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"24365 results found.
- GRB 260101A: Swift-BAT refined analysis
- Swift GRB 251230A: Global MASTER-Net OT detection
- Fermi GRB 260107A: Global MASTER-Net observations report
- GRB 260107A: Fermi GBM Final Real-time Localization
- EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
- The EP-WXT trigger 01709251112 is likely a flaring star
- Fermi GRB 260105A: Global MASTER-Net observations report
- GRB 260105B: Fermi GBM Detection
- EP260105a: FTW optical observations
- EP260104a: FTW optical observations
- GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
- GRB 260105A: SVOM/GRM observation
- GRB 260105B: SVOM/GRM observation
- The EP-WXT trigger 01709251028 is likely a flaring star
- Fermi GRB 260105B: Global MASTER-Net observations report
- EP260105a: SVOM/VT optical upperlimit
- GRB 260105B: Fermi GBM Final Real-time Localization
- GRB 260105A: Fermi GBM Final Real-time Localization
- FRB 20251229A: A potentially hyperactive repeating fast radio burst source
- EP260105a: refined analysis of the EP-WXT and EP-FXT observations
- EP260104a: Global MASTER-Net observations report
- EP260105a: Global MASTER-Net observations report
- GRB 260104C: Fermi GBM Final Real-time Localization
- Fermi GRB 260104B: Global MASTER-Net observations report
- Swift GRB 260104A: Global MASTER-Net observations report
- GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
- GRB 260104A: Swift-XRT refined Analysis
- GRB 260103A: GECAM-B observation of a burst
- GRB 260104B: Fermi GBM Final Localization
- Fermi-LAT Gamma-ray Observations of IceCube-251225A
- SVOM GRB260103.08: Global MASTER-Net observations report
- GRB 260102B: Fermi GBM Final Real-time Localization
- SVOM GRB260102A: Global MASTER-Net observations report
- Fermi GBM Sub-Threshold Detection of GRB 260102A
- GRB 260102A: EP-FXT follow-up observation
- EP260101a: Global MASTER-Net observations report
- GRB 260102A: LCO optical upper limits
- GRB 260102A: Swift-XRT 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: NOT spectroscopic observations
- GRB 260101A: SVOM/GRM observation
- GRB 260101A: Swift-XRT refined Analysis
- Swift GRB 260101A: Global MASTER-Net observations report
- GRB 260101A: Fermi GBM Final Real-time Localization
- SVOM GRB251231.57: Global MASTER-Net observations report
- GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
- GRB 251230A: GRANDMA/TAROT Early Detection
- GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
- EP251229a: Optical upper limit with Kinder observations
- GRB 251230A: 1.3m DFOT optical upper limit
- GRB 251231A: Fermi GBM Final Real-time Localization
- EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
- GRB251230A: 7DT optical upper limits
- EP251229a: BOOTES-2 early optical upper limit
- GRB 251230A / EP251230a: SVOM/VT optical observation
- EP251229a: refined analysis of the EP-WXT and EP-FXT observations
- EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
- GRB 251230A: Optical Observations via Virtual Telescope Project, Italy
- LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
- Swift GRB 251230A: Global MASTER-Net observations report
- EP251229a: Global MASTER-Net observations report
- GRB 251222A/EP251222b: 1.6m Mephisto optical followup
- Fermi GRB 251228A: Global MASTER-Net observations report
- The EP-WXT trigger 01709250662 is likely a flaring star
- GRB 251228A: Fermi GBM Final Real-time Localization
- GRB 251226A: SVOM/GRM observation
- GRB 251226A: GECAM-B detection
- SVOM GRB251227.07: Global MASTER-Net observations report
- IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
- The EP-WXT trigger 01709250617 is likely a flaring star
- IceCube Alert 251225.84: Global MASTER-Net observations report
- IceCube-251225A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 251222A: NUTTelA-TAO Early Measurements
- GRB 251222A/EP251222b: Optical detection with Kinder observations
- GRB 251221A: Swift-BAT refined analysis
- GRB 251129A / EP251129a: VLA detection of a radio counterpart
- EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
- GRB 251222A: Continued 1.3m DFOT optical observation
- EP251220a: 3.6m DOT optical afterglow detection
- GRB 251222A: Fermi GBM Observation
- EP251222a: Global MASTER-Net observations report
- EP251222a: refined analysis of the EP-WXT and EP-FXT observations
- EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
- Konus-Wind detection of GRB 251222A / EP251222b
- GRB 251222A / EP251222b: LCO detection of the optical counterpart
- EP251222a: GOTO optical upper limit
- GRB 251222A / EP251222b: LCO optical observations
- GRB 251222A: 1.3m DFOT optical detection
- GRB251221A: 7DT optical upper limits
- GRB 251222A / EP251222b: SVOM/VT optical rebrightening
- EP251222b/GRB 251222A: SVOM/GRM observation
- EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
- The EP-WXT trigger 01709250397 is likely a flaring star
- EP251221a: Global MASTER-Net observations report
- EP251221a: NOT optical upper limit
- GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
- GRB 251222A: NOT optical observations