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"39059 results found.
- GRB 260727A: Liverpool Telescope optical upper limits
- GRB 260728A: Fermi GBM Final Localization
- GRB 260727A: EP/FXT follow-up observations
- 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
- 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 260727B: Fermi GBM Final Real-time Localization
- Fermi GRB 260726A: Global MASTER-Net observations report
- GRB 260727A: SVOM detection of a bright long burst
- GRB 260726A: SVOM detection of a burst
- GRB 260726A: Fermi GBM Final Real-time Localization
- GRB 260616A: cubesat Avion detection
- GRB 260602B: cubesat Avion detection
- GRB 260601A: cubesat Avion detection
- IPN triangulation of GRB 260706B
- GRB 260718A: SVOM/ECLAIRs refined analysis
- Fermi Gamma-ray Burst Monitor trigger 806592752 / 260724564 is not a GRB
- EP260723a: COLIBRÍ optical observations
- GRB 260723A: Fermi GBM Final Localization
- IceCube Alert 260722A: Global MASTER-Net observations report
- Konus-Wind detection of GRB 260721A
- GRB 260722A: Fermi GBM Final Real-time Localization
- IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
- Fermi GBM trigger 806384210/260722151 is not a GRB
- 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
- Fermi trigger No 806104130: Global MASTER-Net observations report
- Fermi GRB 260718A: Global MASTER-Net observations report
- 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 260310A / AT2026fgk: Late-time Chandra Detection
- GRB 260714B: GECAM-B observation of a burst
- GRB 260618B: EP-FXT follow-up observation upper limit
- GRB 260714B: COLIBRÍ optical counterpart candidate
- SVOM sb26071506: Global MASTER-Net observations report
- sb26071506: SVOM detection of a X-ray transient
- GRB 260715A: Fermi GBM Final Real-time Localization
- 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 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
- GRB 260714B: Fermi GBM Final Real-time Localization
- GRB 260706A: ATCA detection of possible radio counterpart
- GRB 260705A: ATCA radio observations
- GRB 260714A: Fermi GBM Final Real-time Localization
- 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
- EP260623a: KAIT optical observations
- GRB 260708A: GRANDMA Optical Observations
- Fermi-LAT Gamma-ray Observations of IceCube-260708A
- GRB 260710A: Insight-HXMT/HE detection
- Fermi-LAT Gamma-ray Observations of IceCube-260704A
- IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 260708A: LCO optical observations
- GRB 260710A: Fermi GBM Detection
- GRB 260709A: SVOM/GRM detection
- GRB 260709A: GECAM-B observation
- GRB 260705C: AstroSat CZTI detection
- GRB 260710A: Fermi GBM Final Real-time Localization
- 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
- GRB 260708A: Fermi-GBM observation
- Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
- IceCube Alert 260709A: Global MASTER-Net observations report
- GRB 260709A: Fermi GBM Final Real-time Localization
- IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
- LAT GRB260708.42: Global MASTER-Net observations report
- GRB 260708A: Fermi-LAT detection
- GRB 260705B: SVOM/GRM observation
- GRB 260708A: Fermi-GBM detection
- GRB 260706A: Further EP-FXT follow-up observation
- GRB 260706A: SVOM/VT optical upper limits
- EP260707a (by EP-FXT): NOT optical upper limit
- EP260707a: TRT optical upper limit
- Fermi GBM trigger 805087514/260707142 (GRB 260707A) is not a GRB
- GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B