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"15243 results found.
- IceCube cascade alert 142200_1517143 retraction
- GRB 260226A: Insight-HXMT/HE detection of the very bright burst
- Konus-Wind detection of GRB 260226A
- EP260214a: VLT/FORS2 optical observations
- GRB 260225A: WINTER J-band upper limit
- GRB 260226A: COLIBRÍ optical upper limits
- EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
- GRB 260226A: LAST optical upper limit
- GRB 260226A: Fermi-LAT refined analysis
- GRB 260226A: AstroSat CZTI detection of bright long burst
- GRB 260226A: Fermi-LAT detection of a bright burst
- GRB 260225A: EP-FXT follow-up observation
- GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
- GRB 260225A: SVOM detection of a burst
- EP260213a: Mephisto optical upper limits
- sb26021801: SVOM/VT optical upper limits
- GRB 260223A: COLIBRÍ optical afterglow decay confirmation
- GRB 260223A: SVOM/GRM observation
- GRB 260223A: COLIBRÍ further optical observations and a brightening
- GRB 260223A: COLIBRÍ optical observations
- EP260221a: COLIBRÍ optical counterpart candidate
- EP260221a: EP-FXT follow-up observation
- ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
- GRB 260219A: AstroSat CZTI detection
- IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
- GRB 260219A: GECAM-B observation of a long burst
- SVOM alert sb26021801: LAST optical upper limit
- Fermi-LAT Gamma-ray Observations of IceCube-260217A
- GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
- sb26021801: SVOM detection of a long faint X-ray transient
- EP260214b: 1.3m DFOT optical upper limit
- Konus-Wind detection of GRB 260212A
- IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 260213A: GECAM-B observation of a short burst
- EP260214b: Liverpool Telescope optical observations
- GRB 260206A: probable hard X-ray burst from 4U 0513-40
- EP260214b: Optical upper limit with Kinder observations
- EP260214a: Optical upper limits with Kinder observations
- EP260214b: DDOTI Optical Detection
- EP260214a: NOT optical upper limits
- EP260214a: COLIBRÍ optical upper limits
- GRB 260211A: SVOM/VT optical counterpart
- EP260214b: COLIBRÍ optical observations
- GRB 260212A: AstroSat CZTI detection
- GRB 260212A: Fermi GBM Observation
- EP260213a: COLIBRÍ optical upper limits
- GRB 260212A: GECAM-B observation
- EP260213a: Optical upper limits with Kinder observations
- GRB 260212A: SVOM/GRM observation of a long burst
- GRB 260211A - SVOM/ECLAIRs refined analysis
- GRB 260204A: SVOM/ECLAIRs refined analysis
- GRB 260211A: LAST optical upper limit
- GRB 260210A: SVOM/GRM observation
- Konus-Wind detection of GRB 260207B
- GRB 260128B: SVOM/ECLAIRs refined analysis
- GRID detection of GRB 260207B
- GRB260131A/B: 3.6m DOT Optical Observations
- GRB 260211A: SVOM detection of a burst
- Konus-Wind detection of GRB 260209B
- Konus-Wind detection of GRB 260127B
- GRB 260208A: LCO detection of the optical counterpart
- EP260210a: Optical upper limits with Kinder observations
- GRB 260210A: AstroSat CZTI detection
- GRB 260208C: AstroSat CZTI detection
- GRB 260208B: refined analysis of the EP-FXT observation
- GRB 260207B: AstroSat CZTI detection
- GRB 260208C: SVOM/GRM observation
- GRB 260208B: AstroSat CZTI detection of a bright long burst
- GRB260208A: Liverpool Telescope optical follow-up observations
- GRB 260208A: Fermi GBM Observation
- GRB 260208B: Swift-XRT observations
- GRB 260131A/B: continued Mondy optical observations
- GRB 260204A: Swift/UVOT Upper Limits
- GRB 260208A: 1.3m DFOT optical detection
- GRB 260208A: GECAM-B observation of a bright burst
- GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
- GRB 260208B: Swift ToO observations
- GRB 260208B: SVOM/GRM observation of a bright burst
- GRB 260208B: Fermi-LAT detection
- GRB 260208A: Fermi-LAT detection
- GRB 260207B: GECAM-B observation
- GRB 260208A: Swift ToO observations
- GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
- GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
- GRB 260131A/B: Mondy and Terskol optical observations
- GRB 260206A: Tiled Swift observations
- GRB 260204A: Swift-XRT observations
- GRB 260204A: LCO optical afterglow detection
- EP260110a: Late GTC/EMIR near-infrared observations
- GRB 260204A: SVOM detection of a burst
- GRB 260121A: 239Alferov CubeSat detection
- Konus-Wind detection of GRB 260121A
- GRB 260131A/B: OHP/T193 optical observations
- GRID detection of GRB 260131A/B
- GRB 260131A/B: GTC/OSIRIS+ redshift confimation
- GRB 260130A: Insight-HXMT/HE detection
- 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