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').
- LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the DDOTI optical candidates
- GRB 250208A: Fermi GBM Final Real-time Localization
- EP250207a: EP-WXT detection and XRT follow-up observation
- LIGO/Virgo/KAGRA S250208ad: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250206dm: MMT galaxy targeted observations
- GRB 250207A: Swift-XRT refined Analysis
- LIGO/Virgo/KAGRA S250206dm: FRB 20250206A & "Time Machine" Effect.
- EP-WXT trigger 01709131361: correction to GCN 39214
- EP trigger 01709131361 (possible EP250207a): NOT optical observations and flaring star
- GRB 250207A: Enhanced Swift-XRT position
- CHIME/FRB source FRB 20250206A detected less than 1 minute after LIGO-Virgo-Kagra (LVK) S250206dm, however the probability of spatial coincidence is order 0.1%
- LIGO/Virgo/KAGRA S250206dm: GOTO counterpart search update - AT2025bar
- EP-WXT trigger 01709131361 / LIGO/Virgo/KAGRA S250206dm: FTW optical and NIR observations
- GRB 250129A: ABObservatory SLOAN r’ afterglow detection
- GRB 250207A: REM IR afterglow detection
- LIGO/Virgo/KAGRA S250206dm: ATLAS observations of the skymap
- LIGO/Virgo/KAGRA S250206dm: Pan-STARRS survey of the skymap for optical transients
- GRB 250207A: FRAM-Auger optical detection
- LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limits
- GRB 250207B: Tiled Swift observations
- LIGO/Virgo/KAGRA S250207bg: NED Galaxies in the Localization Volume
- Konus-Wind detection of GRB 250204B
- IGO/Virgo/KAGRA S250206dm: Virtual Telescope Project upper limit for the Neutrino IceCube Candidate
- IceCube-250207A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 250207A: REM optical afterglow detection
- LIGO/Virgo/KAGRA S250207bg: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250206dm:GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
- GRB 250207A: Swift/UVOT Detection
- LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limit for the Neutrino IceCube Candidate
- LIGO/Virgo/KAGRA S250206dm: GOTO observations of optical candidates AT 2025azn and AT 2025azm
- LIGO/Virgo/KAGRA S250206dm: SOAR galaxy targeted observations
- LIGO/Virgo/KAGRA S250206dm: Pan-STARRS observations of AT2025azm and AT2025azn
- LIGO/Virgo/KAGRA S250206dm: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the AT 2025azn Optical Candidate
- GRB 250129A: Continued AbAO and Mondy optical observations
- LIGO/Virgo/KAGRA S250206dm: SAGUARO Detection of Two Potential Optical Counterparts
- GRB 250207B: MAXI/GSC detection
- The EP-WXT trigger 01709131347 is likely a flaring star
- The EP-WXT trigger 01709131332 is likely a flaring star
- The EP-WXT trigger 01709131290 is likely a flaring star
- 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
- GRB 250207A: Fermi GBM Final Real-time Localization
- 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 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
- LIGO/Virgo/KAGRA S250205ee: Updated Sky localization and Source Classification
- 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