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 190114A: Enhanced Swift-XRT position
- GRB 190114A: VLT/X-shooter redshift
- GRB 190114A: Prompt enhanced Swift-XRT position
- GRB 190114A: Possible UVOT Detection
- GRB 190114A: Swift detection of a burst
- GRB 190110A：Insight-HXMT/HE detection
- Konus-Wind observation of GRB 190110A
- GRB 190110A, Swift-BAT refined analysis
- Correction to GCN Circular 23663: GRB 190109A: Swift UVOT Upper Limits
- Konus-Wind observation of GRB 190103A
- GRB 190110A: Fermi GBM detection
- GRB 190110A: Swift detection of a burst
- GRB 181228A: FRAM-ORM optical limit
- GRB 190106A: GMG continued observation
- IceCube-190104A: AstroSat CZTI counterpart search
- GRB 190109B: Fermi GBM observation
- GRB 190106A: OSN Afterglow Observations
- GRB 190109B: Swift/UVOT Upper Limits
- GRB 190109A: Swift/UVOT Upper Limits
- GRB 190109B: Swift-XRT refined Analysis
- GRB 190106A: optical observations, possible jet break detection
- GRB 190106A: Liverpool Telescope observations
- GRB 190109B: Swift-BAT refined analysis
- GRB 190109A: Fermi GBM observation
- Correction to the GCN circ. 23654 / GRB 190109B: Mondy optical upper limit
- GRB 190109B: COATLI Optical Observations
- GRB 190109B: BOOTES-5/JGT optical observations
- GRB 190109B: Mondy optical upper limit
- GRB 190109A: Swift-BAT refined analysis
- GRB 190109B: Enhanced Swift-XRT position
- GRB 190109B: Swift-XRT observations
- INTEGRAL Weak#8189: AROMA-N Optical Observation
- GRB190109A: MITSuME Akeno optical upper limits
- GRB 190109B: Swift detection of a burst
- CALET Gamma-Ray Burst Monitor: Policy change in the GCN circulars
- IPN triangulation of GRB 190103A (long)
- GRB 190109A: Swift-XRT refined Analysis
- GRB 190109A: Enhanced Swift-XRT position
- GRB 190109A: Prompt enhanced Swift-XRT position
- GRB 190109A: Swift detection of a burst
- IceCube-190104A: Swift-XRT observations
- GRB 190106A: Mondy optical observations
- Trigger 882561: Swift detection of MAXI J1631-479
- GRB 190106A : continued TSHAO optical observations
- Konus-Wind observation of GRB 190106A
- GRB 190106A: NEXT-0.6m and Xinglong-2.16m photometric single powerlaw decay
- IERCOO/ICSP optical observation of GRB 190106A
- GRB 190106A: GMG photometry in the 2nd night
- GRB 190106A: Swift-XRT refined Analysis
- GRB 190106A: VLT/X-shooter redshift confirmation
- GRB 190103B: CALET Gamma-Ray Burst Monitor detection
- GRB 190106A: GMG spectral results
- GRB 190106A: update of the Xinglong-2.16m spectroscopy
- GRB 190106A: OASDG optical observations
- GRB 190106A: BOOTES-4/MET optical observations
- GRB 190106A: Swift/UVOT Detection
- GRB 190106A: Swift-BAT refined analysis
- GRB 190106A: Bassano Bresciano Observatory optical detection
- GRB 190106A: Xinglong-2.16m spectroscopy
- GRB 190106A: GWAC-F60B optical detection
- Fermi GBM Observations of IceCube-190104A
- GRB 190106A : TSHAO optical observations
- GRB 190106A: Enhanced Swift-XRT position
- GRB 190106A: GMG detection
- GRB 190106A: MITSuME Akeno optical observation
- GRB 190106A: MASTER Amur OT detection
- GRB 190106A: Swift detection of a burst with an optical counterpart
- SWIFT GRB190106.57 Global MASTER-Net OT detection
- Search for Counterparts to IceCube-190104A with IceCube
- Konus-Wind observation of GRB 190103B
- Search for counterpart to IceCube-190104A with ANTARES
- IceCube-190104A: MASTER optical observation
- GRB 190103A: AstroSat CZTI detection
- Fermi LAT Gamma-ray Observations of IceCube-190104A
- GRB 190103B: Bassano Bresciano observatory upper limit
- GRB 190103B: Swift-BAT refined analysis
- IceCube-190104A - IceCube observation of a high-energy neutrino candidate event
- GRB 190103B: Swift-XRT refined Analysis
- GRB 190103B: Enhanced Swift-XRT position
- GRB 190103B: Swift detection of a burst
- GRB 181201A: photometric signature of the SN
- GRB 190103A: AGILE/MCAL detection of a burst
- GRB 181231A: BOOTES-2/TELMA optical observations
- GRB 181231A: Fermi GBM detection
- GRB 181231A: Fermi-LAT detection
- GRB 181228A: Mondy and AbAO optical upper limits
- GRB 181225A: further Swift-XRT observations
- GRB 181228A: Global MASTER Net OT is the same REM IR transient
- GRB 181228A: possible NOT optical detection
- Fermi GBM trigger 567868083/181230547 is not a GRB
- GRB 181227A: CALET Gamma-Ray Burst Monitor detection
- GRB 181228A: MITSuME Akeno optical upper limits
- Konus-Wind observation of GRB 181227A
- GRB 181228A: Xinglong-2.16m optical upper limit
- FRB 181228: Global MASTER Net optical inspection
- GRB 181227A: Global MASTER Net oprtical inspection
- Swift Trigger 880127 is not a GRB
- GRB 181228A: Swift-XRT refined Analysis
- GRB 181228A: Swift-BAT refined analysis
- GRB 181222B: Swift follow-up observations of MASTER optical transient J204928.79+245744.0