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"15247 results found.
- GRB 260130A: GECAM-B observation of a short burst
- GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
- GRB 260127B: Insight-HXMT/HE detection
- GRB 260127B: GECAM-B observation of a short burst
- GRB 260127A: GECAM-B observation
- EP260131a: Liverpool Telescope optical upper limits
- EP260131a: COLIBRÍ further observations
- Konus-Wind detection of GRB 260128A / EP260128a
- GRB 260131A: Insight-HXMT/HE detection
- Konus-Wind detection of GRB 260131A/B
- EP260131a: COLIBRÍ observations of slow optical fading
- EP260131a: NOT early detection of the counterpart in "rapid response mode"
- EP260131a: COLIBRÍ optical observations of the counterpart
- GRB 260127B: AstroSat CZTI detection
- GRB 260130A: Fermi GBM Detection
- GRB 260127B: Fermi GBM Detection
- EP260128a / GRB 260128A: COLIBRÍ optical upper limit
- EP260128a / GRB 260128A: NOT and TNG optical and NIR upper limits
- GRB 260128B: SVOM detection of a burst through offline search
- GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
- EP260128a: NOT optical counterpart candidate
- EP260128a: refined analysis of the EP-WXT and autonomous EP-FXT observations
- IceCube-260125A: No Candidate Transients from the Zwicky Transient Facility
- GRB 260127A: Fermi GBM Observation
- IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
- GRB 260127A: COLIBRÍ optical observations
- GRB 260127A: NOT optical observations
- GRB 260127B: Swift ToO observations
- GRB 260127A : MITSuME Akeno optical afterglow candidate detection
- GRB 260127A: SVOM/C-GFT optical observations
- EP260126a: Optical upper limit with Kinder observations
- Fermi-LAT Gamma-ray Observations of IceCube-260125A
- GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
- Konus-Wind detection of GRB 260120B
- GRB 251222A: SVOM/ECLAIRs refined analysis
- GRB 260125A: Swift ToO observations
- IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 260114A: SVOM/VT optical upper limits
- GRB 260120A: AstroSat CZTI detection
- GRB 260120B: SVOM/GRM observation
- GRB 260120A: GECAM-B observation
- GRB 260120B: AstroSat CZTI detection
- GRB 260114A: Insight-HXMT/HE detection
- GRB 260122B: Swift detection of a burst
- EP260119a: Mondy and SAO RAS optical upper limits
- IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
- 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: COLIBRÍ optical upper limits
- GRB 260101A: 239Alferov CubeSat detection
- EP260119a: Liverpool Telescope optical follow-up observations
- Trigger 1442421: Swift detection of HMXB 1A 1118-61
- EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
- EP260119a: update of EP-FXT follow-up observation
- EP260119a: NOT optical observations
- EP260116a: COLIBRÍ detection of a fading optical source
- GRB 251208D: SVOM/ECLAIRs refined analysis
- GRB 251208D: SVOM/ECLAIRs refined analysis
- GRB 260117A: Swift-XRT afterglow detection
- EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
- GRB 260115A: AstroSat CZTI detection
- GRB 260117A: ZTSh optical upper limit
- EP260119a: COLIBRÍ optical counterpart candidate
- GRB 260110A: SVOM detection of a burst through offline search
- Fermi-LAT Gamma-ray Observations of IceCube-260115A
- Swift trigger on the HMXB 1A 1118-61
- GRB 260117A: Swift ToO observations
- GRB 260117A: SVOM detection of a long faint burst
- EP 260116a: COLIBRÍ optical upper limit
- GRB 260115A: GECAM-B observation
- FRB 20251229A: COLIBRÍ further inspection of the updated localization
- FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
- GRB 260114A: VLT/MUSE spectroscopic observations
- IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
- GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
- IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
- IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
- GRB260114A: STEP/T80S optical limits
- Konus-Wind detection of GRB 260114A
- GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
- GRB 260114A: COLIBRÍ optical upper limits
- GRB 260114A: TNG NIR upper limit
- GRB 260114A: NOT optical observations
- Konus-Wind detection of GRB 251230A / EP251230a
- GRB 260114A: SVOM/GRM observation of a short burst
- GRB 260114A: GECAM-B observation of a short burst
- GRB 260114A: Fermi GBM observation
- GRB 260112B: GECAM-B observation
- Fermi-LAT Gamma-ray Observations of IceCube-260111A
- IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
- EP260110a: TRT optical upper limits
- Konus-Wind detection of GRB 260101A
- GRB 260111A: Swift-XRT observations
- Swift Trigger 1439093: is probably not GRB 260113A
- GRB 260111A: GECAM-B observation of a burst
- GRB 260111A: Fermi GBM Observation
- GRB 260111A: Swift ToO observations
- GRB 251230A: Mondy Optical Observations