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"- 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
- 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
- Konus-Wind detection of GRB 250201A
- IPN triangulation of GRB 250201A
- LIGO/Virgo/KAGRA S250205bk: Updated Sky localization
- Konus-Wind detection of GRB 250202B
- 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 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
- 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 250202C: GRBAlpha detection
- GRB 250202B: Fermi GBM Detection
- IceCube-250203A - IceCube observation of a high-energy neutrino candidate track-like event
- 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
- The EP-WXT trigger 01709131196 is likely a flaring star
- GRB 250202C: Fermi GBM Final Real-time Localization
- LIGO/Virgo/KAGRA S250202cu: Identification of a GW compact binary merger candidate
- GRB 250129A: SVOM/C-GFT optical observations
- The EP-WXT trigger 01709131153 is not a real source
- GRB 250202B: AstroSat CZTI detection of a bright long GRB
- LIGO/Virgo/KAGRA S250202ad: Retraction of GW compact binary merger candidate
- 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
- LIGO/Virgo/KAGRA S250201i: Coverage and upper limits from MAXI/GSC observations
- GRB 250129A: Skynet Continued Optical 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: 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
- Ep250125A: 1.3m DFOT optical 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
- 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
- Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
- GRB 250129A: LCO optical observations
- GRB 250129A: NOT optical observations and redshift confirmation
- GRB 250129A: GOTO optical observations show brightening afterglow
- GRB 250129A: VLT/X-shooter redshift of z = 2.151
- Swift GRB 250129A: Global MASTER-Net observations report
- GRB 250128B: Enhanced Swift-XRT position
- The EP-WXT trigger 01709131085 is likely a flaring star
- Fermi GRB 250128B: Global MASTER-Net observations report