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"- GRB 210822A: Swift/UVOT Detection
- Swift GRB 210824A: Global MASTER-Net observations report
- GRB 210824A: BOOTES-5/JGT optical upper limit
- GRB 210824A: Fermi GBM Observation
- Fermi GRB 210824A: Global MASTER-Net observations report
- GRB 210824A: Nanshan/NEXT optical upper limit
- GRB 210824A: Swift-XRT refined Analysis
- GRB 210822A: GROND observations
- GRB 210824A: Enhanced Swift-XRT position
- GRB 210822A: Abbey Ridge Observatory optical afterglow observation
- GRB 210824A: Swift detection of a burst
- GRB 210824A: Fermi GBM Final Real-time Localization
- GRB 210822B: DDOTI Upper Limits on the Afterglow
- GRB 210822A: Detection by GRBAlpha
- GRB 210822A: GECAM refined analysis
- GRB 210820A: GROND observations
- Konus-Wind detection of GRB 210822A
- GRB 210822A: AstroSat CZTI detection
- GRB 210822A: NOT photometry and spectroscopy
- GRB 210822A: Swift-XRT refined Analysis
- Fermi trigger No 651306769: Global MASTER-Net observations report
- GRB 210822A: Swift-BAT refined analysis
- GRB 210820A: NUTTelA-TAO / BSTI Early Optical Limits (Preliminary)
- GRB 210822A: Fermi-LAT detection
- GRB 210820A: Swift/UVOT Detection
- Fermi GRB 210822B: Global MASTER-Net observations report
- GRB 210822A: Nanshan/NEXT optical observations
- GRB 210822B: Fermi GBM Final Real-time Localization
- GRB 210822A: Enhanced Swift-XRT position
- Swift GRB 210822A: Global MASTER-Net observations report
- GRB 210822A: RATIR Optical Detections
- GRB 210822A: KAIT Optical Afterglow Confirmation
- GRB 210822A: GECAM detection
- GRB 210822A: Swift detection of a burst with an optical afterglow
- Fermi GRB 210821A: Global MASTER-Net observations report
- GRB 210820A: Swift-BAT refined analysis
- GRB 210820A: LT optical upper limit
- GRB 210820A: LCO Optical Upper Limit
- GRB 210820A: RATIR Optical Detections
- GRB 210821A: Fermi GBM Final Real-time Localization
- 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
- Swift GRB 210820A: Global MASTER-Net observations report
- GRB 210820B: Fermi GBM Final Localization
- GRB 210820A: Swift detection of a burst with an optical counterpart
- Fermi trigger No 651110719: Global MASTER-Net observations report
- Swift GRB210818.68: Global MASTER-Net observations report
- Swift GRB 210818A: Global MASTER-Net observations report
- GRB 210818A: Swift-XRT refined Analysis
- GRB 210818A: Swift-BAT refined analysis
- GRB 210726A: VLA radio afterglow detection
- Konus-Wind detection of GRB 210818A
- Swift Trigger 1069242 is Cyg X-1
- GRB 210818A: AstroSat CZTI detection
- GRB 210818A: AGILE 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
- IceCube-210730A: not observable by Fermi-GBM
- IceCube-210811A: Upper limits from Fermi-GBM Observations
- GRB 210815A: BALROG localization (Fermi Trigger 650687034 / GRB 210815100)
- GRB 210815A: Fermi GBM Final Real-time Localization
- Fermi trigger No 650687034: Global MASTER-Net observations report
- GRB 210812A is consistent with being a lensed GRB
- IceCube-210811A: No Candidate Counterparts from the Zwicky Transient Facility
- GRB 210712A: Fermi GBM observation
- GRB 210813A: BALROG localization (Fermi Trigger 650508868 / GRB 210813038)
- Fermi GRB 210813A: Global MASTER-Net observations report
- GRB 210813A: Fermi GBM Final Real-time Localization
- Fermi-LAT Gamma-ray Observations of IceCube-210811A
- Retraction of Fermi GBM GCN 30630 and GCN 30632
- GRB 210807A: continued Assy, AbAO and Mondy observations
- Fermi GRB 210812A: Global MASTER-Net observations report
- GRB 210812B: Fermi GBM Final Real-time Localization
- GRB 210812A: BALROG localization (Fermi Trigger 650479626 / GRB 210812699)
- GRB 210812A: Fermi GBM Final Real-time Localization
- GRB 080102A: Fermi GBM Final Real-time Localization
- SGR 1935+2154: SPI INTEGRAL observations on 2021 August 5
- GRB 080101A: Fermi GBM Final Real-time Localization
- GRB 210730A: Tautenburg observations
- GRB 210807A: Tautenburg observations
- IceCube-210811A - IceCube observation of a high-energy neutrino candidate track-like event
- IceCube Alert 210811.09: Global MASTER-Net observations report
- GRB 210807C: Swift-BAT refined analysis
- GRB 210807A: Detection by GRBAlpha
- GRB 210807A: Swift-BAT refined analysis
- GRB 210802A: Further Swift/XRT observation and afterglow confirmation
- 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 210807A: correction to the GCN Circ. #30614 Assy optical observations
- GRB 210807C: Enhanced Swift-XRT position
- GRB 210610B: Assy optical observations
- Swift GRB210807.74: Global MASTER-Net observations report
- Fermi GRB 210807C: Global MASTER-Net observations report
- Swift GRB210807.96: Global MASTER-Net observations report