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.
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').
32054 results found.
- GRB 250204B: GRBAlpha detection
- GRB 250204A: GRBAlpha detection
- GRB 250207A: 1.3m DFOT Optical observations
- GRB 250206A: Swift-XRT observations
- GRB 250129A: GRANDMA Continued Afterglow Detection
- GRB 250207A: Swift-BAT refined analysis
- GRB 250205A: 1.3m DFOT optical upper limit
- GRB 250206A: Tiled Swift observations
- GRB 250206A: EIRSAT-1 GMOD Detection
- GRB 250206A: Fermi-LAT detection
- GRB 250207B: Swift-XRT observations
- GRB 250208A: Fermi GBM Final Real-time Localization
- GRB 250207A: Swift-XRT refined Analysis
- GRB 250207A: Enhanced Swift-XRT position
- GRB 250129A: ABObservatory SLOAN r’ afterglow detection
- GRB 250207A: REM IR afterglow detection
- GRB 250207A: FRAM-Auger optical detection
- GRB 250207B: Tiled Swift observations
- Konus-Wind detection of GRB 250204B
- GRB 250207A: REM optical afterglow detection
- GRB 250207A: Swift/UVOT Detection
- LIGO/Virgo/KAGRA S250206dm: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- GRB 250129A: Continued AbAO and Mondy optical observations
- GRB 250207B: MAXI/GSC detection
- GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
- LIGO/Virgo/KAGRA S250206dm: Upper limits from Fermi-GBM Observations
- GRB 250207A: Swift detection of a burst with optical counterpart
- GRB 250207A: Fermi GBM Final Real-time Localization
- GRB 250206A: BALROG localization (Fermi Trigger 760564296 / GRB 250206827)
- GRB 250206A: Fermi GBM Final Real-time Localization
- GRB 250205A: Fermi GBM Observation
- GRB 250205A: REM NIR upper limit
- EP250205a/GRB 250205A: FTW optical and NIR observations of the counterpart
- GRB 250205A: Swift/UVOT Upper Limits
- EP250205a/GRB 250205A: correction to the source localization
- 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: GOTO optical upper limits
- GRB 250205A: OHP/T193 optical counterpart candidate
- GRB 250205A: Liverpool Telescope optical counterpart candidate detection
- GRB 250205A: SVOM detection of a burst
- Konus-Wind detection of GRB 250201A
- IPN triangulation of GRB 250201A
- Konus-Wind detection of GRB 250202B
- 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
- GRB 250204B: AstroSat CZTI detection of a short burst
- GRB 250204B: Fermi GBM Final Localization
- GRB 250129A: LCO late afterglow detection
- GRB 250129A: AbAO AS-32 and Mondy AZT-33IK optical observations
- GRB 250204A: Fermi GBM Final Real-time Localization
- GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
- GRB 250202B: NuSTAR detection of the prompt emission
- GRB 250202C: GRBAlpha detection
- 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
- GRB 250202C: Fermi GBM Final Real-time Localization
- GRB 250129A: SVOM/C-GFT optical observations
- GRB 250202B: AstroSat CZTI detection of a bright long GRB
- GRB 250202B: Fermi GBM Final Real-time Localization
- Swift GRB250129A: MASTER 4 days observations report
- GRB 250202A: Fermi GBM Final Real-time Localization
- GRB 250201A: INTEGRAL SPI/ACS detection
- Konus-Wind detection of GRB 250129A
- GRB 250129A: 1.3m DFOT Optical observations
- GRB 250129A: Liverpool Telescope observations suggest continued engine activity
- GRB 250201A: BALROG localization (Fermi Trigger 760096791 / GRB 250201417)
- GRB 250201A: Fermi GBM Final Real-time Localization
- GRB 250129A: Skynet Continued Optical Observations
- GRB 250129A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations
- GRB 250129A: SAO RAS optical observations
- GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow
- GRB 250129A: optical photometry from Konkoly
- GRB 250129A: COLIBRÍ Optical Observations
- GRB 250128B: VLA possible radio detection
- GRB 250129A: continued KAIT observations indicating steep decay after 28.5h
- GRB 250129A: iTelescope optical observation
- GRB 250129A: NOT optical observations of continuining activity
- 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 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
- GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
- GRB 250128B: VLA radio upper limit
- GRB 250129A: Skynet optical observations
- GRB 250129A: KAIT optical observations of the rebrightening around 5.1 hours
- GRB 250129A: Swift-XRT refined Analysis
- GRB 250128B: Gemini-North optical extended source detection
- The EP-WXT trigger 01709131085: KAIT confirmation of the stellar flare
- GRB 250128B: TNG optical upper limit