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"35958 results found.
- GRB 250217C: Tiled Swift observations
- GRB 250217C: Fermi GBM Observation
- GRB 250215A / EP250215A: Encouraging Follow-up Observations of a BdHN I with a Rest-Frame Duration 2.3 s at z=4.61
- IPN triangulation of GRB 250217C (short)
- GRB 250213A: Swift-XRT observations
- LIGO/Virgo/KAGRA S250206dm: AZT-33IK Target Optical Observations
- GRB 250216A: AstroSat CZTI detection
- GRB 250217C: AstroSat CZTI detection of a short burst
- Fermi GRB 250217C: Global MASTER-Net observations report
- GRB 250217C: Fermi GBM Final Real-time Localization
- LIGO/Virgo/KAGRA S250206dm: observation in AbAO, optical transient near NED/GLADE+ galaxy WISEA J021210.14+514821.7
- Fermi GRB 250217A: Global MASTER-Net observations report
- GRANDMA/OPD observations of GRB250215A
- GRB 250217B: Fermi GBM Final Real-time Localization
- GRB 250217A: Fermi GBM Final Real-time Localization
- Fermi GRB 250216A: Global MASTER-Net observations report
- GRB 250215A / EP250215a: LCO detection of the afterglow
- GRB 250216A: Fermi GBM Final Real-time Localization
- GRB 250215A: Swift/UVOT Upper Limits
- GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
- EP250215a / GRB 250215A : GTC redshift z = 4.61
- GRB 250215A: Fermi GBM Observation
- EP250215a / GRB 250215A : NOT optical observations
- GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
- GRB 250215A / EP250215a: Gemini-South optical observation of a likely rebrightening
- GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
- GRB 250215A: Swift-XRT refined Analysis
- GRB 250215A: SVOM/GRM observation
- EP250215a / GRB 250215A: AstroSat CZTI detection
- GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
- EP250215A/GRB 250215A: INTEGRAL SPI-ACS detection
- EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
- EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
- Fermi GRB 250215A: Global MASTER-Net observations report
- GRB 250215A: Fermi GBM Final Real-time Localization
- GRB 250213A:SVOM/VT optical candidate
- Fermi Gamma-ray Burst Monitor trigger 761206993/250214266 is not a GRB
- Fermi GRB 250214A: Global MASTER-Net observations report
- GRB 250213A: Swift ToO observations
- GRB 250214A: Fermi GBM Final Real-time Localization
- GRB 250213A: SVOM detection of a burst
- GRB 250205A: VIRT Optical Upper Limit
- GRB 250205A: Leavitt Observatory optical upper limit
- GRB 250210A: GRBAlpha detection
- Fermi GRB 250212A: Global MASTER-Net observations report
- GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
- GRB 250211A: SVOM trigger sb25021103 is not a GRB
- GRB 250211B: A long GRB detected by INTEGRAL
- GRB 250211A: Swift ToO observations
- GRB 250212A: Fermi GBM Final Real-time Localization
- GRB 250207A: Fermi GBM Observation
- GRB 250206A: Fermi GBM Observation
- GRB 250205A / EP250205A: radio detection with the VLA
- Konus-Wind detection of GRB 250207A
- Konus-Wind detection of GRB 250206A
- GRB 250210A: SVOM/GRM observation of a long burst
- Fermi Gamma-ray Burst Monitor trigger 760945500/250211240 is not a GRB
- GRB 250207A: Skynet optical afterglow observations
- GRB 241128A: VIRT Optical Upper Limit
- EP250207A: Upper limits from Fermi-GBM Observations
- GRB 250210A: INTEGRAL SPI-ACS detection
- GRB 250210A: AstroSat CZTI detection
- GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
- Fermi GRB 250210A: Global MASTER-Net observations report
- GRB 250210A: Fermi GBM Final Real-time Localization
- LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
- 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