GCN Circulars
GCN Circulars are rapid bulletins submitted by and distributed to the community. See the documentation for help with subscribing to or submitting Circulars.
Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
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"28116 results found.
- GRB 260204A: Swift/UVOT Upper Limits
- GRB 260208B: COLIBRÍ optical observations
- GRB 260208A: Mondy optical observations
- GRB 260208A: 1.3m DFOT optical detection
- GRB 260208A: COLIBRÍ optical observations
- GRB 260208B: EP-FXT observation
- Fermi GRB 260208C: Global MASTER-Net observations report
- GRB 260208B: SVOM/VT optical candidate
- GRB 260208A: GECAM-B observation of a bright burst
- GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
- GRB 260208A: SVOM/VT optical observation
- Fermi GRB 260208D: Global MASTER-Net observations report
- GRB 260208A: Swift-XRT observations
- GRB 260208B: SVOM/GRM observation of a bright burst
- GRB 260208B: Fermi GBM Detection
- LAT GRB 260208B: Global MASTER-Net observations report
- GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
- GRB 260208B: BALROG localization (Fermi Trigger 792237169 / GRB 260208412)
- Fermi GRB 260208A: Global MASTER-Net observations report
- GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
- GRB 260131A/B: Mondy and Terskol optical observations
- Fermi GRB 260207B: Global MASTER-Net observations report
- GRB 260206A: Swift-XRT observations
- Fermi trigger No 792135758: Global MASTER-Net observations report
- GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
- GRB 260204A: Swift-XRT observations
- GRB 260204A: SVOM/VT optical candidate
- GRB 260204A : MASTER Global robotic net optical observations
- Fermi GBM Sub-Threshold Detection of GRB 260204A
- GRB 260204A: LCO optical upper limits
- EP260110a: Late GTC/EMIR near-infrared observations
- GRB 260121A: 239Alferov CubeSat detection
- GRB 260131A: KAIT optical observations
- GRB 251230A: MeerLICHT afterglow detection
- GRB 260131A/B: GTC/OSIRIS+ redshift confimation
- GRB 260130A: Insight-HXMT/HE detection
- GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
- GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
- GRB 260127A: GECAM-B observation
- EP260131a: Liverpool Telescope optical upper limits
- EP260131a: COLIBRÍ further observations
- EP260131a: SVOM/VT optical observation
- EP260131a: Xinglong optical upper limit
- GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
- GRB 260131A/B: Fermi GBM Observation
- EP260131a: COLIBRÍ observations of slow optical fading
- EP260131a: refined analysis of the EP-WXT and autonomous EP-FXT observations
- EP260131a: NOT early detection of the counterpart in "rapid response mode"
- GRB 260131B: MAXI/GSC detection
- EP260131a: COLIBRÍ optical observations of the counterpart
- EP260131a: Las Cumbres detection of an optical counterpart
- GRB 260127B: AstroSat CZTI detection
- GRB 260130A: Fermi GBM Detection
- EP260131a: Einstein Probe detection of an X-ray transient
- GRB 260127B: Fermi GBM Detection
- EP260128a / GRB 260128A: COLIBRÍ optical upper limit
- Fermi GRB 260130A: Global MASTER-Net observations report
- Fermi GRB 260129A: Global MASTER-Net observations report
- GRB 260128B: LCO optical upper limits
- GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
- EP260128a: J band upper limit by SYSU 80cm infrared telescope
- GRB 260127A: Swift-BAT refined analysis
- GRB 260127B: Swift-XRT observations
- GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
- GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
- EP260128a: NOT optical counterpart candidate
- EP260128a: refined analysis of the EP-WXT and autonomous EP-FXT observations
- EP260128a: Liverpool Telescope optical observations and possible counterpart
- EP260128a: LCO optical upper limits
- EP260128a: Global MASTER-Net observations report
- EP260128a: Einstein Probe detection of an X-ray transient
- Fermi GRB 260127A: Global MASTER-Net observations report
- GRB 260127A: Fermi GBM Observation
- IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
- GRB 260127A: COLIBRÍ optical observations
- EP260126a: Seimei/TriCCS optical upper limit
- GRB 260127A : MITSuME Akeno optical afterglow candidate detection
- GRB 260127A: Swift-XRT refined Analysis
- GRB 260127A: SVOM/C-GFT optical observations
- GRB 260127A: Enhanced Swift-XRT position
- Fermi GRB 260127B: Global MASTER-Net observations report
- Swift GRB 260127A: Global MASTER-Net observations report
- GRB 260127A: LCO optical afterglow discovery
- GRB 260127A: Swift detection of a burst
- GRB 260125A: Swift-XRT observations
- EP260126a: Optical upper limit with Kinder observations
- EP260126a: Liverpool Telescope optical upper limits
- EP260126a: Further NOT optical upper limits
- EP260126a: COLIBRÍ optical upper limits
- EP260126a: NOT optical observations
- EP260126a: Einstein Probe detection of a fast X-ray transient
- Fermi-LAT Gamma-ray Observations of IceCube-260125A
- GRB 251222A: SVOM/ECLAIRs refined analysis
- GRB 260125A: GOTO candidate optical counterpart
- Fermi GRB 260125B: Global MASTER-Net observations report
- GRB 260114A: SVOM/VT optical upper limits
- GRB 260122B: Swift-BAT refined analysis
- GRB 260120B: SVOM/GRM observation
- Swift GRB260122.97: Global MASTER-Net observations report
- EP260119a: Assy AZT-20 optical observations