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"- GRB 260131A/B: radio detection with the VLA
- EP260302a: MeerKAT radio counterpart
- GRB260307A: GECAM-B observation of a burst
- GRB 260308A: SVOM/GRM observation of a short GRB
- EP260306a: Mondy optical upper limit
- GRB 260310A: AstroSat CZTI detection of a long burst
- GRB 260311A: Fermi GBM Final Real-time Localization
- Fermi GRB 260310B: Global MASTER-Net observations report
- GRB 260310B: Fermi GBM Final Real-time Localization
- Fermi GRB 260310A: Global MASTER-Net observations report
- GRB 260307B: SVOM/ECLAIRs refined analysis
- GRB 260208A: radio detection with the VLA
- GRB 260310A: Fermi GBM Final Real-time Localization
- GRB 260307A: Glowbug gamma-ray detection
- GRB 260308A: Fermi GBM Final Real-time Localization
- Fermi GBM Sub-Threshold Detection of GRB 260307B
- GRB 260307B: Mephisto optical upper limits
- GRB 260307B: possible NOT optical counterpart
- GRB 260307B: SVOM/VT upper limit with X band data analysis
- Fermi GRB 260307A: Global MASTER-Net observations report
- GRB260307B: GROWTH-India Telescope optical upper limit
- GRB 260307B: SVOM/VT optical candidate
- GRB 260307B: SVOM/C-GFT upper limit
- GRB 260307B: SVOM detection of a burst
- GRB 260307A: Fermi GBM Final Localization
- GRB 260211A: late-time NOT i-band observations consistent with archival flux
- EP260306a: refined analysis of the EP-WXT and EP-FXT observations
- GRB 260207A: TESS Detection and Possible VLA Counterpart
- EP260302a: SVOM/VT optical observation
- EP260306a: Gemini-North redshift z = 4.773
- EP260306a: SVOM/VT optical observation
- EP260302a: Gemini-South redshift z = 1.535
- EP260306a: COLIBRÍ optical observations of the fading and red counterpart
- EP260306a: Einstein Probe detection of an X-ray transient
- The EP-WXT trigger 01709258759: Las Cumbres discovery of the optical counterpart
- EP260302a: Optical afterglow rebrightening
- GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
- GRB 260303A: 1.3m DFOT optical upper limit (duplicate submission)
- GRB 260303A: 1.3m DFOT optical upper limit
- EP260214b: ATCA 6 GHz observations
- GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
- GRB 260303A: SVOM/ECLAIRs refined analysis
- Fermi GRB 260305A: Global MASTER-Net observations report
- GRB 260305A: Fermi GBM Final Real-time Localization
- GRB 260303B: AstroSat CZTI detection
- GRB 260304A: AstroSat CZTI detection of a long burst
- SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
- GRB 260303A: SVOM/VT optical observations
- GRB 260303A: J-band observations with WINTER
- GRB 260303B: NuSTAR detection of prompt emission
- EP260302a: Global MASTER-Net observations report
- Fermi GRB 260303B: Global MASTER-Net observations report
- IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
- GRB 260228A: SVOM/ECLAIRs refined analysis
- GRB 260225A: SVOM/ECLAIRs refined analysis
- GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
- GRB 260303B: Fermi GBM Final Real-time Localization
- EP260302a: analysis of the follow-up EP-FXT observation
- EP260227a: Gemini-South optical observations
- EP260302a: LCO observations
- EP260302a: BOOTES-7 optical counterpart detection at early times
- GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
- GRB 260303A: SVOM detection of a burst
- GRB 260228A: EP-FXT follow-up observation
- EP260302a: Einstein Probe detection of an X-ray transient
- The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
- GRB 251130B: TERI Gamma-ray detection
- GRB 260208A: TERI Gamma-ray detection
- GRB 260302A: Fermi GBM Final Real-time Localization
- EP260227a: Mondy optical observations
- GRB 260228A: CAHA 2.2m telescope optical upper limit
- GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- EP260227a: Mephisto optical detection
- GRID detection of GRB 260225D
- EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
- EP260227a: further LCO observations
- EP260227a: SVOM/VT optical observation
- GRB 260228A: SVOM/VT optical upper limits
- GRB 260225D: SVOM/GRM observation
- EP260227A: 3.6m DOT optical afterglow detection
- GRB 260225B: SVOM/GRM observation
- GRB 260228A: SVOM detection of a burst
- EP260227a: FTW optical and NIR observations
- EP260227a: Liverpool Telescope optical observations
- EP260227a: LCOGT Optical Observations
- GRB 260226A: Asiago r-band upper limit
- EP260227a: Thai National Telescope observations
- EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
- EP260227a: Liverpool Telescope observations
- EP260227a: COLIBRÍ optical observations
- EP260227a: NOT optical observations
- GRB 260225A: SVOM/VT optical continued observations and upper limit
- GRID detection of GRB 260223A
- EP260227a: Global MASTER-Net observations report
- EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
- The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
- EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
- IceCube cascade alert 142200_1517143 retraction
- GRB 260226A: Insight-HXMT/HE detection of the very bright burst
- Konus-Wind detection of GRB 260226A