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"26301 results found.
- GRB 260727A: Glowbug gamma-ray detection
- GRB 260726A: J-band upper limit with WINTER
- GRB 260727A: J-band upper limit with WINTER
- GRB 260726A: SVOM/VT optical candidate
- GRB 260726A: SVOM ECLAIRs improved position and MXT possible detection of a counterpart
- GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
- EP260723a: SVOM/ECLAIRs Upper Limit
- GRB 260727A: GOTO early optical upper limit
- GRB 260727A: AstroSat CZTI detection
- GRB 260727A: Kilonova-Catcher optical upper limit
- GRB 260727A: LCO optical upper limits
- GRB 260727A: SVOM detection of a bright long burst
- GRB 260726A: SVOM detection of a burst
- IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
- EP260723a: further EP-FXT follow-up observation
- EP260725a: EP-FXT follow-up observation and association with a bright flaring star
- EP260725a: EP-WXT detection of an X-ray transient
- GRB 260616A: cubesat Avion detection
- EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
- GRB 260602B: cubesat Avion detection
- GRB 260601A: cubesat Avion detection
- EP260723a: EP-FXT follow-up observation
- IPN triangulation of GRB 260706B
- GRB 260718A: SVOM/ECLAIRs refined analysis
- EP260723a: SVOM/VT optical observation
- EP260723a: COLIBRÍ optical observations
- EP260723a: NOT optical conterpart confirmation
- EP260723a: EP-WXT detection of a fast X-ray transient
- IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
- Konus-Wind detection of GRB 260721A
- IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 260721A: NuSTAR detection of prompt emission
- Konus-Wind detection of GRB 260714B
- SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
- GRB 260705A: Retraction of optical counterpart
- GRB 260714B: Insight-HXMT/HE detection
- GRB 260718A: EP-FXT follow-up observation
- GRB 260718A: LCO optical upper limits
- GRB 260711A: SVOM/GRM observation
- GRB 260710A: SVOM/GRM observation
- GRB 260718A: Fermi GBM Observation
- GRB 260718A : GRANDMA and KNC upper limits
- GRB 260718A: SVOM/VT optical upper limits
- GRB 260718A: SVOM/VT optical upper limits from VHF data
- GRB 260718A: SVOM detection of a burst
- GRB 260714B: SVOM/GRM observation
- GRB 260714B: GECAM-B observation of a burst
- GRB 260618B: EP-FXT follow-up observation upper limit
- GRB 260714B: COLIBRÍ optical counterpart candidate
- IceCube-260708A: Follow-up studies of cosmic-ray origin of high-energy neutrino alert
- SVOM sb26071506: Global MASTER-Net observations report
- sb26071506: SVOM detection of a X-ray transient
- IceCube-260712A: No candidates with the Zwicky Transient Facility (ZTF)
- EP260703a: SVOM/ECLAIRs Upper Limit
- GRB 260710A: AstroSat CZTI detection
- GRB 260709A: AstroSat CZTI detection
- GRB 260714B: AstroSat CZTI detection
- GRB 260714B: Fermi-LAT detection
- GRB 260714B: Fermi GBM Detection
- GRB 260706A: ATCA detection of possible radio counterpart
- GRB 260705A: ATCA radio observations
- EP260713a: Einstein Probe detection of an X-ray transient
- GRB 260619A: SVOM/VT continuous optical observations
- GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
- GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
- GRB 260708A: GRANDMA Optical Observations
- Fermi-LAT Gamma-ray Observations of IceCube-260708A
- GRB 260710A: Insight-HXMT/HE detection
- IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 260708A: LCO optical observations
- EP260711a: Einstein Probe detection of an X-ray transient
- GRB 260710A: Fermi GBM Detection
- GRB 260709A: SVOM/GRM detection
- GRB 260709A: GECAM-B observation
- IceCube-260708A: Observations with the Vera C. Rubin Observatory
- EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
- GRB 260705C: AstroSat CZTI detection
- GRB 260708A: Glowbug gamma-ray detection
- GRB 260704A: SVOM/ECLAIRs refined analysis
- GRB 260706A : GRANDMA Upper limits
- GRB 260708A: Kilonova-Catcher optical afterglow detection
- GRB 260708A: GECAM-B observation of a burst
- IceCube-260708A: One candidate from the Zwicky Transient Facility
- GRB 260708A: Fermi-GBM observation
- Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
- IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 260708A: Fermi-LAT detection
- GRB 260705B: SVOM/GRM observation
- GRB 260706A: Further EP-FXT follow-up observation
- GRB 260706A: SVOM/VT optical upper limits
- EP260707a (by EP-FXT): NOT optical upper limit
- EP260707a is not a real source
- EP260707a: TRT optical upper limit
- EP260707a: Einstein Probe detection of an X-ray transient
- Nova AT2026oyp (ASASSN-26dt): Pre-outburst Swift UVOT observation
- GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
- GRB 260705C: Glowbug gamma-ray detection of a short burst
- GRB 260706A: SVOM/ECLAIRs refined analysis
- GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
- GRB 260706A: SVOM/GRM observation