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.
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"38348 results found.
- GRB 260117A: Swift-XRT afterglow detection
- EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
- EP260119a: Global MASTER-Net observations report
- GRB 260115A: AstroSat CZTI detection
- EP260119a: LCO optical observations
- GRB 260117A: ZTSh optical upper limit
- EP260119a: COLIBRÍ optical counterpart candidate
- GRB 260110A: SVOM detection of a burst through offline search
- Swift GRB260118.48: Global MASTER-Net observations report
- GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
- SVOM GRB260117.82: Global MASTER-Net observations report
- 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: Swift ToO observations
- GRB 260117A: SVOM detection of a long faint burst
- EP 260116a: COLIBRÍ optical upper limit
- Swift triggered on the HMXB 1A 1118-61
- GRB 260115A: GECAM-B observation
- FRB 20251229A: COLIBRÍ further inspection of the updated localization
- EP260116A: 1.3m DFOT optical upper limit
- GRB 260114A: VLT/MUSE spectroscopic observations
- EP260116a: Global MASTER-Net observations report
- GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
- GRB 260114A: VLT/HAWK-I further near-infrared upper limits
- IceCube Alert 260115.73: Global MASTER-Net observations report
- 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
- GRB 251222A: radio detection with the VLA
- GRB 260114A: VLT/HAWK-I near-infrared upper limits
- Konus-Wind detection of GRB 260114A
- GRB 260114A: Swift-XRT refined Analysis
- 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
- Konus-Wind detection of GRB 251230A / EP251230a
- GRB 260114A: SVOM/GRM observation of a short burst
- Swift GRB 260114A: Global MASTER-Net observations report
- 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: Swift detection of a short burst
- GRB 260114A: Fermi GBM Final Real-time Localization
- EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
- Swift GRB260113.43: Global MASTER-Net observations report
- 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: COLIBRÍ optical afterglow candidate
- GRB 260111A: GECAM-B observation of a burst
- GRB 260111A: Fermi GBM Observation
- Swift Trigger 1434591 is not a GRB
- GRB 260111A: GOTO optical upper limits
- GRB 260112B: Fermi GBM Final Real-time Localization
- GRB 260111A: Swift ToO observations
- GRB 251230A: Mondy Optical Observations
- GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
- GRB 260112A: Fermi GBM Final Real-time Localization
- IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
- IceCube Alert 260111A: Global MASTER-Net observations report
- EP260110a: Global MASTER-Net observations report
- Fermi GRB 260111A: Global MASTER-Net observations report
- GRB 260111A: Fermi GBM Final Real-time Localization
- EP260110a: KAIT optical upper limit
- EP 260110a: COLIBRÍ optical observations
- EP260110a: SVOM/C-GFT upper limit
- GRB 260109C: LCO optical upper limits
- GRB 260109C: Kilonova-Catcher optical upper limit
- EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
- Swift Trigger 1434591: possible GRB 260109C
- GRB 260109B: Fermi GBM Final Real-time Localization
- GRB 260102A: Swift-XRT afterglow detection
- GRB 260109A: Fermi GBM Final Real-time Localization
- GRB 260104A: Swift-BAT refined analysis
- GRB 260101A: Swift-BAT refined analysis
- Swift GRB 251230A: Global MASTER-Net OT detection
- Fermi GRB 260107A: Global MASTER-Net observations report
- GRB 260102A: AbAO optical observations
- GRB 260107A: Fermi GBM Final Real-time Localization
- Fermi GRB 260105A: Global MASTER-Net observations report
- GRB 260105B: Fermi GBM Detection
- GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
- GRB 260105A: SVOM/GRM observation
- GRB 260105B: SVOM/GRM observation
- FRB 20251229A: COLIBRÍ optical upper limits
- Fermi GRB 260105B: Global MASTER-Net observations report
- GRB 260105B: Fermi GBM Final Real-time Localization
- GRB 260105A: Fermi GBM Final Real-time Localization
- EP260104a: Global MASTER-Net observations report
- GRB 260101A: COLIBRÍ optical upper limits