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"15246 results found.
- EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
- Konus-Wind detection of GRB 260411B
- GRB 260417A: AstroSat CZTI detection
- IPN triangulation of GRB 260411B
- EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
- EP260416a: KAIT optical upper limit
- GRB 260414A: Insight-HXMT/HE detection
- EP260416a: COLIBRÍ confirmation of the optical rebrightening
- EP260416a: WFST optical observations and rebrightening
- EP260416a: SVOM/VT optical observation
- GRB 260411B: Glowbug gamma-ray detection
- GRB 260415A: Insight-HXMT/HE detection
- COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
- GOTO26djh/AT2026jpw: EP-FXT X-ray counterpart detection
- GOTO discovery of fast-fading transient GOTO26djh/AT2026jpw, a candidate orphan afterglow
- 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 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
- GRB 260412A: GECAM-B observation of a long burst
- 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 260411B: COLIBRÍ optical observations
- GRB 260410B: Fermi GBM 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
- EP260409a: Gemini/FLAMINGOS2 J-band counterpart
- EP-WXT01709259790: Optical Upper limits with kinder observations
- GRB 260410A: Fermi GBM Observation
- GRB 260410B: SVOM/GRM detection of a short faint burst
- GRB 260410A: Fermi-LAT detection
- GRB 260407A: GECAM-A detection
- GRB 260407A: Insight-HXMT/HE detection
- GRB 260402A: SVOM/ECLAIRs refined analysis
- GRB 260310A / AT2026fgk: X-ray rebrightening
- EP260402a / GRB 260402A: Mephisto optical upper limits
- EP260403a: Mephisto optical upper limits
- GRID detection of GRB 260401A
- GRB 260403A: GECAM-B observation of a long burst
- EP260324A / AT 2026hir: COLIBRÍ further optical observations
- GRB 260330B: SVOM/ECLAIRs refined analysis
- EP260403a: LCO optical observations of the counterpart
- GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
- EP260403a: LCO optical counterpart detection
- GRB 260403A: AstroSat CZTI detection
- GRB 260402B: GECAM-B observation
- EP260402a/GRB 260402A: Jinshan near-infrared upper limit
- GRB 260402C: AstroSat CZTI detection of a long burst
- EP260324A / AT 2026hir: COLIBRÍ optical observations
- GRB 260402A: WINTER J-band upper limit
- GRB260402A: GROWTH-India Telescope optical upper limit
- GRB 260401A: SVOM/GRM observation
- GRB 260401A: GECAM-B observation
- GRB 260402A: SVOM/MXT candidate X-ray afterglow
- GRB 260402A: SVOM detection of a burst
- GRB 260401A: Fermi GBM Observation
- EP260329b: Mondy and Assy-Turgen optical upper limits
- GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
- EP260329b: GOTO detection of optical counterpart
- Konus-Wind detection of GRB 260320A
- Konus-Wind detection of GRB 260316B
- GRB 260321A: SVOM/ECLAIRs refined analysis
- GRB 260310A: VLA Multi-frequency Radio Observations
- GRB 260330B: SVOM detection of a burst
- EP260324a / AT2026hir: g- and r-band optical follow-up with the PKU 60cm Telescope
- EP260329a: COLIBRÍ optical upper limit
- EP260329a: EP-FXT follow up observation
- GRB 260327A: Insight-HXMT/HE detection
- EP260329b: Optical follow-up with Kinder observations
- EP 260329b: COLIBRÍ optical observations
- EP260329a: Optical upper limit with Kinder observations
- EP260329b: LCO optical observations of the counterpart
- GRB 260326A: Insight-HXMT/HE detection
- EP260329b: Einstein Probe detection of an X-ray transient
- EP-WXT trigger 01709259209: TRT optical counterpart detection
- GRID detection of GRB 260326A
- EP260327a: refined analysis of the EP-WXT and autonomous EP-FXT observations
- GRB 260327A: AstroSat CZTI detection of a long burst
- EP260324a: GROWTH-India Telescope optical observation
- GRB 260310A / AT 2026fgk: COLIBRÍ photometric evidence of the emerging supernova
- GRB 260310A: OSIRIS+/GTC spectroscopic detection of the associated BL-Ic, SN 2026fgk
- EP260324a: ZTF discovery of the optical counterpart ZTF26aapviim/AT2026hir
- GRB 260310A / AT2026fgk: R- and I-band observations with the PKU 60 cm optical telescope
- GRB 260326A: Fermi GBM Detection
- EP260321a: Upper limits from a neutrino search with IceCube
- GRB 260310A/AT2026fgk: Kilonova-Catcher late optical afterglow detection at about 15 days post trigger time
- EP260321a: J-band observations by the SYSU 80 cm infrared telescope
- GRID detection of GRB 260320A
- GRB 260310A: LBT optical observations
- EP260321A: Mondy optical observations
- GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limits at the FXT positions