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"6520 results found.
- GRB 210305A: Fermi GBM observation
- GRB 210308A: Fermi GBM detection
- GRB 210305A: Swift-XRT refined Analysis
- GRB 210307A: Swift-XRT refined Analysis
- GRB 210306A: Swift-XRT refined Analysis
- GRB 210306A: Fermi GBM observation
- GRB 210306A: iTelescope T24 optical observations
- GRB 210306A: Fermi-LAT detection
- GRB 210306A: iTelescope optical afterglow observations
- GRB 210217A: 3.6m DOT optical observations
- GRB 210226A: Fermi GBM detection
- GRB 210226A: Swift-XRT refined Analysis
- GRB 210218A: Swift-XRT confirmation of afterglow
- GRB 210222B: Swift-XRT refined Analysis
- GRB 210218A: Swift/UVOT observations
- GRB 210218A: Swift-XRT observations
- GRB 210217A: Swift-XRT refined Analysis
- GRB 210205A: observations with the 3.6m DOT, a potential dark burst?
- Fermi/GBM observation of a burst from SGR 1830-0645
- GRB 210210A: Konus-Wind detection and joint Konus-Wind + Swift-BAT spectral analysis
- GRB 210212A: Swift-XRT refined Analysis
- GRB 210204A: observations with the 3.6m Devasthal Optical Telescope and possible jet break
- GRB 210211A: Swift-XRT refined Analysis
- GRB 210211A: Fermi GBM observation
- Swift-XRT observations of IceCube-210210A
- Fermi-LAT Gamma-ray Observations of IceCube-210210A
- IceCube-210210A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- GRB 210210A: Swift-XRT refined Analysis
- GRB 210208A: GIT optical upper limit
- GRB 210209A: Swift-XRT refined Analysis
- GRB 210207B: Swift-XRT refined Analysis
- Konus-Wind detection of GRB 210204A (correction to GCN 29415)
- Konus-Wind detection of GRB 210204A / ZTF21aagwbjr
- GRB 210204A: Optical Observations from HCT
- GRB 210204A / ZTF21aagwbjr: Swift-XRT observations
- GRB 210205A: Swift-XRT refined Analysis
- GRB 210204: Fermi GBM observation
- GRB 210202A: Fermi GBM detection
- GRB 210202A: Fermi-LAT detection
- Continued Chandra observations of GW170817 at ~3.3 years since merger
- GRB 140330A: Swift-XRT refined Analysis
- GRB 140320B: Swift-XRT refined Analysis
- GRB 140402A: Swift-XRT refined Analysis
- GRB 140104B: Swift-XRT refined Analysis
- ZTF21aaeyldq: Observations with the 3.6m DOT
- GRB 210120A: Fermi GBM detection
- IPN triangulation of GRB 210124B (short)
- GRB 210120A : 1.3m DFOT optical observations
- GRB 210112A: 3.6m DOT optical detection
- GRB 210119A: Fermi GBM observation
- Correction to GCN 29288: NuEm-210111A: No counterpart candidates in INTEGRAL SPI-ACS observation
- GRB 201221D: near-infrared observation with LBT
- ZTF21aaeyldq: observations with the 3.6m Devasthal Optical Telescope
- GRB 210112A: Swift-XRT refined Analysis
- NuEm-210111A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- Correction to GCN 29278: GRB 201216C XRT refined analysis
- GRB 201216C: Swift-XRT refined Analysis
- GRB 210102B: further Swift-XRT observations
- GRB 210104A: iTelescope optical upper limit
- GW170817: HST observations at 3.4 years from merger
- GRB 210104A: Swift-XRT refined Analysis
- GRB 210104B: Swift-XRT refined Analysis
- GRB 210104A: DOAO optical afterglow observations
- GRB 210104A: Nanshan/NEXT optical powerlaw decay
- GRB 210104A: Fermi GBM detection
- GRB 210102B: Swift-XRT observations
- GRB 210102C: Fermi GBM detection
- GRB 201227A: Chilescope optical observations, possible optical counterpart
- GRB 201227A: GRAWITA VST-ESO PARANAL observations
- GRB 201227A: Fermi GBM observation
- GRB 201229A: SAO RAS optical observations
- GRB 201227A: Swift-XRT observations
- GRB 201229A: Swift-XRT refined Analysis
- GRB 201104B: Maidanak and CrAO optical observations
- GRB 201223A: 1.3m DFOT and 1.04m ST optical observations
- GRB 201223A: Swift-XRT refined Analysis
- GRB 201223A: GROWTH-India Telescope (GIT) photometric follow-up.
- GRB 201223A: iTelescope optical afterglow observations
- GRB 201223A: Fermi GBM Detection
- Swift-XRT observations of Icecube 201222A
- IceCube-201222A: No significant detection in HAWC
- IceCube-201221A: No significant detection in HAWC
- GRB 201221A: Konus-Wind detection and joint Konus-Wind + Swift-BAT spectral analysis
- GRB 201221D: Fermi GBM detection
- Swift Trigger 1014012 (possible GRB 201221C) is likely not an astrophysical event
- GRB 201216A - further Swift-XRT observations
- Fermi-LAT Gamma-ray Observations of IceCube-201222A
- Fermi-LAT Gamma-ray Observations of IceCube-201221A
- IceCube-201222A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- GRB 201221D: Swift-XRT refined Analysis
- GRB 201221A: Swift/UVOT Upper Limits
- GRB 201221A: Swift-XRT refined Analysis
- IceCube-201221A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- GRB 201214A: Swift-XRT afterglow detection
- GRB 201214A: 1.3m DFOT, optical upper limits
- GRB201216C: No significant detection in HAWC
- GRB 201216C: Fermi-LAT upper limit
- GRB 201216C: Fermi GBM detection
- GRB 201216A: Fermi GBM detection
- GRB 201216A: Swift-XRT observations