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"32479 results found.
- GRB 260809A: NOT optical observations
- GRB260809A: MAO/AZT-22 optical observations
- GRB260809A: OHP/T193 optical observations
- IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
- GRB 260809A: SVOM/VT optical counterpart
- EP260809a: J-band upper limit with WINTER
- GRB 260808B: J-band upper limit with WINTER
- GRB 260808B: SVOM/ECLAIRs refined analysis
- EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
- GRB 260808B: Liverpool Telescope optical observations
- GRB 260808B: NOT optical observations
- GRB 260808B: LCO optical observations
- GRB 260808A: NuSTAR detection of prompt emission
- EP260809a: COLIBRÍ optical observations
- EP260809a: LCO optical observation
- GRB260808B: OHP/T193 optical observations
- GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
- GRB 260808B: SVOM/VT optical afterglow confirmation
- GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
- GRB 260808B: SVOM/VT optical candidate from VHF data
- Fermi GRB 260808A: Global MASTER-Net observations report
- EP260806a: ZTF serendipitous detection of ZTF26abmjjnm / AT 2026yeh
- IceCube-260805A: One candidate from the Zwicky Transient Facility
- GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- IceCube-260807A - IceCube observation of a high-energy neutrino candidate track-like event
- EP260806a: COLIBRÍ optical observations
- EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
- EP260806a: SVOM/VT optical observation
- EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
- EP260806a: OSIRIS+/GTC redshift z=0.089
- EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
- EP260806a: LCO likely optical counterpart
- GRB 260715A: cubesat Avion detection
- GRB 260709A: cubesat Avion detection
- GRB 260708A: cubesat Avion detection
- SN 2026stf / GRB 260708A: ATLAS forced photometry
- IceCube-260805A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 260730B: Glowbug gamma-ray detection
- GRB 260805B: Glowbug gamma-ray detection
- Fermi GRB 260805A: Global MASTER-Net observations report
- GRB 260804A: Glowbug gamma-ray detection
- GRB 260730B: CALET Gamma-Ray Burst Monitor detection
- GRB 260708A / SN 2026stf: Spectroscopic host redshift z = 0.055 and confirmation of an associated type Ic-BL supernova
- GRB 260708A: LCO further optical observations show supernova features
- Fermi GRB 260802B: Global MASTER-Net observations report
- GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
- GRB 260802A / EP J223759.5+531421: SVOM/VT optical upper limit
- GRB 260802A: SVOM/VT optical upper limits from VHF data
- GRB 260802A: LCO optical upper limits
- GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 260727A: EP-FXT further follow-up observations and candidate afterglow
- GRB 260618B: SVOM/VT continued optical observations indicated a steeper and redder decay
- Fermi-LAT Gamma-ray Observations of IceCube-260722A
- GRB 260730B: AstroSat CZTI detection
- EP260731a: COLIBRÍ optical upper limit
- EP260731a: NOT optical upper limit
- GRB 260730B: NuSTAR detection of prompt emission
- GRB 260727A: SVOM/ECLAIRs refined analysis
- GRB 260726A: SVOM/ECLAIRs refined analysis
- 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
- 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
- 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 260727A: EP/FXT follow-up observations
- EP260727a: Einstein Probe detection of an X-ray transient
- 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
- Fermi GRB 260726A: Global MASTER-Net observations report
- 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
- 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