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"11546 results found.
- GRB 260130A: GECAM-B observation of a short burst
- GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
- GRB 260131A/B: EP/FXT X-ray afterglow detection
- GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
- GRB 260127B: Insight-HXMT/HE detection
- GRB 260127B: GECAM-B observation of a short burst
- GRB 260127A: GECAM-B observation
- GRB 260131A: NOT spectroscopic redshift z = 1.434
- Konus-Wind detection of GRB 260128A / EP260128a
- GRB 260131A: Insight-HXMT/HE detection
- Konus-Wind detection of GRB 260131A/B
- GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
- GRB 260131A/B: GOTO candidate optical counterpart consistent with the MAXI localisation
- GRB 260131A/B: Fermi GBM Observation
- GRB 260131A: Fermi GBM Final Real-time Localization
- GRB 260127B: AstroSat CZTI detection
- GRB 260130A: Fermi GBM Detection
- GRB 260127B: Fermi GBM Detection
- Fermi GRB 260130A: Global MASTER-Net observations report
- GRB 260130A: Fermi GBM Final Real-time Localization
- Fermi GRB 260129A: Global MASTER-Net observations report
- IPN triangulation of GRB 260121A
- GRB 260129B: Fermi GBM Final Localization
- GRB 260129A: Fermi GBM Final Localization
- IPN triangulation of GRB 260127B (short)
- 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
- Fermi GRB 260127A: Global MASTER-Net observations report
- GRB 260127A: Fermi GBM Observation
- GRB 260127A: COLIBRÍ optical observations
- GRB 260127A: NOT optical observations
- GRB 260127B: Swift ToO observations
- GRB 260127A : MITSuME Akeno optical afterglow candidate detection
- GRB 260127B: GOTO candidate optical counterpart
- GRB 260127A: SVOM/C-GFT optical observations
- Fermi GRB 260127B: Global MASTER-Net observations report
- GRB 260127B: Fermi GBM Final Real-time Localization
- GRB 260127A: LCO optical afterglow discovery
- GRB 260127A: Fermi GBM Final Real-time Localization
- GRB 260125A: Swift-XRT 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 260125A: Swift ToO observations
- GRB 260125A: GOTO candidate optical counterpart
- Fermi GRB 260125B: Global MASTER-Net observations report
- IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 260125B: Fermi GBM Final Real-time Localization
- GRB 260125A: Fermi GBM Final Real-time Localization
- 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 260122A: Fermi GBM Final Real-time Localization
- Fermi GRB 260120C: Global MASTER-Net observations report
- GRB 260120B: Fermi GBM Observation
- GRB 260120B: COLIBRÍ optical upper limits
- GRB 260120B: SVOM/C-GFT optical counterpart detection
- GRB 260120C: Fermi GBM Final Real-time Localization
- GRB 260101A: 239Alferov CubeSat detection
- GRB 260120B: Fermi GBM Final Real-time Localization
- Fermi trigger No 790601190: Global MASTER-Net observations report
- Fermi trigger No 790570272: Global MASTER-Net observations report
- GRB 251202A: further radio observations with the VLA
- GRB 260120A: Fermi GBM Final Real-time Localization
- GRB 260115A: AstroSat CZTI detection
- Fermi-LAT Gamma-ray Observations of IceCube-260115A
- GRB 260115A: GECAM-B observation
- GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
- IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
- Fermi GRB 260115A: Global MASTER-Net observations report
- GRB 260115A: Fermi GBM Final Real-time Localization
- GRB260114A: STEP/T80S optical limits
- GRB 251222A: radio detection with the VLA
- GRB 260114A: VLT/HAWK-I near-infrared upper limits
- Konus-Wind detection of GRB 260114A
- GRB 260114A: 6 GHz VLA observations
- GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
- GRB 260114A : MITSuME Akeno optical upper limits
- GRB 260114A: COLIBRÍ optical upper limits
- GRB 260114A: TNG NIR upper limit
- GRB 260114A: NOT optical observations
- GRB 260114A: SVOM/GRM observation of a short burst
- GRB 260114A: GECAM-B observation of a short burst
- GRB 260114A: Mondy optical observations
- GRB 260114A: Fermi GBM observation
- GRB 260112B: GECAM-B observation
- GRB 260114A: GMG Optical Observation
- Fermi-LAT Gamma-ray Observations of IceCube-260111A
- GRB 260114A: Fermi GBM Final Real-time Localization
- Konus-Wind detection of GRB 260101A
- GRB 260111A: Swift-XRT observations
- GRB 260111A: COLIBRÍ optical afterglow candidate
- GRB 260111A: GECAM-B observation of a burst
- GRB 260111A: Fermi GBM Observation
- GRB 260111A: GOTO optical upper limits