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').
- GRB 240615A: J-band upper limits from WINTER
- GRB 240615A: Fermi GBM Observation
- LIGO/Virgo/KAGRA S240615ea: Updated Sky localization
- GRB 240615A: Swift-XRT observations
- GRB 240615A: GECAM detection
- X-ray transient EP240414a: Chandra late time observation
- GRB 240615A: FLWO-1.2m optical upper limits
- Fermi trigger No 740221779: Global MASTER-Net observations report
- Fermi GRB 240616A: Global MASTER-Net observations report
- Konus-Wind detection of GRB 240615A (short/hard)
- GRB 240615A: GOTO optical upper limits
- Fermi trigger No 740166710: Global MASTER-Net observations report
- GRB 240616A: Fermi GBM Final Real-time Localization
- GRB 240615A: Swift ToO observations
- GRB 240615A: Swift/BAT-GUANO arcminute localization of a short burst
- GRB 240615A: Fermi GBM Final Real-time Localization
- LIGO/Virgo/KAGRA S240615ea: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240615dg: Identification of a GW compact binary merger candidate
- GRB 240603A: VZLUSAT-2 detection
- GRB 240612A: GRBAlpha detection
- GRB 240613A: Fermi GBM Final Real-time Localization
- Fermi GRB 240612B: Global MASTER-Net observations report
- Fermi GRB 240612A: Global MASTER-Net observations report
- GRB 240612B: Fermi GBM Final Real-time Localization
- GRB 240612A: Fermi GBM Final Real-time Localization
- GRB 240607A: GECAM detection of a bright long burst
- Fermi GRB 240611A: Global MASTER-Net observations report
- Konus-Wind detection of GRB 240607A
- GRB 240611A: Fermi GBM Final Real-time Localization
- EXO 0748-676: Swift-BAT refined analysis
- GRB240529A: 3.6m TNG NIR detection 8d after the burst
- GRB 240529A: LBT optical detection and late temporal decay
- GRB 240529A : MITSuME Akeno optical afterglow detection
- Trigger 1236151: Swift detection of EXO 0748-676
- Fermi GRB 240610A: Global MASTER-Net observations report
- GRB 240610A: Fermi GBM Final Real-time Localization
- IPN triangulation of GRB 240607A
- Fermi Gamma-ray Burst Monitor trigger 739632045/240609556 is not a GRB
- Fermi trigger No 739632045: Global MASTER-Net observations report
- Fermi GRB 240608A: Global MASTER-Net observations report
- Konus-Wind detection of GRB 240606B
- Fermi trigger No 739506569: Global MASTER-Net observations report
- GRB 240608A: Fermi GBM Final Real-time Localization
- Fermi GRB 240607A: Global MASTER-Net observations report
- GRB 240529A: NOEMA detection
- GRB 240607A: Fermi GBM Observation
- GRB 240606B: Fermi GBM Observation
- Swift Trigger 1235109: consistent with noise and not astrophysical
- GRB 240607A: AstroSat CZTI detection of bright long burst
- GRB 240607A: Fermi GBM detection of a very bright burst
- GRB 240529A: radio detection with AMI-LA
- GRB 240607A: BALROG localization (Fermi Trigger 739450879 / GRB 240607459)
- GRB 240607A: Fermi GBM Final Real-time Localization
- GRB 240606B: GECAM-B detection a long burst
- Fermi trigger No 739373591: Global MASTER-Net observations report
- GRB 240606B: Swift-XRT afterglow detection
- Swift GRB240606.15: Global MASTER-Net observations report
- GRB 240606B: Swift ToO observations
- GRB 240606B: Swift/BAT-GUANO arcminute localization of a burst
- Konus-Wind detection of GRB 240603A
- Swift Trigger 1235109: a possible GRB 240606A
- Fermi GRB 240604A: Global MASTER-Net observations report
- IPN triangulation of GRB 240531A (short)
- Fermi GRB 240605A: Global MASTER-Net observations report
- Fermi GRB 240605C: Global MASTER-Net observations report
- Fermi Gamma-ray Burst Monitor trigger 739290883/240605607 is not a GRB
- LIGO/Virgo/KAGRA S240601co: Updated Sky localization
- GRB 240605C: Fermi GBM Final Real-time Localization
- IPN triangulation of GRB 240603A
- GRB 240605B: Fermi GBM Final Real-time Localization
- GRB 240604A: Fermi GBM Final Localization
- GRB 240605A: Fermi GBM Final Real-time Localization
- GRB 240604A: GECAM detection of a long burst
- GRB 240529A: SAO RAS optical observations
- Swift Trigger 1232755: likely consistent with noise and not astrophysical
- Fermi GRB 240603C: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S240601co: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S240530a: Upper limits from Swift/BAT-GUANO
- GRB 240603A: Fermi GBM Final Localization
- GRB 240603C: BALROG localization (Fermi Trigger 739102156 / GRB 240603423)
- GRB 240603C: Fermi GBM Final Real-time Localization
- Swift Trigger 1232465: consistent with noise
- GRB 240603B: Swift detection of a possible burst
- GRB 240529A: MASTER prompt OT detection
- GRB 240603A: GECAM detection of a short burst
- GRB 240529A: continued SAO RAS optical observations
- Fermi GRB 240602A: Global MASTER-Net observations report
- GRB 240529A: OSN optical detection
- The EP-WXT source triggered on June 1st is likely a flaring star
- GRB 240529A: further SAO RAS optical observations
- LIGO/Virgo/KAGRA S240601aj: Updated Sky localization
- GRB 240602A: Fermi GBM Final Real-time Localization
- LIGO/Virgo/KAGRA S240601co: Identification of a GW compact binary merger candidate
- Swift Trigger 1232465 is not a GRB
- GRB 240529A: AKO Optical Afterglow Follow-Up Observations
- LIGO/Virgo/KAGRA S240530a: Updated Sky localization
- LXT 240528A: GSP optical upper limit
- GRB 240529A: 1.3m DFOT Optical observations
- LIGO/Virgo/KAGRA S240527en: Updated Sky localization
- LIGO/Virgo/KAGRA S240601aj: Identification of a GW compact binary merger candidate