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.
Lucene Examples (click to copy):
subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"
23225 results found.
- EP250207b: NOT optical counterpart candidate
- GRB 250211B: A long GRB detected by INTEGRAL
- LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
- Integral GRB250211.89: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
- GRB 250207A: Fermi GBM Observation
- GRB 250206A: Fermi GBM Observation
- GRB 250205A / EP250205A: radio detection with the VLA
- EP250207b: Tentative z-band brightening source
- LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
- Konus-Wind detection of GRB 250207A
- Konus-Wind detection of GRB 250206A
- GRB 250210A: SVOM/GRM observation of a long burst
- EP250207b: Liverpool Telescope possible optical counterpart
- EP250207b: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S250211be: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250211aa: Updated Sky localization and EM Bright Classification
- LIGO/Virgo/KAGRA S250211aa: Identification of a GW compact binary merger candidate
- GRB 250207A: Skynet optical afterglow observations
- GRB 241128A: VIRT Optical Upper Limit
- EP250207b: Gemini GMOS-N z-band observations
- GRB 250210A: AstroSat CZTI detection
- EP250207b: a new X-ray transient detected by Einstein Probe
- LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
- IceCube-250207A: Upper limits from a search for additional neutrino events in IceCube
- LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of AT2025bbo and Galaxies in the Localization Volume
- LIGO/Virgo/KAGRA S250206dm: Observations from WINTER
- LIGO/Virgo/KAGRA S250206dm: Optical observations of candidate AT 2025bbo with Kinder
- Fermi-LAT Gamma-ray Observations of IceCube-250207A
- GRB 250207A: 1.3m DFOT Optical observations
- LIGO/Virgo/KAGRA S250206dm: WFST follow-up observations
- LIGO/Virgo/KAGRA S250206dm: FRB 20250206A BOOTES-5 and 2.2m CAHA optical upper limits
- GRB 250129A: GRANDMA Continued Afterglow Detection
- LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
- GRB 250205A: 1.3m DFOT optical upper limit
- LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Observations
- GRB 250207B: Swift-XRT observations
- LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
- LIGO/Virgo/KAGRA S250206dm: Candidates from the Zwicky Transient Facility
- LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the DDOTI optical candidates
- EP250207a: EP-WXT detection and XRT follow-up observation
- LIGO/Virgo/KAGRA S250208ad: Identification of a GW compact binary merger candidate
- GRB 250207A: Swift-XRT refined Analysis
- LIGO/Virgo/KAGRA S250206dm: FRB 20250206A & "Time Machine" Effect.
- 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%
- GRB 250129A: ABObservatory SLOAN r’ afterglow detection
- GRB 250207A: REM IR afterglow detection
- LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limits
- Konus-Wind detection of GRB 250204B
- IGO/Virgo/KAGRA S250206dm: Virtual Telescope Project upper limit for the Neutrino IceCube Candidate
- 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: 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
- 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 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: Two counterpart neutrino candidates from IceCube neutrino searches
- LIGO/Virgo/KAGRA S250206dm: Identification of a GW compact binary merger candidate
- 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
- Konus-Wind detection of GRB 250201A
- IPN triangulation of GRB 250201A
- Konus-Wind detection of GRB 250202B
- LIGO/Virgo/KAGRA S250205bk: Identification of a GW compact binary merger candidate
- IPN triangulation of GRB 250202B
- 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: Fermi GBM Detection
- GRB 250129a: Liverpool Telescope optical follow-up