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').
23965 results found.
- GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
- LIGO/Virgo/KAGRA S250206dm: Updated-6 NED Galaxies in the Localization Volume
- LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
- LIGO/Virgo/KAGRA S250206dm: Upper limits from Fermi-GBM Observations
- GRB 250207A: Swift detection of a burst with optical counterpart
- Fermi-LAT Gamma-ray Observations of IceCube-250203A
- LIGO/Virgo/KAGRA S250206dm: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
- LIGO/Virgo/KAGRA S250206dm: Updated NED Galaxies in the Localization Volume
- LIGO/Virgo/KAGRA S250206dm: Two counterpart neutrino candidates from IceCube neutrino searches
- LIGO/Virgo/KAGRA S250206dm: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250206dm: NED Galaxies in the Localization Volume
- GRB 250206A: BALROG localization (Fermi Trigger 760564296 / GRB 250206827)
- GRB 250205A: Fermi GBM Observation
- GRB 250205A: REM NIR upper limit
- GRB 250205A: Swift/UVOT Upper Limits
- LIGO/Virgo/KAGRA S250205ee: Updated Sky localization and Source Classification
- EP250205a/GRB 250205A: Einstein Probe observation
- GRB 250127C: SVOM/GRM observation of a burst
- GRB 250204B: SVOM/GRM observation of a likely short burst
- GRB 250205A: COLIBRÍ/DDRAGO Optical Afterglow Detection
- GRB 250205A: Swift/XRT detection
- GRB 250205A: Redshift from OSIRIS+/GTC z = 3.55
- GRB250205A: SVOM/VT optical afterglow detection
- GRB 250205A: OHP/T193 optical counterpart candidate
- LIGO/Virgo/KAGRA S250205ee: Identification of a GW compact binary merger candidate
- GRB 250205A: SVOM detection of a burst
- LIGO/Virgo/KAGRA S250205bk: NED Galaxies in the Localization Volume
- IPN triangulation of GRB 250201A
- LIGO/Virgo/KAGRA S250205bk: Updated Sky localization
- LIGO/Virgo/KAGRA S250205bk: Identification of a GW compact binary merger candidate
- GRB 250129A: Swift-BAT refined analysis
- EP 250108A: Upper limits from Fermi-GBM Observations
- IPN triangulation of GRB 250204B (short/hard)
- IPN triangulation of GRB 250202B
- LIGO/Virgo/KAGRA S250204ax: Updated Sky localization
- GRB 250204B: AstroSat CZTI detection of a short burst
- GRB 250129A: LCO late afterglow detection
- GRB 250129A: AbAO AS-32 and Mondy AZT-33IK optical observations
- LIGO/Virgo/KAGRA S250204ax: Identification of a GW compact binary merger candidate
- GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
- GRB 250202B: NuSTAR detection of the prompt emission
- GRB 250202B: Fermi GBM Detection
- GRB 250129a: Liverpool Telescope optical follow-up
- GRB 240129A: further SAO RAS optical observations
- GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
- LIGO/Virgo/KAGRA S250202cu: Updated Sky localization
- LIGO/Virgo/KAGRA S250202cu: Identification of a GW compact binary merger candidate
- GRB 250129A: SVOM/C-GFT optical observations
- GRB 250202B: AstroSat CZTI detection of a bright long GRB
- Swift GRB250129A: MASTER 4 days observations report
- GRB 250129A: 1.3m DFOT Optical observations
- GRB 250201A: BALROG localization (Fermi Trigger 760096791 / GRB 250201417)
- GRB 250201A: Fermi GBM Final Real-time Localization
- LIGO/Virgo/KAGRA S250201i: Coverage and upper limits from MAXI/GSC observations
- GRB 250129A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations
- EP250108A / SN 2025kg: Upper limits from a neutrino search with IceCube
- GRB 250129A: SAO RAS optical observations
- GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow
- GRB 250129A: COLIBRÍ Optical Observations
- GRB 250129A: iTelescope optical observation
- GRB 250129a: Liverpool Telescope optical follow-up
- GRB 250129A: TNG NIR afterglow detection
- GRB 250129A: AKO Optical Afterglow Detection
- GRB 250129A: GRANDMA/TAROT optical afterglow detection
- GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
- GRB 250128B: VLA radio upper limit
- Ep250125A: 1.3m DFOT optical upper limit
- GRB 250129A: Skynet optical observations
- GRB 250129A: Swift-XRT refined Analysis
- GRB 250128B: Gemini-North optical extended source detection
- GRB 250128B: TNG optical upper limit
- GRB 250129A: Swift/UVOT Detection
- GRB 250128B: VLT/HAWKI near-infrared observations
- GRB 250127A: CrAO and Terskol optical upper limits
- GRB 250129A: Enhanced Swift-XRT position
- GRB 250128B: NOT optical upper limit
- GRB 250128B: VLT/FORS2 optical observations
- GRB 250129A: REM optical/NIR afterglow detection
- GRB 250129A: OHP/T193 optical and spectroscopy observations
- GRB 250129A: Early afterglow detection by LCO.
- GRB 250128B: OHP/T193 optical upper limit
- GRB 250129A: LCO optical observations
- GRB 250128B: Enhanced Swift-XRT position
- GRB 250129A: Swift detection of a burst with an optical counterpart
- Swift GRB 250129A: Global MASTER-Net OT detection
- GRB 250128B: Swift-XRT refined Analysis
- GRB 250128B: GOTO optical upper limit
- EP250125a: Upper limits from Swift/BAT-GUANO
- GRB 250128B: LCO optical observations
- GRB 250128B: Swift detection of a short burst
- GRB 250127A: Swift-XRT observations
- GRB 250127B: DDOTI Upper Limit on the Afterglow
- Fermi-LAT Gamma-ray Observations of IceCube-250102A
- Fermi GRB 250128A: Global MASTER-Net observations report
- GRB 250117A: Fermi GBM Observation
- Fermi-LAT Gamma-ray Observations of IceCube-250101A
- IPN triangulation of GRB 250119C
- GRB 250127A: LCO optical upper limit
- GRB 241223A: cubesat Avion detection