GCN Circulars
GCN Circulars are rapid bulletins submitted by and distributed to the community. See the documentation for help with subscribing to or submitting Circulars.
Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
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"- EP260731a: NOT optical upper limit
- GRB 260730B: NuSTAR detection of prompt emission
- EP260731a: Einstein Probe detection of an X-ray transient
- GRB 260727A: SVOM/ECLAIRs refined analysis
- GRB 260726A: SVOM/ECLAIRs refined analysis
- GRB260730A: Fermi GBM Final Localization
- EP260728a: COLIBRÍ optical upper limit
- EP260727a: VLT/X-shooter spectroscopic redshift z = 2.817
- The EP-WXT trigger 01709277130 (EP260729a): refined EP-WXT analysis and association with a flaring star
- EP 260729a: Ondrejov D50 optical detection supports stellar flare origin
- EP260729a: Einstein Probe detection of an X-ray transient
- EP260727a: SAO RAS optical observations
- GRB 260727A: AbAO and SAO RAS optical observations
- EP260728a: EP-FXT follow-up observation
- GRB 260726A: EP-FXT follow-up observations
- EP260728a: Einstein Probe detection of a fast X-ray transient
- GRB 260727A: SVOM/GRM observation
- GRB 260726A: Fermi GBM Observation
- EP260727a: 1.5m OSN optical counterpart detection
- EP260727a:refined analysis of the EP-WXT and EP-FXT observation
- EP260727a: OHP/T193 optical observations
- Konus-Wind detection of GRB 260727A
- GRB 260726A: Liverpool Telescope optical observations
- GRB 260727A: Liverpool Telescope optical upper limits
- EP260727a: Liverpool Telescope confirmation of optical counterpart
- EP260727a: NUTTELA-TAO Early Optical Limits
- GRB 260728A: Fermi GBM Final Localization
- GRB 260727A: EP/FXT follow-up observations
- EP260727a: Einstein Probe detection of an X-ray transient
- The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
- 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 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
- 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
- Fermi Gamma-ray Burst Monitor trigger 806592752 / 260724564 is not a GRB
- EP260723a: SVOM/VT optical observation
- EP260723a: COLIBRÍ optical observations
- EP260723a: NOT optical conterpart confirmation
- EP260723a: Liverpool Telescope likely optical counterpart
- EP260723a: EP-WXT detection of a fast X-ray transient
- GRB 260723A: Fermi GBM Final Localization
- IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
- IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
- 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
- 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)
- GRB 260715A: Fermi GBM Final Real-time Localization
- EP260703a: SVOM/ECLAIRs Upper Limit
- GRB 260710A: AstroSat CZTI detection
- GRB 260709A: AstroSat CZTI detection