GCN Circulars
GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"- IPN triangulation of GRB 210212B (consistent with ZTF21aakruew/AT2021cwd)
- GRB 210212A: 1.3m DFOT Optical upper limit
- GRB 210213B: Insight-HXMT/HE detection
- ZTF21aakruew/AT2021cwd: ZTF and LT discovery of a hostless, red, and rapidly fading optical transient
- GRB 210212A: Gemini South optical observations
- IceCube alert 134994_1103075 retraction
- Fermi GRB 210213A: Global MASTER-Net observations report
- IceCube Alert 210213.78: Global MASTER-Net observations report
- GRB 210213A: Fermi GBM Final Real-time Localization
- GRB 210210A: CAHA 2nd epoch and jet break confirmation
- IceCube-210210A: Four Candidate Optical Counterparts from DECam Observations
- Swift Trigger 1032350: Detection of SGR 1830-0645
- GRB 210204A (ZTF21aagwbjr/AT2021buv): continued CrAO and AbAO optical observations
- GRB 210212A: Possible host galaxy counterpart with the NOT
- Swift GRB 210212A: Global MASTER-Net observations report
- GRB 210212A: MITSuME Akeno optical upper limits
- GRB 210212A: Swift-XRT refined Analysis
- GRB 210212A: BOOTES-4/MET optical upper limit
- 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 210204A: observations with the 3.6m Devasthal Optical Telescope and possible jet break
- GRB 210212A: Enhanced Swift-XRT position
- GRB 210210A : 1.3m DFOT optical observations
- 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
- GRB 210210A: CAHA detection and likely jet break
- 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
- Swift GRB210211.36: Global MASTER-Net observations report
- GRB 210211A: Fermi GBM Final Real-time Localization
- GRB 210210A: FRAM-ORM afterglow detection
- Fermi trigger No 634659312: Global MASTER-Net observations report
- GRB 210210A: Swift-BAT refined analysis
- IceCube Alert 210210.50: Global MASTER-Net observations report
- Fermi GRB 210210B: Global MASTER-Net observations report
- IceCube-210210A: Upper limits from Fermi-GBM Observations
- IceCube-210210A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- GRB 210210B: Fermi GBM Final Real-time Localization
- IceCube-210210A: Two Candidate Counterparts from the Zwicky Transient Facility
- GRB 210209A: BOOTES-4/MET optical upper limit
- GRB 210210A: LCO Optical Afterglow Detection
- Swift GRB 210209A: Global MASTER-Net observations report
- GRB 210210A: Swift/UVOT Detection
- GRB 210112A: LBT host detection and correction to GCN 29319 (CAHA observations)
- GRB 210209A: MITSuME Akeno optical upper limits
- IceCube-210210A: IceCube observation of a high-energy neutrino candidate event
- GRB 210209A: Swift/UVOT Upper Limits
- GRB 210210A: Swift-XRT refined Analysis
- GRB 210208A: GIT optical upper limit
- GRB 210210A: Redshift from OSIRIS/GTC
- 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)
- Swift GRB 210210A: Global MASTER-Net observations report
- 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
- GRB 210104A: LBT observations
- GRB 210208A: BOOTES-2/TELMA optical upper limit
- GRB 210204A (ZTF21aagwbjr/AT2021buv): continued Mondy optical observations
- GRB 210207B: AstroSat CZTI detection
- GRB 210207B: Swift/UVOT Detection
- GRB 210207B: Swift-BAT refined analysis
- GRB 210207B: Insight-HXMT/HE detection
- GRB 210204A: LBT observations and jet break
- GRB 210204A: redshift revision of ZTF21aagwbjr/AT2021buv (correction to GCN 29411)
- GRB 210207B: LCO Optical Afterglow Detection
- GRB 210207B: KAIT Optical Observations
- GRB 210208A: A long GRB detected by INTEGRAL
- GRB 210207B: AGILE observations
- GRB 210207B: Swift-XRT refined Analysis
- Konus-Wind detection of GRB 210207B
- SGR 1935+2154: MAXI/GSC detection
- Konus-Wind detection of GRB 210204A (correction to GCN 29415)
- GRB 210207B: AbAO optical upper limit
- GRB 210207B: Enhanced Swift-XRT position
- GRB 210207B: optical detection with 3.6m Devasthal Optical Telescope
- GRB 210207B: Swift detection of a burst with a bright optical counterpart
- Fermi GRB 210207A: Global MASTER-Net observations report
- GRB 210207A: BALROG localization (Fermi Trigger / GRB 210207603)
- GRB 210204A (ZTF21aagwbjr/AT2021buv): Mondy and AbAO optical observations
- GRB 210207A: Fermi GBM Final Real-time Localization
- Konus-Wind detection of GRB 210204A / ZTF21aagwbjr
- GRB 210204A: Optical Observations from HCT
- GRB 210204A / ZTF21aagwbjr: Swift-XRT observations
- GRB 210204A: Swift ToO observations