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').
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"32533 results found.
- X-ray transient EP240315a: second epoch e-MERLIN radio observations
- GRB 240405A: GRBAlpha detection
- IceCube-240327B: GRANDMA/Kilonova-Catcher observations of 4FGL J0555.9+0030 and optical upper limits
- Fermi GRB 240408A: Global MASTER-Net observations report
- GRB 240402C: CALET Gamma-Ray Burst Monitor detection
- Fermi GRB 240407A: Global MASTER-Net observations report
- Fermi-LAT gamma-ray observations of IceCube-240327B
- Fermi-LAT gamma-ray observations of IceCube-240327A
- LXT 240402A/GRB 240402B: rest-frame energetics from Konus-Wind observation
- Fermi GRB 240405B: Global MASTER-Net observations report
- GRB 240402C: Glowbug gamma-ray detection
- GRB 240331A: GRBAlpha detection
- LXT 240402A/GRB 240402B: GECAM-C refined analysis
- Swift satellite resumes pointed science observations
- 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
- IceCube-240327B: GRANDMA observations of 4FGL J0555.9+0030
- GRB/FXT 240402B: VLT/FORS2 optical afterglow candidate
- X-ray transient LXT240402A: AST3-3 optical upper limits
- LXT 240402A: EP-FXT detection of the X-ray afterglow
- Fermi GRB 240404A: Global MASTER-Net observations report
- LXT 240402A: MASTER optical observations with AGN in error-box
- GRB 240402B: GWAC-F50A optical upper limit
- GRB 240402B: GECAM-C detection
- Fermi GRB 240402A: Global MASTER-Net observations report
- X-ray transient EP240331a: Kinder optical upper limits
- X-ray transient EP240331A: GRANDMA-Kilonova catcher optical upper limit
- EP240331A: MASTER optical observations
- Transient EP240315a: J-band observations of AT2024eju with WIRC
- IceCube-240327B: Upper limits from a search for additional neutrino events in IceCube
- IceCube-240327A: Upper limits from a search for additional neutrino events in IceCube
- GRB 240329A: Glowbug gamma-ray detection
- GRB 240331A: AstroSat CZTI detection
- GRB 240329A: AstroSat CZTI detection
- GRB 240329A: GRBAlpha detection
- Fermi GRB 240329A: Global MASTER-Net observations report
- Fermi GRB 240328B: Global MASTER-Net observations report
- Fermi GRB 240328A: Global MASTER-Net observations report
- X-ray transient EP240315a: continued ATCA monitoring
- IceCube-240327B: No candidates from the Zwicky Transient Facility
- X-ray transient EP 240315a: Second epoch Chandra observations
- X-ray transient EP240315a: e-MERLIN radio observations
- X-ray transient EP240315a: Ondrejov D50 optical limit
- Transient EPW20240219aa: REM optical/NIR further observations
- GRB 240320A: Glowbug gamma-ray detection
- GRB 240318A: Fermi GBM Observation
- 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
- IPN triangulation of GRB 240315C (consistent with a fast X-ray transient EP240315a)
- GRB 240317B: Swift/BAT-GUANO Angular Error Correction
- 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
- 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 240317A: 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
- X-ray transient EP240315a: orphan FXT?
- 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
- AT2024eju: followup observations with Liverpool Telescope suggest a fading transient
- X-ray transient EP240315a: ATLAS detection of a possible optical counterpart AT2024eju
- GRID detection of GRB 240306A
- Changes to the Fermi-GBM Triggering Thresholds
- Fermi GRB 240314A: Global MASTER-Net observations report
- GRB240204A: VIRT optical upper limit
- GRB 240312A: Glowbug gamma-ray detection
- GRB 240310A: MASTER OT J200702.72-263928.7 inside 3sigma
- Fermi-LAT gamma-ray observations of IceCube-240307A
- Fermi GRB 240310A: Global MASTER-Net observations report
- 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 231215A: further radio observations with the VLA
- GRB 240306A: Fermi GBM observation
- GRB 240229A: Glowbug gamma-ray detection
- GRB 240227A (short): Glowbug gamma-ray detection
- 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 240305A: Fermi GBM observation
- Fermi-LAT gamma-ray observations of IceCube-240229A