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 260120B: Fermi GBM Final Real-time Localization
- EP260119A: Mondy I-Band Observations
- Fermi trigger No 790601190: Global MASTER-Net observations report
- Fermi trigger No 790570272: Global MASTER-Net observations report
- GRB 260114A: Swift/UVOT Upper Limits
- EP260119a: Liverpool Telescope optical follow-up observations
- GRB 251202A: further radio observations with the VLA
- Trigger 1442421: Swift detection of HMXB 1A 1118-61
- EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
- EP260119a: KAIT optical observations
- GRB 260120A: Fermi GBM Final Real-time Localization
- EP260119a: SVOM/VT optical observation
- EP260119a: update of EP-FXT follow-up observation
- EP260119a: NOT optical observations
- EP260119a: SAO RAS optical observations
- SVOM GRB260119.92: Global MASTER-Net observations report
- SVOM GRB260119.92: Global MASTER-Net observations report
- SVOM GRB260119.90: Global MASTER-Net observations report
- 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
- 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
- EP260119a: preliminary result from the EP-FXT observation
- GRB 260110A: SVOM detection of a burst through offline search
- EP260119a: EP-WXT detection of a fast X-ray transient
- Swift GRB260118.48: Global MASTER-Net observations report
- GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
- SVOM GRB260117.82: Global MASTER-Net observations report
- Fermi-LAT Gamma-ray Observations of IceCube-260115A
- 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: Liverpool Telescope upper limits
- FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
- EP260116A: 1.3m DFOT optical upper limit
- GRB 260114A: VLT/MUSE spectroscopic observations
- IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
- EP260116a: Global MASTER-Net observations report
- GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
- EP260116a: Xinglong optical upper limit
- EP260116a: Einstein Probe detection of an X-ray transient
- 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)
- IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
- 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: 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
- IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
- Swift GRB260113.43: Global MASTER-Net observations report
- EP260110a: NOT and GTC Optical and Near-Infrared Observations
- 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
- The EP-WXT trigger 01709251266 is likely a flaring star
- 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