fermi GBM Final Real-time Localization
- Fermi GRB 251102A: Global MASTER-Net observations report
- GRB 251102A: Fermi GBM Final Real-time Localization
- GRB 251031A: Fermi GBM Observation
- GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
- GRB 251031A: BALROG localization (Fermi Trigger 783588065 / GRB 251031306)
- GRB 251031A: Fermi GBM Final Real-time Localization
- GRB 251025C: SVOM/GRM observation
- GRB 251028A: GECAM-B detection
- GRB 251028A: SVOM/GRM observation
- GRB 251028A: Fermi GBM Observation
- GRB 251026B: LBT near-infrared observations
- GRB 250926A: VZLUSAT-2 detection
- GRB 251026B: Fermi GBM Observation
- GRB 251026A/EP251026a: SVOM/VT optical counterpart
- GRB 251026A/EP251026a: EP-FXT follow-up observation
- The EP-WXT trigger 01709247588 is likely a flaring star
- GRB 251028B: Fermi/GBM observation
- GRB 251028B: Swift/BAT-GUANO localization skymap of a burst
- GRB 251028B: CALET Gamma-Ray Burst Monitor detection
- Fermi GRB 251028B: Global MASTER-Net observations report
- GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
- GRB 251028B: Fermi GBM Final Localization Correction
- GRB251026B: PRIME H-band upper limit
- GRB251025B: 3.6m DOT Optical Observations
- GRB 251028A: BALROG localization (Fermi Trigger 783314796 / GRB 251028143)
- GRB 251028A: Fermi GBM Final Real-time Localization
- The EP-WXT trigger 01709247525 is not a real source
- SVOM trigger sb25102702/GRB 251027A is not a GRB
- GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
- GRB 251027A: Swift-XRT observations
- EP251027.145: COLIBRÍ optical upper limits
- GRB 251022A: SVOM/GRM observation
- GRB 251026A/EP251026a: Einstein Probe detection of a fast X-ray transient
- GRB 251027A: LCO optical upper limit
- GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 251025B: Kilonova-Catcher optical afterglow detection
- GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
- GRB 251027A: SVOM detection of a faint burst
- GRB 251026B: Tentative GOTO optical counterpart candidate
- GRB 251025C: CALET Gamma-Ray Burst Monitor detection
- Fermi GRB 251026B: Global MASTER-Net observations report
- Fermi GRB 251025C: Global MASTER-Net observations report
- GRB 251026A: Swift-XRT observations
- GRB 251025B: J-band detection with WINTER
- IceCube-251025A: DDOTI Optical Upper Limit
- GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 251026B: Fermi GBM Final Localization
- GRB 251026A: SVOM detection of a long burst
- 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 251025C: Fermi GBM Final Real-time Localization
- GRB 251025B: GROWTH-India Telescope optical observations
- GRB 251024A: Swift/UVOT Upper Limits
- GRB 251024A: Swift-BAT refined analysis
- IceCube Alert 251025.57: Global MASTER-Net observations report
- GRB 251024A: Swift-XRT refined Analysis
- GRB 251025A (sb25102501): stellar flare confirmed
- GRB 251025B: SVOM/VT optical observations with VHF data
- GRB 251025B: SVOM/C-GFT optical counterpart detection
- GRB 251025B: SVOM detection of a burst
- GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
- GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit