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.
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
- GRB 231129C: Swift/BAT-GUANO localization of a burst outside the coded FOV
- GRB 231129A: Swift-BAT refined analysis
- GRB 231129C: MASTER OT detection
- GRB 231129A: BOOTES-5/JGT optical upper limit
- GRB 231129C: Fermi-LAT detection
- GRB 231129A: JinShan optical upper limit
- GRB 231129C: GRBAlpha detection
- GRB 231129C: Glowbug gamma-ray detection
- GRB 231129C: Swift-XRT observations
- GRB 231129A: Swift/UVOT Upper Limits
- GRB 231129A: optical upper limit in Mondy observatory
- GRB 231129C: GECAM-B detection of a bright burst
- GRB 231129C: AstroSat CZTI detection
- GRB 231129C: iTelescope OT retraction
- GRB 231129C: CALET Gamma-Ray Burst Monitor detection
- GRB 231129C: Fermi GBM Observation of a very bright GRB
- GRB 231129C: iTelescope likely optical afterglow AT 2023yph discovery
- GRB 231129C: Tiled Swift observations
- GRB 231127A: GRBAlpha detection
- GRB 231129C: MAXI/GSC detection
- GRB 231129C: BALROG localization (Fermi Trigger / GRB 231129799)
- GRB 231129C: Fermi GBM detection of a very bright burst
- GRB 231129A: Enhanced Swift-XRT position
- LIGO/Virgo/KAGRA S231129ac: Updated Sky localization
- GRB 231129A: Swift-XRT refined Analysis
- GRB 231129C: Fermi GBM Final Real-time Localization
- Fermi trigger No 722977823: Global MASTER-Net observations report
- GRB 231129B: Tiled Swift observations
- GRB 231129B: MAXI/GSC detection
- Fermi-LAT gamma-ray observations of IceCube-231125A
- Integral GRB231129.21: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S231129ac: Identification of a GW compact binary merger candidate
- GRB 231129A: GECAM-C detection of a long burst
- GRB 231129A: INTEGRAL detection of a long GRB
- GRB 231129A: Swift detection of a burst
- LIGO/Virgo/KAGRA S231127cg: Updated Sky localization
- GRB 231128A: Fermi GBM Final Real-time Localization
- GRB 231123C: Fermi GBM Observation
- GRB 231123B: Fermi GBM Observation
- IceCube-231125A: Upper limits from a search for additional neutrino events in IceCube
- LIGO/Virgo/KAGRA S231127cg: Identification of a GW compact binary merger candidate
- GRB 231117A: MeerKAT 1.3GHz detection
- GRB 231127A: CALET Gamma-Ray Burst Monitor detection
- GRB 231125A: GRBAlpha detection
- GRB 231125A: CALET Gamma-Ray Burst Monitor detection
- GRB 231127A: AstroSat CZTI detection
- GRB 231125A (short): Glowbug gamma-ray detection
- GRB 231123B: Swift/BAT-GUANO detection of a burst outside the coded FOV
- Update of IceCube-231125A - Corrected errors
- GRB 231124A: GRBAlpha detection
- IceCube-231125A - IceCube observation of a high-energy neutrino candidate track-like event
- Fermi trigger No 722653947: Global MASTER-Net observations report
- GRB 231125A: AstroSat CZTI detection of a short burst
- GRB 231111A: Optical follow-up observations at Terskol, AbAO, Maidanak, Mondy, Assy
- GRB 231126A: Fermi GBM Final Real-time Localization
- GRB 231123C: Insight-HXMT/HE detection
- Fermi trigger No 722460326: Global MASTER-Net observations report
- Fermi trigger No 722507896: Global MASTER-Net observations report
- GRB 231123C (short): Glowbug gamma-ray detection
- GRB 231124A: Glowbug gamma-ray detection
- GRB230728A: VIRT optical upper limit
- GRB230506C: VIRT optical upper limit
- GRB230506B: VIRT optical upper limit
- GRB 231123C: Swift/BAT-GUANO detection of a short burst likely outside the coded FOV
- Fermi trigger No 722462310: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S231118an: Updated Sky localization and EM Bright Classification
- GRB 231124A: CALET Gamma-Ray Burst Monitor detection
- GRB 231115A: XMM-Newton observation
- GRB 231124A: Fermi GBM Final Real-time Localization
- GRB 231123A: AstroSat CZTI detection
- GRB 231117A: Mondy optical observations
- GRB 231123C: Fermi GBM Final Real-time Localization
- GRB 231123B: Fermi GBM Final Real-time Localization
- Fermi trigger No 722400249: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S231123cg: Identification of a GW compact binary merger candidate
- GRB 231118A: REM optical afterglow detection
- GRB 231122B: AstroSat CZTI detection
- GRB 231122B: CALET Gamma-Ray Burst Monitor detection
- GRB 231122B: Swift/BAT-GUANO detection of a long burst outside the coded FOV
- GRB 231117A: Chandra afterglow detection
- GRB 231123A: Fermi GBM Final Real-time Localization
- GRB 231122B: Glowbug gamma-ray detection
- GRB 231117A: Continued GTC Observations
- Fermi trigger No 722349867: Global MASTER-Net observations report
- GRB 231122A: GECAM detection
- GRB 231122B: GECAM detection
- GRB 231122A: Fermi GBM Final Real-time Localization
- GRB 231118A: ATCA detection of radio counterpart
- GRB 231117A: Swift/UVOT late time observations
- GRB 231117A: GTC Near-Infrared Observations
- GRB 231117A: Swift-BAT refined analysis
- GRB 231118A: GRBAlpha detection
- LIGO/Virgo/KAGRA S231118d: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S231118an: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S231114n: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S231113bb: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S231119u: Updated Sky localization and Source Classification
- LIGO/Virgo/KAGRA S231118ab: Updated Sky localization and Source Classification
- LIGO/Virgo/KAGRA S231118d: Updated Sky localization and Source Classification
- GRB 231118A: VZLUSAT-2 detection