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.
Advanced Search Examples (click to copy):
subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"
6094 results found.
- GRB 250215A: Swift-XRT refined Analysis
- EP250207B: Chandra localization of the X-ray counterpart
- GRB 250207A: Fermi GBM Observation
- GRB 250206A: Fermi GBM Observation
- GRB 250210A: SVOM/GRM observation of a long burst
- LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
- 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
- GRB 250206A: Swift-XRT observations
- LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
- GRB 250205A: 1.3m DFOT optical upper limit
- GRB 250206A: Fermi-LAT detection
- GRB 250207B: Swift-XRT observations
- GRB 250207A: Swift-XRT refined Analysis
- LIGO/Virgo/KAGRA S250206dm: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- LIGO/Virgo/KAGRA S250206dm: SAGUARO Detection of Two Potential Optical Counterparts
- Fermi-LAT Gamma-ray Observations of IceCube-250203A
- GRB 250205A: Fermi GBM Observation
- GRB 250204B: SVOM/GRM observation of a likely short burst
- GRB 250205A: Swift/XRT detection
- GRB 250205A: OHP/T193 optical counterpart candidate
- GRB 250204B: AstroSat CZTI detection of a short burst
- GRB 250129A: LCO late afterglow detection
- GRB 250202B: Fermi GBM Detection
- GRB 240129A: further SAO RAS optical observations
- GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
- Konus-Wind detection of GRB 250129A
- GRB 250129A: 1.3m DFOT Optical observations
- GRB 250129A: Skynet Continued Optical Observations
- GRB 250129A: SAO RAS optical observations
- GRB 250129A: optical photometry from Konkoly
- GRB 250129A: iTelescope optical observation
- 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
- Ep250125A: 1.3m DFOT optical upper limit
- GRB 250129A: Swift-XRT refined Analysis
- GRB 250128B: NOT optical upper limit
- GRB 250129A: NOT optical observations and redshift confirmation
- GRB 250128B: Swift-XRT refined Analysis
- GRB 250128B: Fermi GBM Observation
- GRB 250127A: Swift-XRT observations
- Fermi-LAT Gamma-ray Observations of IceCube-250102A
- GRB 250127A: EP-FXT afterglow detection
- GRB 250117A: Fermi GBM Observation
- Fermi-LAT Gamma-ray Observations of IceCube-250101A
- GRB 250118A: Fermi GBM Observation
- EP250125a: Optical upper limit with Kinder observations
- GRB 250119C: Fermi GBM Observation
- GRB 250121A: Fermi GBM Observation
- GRB 250121A: Fermi-LAT detection
- LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
- Fermi-LAT Gamma-ray Observations of IceCube-241224A
- GRB 250119B: Fermi GBM Observation
- EP250108a/AT2025kg: 1.3m DFOT Optical observations
- GRB 250116A: Fermi-LAT detection
- GRB 250116A: Fermi GBM Observation of an Extremely Interesting Burst
- GRB 250114B: Swift-XRT afterglow detection
- GRB 250114B: Swift-XRT observations
- GRB 250114A: Swift-XRT refined Analysis
- GRB 250114B : GIT optical upper limit
- EP250111a: SAO RAS optical upper limit
- EP250108a / AT 2025kg: SAO RAS optical observations
- GRB 250106A: Swift-XRT afterglow detection
- GRB 250101B: Fermi GBM Observation
- GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
- GRB 250108A: Swift/XRT afterglow fading
- EP-WXT trigger EP250108a:Xinglong optical follow-up observations
- EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
- EP250108a: EP-FXT follow-up observation
- GRB 250109A: Fermi GBM Observation
- GRB 250108B: Swift-XRT refined Analysis
- GRB 250108A: Swift-XRT afterglow detection
- GRB 250103A: Swift-XRT afterglow detection
- GRB 250107A: Fermi GBM Observation
- GRB 241228B: Fermi-LAT detection
- EPWXT01709129925: Xinglong optical observations
- GRB 250106A: Swift-XRT observations
- GRB 250103B: Swift-XRT refined Analysis
- GRB 250103A: Swift-XRT observations
- GRB 250101A: 1.3m DFOT optical afterglow detection
- GRB 241229A: 1.3m DFOT upper limit
- GRB 241228B: 1.3m DFOT Optical observations
- GRB 241228A: 1.3m DFOT upper limit
- GRB 250103A: Fermi GBM Observation
- GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
- GRB 250101A: further SAO RAS optical observations
- GRB 250101A: Swift-XRT refined Analysis
- GRB 250101A: SAO RAS optical observations
- GRB 241229A: EP-FXT X-ray afterglow confirmation
- GRB 241229B: SAO RAS optical upper limit
- GRB 241228B: SAO RAS optical observations
- GRB 241229A: SAO RAS optical observations
- GRB 241229A: Swift-XRT observations
- GRB 241229A: EP-FXT afterglow candidates
- EP240702a: 7DT Optical upper limits
- GRB 241228B: Fermi GBM Observation
- GRB 241228B: Swift-XRT afterglow detection
- GRB 241229B: Fermi GBM Observation
- GRB 241229B: Swift-XRT refined Analysis