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"27394 results found.
- GRB 210930A: Enhanced Swift-XRT position
- Fermi trigger No 654658271: Global MASTER-Net observations report
- GRB 210930A: Swift detection of a burst
- Fermi-LAT Gamma-ray Observations of IceCubeCascade-210926A
- GRB 210927A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 654396242)
- IPN triangulation of GRB 210925B
- GRB 210919A: iTelescope T-11 upper limits
- IceCube-210926A: No neutrino counterpart candidates in ANTARES search
- GRB 210926A: GECAM detection
- IceCube-210922A: JCMT/SCUBA2 observations
- GRB 210925A: GECAM detection
- IceCube-210922A: No significant detection in HAWC
- IceCube-210922A: No neutrino counterpart candidates in ANTARES search
- GRB 210923B: GECAM detection
- GRB 210919A: DECam Upper Limits
- Fermi-LAT Gamma-ray Observations of IceCube-210922A
- GRB 210919A: Swift-BAT refined analysis
- GRB 210912A: LBT optical observations
- GRB 210919A: Lowell Discovery Telescope upper limits (correction to GCN 30859)
- GRB 210919A: Swift/UVOT Upper Limits
- GRB 210919A: LOAO and LSGT optical upper limits
- GRB 210919A: MITSuME Akeno optical upper limits
- GRB 210919A: NOT upper limits
- GRB 210919A: AbAO optical upper limit
- GRB 210919A: Enhanced Swift-XRT position
- GRB 210919A: LCO Optical Upper Limit
- GRB 210919A: Swift detection of a short burst
- Swift trigger 1073821: detection of IGR J16418-4532
- GRB 210912A: BOOTES-5/JGT optical afterglow candidate (Correction to GCNC 30823)
- GRB 210912A: Swift-BAT refined analysis
- Konus-Wind observation of the recent SGR 1935+2154 activity
- GRB 210912A: Tautenburg observations
- GRB 210912A: Swift-XRT refined Analysis
- GRB 210912A: Swift/UVOT Detection
- Fermi GBM observation of another bright burst in the direction of SGR 1935+2154
- GRB 210912A: Enhanced Swift-XRT position
- GRB 210912A: Mondy optical afterglow confirmation
- GRB 210912A: BOOTES-5/JGT optical afterglow candidate
- GRB 210912A: Swift detection of a burst
- Fermi trigger No 653083551: Global MASTER-Net observations report
- Fermi trigger No 653066130: Global MASTER-Net observations report
- Swift GRB210910.42: Global MASTER-Net observations report
- Konus-Wind detection of the second intermediate flare from SGR 1935+2154
- IPN triangulation of a bright burst from SGR 1935+2154
- GRB 210826A: further Swift-XRT observations
- GRB 210909B: GECAM detection
- Swift detection of a burst from SGR Swift J1555.2-5402
- GECAM observation of a burst from SGR J1935+2154
- GECAM observation of a burst from SGR J1935+2154
- Fermi trigger No 652927551: Global MASTER-Net observations report
- GRB 210619B: Maidanak and Assy optical observations, broken power law parametrization
- GRB 210905A: Swift/UVOT Upper Limits
- GRB 210905A: AstroSat CZTI detection
- GRB 210905A, GROND observations
- Fermi GBM Sub-Threshold Detection of GRB 210905A
- GRB 210905A: Swift-XRT refined Analysis
- GRB 210610A: Maidanak and AbAO optical observations
- GRB 210827B: GECAM detection
- GRB 210905A: REM NIR afterglow detection
- GRB 210905A: Continued LCO Optical Observations
- GRB 210905A: LCO Optical Detection
- GRB 210905A: Enhanced Swift-XRT position
- GRB 210901A: Swift/UVOT Upper Limits
- GRB 210905A: Swift detection of a burst
- GRB 210820A: TSHAO optical upper limit
- GRB 210901A: GROND observations
- GRB 210901A: Swift-XRT refined Analysis
- GRB 210901A: Swift-BAT refined analysis
- GRB 210901A: Enhanced Swift-XRT position
- GRB 210901A: LCO Optical Upper Limit
- GRB 210901A: Swift detection of a burst
- GRB 210827A: further Swift-XRT observations
- GRB 210827A: Fermi GBM Observation
- GRB 210826A: AstroSat CZTI detection
- Fermi GRB 210827A: Global MASTER-Net observations report
- GRB 210827A: Swift-XRT observations
- GRB 210827A: Swift/BAT-GUANO detection and arcminute localization
- GRB 210820A: CAHA 2.2m Optical Detection
- GRB 210824A: Swift/UVOT Upper Limits
- GRB 210826A: Swift/UVOT Upper Limits
- POLAR detection of a SGR-like burst
- GRB 210827B: BALROG localization (Fermi Trigger 651751821 / GRB 210827424)
- GRB 210826A: Swift-XRT observations
- GRB 210824A: Swift-BAT refined analysis
- GRB 210824A: MITSuME Akeno optical upper limits
- GRB 210826A: BALROG localization (Fermi Trigger 651654110 / GRB 210826293)
- Swift GRB210825.29: Global MASTER-Net observations report
- Swift detection of an outburst from SGR Swift J1555.2-5402
- GRB 210822A: Swift/UVOT Detection
- GRB 210824A: Fermi GBM Observation
- GRB 210824A: Nanshan/NEXT optical upper limit
- GRB 210824A: Swift-XRT refined Analysis
- GRB 210822A: GROND observations
- GRB 210824A: Enhanced Swift-XRT position
- GRB 210824A: Swift detection of a burst
- GRB 210822B: DDOTI Upper Limits on the Afterglow
- GRB 210820A: GROND observations
- Konus-Wind detection of GRB 210822A
- GRB 210822A: AstroSat CZTI detection
- GRB 210822A: NOT photometry and spectroscopy