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"27395 results found.
- GRB 210822A: NOT photometry and spectroscopy
- GRB 210822A: Swift-XRT refined Analysis
- GRB 210822A: Swift-BAT refined analysis
- GRB 210820A: NUTTelA-TAO / BSTI Early Optical Limits (Preliminary)
- GRB 210820A: Swift/UVOT Detection
- GRB 210822A: Nanshan/NEXT optical observations
- GRB 210822A: Enhanced Swift-XRT position
- GRB 210822A: RATIR Optical Detections
- GRB 210822A: Swift detection of a burst with an optical afterglow
- GRB 210820A: Swift-BAT refined analysis
- GRB 210820A: LCO Optical Upper Limit
- GRB 210820A: RATIR Optical Detections
- GRB 210820A: NOT optical upper limit
- GRB 210820A: Nanshan/NEXT optical upper limit
- GRB 210820A: Swift-XRT refined Analysis
- GRB 210820A: Enhanced Swift-XRT position
- GRB 210820A: Swift detection of a burst with an optical counterpart
- GRB 210818A: Swift-XRT refined Analysis
- GRB 210818A: Swift-BAT refined analysis
- Swift Trigger 1069242 is Cyg X-1
- GRB 210818A: AstroSat CZTI detection
- GRB 210818A: Enhanced Swift-XRT position
- GRB 210818A: Swift detection of a burst with an optical counterpart
- IceCube-210811A: Upper limits from a search for additional neutrino events in IceCube
- GRB 210815A: BALROG localization (Fermi Trigger 650687034 / GRB 210815100)
- GRB 210712A: Fermi GBM observation
- GRB 210813A: BALROG localization (Fermi Trigger 650508868 / GRB 210813038)
- Fermi-LAT Gamma-ray Observations of IceCube-210811A
- GRB 210812A: BALROG localization (Fermi Trigger 650479626 / GRB 210812699)
- GRB 080101A: Fermi GBM Final Real-time Localization
- GRB 210730A: Tautenburg observations
- GRB 210807A: Tautenburg observations
- GRB 210807C: Swift-BAT refined analysis
- GRB 210807A: Swift-BAT refined analysis
- GRB 210807C: Swift-XRT refined Analysis
- GRB 210807C: Fermi GBM detection
- GRB 210807C: Swift/UVOT Upper Limits
- GRB 210807A: Swift/UVOT Detection
- GRB 210807A: Swift-XRT refined Analysis
- GRB 210807C: Enhanced Swift-XRT position
- GRB 210610B: Assy optical observations
- GRB 210807C: Swift detection of a burst
- GRB 210807A: Enhanced Swift-XRT position
- GRB 210807A: Swift detection of a burst with an optical counterpart
- IPN Triangulation of a bright burst from SGR 1935+2154
- GRB 210802A: MITSuME Okayama optical upper limits
- GRB 210803A: Fermi GBM observation
- Fermi trigger No 649684549: Global MASTER-Net observations report
- GRB 210802A: DDOTI Upper Limits
- GRB 210802A: BOOTES-2/TELMA optical upper limit
- GRB 210802A: Swift-XRT afterglow detection
- GRB 210802A: Fermi GBM detection
- GRB 210803A: BALROG localization (Fermi Trigger 649684549 / GRB 210803497)
- Fermi trigger No 649627691: Global MASTER-Net observations report
- GRB 210801A: Fermi GBM detection
- GRB 210731A: VLT/X-shooter redshift
- IceCube-210730A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- GRB 210731A: Swift-BAT refined analysis
- GRB 210801A: BALROG localization (Fermi Trigger 649519043 / GRB 210801581)
- GRB 210731A: Swift-XRT refined Analysis
- Fermi trigger No 649519043: Global MASTER-Net observations report
- GRB 210731A: GROND observations
- GRB 210731A: Fermi GBM Observation
- GRB 210731A: Swift/UVOT Detection of an optical afterglow
- GRB 210731A: MeerLICHT optical afterglow detection
- GRB210731A: Enhanced Swift-XRT position
- GRB 210731A: Swift detection of a burst
- Fermi-LAT Gamma-ray Observations of IceCube-210730A
- GRB 210730A: Campo Imperatore optical observations
- GRB 210730A: BOOTES-5/JGT and 2.2m CAHA telescopes optical limit
- GRB 210730A: TNG optical observations
- GRB 210730A: Fermi GBM observation
- GRB 210730A: AstroSat CZTI detection
- GRB 210730A: Swift-BAT refined analysis
- GRB 210730A: Swift-XRT refined Analysis
- GRB 210730A: Swift/UVOT Upper Limits
- GRB 210730A: Enhanced Swift-XRT position
- GRB 210730A: Swift detection of a burst near M82
- Fermi GBM Sub-Threshold Detection of GRB 210725B
- GRB 210726A: 6 GHz VLA radio upper limit
- IPN triangulation of GRB 210727A (short)
- Fermi GBM Sub-Threshold Detection of GRB 210726A
- GRB 210714A: Fermi GBM observation
- GRB 210726A: Swift-XRT refined Analysis
- GRB 210726A: Swift-BAT refined analysis
- GRB 210726A: RATIR Optical Upper Limits and Candidate Host Galaxy
- GRB 210727A: BALROG localization (Fermi Trigger 649072251 / GRB 210727410)
- GRB 210725A: AbAO optical upper limit
- GRB 210724A: Swift/UVOT Upper Limits
- GRB 210723A: Swift/UVOT Upper Limits
- GRB 210725A: Swift/UVOT Upper Limits
- GRB 210725B: Swift/UVOT Upper Limits
- GRB 210726A: Enhanced Swift-XRT position
- GRB 210726A: Swift detection of a burst
- GRB 210725B: Swift-XRT refined Analysis
- GRB 210725A: Fermi GBM detection
- GRB 210724A: Zeiss-1000 of Koshka observatory, optical upper limit
- GRB 210725A: Swift-XRT refined Analysis
- GRB 210725B: Swift-BAT refined analysis
- GRB 210724A: Swift-XRT refined Analysis