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').
- Fermi trigger No 740744838: Global MASTER-Net observations report
- EP240618a: NOT optical counterpart candidate
- LIGO/Virgo/KAGRA S240621em: Updated Sky localization and Source Classification
- GRB 240529A: JinShan optical observations
- LIGO/Virgo/KAGRA S240621dy: Updated Sky localization and Source Classification
- LIGO/Virgo/KAGRA S240621eb: Updated Sky localization and Source Classification
- EP240618a: GSP optical upper limit
- LIGO/Virgo/KAGRA S240622h: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240621em: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240621eb: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240621dy: Identification of a GW compact binary merger candidate
- IPN triangulation of GRB 240615A (short)
- X-ray transient EP240618a: Fermi/GBM non-detection
- GRB 240619A: GRBAlpha detection
- EP240618a: Swift/XRT upper limit
- EP240617a: tentative Swift/XRT detection of the afterglow
- GRB 240619A: Swift-XRT probable afterglow detection
- GRB 240619A: Swift ToO observations
- GRB 240619A: CALET Gamma-Ray Burst Monitor detection
- GRB 240619C: NuSTAR automated detection of the GRB
- GRB 240619A: Fermi GBM Observation
- Fermi GBM Sub-Threshold Detection of GRB 240619C
- GRB 240619A: GOTO candidate optical afterglow
- EP240618a: Abastumani optical observationsEP240618a
- GRB 240615A: NOT optical observations
- EP240618a: GRANDMA Optical Upper Limits
- GRB 240619C: AstroSat CZTI detection
- EP240618a: TRT optical upper limit
- Fermi trigger No 740474239: Global MASTER-Net observations report
- Fermi GRB 240619A: Global MASTER-Net observations report
- EP240617a: STEP/T80S optical limits
- GRB 240615A: possible transient detection from Wendelstein observations
- LIGO/Virgo S240615dg: GRANDMA/FRAM-CTA-N Observations
- LIGO/Virgo/KAGRA S240615dg: Updated Sky localization
- LIGO/Virgo/KAGRA S240618ah: Updated Sky localization
- EP240618a: OHP/T193 MISTRAL i' and Y band upper limits
- EP240618a: BOOTES-6/DPRT optical upper limit
- Fermi Gamma-ray Burst Monitor trigger 740474239/240619304 is not a GRB
- GRB 240619B: Fermi GBM Final Real-time Localization
- LIGO/Virgo S240615dg: Swift XRT observations, 39 X-ray sources
- Fermi trigger No 740430582: Global MASTER-Net observations report
- GRB240615A: 1.3m DFOT optical upper limit
- GRB 240619A: BALROG localization (Fermi Trigger 740461416 / GRB 240619155)
- GRB 240619A: Fermi GBM Final Real-time Localization
- EP240617a: BOOTES-6/DPRT optical upper limit
- EP240617a is likely a GRB event
- EP240617a: EP-WXT detection of a fast X-ray transient
- EP240618a: EP-WXT detection of a fast X-ray transient and EP-FXT quick follow-up
- LIGO/Virgo/KAGRA S240618ah: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240615ea: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S240615dg: Upper limits from Swift/BAT-GUANO
- 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