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"- Konus-Wind observation of GRB 190304A
- IPN Triangulation of GRB 190304A (long)
- GRB 190306A: Swift-XRT observations
- GRB 190306B: Insight-HXMT/HE detection
- Konus-Wind observation of GRB 190305A
- GRB 190306A: Tiled Swift observations
- GRB 190306A: MAXI/GSC detection
- IPN Triangulation of GRB 190305A
- GRB 190305A: Swift-XRT observations
- GRB 190305A: Insight-HXMT/HE detection
- GRB 190305A: MAXI/GSC detection
- Swift Trigger 891843 is not a GRB
- GRB 190305A: Tiled Swift observations
- GRB 190305A: AGILE/MCAL detection of a burst
- GRB 190226A: Insight-HXMT/HE detection
- Trigger 890732: Swift detection of MAXI J1631-479
- INTEGRAL observation of IceCube-190221A
- Search for additional neutrino events from the direction of IceCube-190221A with IceCube
- IceCube-190221A: Swift-XRT Follow-up Observations
- IceCube-190221A: Fermi-LAT Gamma-ray observations
- Fermi-GBM Observations of IceCube-190221A
- IceCube-190221A: MASTER Global Robotic Net optical observation
- GRB 190220B: Fermi GBM observation
- GRB 190219A: CrAO and AbAO optical upper limit
- GRB 190220B: Kitab Observatory optical upper limit
- IceCube-190221A - IceCube observation of a high-energy neutrino candidate event
- GRB 190220A: Swift-XRT refined Analysis
- GRB 190220B: BOOTES-4 optical observation
- GRB 190220B: a long GRB detected by IBAS
- GRB 190220A: Swift-BAT refined analysis
- GRB 190219A: Swift-BAT refined analysis
- GRB 190220A: Enhanced Swift-XRT position
- GRB 190219A: NOT optical afterglow candidate
- GRB 190219A: NEXT-0.6m optical upper limit
- GRB 190219A: Swift-XRT refined Analysis
- GRB 190220A: Swift detection of a burst with an optical counterpart
- GRB 190219A: Enhanced Swift-XRT position
- GRB 190219A: CAHA 2.2m observations
- GRB190219A: MASTER Global Robotic Net optical observation
- GRB 190219A: BOOTES-1 optical limits
- GRB 190219A: Prompt enhanced Swift-XRT position
- GRB 190219A: Swift detection of a burst
- GRB 190215A: AstroSat CZTI detection
- Trigger 889483: Swift detection of Swift J1858.6-0814
- GRB 190215A: Insight-HXMT/HE detection
- GRB 190215A: Fermi GBM detection
- GRB 190212A: Insight-HXMT/HE detection
- GRB190211A: GROWTH-India detection of optical afterglow
- GRB 190211A: Tautenburg observations
- GRB 190211A: Swift/UVOT Detection
- GRB 190211A: DOAO optical observation
- GRB 190206A: AstroSat CZTI detection
- GRB190211A: MITSuME Akeno optical observation
- GRB 190211A: NOT optical observations
- GRB 180703A: VLT/MUSE host galaxy redshift measurement
- GRB 190211A: Swift-XRT refined Analysis
- GRB 190211A: Swift-BAT refined analysis
- GRB 190211A: BOOTES-4/MET optical afterglow confirmation
- GRB190211A: MASTER Global Robotic Net optical observation
- GRB 190211A: NEXT-0.6m optical afterglow detection
- GRB 190211A: Swift detection of a burst
- Trigger 888312: Swift detection of 4U 1901+03
- GRB 190202A: Terskol 2-m optical observations
- Konus-Wind observation of GRB 190206A
- IPN Triangulation of GRB 190206A (short/extremely bright)
- GRB 190203A: Mondy optical observations
- GRB 190204A: CALET Gamma-Ray Burst Monitor detection
- Retraction of IceCube GCN/AMON NOTICE 36142391_132143
- GRB 190202A: AstroSat CZTI detection
- GRB190202A: GROWTH-India detection of optical afterglow
- GRB 190203A: Swift-BAT refined analysis
- GRB 190204A: Swift-BAT refined analysis
- GRB 190202A: Xinglong-2.16m optical observations
- GRB 190202A: SAO RAS further optical observations
- Konus-Wind observation of GRB 190204A
- GRB 190204A: SAO RAS optical observations
- GRB 190204A: Mondy optical upper limit
- GRB 190203A: AstroSat CZTI detection
- GRB190203A: UVOT analysis
- GRB 190203A: COATLI Optical Observations
- GRB 190204A: Swift/UVOT Detection
- GRB 190204A: Enhanced Swift-XRT position
- GRB 190204A: COATLI Optical Detection of the Fading Afterglow
- GRB 190203A: Liverpool Telescope near-IR observations
- Konus-Wind observation of GRB 190203A
- GRB 190203A: Swift-XRT refined Analysis
- GRB 190204A: Swift-XRT refined Analysis
- GRB 190204A: AstroSat CZTI detection
- Swift Trigger 887541: MASTER inspect
- GRB 190204A: MAXI/GSC detection
- GRB 190202A: R and I band observation from HCT
- GRB 190204A: Swift detection of a burst with a possible optical counterpart
- Swift Trigger 887541: MASTER optical observation
- GRB 190203A: MASTER OT detection
- Swift Trigger 887541: Swift detection of Swift J1728.9-3613
- GRB 190203A: Enhanced Swift-XRT position
- GRB 190203A: SAO RAS optical observations, afterglow fading
- GRB 190203A: Koshka Zeiss-1000 optical upper limit
- GRB 190203A: Swift detection of a burst with an optical counterpart
- GRB 190202A: SAO RAS optical observations