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.
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"28084 results found.
- Trigger 1035744: Swift detection of Sco X-1 due to Star Tracker loss of lock
- GRB 210217A: 3.6m DOT optical observations
- GRB 210226A: Swift/UVOT Upper Limits
- Fermi trigger No 636187116: Global MASTER-Net observations report
- GRB 210228A: GECAM detection
- GRB 210225A: Insight-HXMT/HE detection
- Integral GRB210227.19: Global MASTER-Net OT detection
- GRB 210226A: Swift-BAT refined analysis
- GRB 210226A: Fermi GBM detection
- GRB 210217A: Mondy optical observations
- GRB 210226A: Swift-XRT refined Analysis
- GRB 210218A: Swift-XRT confirmation of afterglow
- GRB 210226A: Burke-Gaffney Observatory optical upper limit
- GRB 210226A: Enhanced Swift-XRT position
- GRB 210222B: 1.3m DFOT Optical upper limit
- GRB 210226A: Swift detection of a burst
- GRB 210222B: REM observations of the optical/NIR afterglow
- GRB 210222B: MITSuME Akeno optical upper limits
- GRB 210222B: Zeiss-1000 of Koshka observatory, optical observations
- GRB 210222B: VIRT optical detection
- GRB 210222B: Swift-BAT refined analysis
- GRB 210222B: Swift-XRT refined Analysis
- GRB 210222B: Swift/UVOT Detection
- GRB 210218A: Swift/UVOT observations
- GRB 210217A: Swift/UVOT Detection
- GRB 210222B: MASTER OT observation
- GRB 210222B: Redshift from FORS2/VLT
- GRB 210222B: NEXT early optical afterglow observations
- GRB 210222B: GOTO confirmation of afterglow detection (correction to GCN29548)
- GRB 210222B: Liverpool Telescope optical detection
- GRB 210222B: GOTO confirmation of afterglow detection
- GRB210222B: LCO Optical Afterglow Detection
- GRB210222B: BOOTES-1 optical afterglow detection
- GRB 210222B: Swift detection of a burst with an optical counterpart
- GRB 210222A: MAXI/GSC detection
- GRB 210218A: Swift-XRT observations
- GRB 210212A: Lowell Discovery Telescope observations
- GRB 210217A: Swift-XRT refined Analysis
- GRB 210218A: Swift-BAT refined analysis
- Fermi GBM Sub-Threshold Detection of GRB 210217A
- GRB 210217A: Liverpool Telescope First Hour Observations
- GRB 210217A: Swift-BAT refined analysis
- GRB 210218A: MITSuME Akeno optical upper limits
- GRB 210218A: NEXT optical upper limit
- ZTF21aakruew/AT2021cwd: GROND observations
- GRB 210212A: REM early-time optical/NIR upper limits
- GRB 210217A: Enhanced Swift-XRT position
- GRB 210217A: NEXT early optical afterglow observations
- GRB 210212A: Mondy optical observations
- GRB 210217A: Swift detection of a burst with an optical counterpart
- IceCube-210210A: Two Additional Optical Candidate Counterparts Found by DECam
- GRB 210208A: 1.3m DFOT Optical upper limit
- Swift Trigger 1033144: Detection of SGR 1830-0645
- GRB 210211A: ePESSTO+ NTT optical observations
- Konus-Wind detection of GRB 210212B / ZTF21aakruew
- IPN triangulation of GRB 210212B (consistent with ZTF21aakruew/AT2021cwd)
- GRB 210212A: 1.3m DFOT Optical upper limit
- GRB 210213B: Insight-HXMT/HE detection
- GRB 210212A: Gemini South optical observations
- IceCube-210210A: Four Candidate Optical Counterparts from DECam Observations
- Swift Trigger 1032350: Detection of SGR 1830-0645
- GRB 210212A: Possible host galaxy counterpart with the NOT
- GRB 210212A: MITSuME Akeno optical upper limits
- GRB 210212A: Swift-XRT refined Analysis
- IceCube-210210A: Upper limits from a search for additional neutrino events in IceCube
- GRB 210212A: Swift/UVOT Upper Limits
- GRB 210212A: Swift-BAT refined analysis
- GRB 210212A: Enhanced Swift-XRT position
- GRB 210212A: Swift detection of a burst
- GRB 210207B: GECAM detection
- GRB 210211A: Swift/UVOT Detection
- GRB 210211A: Swift-XRT refined Analysis
- GRB 210211A: Swift-BAT refined analysis
- GRB 210211A: Fermi GBM observation
- GRB 210210A as a BdHN II
- Swift-XRT observations of IceCube-210210A
- GRB 210209A: Swift-BAT refined analysis
- GRB 210211A: Enhanced Swift-XRT position
- GRB 210211A: MASTER optical observation of REM OT
- IceCube-210210A: No neutrino counterpart in ANTARES
- GRB 210211A: REM optical/NIR afterglow detection
- Fermi-LAT Gamma-ray Observations of IceCube-210210A
- GRB 210211A: Swift detection of a burst
- GRB 210210A: Swift-BAT refined analysis
- IceCube-210210A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- GRB 210210A: LCO Optical Afterglow Detection
- GRB 210210A: Swift/UVOT Detection
- GRB 210112A: LBT host detection and correction to GCN 29319 (CAHA observations)
- GRB 210209A: MITSuME Akeno optical upper limits
- GRB 210209A: Swift/UVOT Upper Limits
- GRB 210210A: Swift-XRT refined Analysis
- GRB 210208A: GIT optical upper limit
- GRB 210209A: Swift-XRT refined Analysis
- GRB 210210A: Enhanced Swift-XRT position
- GRB 210210A: MASTER afterglow observation
- ZTF21aahifke/AT2021clk: ZTF discovery of an optical fast transient (possible afterglow)
- GRB 210210A: Swift detection of a burst with an optical counterpart
- GRB 210209A: Enhanced Swift-XRT position
- GRB 210209A: Swift detection of a burst
- GRB 210207B: Continued LCO Observations