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"28253 results found.
- 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
- EP260119a: Mondy and SAO RAS optical upper limits
- EP260119a: Xinglong optical upper limit
- Fermi GRB 260120C: Global MASTER-Net observations report
- GRB 260120B: Swift-BAT refined analysis
- GRB 260120B: Swift-XRT refined Analysis
- EP260116a: COLIBRÍ further observations
- GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
- GRB 260120B: Fermi GBM Observation
- EP260105a: GTC/HiPERCAM optical observations
- GRB 260120B: Swift/UVOT Detection
- GRB 260120B: COLIBRÍ optical upper limits
- SVOM GRB260121.06: Global MASTER-Net observations report
- GRB 260120B: Enhanced Swift-XRT position
- GRB 260120B: SVOM/C-GFT optical counterpart detection
- GRB 260101A: 239Alferov CubeSat detection
- EP260116a: COLIBRÍ observations of a tentative optical rebrightening
- GRB 260120B: Swift detection of a burst
- Swift GRB260120B: Global MASTER-Net observations report
- EP260119A: Mondy I-Band Observations
- Fermi trigger No 790601190: Global MASTER-Net observations report
- Fermi trigger No 790570272: Global MASTER-Net observations report
- GRB 260114A: Swift/UVOT Upper Limits
- EP260119a: Liverpool Telescope optical follow-up observations
- GRB 251202A: further radio observations with the VLA
- EP260119a: KAIT optical observations
- EP260119a: SVOM/VT optical observation
- EP260119a: NOT optical observations
- EP260119a: SAO RAS optical observations
- SVOM GRB260119.92: Global MASTER-Net observations report
- SVOM GRB260119.92: Global MASTER-Net observations report
- SVOM GRB260119.90: Global MASTER-Net observations report
- EP260116a: COLIBRÍ detection of a fading optical source
- GRB 260117A: Swift-XRT afterglow detection
- EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
- EP260119a: Global MASTER-Net observations report
- EP260119a: LCO optical observations
- GRB 260117A: ZTSh optical upper limit
- EP260119a: COLIBRÍ optical counterpart candidate
- EP260119a: EP-WXT detection of a fast X-ray transient
- Swift GRB260118.48: Global MASTER-Net observations report
- GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
- SVOM GRB260117.82: Global MASTER-Net observations report
- Fermi-LAT Gamma-ray Observations of IceCube-260115A
- Swift trigger on the HMXB 1A 1118-61
- GRB 260117A: SVOM/VT optical candidate
- GRB 260117A: SVOM/C-GFT upper limit
- GRB 260117A: Swift-XRT observations
- GRB 260117A: SVOM detection of a long faint burst
- EP 260116a: COLIBRÍ optical upper limit
- Swift triggered on the HMXB 1A 1118-61
- FRB 20251229A: COLIBRÍ further inspection of the updated localization
- EP260116a: Liverpool Telescope upper limits
- FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
- EP260116A: 1.3m DFOT optical upper limit
- GRB 260114A: VLT/MUSE spectroscopic observations
- IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
- EP260116a: Global MASTER-Net observations report
- GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
- EP260116a: Xinglong optical upper limit
- EP260116a: Einstein Probe detection of an X-ray transient
- GRB 260114A: VLT/HAWK-I further near-infrared upper limits
- IceCube Alert 260115.73: Global MASTER-Net observations report
- GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
- IceCube: GCN Notices for high-energy track alerts now streamed via Kafka