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"- IceCube-161210: Konus-Wind upper limits
- GRB 161214A: GROND afterglow observations
- GRB 161214A: TAROT Calern observatory optical observations
- IceCube-161210: CALET Gamma-Ray Burst Monitor upper limits
- GRB 161214A: fading optical afterglow candidate with the LT
- GRB 161214A: A long GRB detected by INTEGRAL
- HAWC follow-up on IceCube-161210
- INTEGRAL SPI-ACS and IBIS/Veto observation of IceCube-161210
- IceCube-161210: MAXI/GSC non-detection
- IceCube-161210: IceCube observation of a high-energy neutrino candidate event
- GRB 161207A: CALET Gamma-Ray Burst Monitor detection
- GRB 161129A: GTC redshift of the likely host galaxy
- GRB 161129A: NOT optical observations and candidate host galaxy
- GRB 161203A: POLAR Detection
- GRB 161129A: KWFC z-band photometry
- GRB 161203A: Astrosat CZTI (Veto) detection
- GRB 161203A: CALET Gamma-Ray Burst Monitor detection
- GRB 161206A: Fermi GBM detection
- Konus-Wind observation of GRB 161202A
- MASTER: Optical Blazar Flare Detection during Fermi trigger 502272781 inspection
- GRB 161129A: POLAR Detection
- GRB 161202A: Astrosat CZTI detection
- GRB 161202A: RATIR Optical and NIR Observations
- GRB 161202A: Swift-BAT refined analysis
- GRB 161202A: Swift/UVOT Upper Limits
- GRB 161202A: Swift-XRT refined Analysis
- GRB 161202A: MITSuME Okayama upper limits
- GRB 161202A: Fermi-LAT detection
- GRB 161202A: Enhanced Swift-XRT position
- GRB 161202A: Swift detection of a burst
- GRB 161129A: Mondy optical observations
- Fermi GBM trigger 502258294/161201175 is not a GRB
- GRB 161129A: ISON/UAFO optical observations
- GRB 161129A: MITSuME Okayama Ks-band Observation
- GRB 160821B: HST detection of the optical and IR counterpart
- Fermi Gamma-ray Burst Monitor trigger 161130183 is not a GRB
- GRB 161129A: Swift-BAT refined analysis
- GRB 161129A: Fermi GBM Detection
- GRB 161129A: MITSuME Okayama Optical Observation
- GRB 161129A: Swift/UVOT Detection
- GRB 161129A: Tautenburg Ic-band observations
- GRB 161129A: TSHAO optical observations / possible afterglow+host galaxy
- GRB161129A : Astrosat CZTI detection
- GRB 161129A: Swift-XRT refined Analysis
- GRB 161129A: Enhanced Swift-XRT position
- GRB 161129A: Swift detection of a burst
- Fermi GBM trigger 501785179/161125699 is not a GRB
- Fermi GBM trigger 501779084/161125628 is not a GRB
- GRB 161123A: Swift-XRT observations
- Swift Trigger 723539 is not an astrophysical event
- GRB 161123A: Tiled Swift observations
- GRB 161123A: MAXI/GSC detection
- GRB 161117A: SMARTS optical/IR afterglow observations
- GRB 161119A: MASTER-SAAO possible OT detection during Fermi Alert
- GRB 161108A: 15 GHz upper limits from AMI
- Swift Trigger 723124 is probably not a GRB
- GRB 161117B: Swift-XRT refined Analysis
- Konus-Wind observation of GRB 161117A
- GRB 161117A iTelescope observation
- GRB 161117A: MASTER-OAFA (Argentina) prompt OT observations
- GRB 161117A: TAROT La Silla observatory optical observations
- GRB 161117A: GMG observation limit
- GRB 161117A: Fermi GBM detection/observation
- GRB 161117B: Swift/UVOT Upper Limits
- GRB 161117A: Swift/UVOT Detection
- GRB 161117B: Swift-BAT refined analysis
- GRB 161117A: Swift-BAT refined analysis
- Swift Trigger 722681 is probably not a GRB
- GRB 161117B: Enhanced Swift-XRT position
- GRB 161117A: Swift-XRT refined Analysis
- GRB 161117A: Enhanced Swift-XRT position
- GRB 161117B: LCO optical observations
- GRB 161117B: Swift detection of a burst
- GRB161117A: REM optical and NIR afterglow detection
- GRB 161117A: VLT/X-shooter spectroscopy and redshift
- GRB 161117A: Swift detection of a burst with an optical counterpart
- GRB 161113A: Swift-BAT refined analysis
- GRB 161113A: Swift/UVOT Upper Limits
- GRB 161113A: Swift-XRT refined Analysis
- GRB 161113A: Kuban State University optical upper limit
- GRB 161113A: Enhanced Swift-XRT position
- GRB 161113A: RATIR Optical and NIR Observations
- GRB 161113A: Swift detection of a burst
- GRB 161109A: CALET Gamma-Ray Burst Monitor detection
- GRB 161109A: Swift/UVOT Upper Limits
- GRB 161104A: Magellan imaging and spectroscopy
- GRB 161108A: continued TSHAO optical observations
- GRB 161104A: Chandra X-ray observations
- GRB 161109A: Lomonosov BDRG gamma ray discovery
- GRB 161109A: Swift-XRT observations
- GRB 161108A: MITSuME Okayama upper limits
- IceCube-161103: CALET Gamma-Ray Burst Monitor upper limits
- GRB 161106A: CALET Gamma-Ray Burst Monitor detection
- GRB 161108A: TSHAO optical observations
- GRB 161108A: Swift/UVOT Upper Limits
- GRB 161109A: Tiled Swift observations
- GRB 161105A: Swift/UVOT Upper Limits
- GRB 161109A: Fermi GBM observation
- GRB 161109A: Fermi-LAT detection
- GRB 161106A: Lomonosov BDRG gamma ray discovery