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"26507 results found.
- Swift trigger on the HMXB 1A 1118-61
- GRB 260117A: SVOM/C-GFT upper limit
- GRB 260117A: Swift-XRT 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
- 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
- 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-260115A - IceCube observation of a high-energy neutrino candidate track-like event
- IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
- 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: 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
- GRB 260114A: GECAM-B observation of a short burst
- GRB 260114A: Mondy optical observations
- GRB 260114A: Fermi GBM observation
- GRB 260114A: GMG Optical Observation
- Fermi-LAT Gamma-ray Observations of IceCube-260111A
- GRB 260114A: Swift detection of a short burst
- 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
- 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: Fermi GBM Observation
- The EP-WXT trigger 01709251266 is likely a flaring star
- GRB 251230A: Mondy Optical Observations
- Swift trigger 1436759 is not an astrophysical event
- EP260110a: KAIT optical upper limit
- EP260110a: refined analysis of the EP-WXT and EP-FXT observations
- EP 260110a: COLIBRÍ optical observations
- EP260110a: SVOM/C-GFT upper limit
- EP260110a: Einstein Probe detection of an X-ray transient
- GRB 260109C: LCO optical upper limits
- GRB 260109C: Kilonova-Catcher optical upper limit
- Swift Trigger 1434591: possible GRB 260109C
- GRB 260102A: Swift-XRT afterglow detection
- GRB 260102A: AbAO optical observations
- EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
- The EP-WXT trigger 01709251112 is likely a flaring star
- GRB 260105B: Fermi GBM Detection
- GRB 260105A: SVOM/GRM observation
- GRB 260105B: SVOM/GRM observation
- The EP-WXT trigger 01709251028 is likely a flaring star
- FRB 20251229A: COLIBR Í optical upper limits
- EP260105a: refined analysis of the EP-WXT and EP-FXT observations
- EP260105a: LCO Optical Upper limit
- EP260104a: Einstein Probe detection of a fast X-ray transient
- GRB 260101A: COLIBRÍ optical upper limits
- EP260105a: Einstein Probe detection of an X-ray transient
- GRB 260104A: COLIBRÍ optical upper limits
- GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
- GRB 260104A: Swift-XRT refined Analysis
- GRB 260104A: Enhanced Swift-XRT position
- GRB 260101A: Swift/UVOT Detection
- GRB 260104A: Swift detection of a burst
- Fermi-LAT Gamma-ray Observations of IceCube-251225A
- GRB 260101A: COLIBRÍ optical observations
- GRB 260102B: Fermi GBM Final Real-time Localization
- GRB 260102A: LCO optical upper limits
- GRB 260102A: Swift-XRT observations
- GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
- GRB 260102A: SVOM/VT optical counterpart
- GRB 260101A: Fermi GBM Observation
- EP260101a: refined analysis of the EP-WXT and EP-FXT observations
- GRB 260102A: SVOM detection of a burst
- GRB 260101A: SVOM/GRM observation
- GRB 260101A: Swift-XRT refined Analysis
- GRB 260101A: Enhanced Swift-XRT position
- EP260101a: Einstein Probe detection of an X-ray transient
- GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
- GRB 260101A: LCO detection of the optical counterpart
- GRB 260101A: Swift detection of a burst with an optical counterpart
- GRB 251230A: GRANDMA/TAROT Early Detection
- GRB 251230A/EP251230a: Optical upper limit with Kinder observations
- EP251229a: Optical upper limit with Kinder observations
- GRB 251230A: 1.3m DFOT optical upper limit
- GRB 251230A: Swift-XRT refined Analysis
- GRB 251222A: Mondy Optical Observations
- EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
- GRB 251230A: Swift/UVOT detection