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 231114A (short): Glowbug gamma-ray detection
- LIGO/Virgo/KAGRA S231113bw: GROWTH-India coverage and upper limits
- GECAM-B observation of a short burst from SGR J1555-5402
- GRB 231114A: Fermi GBM Final Localization
- LIGO/Virgo S231113bw: upper limits from AGILE/MCAL
- LIGO/Virgo/KAGRA S231114n: Identification of a GW compact binary merger candidate
- SGRJ1555-5402: Swift/BAT-GUANO arcminute localization of a SGR flare
- LIGO/Virgo/KAGRA S231113bw: Upper limits from Fermi-GBM Observations
- GRB 231110A: CALET Gamma-Ray Burst Monitor detection
- LIGO/Virgo/KAGRA S231113cd: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S231113bb: Updated Sky localization
- LIGO/Virgo/KAGRA S231113bw: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S231113bw: Identification of a GW compact binary merger candidate
- GRB 231110A: Swift-BAT refined analysis
- GRB231111A: MDM 2.4m Hiltner Telescope Observation
- GRB 231106A: Glowbug gamma-ray detection
- GRB 231111A: Xinglong-2.16m optical observations
- GRB 231110A: Swift-UVOT Upper Limits
- LIGO/Virgo/KAGRA S231113bb: Identification of a GW compact binary merger candidate
- GRB 231111A: Afterglow redshift from OSIRIS+/GTC
- GRB 231104A: VZLUSAT-2 detection
- GRB 231111A: TNG tentative redshift
- GRB 231110A: Glowbug gamma-ray detection
- GRB 231110A: AstroSat CZTI detection
- GRB 231111A NUTTelA-TAO / BSTI Early Measurements
- GRB 231111A: Leavitt Observatory optical observations
- GRB231111A: Optical follow-up observations with Mephisto
- GRB 231111A: GMG observation (correction)
- LIGO/Virgo/KAGRA S231112ag: Retraction of GW compact binary merger candidate
- GRB 231111A: GMG observation upper limit
- GRB 231106B: GRBAlpha detection
- GRB 231111A: Osservatorio Astronomico "Nastro Verde" optical observations with detection of an optical counterpart
- GRB 231110A: Terskol Zeiss-2000 optical upper limit
- GRB 231111A: Swift-XRT refined Analysis
- GRB 231111A: Mondy optical observations
- GRB 231111A: GECAM-C detection of a long burst (correction)
- GRB 231110A: GECAM-B detection (correction)
- GRB 231111A: Enhanced Swift-XRT position
- GRB 231111A: GECAM-C detection of a long burst
- GRB 231110A: GECAM detection
- GRB 231110A: GOTO optical upper limits
- GRB 231110A: SAO RAS optical observations
- GRB 231110A: Swift-XRT afterglow detection
- GRB231111A: YAHPT Observations
- GRB231111A: GIT confirmation of the optical afterglow
- GRB 231111A: MASTER OT earlier detection
- GRB 231111A: Nanshan/HMT optical observations
- GRB 231111A: Swift detection of a burst with an optical counterpart
- Swift GRB231111.60: Global MASTER-Net observations report
- GRB231110A: WFST Observation and upper limits
- Swift GRB231110.89: Global MASTER-Net observations report
- GRB 231110A: Swift detection of a burst
- LIGO/Virgo/KAGRA S231110g: Updated Sky localization
- LIGO/Virgo/KAGRA S231110g: Identification of a GW compact binary merger candidate
- GRB 231109A: Fermi GBM Final Localization
- IceCube-231103A: No candidates from the Zwicky Transient Facility
- LIGO/Virgo/KAGRA S231108u: Updated Sky localization
- Fermi trigger No 721204446: Global MASTER-Net observations report
- Fermi GRB 231108A: Global MASTER-Net observations report
- GRB 231108A: Fermi GBM Final Real-time Localization
- LIGO/Virgo/KAGRA O4 Landscape
- LIGO/Virgo/KAGRA S231108u: Identification of a GW compact binary merger candidate
- GRB 231106A: AstroSat CZTI detection
- GRB 231106A: CALET Gamma-Ray Burst Monitor detection
- GRB 231104A: Swift-BAT refined analysis
- Fermi trigger No 721006392: Global MASTER-Net observations report
- Fermi Gamma-ray Burst Monitor trigger 231107654 / 721064512 is not a GRB
- GRB 231104A: FRAM-ORM optical limit
- LIGO/Virgo/KAGRA S231102w: Upper limits from Swift/BAT-GUANO
- Fermi GRB 231106A: Global MASTER-Net observations report
- GRB 231104A: Wendelstein Optical/Infrared Observations
- GRB 231104A: NuSTAR Observation of the prompt emission
- GRB 231106A: Fermi GBM Final Real-time Localization
- GRB 231104A: 3.6m DOT optical upper limit
- IceCube-231103A: Upper limits from a search for additional neutrino events in IceCube
- LIGO/Virgo/KAGRA S231106y: one counterpart neutrino candidate from IceCube neutrino searches
- Fermi-LAT gamma-ray observations of IceCube-231103A
- GRB 231104A: NOT upper limit
- GRB 231104A: Fermi GBM Observation
- GRB 231104B: Fermi GBM Final Real-time Localization
- Fermi GRB 231103A: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S231104ac: Updated Sky localization
- GRB 231104A: AKO Upper Limit
- GRB 231104A: AstroSat CZTI detection
- GRB 231104A: Swift-XRT refined Analysis
- GRB 231104A: Fermi-LAT detection
- LIGO/Virgo/KAGRA S231104ac: Identification of a GW compact binary merger candidate
- GRB 231104A: Swift/UVOT Upper Limits
- GRB 231104A: Enhanced Swift-XRT position
- GRB231104A: LCOGT Optical Upper Limits
- GRB 231104A: Swift detection of a bright burst
- GRB 231104A: Fermi GBM Final Real-time Localization
- Swift GRB231104.07: Global MASTER-Net observations report
- IceCube Alert 231103.39: Global MASTER-Net observations report
- GRB 231103A: Fermi GBM Final Real-time Localization
- IceCube-231103A - IceCube observation of a high-energy neutrino candidate track-like event
- Fermi-LAT gamma-ray observations of IceCube-231027A
- LIGO/Virgo/KAGRA S231102w: Updated Sky localization
- LIGO/Virgo/KAGRA S231102i: Global MASTER-Net observations report
- GRB 231101A: Glowbug gamma-ray detection