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 221209A: CALET Gamma-Ray Burst Monitor detection
- IceCube-221210A: Upper limits from a search for additional neutrino events in IceCube
- GRB 221212A: Fermi GBM Final Real-time Localization
- Fermi GRB 221211A: Global MASTER-Net observations report
- GRB 221208A: AstroSat CZTI detection
- GRB 221211A: Fermi GBM Final Real-time Localization
- IceCube-221210A - IceCube observation of a high-energy neutrino candidate track-like event
- IceCube Alert 221210.36: Global MASTER-Net observations report
- GRB 221009A: MuSCAT3 observations
- GRB 221209A: AstroSat CZTI detection
- GRB 221210A: Fermi GBM Final Real-time Localization
- GRB 221209B: Fermi GBM Final Real-time Localization
- GRB 221209A: Fermi GBM observation
- GRB 221203C: AstroSat CZTI detection
- GRB 221209A: BALROG localization (Fermi Trigger 692257829 / GRB 221209243)
- GRB 221209A: Fermi GBM Final Real-time Localization
- GRB 221206B: Fermi GBM observation
- GRB 221206B: Swift-XRT observations
- GRB 221206B: Detection by GRBAlpha
- GRB 221206B: Swift/BAT-GUANO candidate arcminute localization
- GRB 221206B: Swift ToO observations
- Swift/BAT trigger #1143281 is not a GRB
- GRB 221206C: Fermi GBM Final Real-time Localization
- GRB 221206B: Fermi GBM Final Real-time Localization
- GRB 221206A: Fermi GBM Final Real-time Localization
- GRB 221205A: Fermi GBM Final Real-time Localization
- Swift GRB221204.45 AKO Upper Limit
- GRB 221202B: Detection by VZLUSAT-2
- Swift GRB221204.45: Global MASTER-Net observations report
- GRB 221203B: Fermi GBM Final Real-time Localization
- GRB 221202A: Swift/UVOT Detection
- GRB 221202A: Swift-BAT refined analysis
- GRB 221202A: VLT/FORS2 Afterglow Discovery
- GRB 221201A: Swift-BAT refined analysis
- GRB 221203A: Fermi GBM Final Real-time Localization
- GRB 221201A: Fermi GBM observation
- GRB 221202A: Swift-XRT refined Analysis
- GRB 221202A: LCOGT Optical Upper Limits
- GRB 221202A: Enhanced Swift-XRT position
- GRB 221202A: MeerLICHT upper limits
- GRB 221202B: Fermi GBM Final Real-time Localization
- GRB 221202A: Swift detection of a burst
- Swift GRB221202.84: Global MASTER-Net observations report
- GCN: GRB 221201A: Swift/UVOT Upper Limits
- GRB 221201A: Swift-XRT refined Analysis
- GRB 221201A: Enhanced Swift-XRT position
- Swift GRB 221201A: Global MASTER-Net observations report
- Konus-Wind detection of GRB 221124A
- GRB 221201A: Swift detection of a burst
- GRB 221201A: Fermi GBM Final Real-time Localization
- Fermi Gamma-ray Burst Monitor trigger 691534074/221130867 is not a GRB
- Optical polarization observation of GRB 221009A
- GRB 221126A: Fermi GBM observation
- IceCube-221124A: Upper limits from a search for additional neutrino events in IceCube
- GRB 221126A: AGILE detection
- GRB 221127A: Detection by GRBAlpha
- GRB 221126A: AstroSat CZTI detection
- IceCube-221124A: BOOTES-4/MET and BOOTES-2/TELMA optical upper limit
- Alert from the HAWC Burst Monitor HAWC-221128A
- GRB 221126A: Swift/BAT-GUANO detection outside the coded FOV
- IPN triangulation of GRB 221124A (long)
- GRB 221126A: Fermi GBM Final Real-time Localization
- GRB 221124A: Swift/BAT-GUANO detection
- Fermi-LAT gamma-ray observations of IceCube-221124A
- GRB 221120A: Detection by VZLUSAT-2
- GRB 221124A: CALET Gamma-Ray Burst Monitor detection
- IceCube-221124A - IceCube observation of a high-energy neutrino candidate track-like event
- IceCube Alert 221124.66: Global MASTER-Net observations report
- GRB 221120A: TURBO Optical Upper Limit
- GRB 221122A: Detection by GRBAlpha
- GRB 221120A: VIRT Optical Upper Limit
- Alert from the HAWC Burst Monitor HAWC-221123A
- GRB 221121A: CALET Gamma-Ray Burst Monitor detection
- GRB 221009A：DAMPE observed a 34.7 GeV photon at 1.36 hour after the GBM trigger
- GRB 221120A: GTC Confirmation of an Underlying Galaxy
- IPN triangulation of GRB 221121A (long)
- GRB 221120A: Swift-BAT refined analysis
- GRB221121A: AstroSat CZTI detection
- GRB 221120A: AKO Telescope Upper Limits
- GRB221120A: WIRC near-IR imaging of the afterglow candidate
- GRB 221120A: Liverpool Telescope Upper Limits
- GRB 221120A: Archival PS1 Imaging of Faint Source near XRT position
- GRB 221120A: Fermi GBM observation
- GRB 221120A: Swift-XRT refined Analysis
- GRB 221120A: Enhanced Swift-XRT position
- GRB221120A: Montarrenti Observatory Upper Limit
- GRB 221121A: Fermi GBM Final Real-time Localization
- GRB 221120A is a short burst
- GRB 221120A: Swift/UVOT Upper Limits
- GRB 221120A: LDT Optical Afterglow Candidate
- GRB 221120A: GIT upper limits on optical afterglow
- GRB 221120A: Swift detection of a likely short burst
- GRB 221119A: Fermi GBM detection
- GRB 221119A: Detection by GRBAlpha
- GRB 221119A: Fermi-LAT detection
- LAT GRB221119.63: Global MASTER-Net observations report
- GRB 221119A: Fermi GBM Final Real-time Localization
- GRB 221009A: Japanese VLBI Network observation
- GRB 221115B: CALET Gamma-Ray Burst Monitor detection
- GRB 221114A: CALET Gamma-Ray Burst Monitor detection