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').
17114 results found.
- LXT 240402A/GRB 240402B: Swift follow-up observations
- GRB 240414A: Mondy optical observations
- GRB 240415A: Prompt Swift-XRT observations
- GRB 240415A: Swift detection of a burst
- GRB 240414A: Swift-XRT refined Analysis
- GRB 240414A: Enhanced Swift-XRT position
- GRB 240414A: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
- GRB 240414A: Skynet Optical Afterglow Observations
- Swift GRB 240414A: Global MASTER-Net observations report
- IPN triangulation of GRB 240410A
- IPN triangulation of GRB 240411A
- GRB 240414A : MITSuME Akeno optical upper limits
- GRB 240414A: Swift detection of a burst
- GRB 240411B: Swift-BAT refined analysis
- GRB 240411B: Swift-XRT refined Analysis
- GRB 240411B: 1.3m DFOT Optical observations
- GRB 240411B: Enhanced Swift-XRT position
- GRB 240411B: Swift detection of a burst
- EP240408A: MASTER optical observations
- EP240408a: GROND detection of a candidate counterpart
- EP240408a: Swift follow-up observation
- Swift Trigger 1220736: detection of 4U 1543-62.
- Swift satellite resumes pointed science observations
- GRB 240318A: Fermi GBM Observation
- Konus-Wind detection of GRB 240315C (possible counterpart of EP240315a)
- GRB 240315C / X-ray transient EP240315a: Swift/BAT detection
- GRB 240318A: Swift/BAT-GUANO detection of a burst outside the coded FOV
- IPN triangulation of GRB 240315C (consistent with a fast X-ray transient EP240315a)
- GRB 240317B: Swift/BAT-GUANO Angular Error Correction
- GRB 240317B: Fermi GBM Observation
- Swift satellite in safe mode
- GRB 240317B: Swift/BAT-GUANO arcminute localization of a burst
- Einstein Probe detected of a fast X-ray transient EP240315a
- GRID detection of GRB 240306A
- Swift Triggers 1220155, 1220156, 1220157, 1220158, 1220160 and 1220161 were not astrophysical
- Swift Triggers 1220093, 1220094, 1220095 and 1220096 are not astrophysical
- Swift Triggers 1220090, 1220091 and 1220092 are not astrophysical
- 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
- Swift Trigger 1219874 is not astrophysical
- Swift GRB240309.61: Global MASTER-Net observations report
- Swift Trigger 1219325 is not a GRB
- GRB 240306A: Fermi GBM observation
- Konus-Wind detection of GRB 231118A
- GRB 240306A: AstroSat CZTI detection
- GRB 240306A: Swift/BAT-GUANO detection of a burst
- GRB 240305A: Fermi GBM observation
- Swift GRB240305.18: Global MASTER-Net observations report
- Swift GRB240305.16: Global MASTER-Net observations report
- GRB 240305A: Swift/BAT-GUANO arcminute localization of a burst
- GRB 240218A: Chandra Detection and Jet Break Confirmation
- Swift Trigger 1218701: Yes, we triggered on Swift J151857.0-572147 again
- Swift Trigger 1218696: Another trigger on Swift J151857.0-572147
- Swift Trigger 1218645: Another detection of Swift J151857.0-572147
- Swift J151857.0-572147: Swift-BAT refined analysis
- GRB 240225B: Swift-XRT afterglow detection
- Swift detection of Swift J151857.0-572147
- Swift GRB 240303A: Global MASTER-Net observations report
- Swift J151857.0-572147: Confirmation of a new galactic transient
- GRB 240215A: Swift-XRT afterglow detection
- GRB 240303A: Swift detection of a burst
- GRB 240225A (short): Glowbug gamma-ray detection
- Swift BAT Triggers 1218081 and 1218082 are not astrophysical
- GRB 240225B: Swift ToO observations
- GRB 240225B: 3.6m DOT observation
- Swift J1727.8-1613 (GRB 230824A): Madrona Peak Observatory - optical follow-up
- Swift Trigger 1217799 is not a GRB
- Swift-BAT triggers 1217733 - 1217736 are not astrophysical events
- Swift-BAT triggers 1217729-1217732 are not astrophysical
- GRB 240225B: Nanshan/HMT optical afterglow detection
- GRB 240225B: Swift-XRT observations
- GRB 240225B: GOTO detection of a candidate optical afterglow
- GRB 240225B: Tiled Swift observations
- Transient EPW20240219aa: Xinglong-2.16m optical upper limit
- GRB 240225A: Swift/BAT-GUANO detection of a short burst
- GRB 240222A: GRBAlpha detection
- Swift-BAT triggers 1217218-1217222 are not astrophysical
- Transient EPW20240219aa: Mondy optical observations
- Insight-HXMT/HE Sub-Threshold Detection of Transient EPW20240219aa
- Swift BAT Sub-Threshold Detection of EPW20240219aa
- GRB 240222A: GECAM detection of a burst
- GRB 240222A: Swift-BAT refined analysis
- GRB 240222A: Swift-XRT refined Analysis
- Swift-BAT triggers 1216907-1216911 are not astrophysical
- GRB 240222A: Fermi GBM Observation
- GRB 240222A: Swift/UVOT Upper Limits
- Swift GRB 240222A: Global MASTER-Net observations report
- Swift Trigger 1216864 is not an astrophysical event
- GRB 240222A: Swift detection of a burst
- Swift-BAT triggers 1216751 and 1216753 are not astrophysical events
- Swift-BAT triggers 1216743-1216748 are not astrophysical
- Swift GRB240221.92: Global MASTER-Net observations report
- GRB 240218A: MeerLICHT upper limits
- GRB 240215B: Fermi GBM Observation
- GRB 240218A: LBT H-band detection
- GRB 240218A: Swift-BAT refined analysis
- Konus-Wind detection of GRB 240218A
- GRB 240218A: Swift-XRT refined Analysis
- GRB 240218A: VLT/X-shooter redshift of z = 6.782