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').
10045 results found.
- LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations
- GRB 240414A: radio detection with the VLA
- GRB 240419B : MITSuME Akeno optical upper limits
- GRB 240421B: Swift/UVOT Upper Limits
- EP240420a: Xinglong decaying optical counterpart
- EP240420a: detection of fading X-ray emission with refined position by EP-FXT
- GRB 240419B: Swift/UVOT Upper Limits
- EP240420a: EP-WXT detection of a fast X-ray transient
- EP240414A: Terskol Zeiss-2000 optical upper limit
- GRB 240418A: Swift/UVOT Upper Limits
- GRB 240419A: VLT/UVES redshift of z = 5.178
- GRB 240419A: VLT optical afterglow detection
- GRB 240418A: TSHAO Zeiss-1000 optical upper limit
- EP240417a: EP-WXT detection of a fast X-ray transient
- LIGO/Virgo/KAGRA S240413p: X-ray upper limits from EP-WXT for the candidate AGN counterpart
- EP240416A: Terskol Zeiss-2000 optical upper limit
- EP240416A: Khureltogoot optical upper limit
- EP 240416a: Xinglong and NOT decaying optical counterpart
- EP240416a: EP-WXT detection of a fast X-ray transient
- GRB 240414A: AbAO optical upprer limit
- EP240414a: EP-FXT follow-up observation
- GRB 240415A: OHP/T193 optical observations
- GRB 240415A: SAO RAS optical observations
- GRB 240415A: Mondy optical transient detection (photometry correction in GCN 36118 )
- GRB 240415A: Mondy optical transient detection
- LXT 240402A/GRB 240402B: Swift follow-up observations
- GRB 240414A: Mondy optical observations
- X-ray transient EP 240414a - GTC spectroscopic observations
- EP240413a: possible detection of the X-ray emission with EP-FXT after 14 hours
- EP240414a: EP-WXT detection of a fast X-ray transient
- GRB 240414A : MITSuME Akeno optical upper limits
- GRB 240414A: Redshift confirmation from GTC/OSIRIS+
- EP240413a: EP-WXT detection of a fast X-ray transient
- GRB 240411B: CrAO/ZTSh optical observations
- GRB 240411B: HiPERCAM/GTC observation
- GRB 240411A: GRBAlpha detection
- GRB 240408B: GRBAlpha detection
- EP240408a: Swift follow-up observation
- GRB 240405A: GRBAlpha detection
- EP240408a: EP-WXT detection of a fast X-ray transient
- Swift Trigger 1220736: detection of 4U 1543-62.
- IceCube-240327B: GRANDMA/Kilonova-Catcher observations of 4FGL J0555.9+0030 and optical upper limits
- GRB 240402C: CALET Gamma-Ray Burst Monitor detection
- GRB 240402C: GRBAlpha detection
- GRB 240331A: GRBAlpha detection
- IceCube-240327B: GRANDMA observations of 4FGL J0555.9+0030
- LXT 240402A: EP-FXT detection of the X-ray afterglow
- X-ray transient LXT 240402A: LEIA detection
- X-ray transient EP240331A: GRANDMA-Kilonova catcher optical upper limit
- IBAS Alert n.10651 not a GRB
- GRB 240329A: GRBAlpha detection
- X-ray transient EP240315a/AT2024eju: TShAO (Zeiss-1000) observatory optical upper limit
- X-ray transient EP240315a: EP-FXT detection of the X-ray afterglow
- X-ray transient EP240315a: Kitab observatory optical upper limitns
- X-ray transient EP240315a: GROND J-band detection
- X-ray transient EP240315a: ATLAS detection of a possible optical counterpart AT2024eju
- Einstein Probe detected of a fast X-ray transient EP240315a
- GRB240204A: VIRT optical upper limit
- GRB 240303C: VZLUSAT-2 detection
- GRB 240310A: MASTER OT J200702.72-263928.7 inside 3sigma
- GRB 240309A: MAXI/GSC detection
- GRB 231215A: further radio observations with the VLA
- GRB 240229A: GRBAlpha detection
- GRB 240303B: VZLUSAT-2 detection
- GRB 240229A: VZLUSAT-2 detection
- GRB 240303B: CALET Gamma-Ray Burst Monitor detection
- GRB 240229A: CALET Gamma-Ray Burst Monitor detection
- GRB 240225B : MITSuME Akeno optical afterglow candidate detection
- GRB 240226A: GRBAlpha detection
- GRB 240225B: Mondy afterglow observations
- GRB 240218A: CMO SAI NIR upper limit
- GRB 240225B: CALET Gamma-Ray Burst Monitor detection
- GRB 240225C: CALET Gamma-Ray Burst Monitor detection
- GRB 240225C: GRBAlpha detection
- GRB 240225B: MAXI/GSC detection
- GRB 240222A: GRBAlpha detection
- Transient EPW20240219aa: Mondy optical observations
- Fermi GBM Sub-Threshold Detection of EPW20240219aa as a likely GRB
- GRB 240218A: VLT/X-shooter redshift of z = 6.782
- GRB 240216A: GRBAlpha detection
- GRB 240215B: GRBAlpha detection
- GRB 240218A: REM detection of a NIR afterglow candidate
- GRB 240213A: GRBAlpha detection
- Swift Triggers 12156887-1215690 are not astrophysical events.
- The AGILE satellite ceased operations and re-entered today into the atmosphere
- The AGILE satellite ceased operations and re-entered today into the atmosphere
- GRB240209A: OHP/T193 detection of the GOTO afterglow candidate AT2024cew / GOTO24pw
- GRB 240214A/1H 0451-560: MAXI/GSC detection
- GRB 240205B: VLT/X-shooter redshift
- GRB 240205B: CALET Gamma-Ray Burst Monitor detection
- GRB 240204A: Mondy optical afterglow observations
- GRB 240204A: Mondy optical afterglow candidate
- GRB 240128A: GRBAlpha detection
- GRB 240128A: CALET Gamma-Ray Burst Monitor detection
- GRB 240128A: MAXI/GSC detection
- GRB 240125A: GRBAlpha detection
- GRB 240123C: GRBAlpha detection
- GRB 240125A: CALET Gamma-Ray Burst Monitor detection
- GRB 240123A: GRBAlpha detection