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"- 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
- GRB 190202A: TSHAO optical observations
- GRB 190202A: NOT optical observations
- GRB 190202A: McDonald 0.8-m telescope optical observation
- GRB 190202A: Swift-XRT refined Analysis
- GRB 190202A: LCO-CTIO optical observations
- GRB 190202A: Fermi GBM observation
- Fermi GBM trigger 570825115/190202772 is not a GRB
- GRB 190202A, Swift-BAT refined analysis
- GRB 190202A: AGILE ratemeters detection
- GRB 190202A: Swift/UVOT Detection
- GRB 190202A: GOTO optical observations
- GRB 190202A: Enhanced Swift-XRT position
- GRB 190202A: Koshka Zeiss-1000 optical observations
- GRB 190202A: Swift detection of a burst with an optical counterpart
- Fermi GBM trigger 570716645/190201517 is not a GRB
- GRB 190131A: Insight-HXMT/HE detection
- GRB 190131A: AstroSat CZTI detection
- GRB 190126A: AstroSat CZTI detection
- Fermi GBM trigger 570659556/190131856 is not a GRB
- GRB 190129B: Insight-HXMT/HE detection
- GRB 190114C: JCMT SCUBA-2 sub-mm observations
- Improved IPN error box for GRB 190129B
- GRB 190129B: GOTO optical observations
- GRB 190129B: DDOTI Detection of the Possible Afterglow and Suggestion of Fading
- GRB 190129B: Swift/UVOT Upper Limits
- GRB 190129B: ePESSTO NTT optical observations
- GRB 190129B: AstroSat CZTI detection
- GRB 190129B: MASTER Global Robotic Net optical observation
- GRB 190129A: CALET Gamma-Ray Burst Monitor detection
- GRB 190129B: GROND possible host candidate
- GRB 190129B: Swift-XRT candidate afterglow detection
- GRB 190129B: Tiled Swift observations
- Fermi GBM Observations of IceCube-190124A
- GRB 190129A: Fermi GBM detection
- Konus-Wind observation of extremely bright GRB 190129B
- IPN Triangulation of GRB 190129B (long/extremely bright)
- INTEGRAL observation of IceCube-190124A
- GRB 190129A: MAXI/GSC detection
- Trigger 886496: Another Swift trigger on MAXI J1348-630
- Swift Trigger 886157: MASTER optical observation
- Trigger 886486: Swift detection of MAXI J1631-479
- Trigger 886266: Another Swift trigger on MAXI J1348-630
- Swift Trigger 886157: Swift detection of a new transient Swift J1728.9-3613
- INTEGRAL triggers from 8205 to 8211 are due to MAXI J1348-630, NOT to a GRB
- GRB 190114C: Optical follow-up from HCT
- Swift Trigger 885960: A third Swift trigger on MAXI J1348-630
- Trigger 885845: A second Swift trigger on MAXI J1348-630
- Trigger 885807: Swift detection of MAXI J1348-630
- Search for counterparts to IceCube-190124A with IceCube
- Search for counterpart to IceCube-190124A with ANTARES
- GRB 190117A: AstroSat CZTI detection
- GRB 190122B: AstroSat CZTI detection
- Fermi-LAT Gamma-ray Observations of IceCube-190124A
- GRB 190123A: IKI-GRB-FuN optical upper limit
- GRB 190123A: NEXT-0.6m optical limit
- GRB 190114C: CHILESCOPE optical observations
- GRB 190123A: AROMA-N Optical Observation
- IceCube-190124A - IceCube observation of a high-energy neutrino candidate event
- GRB 190123A: Swift/UVOT Upper Limits
- Konus-Wind observation of GRB 190122A
- Konus-Wind of observation of GRB 190117A
- GRB 190123A: COATLI Optical Observations
- GRB 190123A: Swift-BAT refined analysis
- GRB 190121A: CALET Gamma-Ray Burst Monitor detection of a short burst
- GRB190123A: MITSuME Akeno optical upper limits
- GRB 190123A: GMG observational limit
- Trigger 885456: Swift detection of MAXI J1631-479
- GRB 190123A: Swift-XRT refined Analysis
- GRB 190123A: GOTO optical limit
- GRB 190123A: Fermi GBM observation
- GRB 190123A: BOOTES-4/MET optical limit
- GRB 190123A: Enhanced Swift-XRT position
- GRB 190123A: MASTER Global Robotic Net optical observation
- GRB 190123A: Swift detection of a burst
- GRB 190122A: Fermi GBM observation
- GRB 190122A: Fermi-LAT detection
- GRB 190114C: RTT150 optical observations
- IPN Triangulation of GRB 190118A (long)
- IPN Triangulation of GRB 190117A (long)
- Trigger 884906: Swift detection of MAXI J1631-479
- GRB 190114C: GMRT detection at 1.26GHz
- Swift ToO Instructions Update
- GRB 190114C: MeerKAT radio observation
- GRB 190117A: Insight-HXMT/HE detection
- Swift ToO Website Down
- GRB 190114C: UKIRT JHK observation (CORRECTIONS)
- GRB 190114C: UKIRT JHK observation continuation - steady fading?
- GRB 190114C: Sardinia Radio Telescope observations (CORRECTION)
- GRB 190114C: REM optical/NIR detection (CORRECTION)
- GRB 190114C: Sardinia Radio Telescope observations
- GRB 190117A: AGILE/MCAL detection of a burst
- GRB 190114C: RATIR Optical and NIR Detections
- GRB 190114C: RT-22 detection at 36.8 GHz
- GRB 190114C: COATLI Optical Detection
- GRB 190114C: ePESSTO NTT optical observations
- GRB 190114C: Continued UKIRT JHK observation
- GRB 190114C: continued CHILESCOPE optical obs