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"15252 results found.
- Swift Trigger 1439093: is probably not GRB 260113A
- GRB 260111A: GECAM-B observation of a burst
- GRB 260111A: Fermi GBM Observation
- GRB 260111A: Swift ToO observations
- GRB 251230A: Mondy Optical Observations
- GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
- EP260110a: SVOM/VT optical upper limits
- IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
- EP260110a: KAIT optical upper limit
- EP 260110a: COLIBRÍ optical observations
- EP260110a: BOOTES-5/JGU optical upper limit
- GRB 260102A: Swift-XRT afterglow detection
- GRB 260105B: Fermi GBM Detection
- GRB 260105A: SVOM/GRM observation
- GRB 260105B: SVOM/GRM observation
- EP260105a: SVOM/VT optical upperlimit
- FRB 20251229A: A potentially hyperactive repeating fast radio burst source
- EP260105a: LCO Optical Upper limit
- EP260104a: Einstein Probe detection of a fast X-ray transient
- GRB 260103A: Insight-HXMT/HE detection
- GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
- GRB 260103A: GECAM-B observation of a burst
- GRB 260103A: SVOM/GRM observation of a possible GRB
- Fermi-LAT Gamma-ray Observations of IceCube-251225A
- GRB 260102A: EP-FXT follow-up observation
- GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
- GRB 251230A / EP251230a: GECAM-B detection
- GRB 251230A / EP251230a: Insight-HXMT/HE detection
- GRB 260102A: Swift ToO observations
- GRB 260101A: Fermi GBM Observation
- GRB 260102A: SVOM detection of a burst
- GRB 260101A: GECAM-B detection
- GRB 260101A: NOT spectroscopic observations
- GRB 260101A: SVOM/GRM observation
- GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
- GRB 251230A: GRANDMA/TAROT Early Detection
- GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
- GRB 251230A/EP251230a: Optical upper limit with Kinder observations
- EP251229a: BOOTES-2 early optical upper limit
- GRB 251230A: Early optical counterpart detection by LCO.
- EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
- LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
- The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
- GRB 251222A/EP251222b: 1.6m Mephisto optical followup
- GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
- GRB 251226A: SVOM/GRM observation
- GRB 251226A: GECAM-B detection
- IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
- 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 251205A: Kilonova-Catcher optical afterglow detection
- GRB 251222A: AbAO optical observations
- GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
- GRB 251129A / EP251129a: VLA detection of a radio counterpart
- GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
- GRB 251222A: Fermi GBM Observation
- EP251220a: CrAO ZTSh optical observations
- GRB 251222A / EP251222b: GECAM-B observation
- Konus-Wind detection of GRB 251222A / EP251222b
- GRB 251222A / EP251222b: LCO detection of the optical counterpart
- EP251222a: NTT/ULTRACAM optical observations
- GRB 251222A / EP251222b: LCO optical observations
- EP251222b/GRB 251222A: SVOM/GRM observation
- GRB 251222A: PRIME near-infrared detection
- GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
- IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
- GRB 251222A: Swift ToO observations
- GRB 251222A: SVOM detection of a long burst
- EP251220a: PRIME upper limit
- EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
- GRB 251221A: PRIME near-infrared observation
- GRB 251221A: UAFO and Mondy optical upper limit
- GRB 251221A: Fermi GBM Observation
- GRB 251220B: SVOM/GRM observation of a short burst
- GRB 251221A: COLIBRÍ detection of the optical counterpart
- GRB 251219A: SVOM/GRM observation of a short burst
- GRB 251219A: GECAM-B detection of a possible magnetar X-ray burst from SGR 1830-0645
- Fermi-LAT Gamma-ray Observations of IceCube-251218A
- GRB 251215A: Swift-XRT afterglow detection
- IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
- IceCube-251218A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 251214B: VIRT Optical Upper Limit
- GRB 251202A/EP251202a: Koshka optical upper limit
- GRB 251214B: Mondy optical upper limit
- GRB 251215A: COLIBRÍ optical upper limit
- EP251214b: KAIT optical upper limit
- GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
- GRB 251215A: Glowbug gamma-ray detection
- GRB 251214B: UAFO optical upper limit
- GRB 251213A: GRID-10B observation
- GRB 251214B: AbAO optical observations
- GRB 251209A: GECAM-B observation of a long burst
- GRB 251214D: GECAM-B observation of a long burst
- GRB 251214B: Fermi GBM Observation
- GRB 251209A: Insight-HXMT/HE detection
- GRB 251215A: Swift ToO observations
- GRID detection of GRB 251213A
- GRB 251203B: AbAO optical observations
- GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst