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 231024A: GRANDMA observations of AT2023vuc/GOTO23baj candidate
- LIGO/Virgo/KAGRA S231102w: Identification of a GW compact binary merger candidate
- New Swift-BAT/GUANO and IceCube Notices Available via GCN Kafka
- Fermi trigger No 720498201: Global MASTER-Net observations report
- GRB 231101A: Fermi GBM Final Real-time Localization
- GRB 231030B: GRBAlpha detection
- GRB 231028B: VZLUSAT-2 detection
- Fermi trigger No 720415645: Global MASTER-Net observations report
- GRB 231030B: Fermi GBM Detection
- GRB 231030B: AstroSat CZTI detection
- Fermi GRB 231030B: Global MASTER-Net observations report
- IPN triangulation of GRB 231020A
- GRB 231030B: BALROG localization (Fermi Trigger 720388704 / GRB 231030832)
- GRB 231030B: Fermi GBM Final Real-time Localization
- GRB 231028A: Swift-BAT refined analysis
- IceCube-231027A: Upper limits from a search for additional neutrino events in IceCube
- LIGO/Virgo/KAGRA S231029y: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S231030av: Retraction of GW compact binary merger candidate
- GRB 231024A: AKO Optical Counterpart Candidate
- GRB 231028A: CALET Gamma-Ray Burst Monitor detection
- Fermi GRB 231030A: Global MASTER-Net observations report
- GRB 231030A: Fermi GBM Final Real-time Localization
- LIGO/Virgo/KAGRA S231029y: One counterpart neutrino candidate from IceCube neutrino searches
- LIGO/Virgo/KAGRA S231029ai: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S231029y: Identification of a GW compact binary merger candidate
- GRID detection of GRB 231020A
- LIGO/Virgo/KAGRA S231029k: Global MASTER-Net observations report
- GRB 231028A: AstroSat CZTI detection
- GRB 231028A: Glowbug gamma-ray detection
- GRB 231028A: Fermi GBM Detection
- Fermi trigger No 720224759: Global MASTER-Net observations report
- Swift GRB 231028A: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S231028bg: Updated Sky localization
- LIGO/Virgo/KAGRA S231028bg: Identification of a GW compact binary merger candidate
- GRB 231028A: Swift detection of a burst
- GRB 231028A: Fermi GBM Final Real-time Localization
- IceCube Alert 231027.18: Global MASTER-Net observations report
- IceCube-231027A - IceCube observation of a high-energy neutrino candidate track-like event
- LIGO/Virgo/KAGRA S231025t: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S231025a: Global MASTER-Net observations report
- GRB 231019A: Glowbug gamma-ray detection
- IC231004A: GRANDMA observations of AT2023uqf/ZTF23abidzvf candidate
- GRB 231025A: Fermi GBM Observation
- GRB 231024A: Fermi GBM Observation
- GRB 231025A: Swift/BAT-GUANO detection of a likely short burst
- GRB 231025A: Fermi GBM Final Localization
- GRB 231024A: X-shooter spectroscopy of AT2023vuc/GOTO23baj reveals a young supernova with flash ionisation features
- GRB 231024A: LCOGT and ZTF detections of the GOTO optical counterpart candidate
- GRB 231020A: AstroSat CZTI detection
- GRB 231020B: AstroSat CZTI detection
- GRB 231024A: GOTO optical counterpart candidate
- LIGO/Virgo/KAGRA S231025a: two counterpart neutrino candidates from IceCube neutrino searches
- GRB 231024A: Fermi GBM Final Localization
- Fermi trigger No 719846439: Global MASTER-Net observations report
- The photometry of the transient in Messier 31 field: GMG observation
- GRB 231018A: Swift/BAT-GUANO detection of a long burst outside the coded FOV
- LIGO/Virgo/KAGRA S231020bw: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S231021az: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S231020bw: Updated Sky localization
- GRB 231020A: Fermi GBM Detection
- GRID detection of GRB 231004A
- GRB 231017A: Mondy optical observations. A possible candidate for an afterglow or host galaxy.
- GRB 231019A: VZLUSAT-2 detection
- GRB 231018A: VZLUSAT-2 detection
- GRB 231020B: BALROG localization (Fermi Trigger 719530557 / GRB 231020900)
- LIGO/Virgo/KAGRA S231020ba: Updated Sky localization and EM Bright Classification
- GRB 231020B: Fermi GBM Final Real-time Localization
- GRB 231020A: BALROG localization (Fermi Trigger / GRB 231020790)
- LIGO/Virgo/KAGRA S231020ba: Upper limits from Fermi-GBM Observations
- GRB 231015A: NuSTAR Detection of Prompt Emission
- Fermi GRB 231020A: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S231020bw: Identification of a GW compact binary merger candidate
- GRB 231020A: Fermi GBM Final Real-time Localization
- GRB 231012A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 705709044)
- LIGO/Virgo/KAGRA S231020ba: Coverage and upper limits from MAXI/GSC observations
- GRB 231017A: 1.3m DFOT Optical upper limit
- LIGO/Virgo/KAGRA S231020ba: Identification of a GW compact binary merger candidate
- IceCube-231004A: Upper limits from Fermi-GBM Observations
- GRB 231018A: GRBAlpha detection
- GRB 231018A: CALET Gamma-Ray Burst Monitor detection
- Fermi GRB 231019A: Global MASTER-Net observations report
- GRB 231018A: Glowbug gamma-ray detection
- Konus-Wind detection of GRB 231018A
- IPN triangulation of GRB 231018A
- GRB 231017A: Swift/UVOT Upper Limit
- GRB 230911C: ATCA detection of possible radio counterpart
- GRB 231019A: Fermi GBM Final Real-time Localization
- GRB 231017A: GOTO optical upper limits
- GRB 231017A: JinShan optical upper limit
- GRB 231018A: GROWTH-India Follow-Up of a Fermi Long GRB
- LIGO/Virgo/KAGRA S231018cb: One counterpart neutrino candidate event from an IceCube neutrino search
- IC231004A: Classification of AT2023uqf/ZTF23abidzvf as a rapidly-evolving supernova with CSM interaction
- GRB 231017A: Las Cumbres optical upper limit
- GRB 231015A: Glowbug gamma-ray detection
- GRB 231017A: LCOGT Optical Upper Limits
- GRB231017A: GROWTH-India upper limits on the optical afterglow
- GRB 231015A: AstroSat CZTI detection
- GRB 231018A: Fermi GBM Detection
- GRB 231017A: Fermi GBM Detection
- GRB 231017A: Swift-XRT observations