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"- GRB 150711A: Swift detection of a burst
- GRB 150710B: Swift ToO observations
- GRB 150710B detected in ground analysis of BAT data
- GRB 150710A: Swift/UVOT Upper Limits
- MASTER OT Detection during Fermi Trigger 458235025 inspection
- GRB 150710A: host galaxy for Swift XRT second candidate
- Swift-XRT observations of GRB 150710A
- Confirmation that Swift trigger 648422 is not an astrophysical source
- Konus-Wind observation of GRB 150710A (Swift trigger 648437)
- GRB 150710A: Swift-BAT refined analysis
- GRB 150710A: RATIR Observations
- Swift trigger 648437: A GRB or a burst from 1RXS J125754.7+141850
- Swift Trigger 648422: Swift-XRT observations
- Trigger 648422: Swift possible detection of a source in NGC4552
- GRB 150626B: AMI 16 GHz detection of the radio counterpart
- Fermi Gamma-ray Burst Monitor Trigger bn150705731 is not a GRB
- Konus-Wind observation of GRB 150702A
- GRB 150702A: Fermi GBM detection
- IPN Triangulation of GRB 150702A
- GRB 150702A: MASTER-SAAO inspection
- GRB 150702A: Swift-XRT observations
- GRB 150702A: Swift ToO observations
- GRB 150702A: Fermi-LAT detection
- Fermi GBM Observations is no longer triggerin on V404 Cyg
- GRB 150622A: Swift-XRT afterglow detection
- Swift Trigger 647642 is probably not an astrophysical source
- Fermi Gamma-ray Burst Monitor Trigger 150626873 is not a GRB
- Fermi Gamma-ray Burst Monitor Trigger bn150628857 is not a GRB
- Fermi Gamma-ray Burst Monitor trigger bn150629779 is not a GRB
- Konus-Wind observation of GRB 150627A
- GRB 150626B, Swift-BAT refined analysis
- V404 Cyg activity (Swift, Fermi, INTGRAL, KONUS, MAXI detection): optical observations in TSHAO, Khureltogot, and AAO
- GRB 150627A: corection to 17978
- GRB 150627A: MASTER-SAAO OT Detection
- GRB 150627A: Swift/UVOT Detection
- GRB 150627A: Swift-XRT afterglow detection
- GRB 150627A: Fermi GBM observation
- GRB 150626B: Swift-XRT refined Analysis
- GRB 150626A: Swift-BAT refined analysis
- GRB 150627A: Swift ToO observations
- GRB 150627A: Fermi-LAT detection
- GRB 150626B: Swift/UVOT Upper Limits
- GRB 150626B: NOT optical upper limits
- GRB 150626B: Enhanced Swift-XRT position
- GRB 150626B: MASTER observations
- GRB 150626B: Swift detection of a burst
- GRB 150626A: Swift-XRT refined Analysis
- GRB 150626A: Swift/UVOT Upper Limits
- Trigger 646721: Swift detection of V 404 Cyg
- GRB 150626A: Enhanced Swift-XRT position
- GRB 150626A: Prompt enhanced Swift-XRT position
- GRB 150626A: Swift detection of a burst
- Swift Trigger 646423 is GS 1354-645
- Trigger 645944: Swift detection of H1745-203
- Fermi Gamma-ray Burst Monitor triggers that are not GRBs
- V404 Cyg: MASTER Swift, Integral alert observations
- Fermi Gamma-ray Burst Monitor triggers bn150622899 and bn150623043 are not GRBs
- GRB 150622A: Swift-XRT observations
- GRB 150622A: Tiled Swift observations
- GRB 150622A: MAXI/GSC detection
- Swift Trigger 645340 was Sco X-1
- Swift Trigger 645340: a possible GRB
- Trigger 645176: Swift detection of V404 Cyg
- V404 Cyg: Fermi GBM observations
- GRB 150616A: Watcher optical upper limit
- Swift triggers again on V404 Cyg
- Swift Trigger 644596 is V404 Cyg
- Swift Trigger 644520 is V404 Cyg
- IBAS trigger 7015 is not a GRB
- GRB 150616A: Swift/UVOT Upper Limits
- GRB 150616A: Swift-BAT refined analysis
- V404 Cyg outburst (Swift trigger 643949 ): TSHAO optical observations
- GRB 150616A: Swift-XRT refined Analysis
- Konus-Wind observation of Galactic transient V404 Cyg in outburst
- GRB 150616A: Enhanced Swift-XRT position
- GRB 150616A: Swift detection of a burst
- Fermi GBM trigger 150616734 is not a GRB
- Fermi GBM trigger 150616594 is not a GRB
- V404 Cyg: Swift/UVOT Detection
- Fermi Gamma-ray Burst Monitor triggers bn150615791 and bn150615798 are not GRBs
- Optical follow-up of Swift trigger on V404 Cyg
- GRB 150615A, Swift-BAT refined analysis
- Swift trigger 643949 is V404 Cyg
- GRB 150615A: Swift-XRT refined Analysis
- Fermi GBM trigger 150615574 is not a GRB
- GRB 150608A: Swift-XRT follow-up observations
- GRB 150615A: Swift/UVOT Detection
- GRB 150615A: Enhanced Swift-XRT position
- GRB 150615A: Swift detection of a burst
- Fermi GBM trigger 150613619 is not a GRB
- Fermi GBM trigger 150612648 is not a GRB
- GRB 150608A: MITSuME Akeno optical upper limits
- Trigger 643078: Swift detection of H1743-322
- Konus-Wind observation of GRB 150608A
- GRB 150608A: Swift-XRT afterglow detection
- Fermi Gamma-ray Burst Monitor trigger 455474712 / 150608698 is not a GRB
- GRB150607A: AAO and CrAO optical observations
- GRB150607A: Discovery Channel Telescope Optical Observations
- GRB 150608A: Tiled Swift observations
- GRB 150608A: MAXI/GSC detection