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"- EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
- EP260416a: NOT tentative spectroscopic redshift of z =1.909
- GRB 260418A: Fermi GBM Final Real-time Localization
- EP260416a: GMG Optical Observation
- Fermi GRB 260417A: Global MASTER-Net observations report
- Konus-Wind detection of GRB 260411B
- GRB 260417B: Fermi GBM Final Real-time Localization
- GRB 260417A: AstroSat CZTI detection
- IPN triangulation of GRB 260411B
- EP260416a: LCO observations confirm end of flaring phase
- EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
- EP260417a: TRT optical counterpart detection
- EP260417a: Einstein Probe detection of an X-ray transient
- EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
- EP260417b: Einstein Probe detection of a fast X-ray transient
- EP-WXT trigger 01709259586: KAIT optical observations
- EP260416a: KAIT optical upper limit
- GRB 260414A: Insight-HXMT/HE detection
- EP260416a: COLIBRÍ confirmation of the optical rebrightening
- EP260416a: WFST optical observations and rebrightening
- GRB 260417A: Fermi GBM Final Real-time Localization
- GOTO26djh/AT2026jpw: ZTSh R,I bands observations of the transient
- EP260416a: SVOM/VT optical observation
- GOTO26djh/AT2026jpw: SVOM/VT optical observation
- GRB 260415B: Glowbug gamma-ray detection
- GRB 260411B: Glowbug gamma-ray detection
- GRB 260415A: Insight-HXMT/HE detection
- EP260416a: COLIBRÍ optical counterpart candidate
- COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
- EP260416a: Global MASTER-Net observations report
- EP260416a: Einstein Probe detection of an X-ray transient
- GOTO26djh/AT2026jpw : MASTER OT observation
- GOTO26djh/AT2026jpw: EP-FXT X-ray counterpart detection
- GOTO26djh/AT2026jpw transient: SAO RAS optical observations
- NOT r-band observations of the transient GOTO26djh/AT2026jpw
- GRB 260415B: NuSTAR detection of long prompt emission
- GOTO discovery of fast-fading transient GOTO26djh/AT2026jpw, a candidate orphan afterglow
- GRB 260415B: Fermi GBM Final Localization
- GRB 260415A: Fermi GBM Final Real-time Localization
- Fermi trigger No 797912738: Global MASTER-Net observations report
- GRB 260414A: Glowbug gamma-ray detection
- EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
- EP260321a: CMO SAI J,K observations
- GRB 260412A: Insight-HXMT/HE detection
- GRB 260414A: Fermi GBM Final Real-time Localization
- The EP-WXT trigger 01709260122 is likely a flaring star
- Fermi GRB 260413A: Global MASTER-Net observations report
- GRB 260410A: Glowbug gamma-ray detection of a short burst
- GRB 260413A: Fermi GBM Final Real-time Localization
- GRB 260410B: Insight-HXMT/HE detection
- GRB 260410A: Insight-HXMT/HE detection
- Konus-Wind detection of GRB 260410A (short/hard)
- GRB 260411B: GECAM-B observation of a long burst
- EP260321a: SVOM/VT optical observations and color changes around peak
- GRB 260410A: CALET Gamma-Ray Burst Monitor detection
- The EP-WXT trigger 01709260010 is likely a flaring star
- GRB 260412A: GECAM-B observation of a long burst
- Fermi GRB 260412A: Global MASTER-Net observations report
- GRB 260412A: Fermi GBM Observation
- GRB 260310A / AT2026fgk: NuSTAR detection of the rebrightening
- GRB 260411B: Fermi-LAT detection
- GRB 260412A: SVOM detection of a long burst
- GRB 260412A: Fermi GBM Final Real-time Localization
- GRB 260411B: COLIBRÍ optical observations
- GRB 260410B: Fermi GBM Observation
- GRB 260411B: Ondrejov D50 optical afterglow detection
- GRB260411B: 3.6m DOT optical observation
- GRB 260411A: SVOM/GRM observation
- GRB 260407B: SVOM/GRM detection of a possible magnetar X-ray burst
- GRB 260411B: SVOM/GRM observation of a long burst
- GRB 260409A: Insight-HXMT/HE detection
- GRB 260411B: Fermi GBM Detection
- GRB 260411B: GOTO optical counterpart candidate
- EP260409a: Gemini/FLAMINGOS2 J-band counterpart
- GRB 260411B: BALROG localization (Fermi Trigger 797587480 / GRB 260411337)
- GRB 260411B: Fermi GBM Final Real-time Localization
- GRB 260411A: Fermi GBM Final Real-time Localization
- GRB 260410A: COLIBRÍ optical upper limit
- EP-WXT01709259790: Optical Upper limits with kinder observations
- GRB 260410A: Fermi GBM Observation
- GRB 260410B: SVOM/GRM detection of a short faint burst
- The EP-WXT trigger 01709259790 is likely a flaring star
- GRB 260410B: Fermi GBM Final Real-time Localization
- EP-WXT01709259790: Xinglong optical upper limit
- GRB 260410A: Fermi-LAT detection
- GRB 260410A: Fermi GBM Final Real-time Localization
- EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
- EP260321a: Chandra X-ray Non-detection
- GRB 260409A: Fermi GBM Final Real-time Localization
- GRB 260310A/AT2026fgk: Kilonova-Catcher SN peak identification
- The EP-WXT trigger 01709259773 is likely a flaring star
- GRB 260407A: GECAM-A detection
- GRB 260407A: Insight-HXMT/HE detection
- EP260409a: SVOM/VT optical upper limits
- EP260409a: COLIBRÍ optical upper limits
- GRB 260407A: CALET Gamma-Ray Burst Monitor detection
- EP260409a: Global MASTER-Net observations report
- EP260409a: Einstein Probe detection of an X-ray transient
- EP260321a: VLA radio detection
- GRB 260404A: Fermi GBM Final Localization