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').
18802 results found.
- IPN triangulation of GRB 240410A
- EP240413a: possible detection of the X-ray emission with EP-FXT after 14 hours
- EP240414a: EP-WXT detection of a fast X-ray transient
- IPN triangulation of GRB 240411A
- GRB 240414A : MITSuME Akeno optical upper limits
- EP240413a: EP-WXT detection of a fast X-ray transient
- GRB 240414A : OHP/T193 redshift determination
- GRB 240414A : OHP/T193 optical counterpart detection
- GRB 240414A: Swift detection of a burst
- GRB 240411B: CrAO/ZTSh optical observations
- GRB 240411B: Kinder observations with Lulin observatory
- LIGO/Virgo/Kagra S240413p: NED Galaxies in the Localization Volume
- LIGO/Virgo/KAGRA S240413p: Identification of a GW compact binary merger candidate
- GRB 240411B: HiPERCAM/GTC observation
- GRB 240411B: 1.3m DFOT Optical observations
- GRB 240411B: OHP/T193 optical observations
- GRB 240405A: Glowbug gamma-ray detection
- GRB 240411B: Enhanced Swift-XRT position
- GRB 240411B: LCO optical afterglow detection
- GRB 240411B: Swift detection of a burst
- EP240408a: Upper limits from GECAM-B Observation
- EP240408a: EP-WXT detection of a fast X-ray transient
- Swift Trigger 1220736: detection of 4U 1543-62.
- GRB 240408B: AstroSat CZTI detection
- GRB 240402C: Glowbug gamma-ray detection
- Swift satellite resumes pointed science observations
- GRB 240403B: Glowbug gamma-ray detection
- GRB 240403A: Glowbug gamma-ray detection
- LXT 240402A/GRB 240402B: Glowbug gamma-ray detection
- X-ray transient LXT 240402A: WFST optical upper limits
- Konus-Wind detection of LXT 240402A/GRB 240402B
- GRB/FXT 240402B: Kinder optical counterpart candidate
- X-ray transient LXT240402A: AST3-3 optical upper limits
- GRB 240402B: GECAM-C detection
- X-ray transient EP240331a: Kinder optical upper limits
- Transient EP240315a: J-band observations of AT2024eju with WIRC
- X-ray transient EP20240331a: MeerLICHT optical upper limits
- GRB 240329A: Glowbug gamma-ray detection
- X-ray transient EP240315a: continued ATCA monitoring
- GRB 240328C: Glowbug gamma-ray detection
- X-ray transient EP 240315a: Second epoch Chandra observations
- X-ray transient EP240315a: Ondrejov D50 optical limit
- Transient EPW20240219aa: REM optical/NIR further observations
- GRB 240320A: Glowbug gamma-ray detection
- X-ray transient EP240315a: ATCA detection of radio counterpart
- IPN triangulation of GRB 240315C (consistent with a fast X-ray transient EP240315a)
- X-ray transient EP 240315a: Chandra observations
- 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
- X-ray transient EP240315a: 3.6 m TNG NIR detection
- X-ray transient EP240315a/AT2024eju: TShAO (Zeiss-1000) observatory optical upper limit
- 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
- X-ray transient EP240315a: orphan FXT?
- X-ray transient EP240315a: Kinder follow-up observations for AT 2024eju with Lulin observatory
- X-ray transient EP240315a: VLT/X-shooter spectroscopic redshift of z = 4.859
- X-ray transient EP240315a: Nanshan/HMT optical upper limit
- AT2024eju: followup observations with Liverpool Telescope suggest a fading transient
- Einstein Probe detected of a fast X-ray transient EP240315a
- Changes to the Fermi-GBM Triggering Thresholds
- GRB240204A: VIRT optical upper limit
- GRB 240312A: Glowbug gamma-ray detection
- GRB 240303C: VZLUSAT-2 detection
- GRB 240310A: MASTER OT J200702.72-263928.7 inside 3sigma
- GRB 240310B: Glowbug gamma-ray detection
- Swift GRB240309.61: Global MASTER-Net observations report
- GRB 231215A: further radio observations with the VLA
- GRB 240229A: Glowbug gamma-ray detection
- GRB 240227A (short): Glowbug gamma-ray detection
- GRB 231028C: Glowbug gamma-ray confirmation of a prior burst
- Konus-Wind detection of GRB 240227A (short/hard)
- Improved IPN triangulation of GRB 240227A (short)
- IPN triangulation of GRB 240229A
- Swift Trigger 1218701: Yes, we triggered on Swift J151857.0-572147 again
- Swift Trigger 1218696: Another trigger on Swift J151857.0-572147
- GRB240218A: ATCA observation of the radio counterpart
- Transient EPW20240219aa: Optical observations with LDT
- Konus-Wind detection of GRB 240303B
- Swift Trigger 1218645: Another detection of Swift J151857.0-572147
- IPN triangulation of GRB 240303B
- GRB 240303B: Fermi GBM Detection
- GRB 240225B: Swift-XRT afterglow detection
- Swift detection of Swift J151857.0-572147
- GRB 240303B: CALET Gamma-Ray Burst Monitor detection
- GRB 240215A: Swift-XRT afterglow detection
- GRB 240303A: Swift detection of a burst
- GRB 240225B: Glowbug gamma-ray detection
- GRB 240225C: Glowbug gamma-ray detection
- GRB 240225A (short): Glowbug gamma-ray detection
- GRB 240229A: DDOTI Upper Limits on the Afterglow
- GRB 240218A: NOEMA upper limit
- GRB 240225B: further SAO RAS optical observations
- Konus-Wind detection of GRB 240225B (long)
- GRB 240225B: VLT/X-shooter redshift