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').
Advanced Search
To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.
Advanced Search Examples (click to copy):
subject:"Swift"body:"GRB"submitter:"Judith Racusin"- Fermi GRB 240320A: Global MASTER-Net observations report
- Konus-Wind detection of GRB 240315C (possible counterpart of EP240315a)
- GRB 240315C / X-ray transient EP240315a: Swift/BAT detection
- Fermi trigger No 732657380: Global MASTER-Net observations report
- GRB 240318A: Swift/BAT-GUANO detection of a burst outside the coded FOV
- X-ray transient EP240315a: ATCA detection of radio counterpart
- GRB 240320A: Fermi GBM Final Real-time Localization
- IPN triangulation of GRB 240315C (consistent with a fast X-ray transient EP240315a)
- GRB 240317B: Swift/BAT-GUANO Angular Error Correction
- Fermi Gamma-ray Burst Monitor trigger 732299243/240316686 is not a GRB
- X-ray transient EP 240315a: Chandra observations
- X-ray transient EP240315a: GTC/HiPERCAM photometry
- X-ray transient EP240315a: MeerKAT radio detection
- X-ray transient EP240315a: GTC/OSIRIS spectroscopic redshift confirmation
- GRB 240318A: Glowbug gamma-ray detection
- GRB 240317C: Glowbug gamma-ray detection
- GRB 240318B: Glowbug gamma-ray detection
- X-ray transient EP240315a: PRIME near infrared detection
- GRB 240317B: Fermi GBM Observation
- X-ray transient EP240315a: 3.6 m TNG NIR detection
- Swift satellite in safe mode
- X-ray transient EP240315a/AT2024eju: TShAO (Zeiss-1000) observatory optical upper limit
- X-ray transient EP240315a: EP-FXT detection of the X-ray afterglow
- Fermi GRB 240318A: Global MASTER-Net observations report
- GRB 240318A: Fermi GBM Final Real-time Localization
- GRB 240317B: Swift/BAT-GUANO arcminute localization of a burst
- GRB 240317A: AstroSat CZTI detection
- GRB 240315B: AstroSat CZTI detection
- X-ray transient EP240315a: Kitab observatory optical upper limitns
- X-ray transient EP240315a: Montarrenti Observatory optical upper limit
- Fermi GRB 240317B: Global MASTER-Net observations report
- Fermi GRB 240317A: Global MASTER-Net observations report
- GRB 240317B: Fermi GBM Final Real-time Localization
- X-ray transient EP240315a: orphan FXT?
- GRB 240317A: Fermi GBM Final Real-time Localization
- X-ray transient EP240315a: Kinder follow-up observations for AT 2024eju with Lulin observatory
- X-ray transient EP240315a: GROND J-band detection
- X-ray transient EP240315a: VLT/X-shooter spectroscopic redshift of z = 4.859
- X-ray transient EP240315a: Nanshan/HMT optical upper limit
- Fermi trigger No 732299243: Global MASTER-Net observations report
- AT2024eju: followup observations with Liverpool Telescope suggest a fading transient
- X-ray transient EP240315a: ATLAS detection of a possible optical counterpart AT2024eju
- Einstein Probe detected of a fast X-ray transient EP240315a
- GRID detection of GRB 240306A
- Changes to the Fermi-GBM Triggering Thresholds
- Swift Triggers 1220155, 1220156, 1220157, 1220158, 1220160 and 1220161 were not astrophysical
- GRB 240315A: Fermi GBM Final Real-time Localization
- Swift Triggers 1220093, 1220094, 1220095 and 1220096 are not astrophysical
- Swift Triggers 1220090, 1220091 and 1220092 are not astrophysical
- Fermi GRB 240314A: Global MASTER-Net observations report
- GRB 240314A: Fermi GBM Final Real-time Localization
- GRB240204A: VIRT optical upper limit
- GRB 240312A: Glowbug gamma-ray detection
- Swift triggers 1219917, 1219917 and 1219922 were not astrophysical
- Swift Trigger 1219909 and 1219910 are not a astrophysical
- Swift Trigger 1219905 is not a GRB
- GRB 240312A: GECAM detection of a long burst
- Swift Trigger 1219874 is not astrophysical
- GRB 240303C: VZLUSAT-2 detection
- GRB 240310A: MASTER OT J200702.72-263928.7 inside 3sigma
- Fermi trigger No 731839490: Global MASTER-Net observations report
- Fermi-LAT gamma-ray observations of IceCube-240307A
- GRB 240310B: Glowbug gamma-ray detection
- Fermi GRB 240310A: Global MASTER-Net observations report
- Swift GRB240309.61: Global MASTER-Net observations report
- GRB 240310A: Fermi GBM Final Real-time Localization
- GRB 240309A: MAXI/GSC detection
- Swift Trigger 1219325 is not a GRB
- IceCube-240307A: Upper limits from a search for additional neutrino events in IceCube
- GRID detection of GRB 240229A (Updated Report)
- GRID detection of GRB 240229A
- GRB 240308A: Fermi GBM Final Localization
- Fermi trigger No 731571927: Global MASTER-Net observations report
- GRB 231215A: further radio observations with the VLA
- GRB 240306A: Fermi GBM observation
- IceCube-240307A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 240229A: Glowbug gamma-ray detection
- GRB 240227A (short): Glowbug gamma-ray detection
- IceCube Alert 240307.32: Global MASTER-Net observations report
- GRB 240229A: GRBAlpha detection
- Konus-Wind detection of GRB 231118A
- GRB 240306A: AstroSat CZTI detection
- Fermi GRB 240306A: Global MASTER-Net observations report
- Fermi GRB 240305A: Global MASTER-Net observations report
- GRB 240306A: Swift/BAT-GUANO detection of a burst
- GRB 240305A: Fermi GBM observation
- Fermi-LAT gamma-ray observations of IceCube-240229A
- GRB 240305C: AstroSat CZTI detection of a short burst
- GRB 240306A: Fermi GBM Final Real-time Localization
- Swift GRB240305.18: Global MASTER-Net observations report
- Swift GRB240305.16: Global MASTER-Net observations report
- Fermi GRB 240305C: Global MASTER-Net observations report
- GRB 240305C: Fermi GBM Final Real-time Localization
- GRB 240305A: Swift/BAT-GUANO arcminute localization of a burst
- GRB 231028C: Glowbug gamma-ray confirmation of a prior burst
- GRB 240218A: ALMA detection
- GRB 240218A: Chandra Detection and Jet Break Confirmation
- GRB 240305B: Fermi GBM Final Localization
- Fermi trigger No 731303574: Global MASTER-Net observations report
- Konus-Wind detection of GRB 240227A (short/hard)