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"- LIGO/Virgo G288732 ANTARES search
- LIGO/VIRGO G288732: Fermi GBM Observations
- LIGO/Virgo G288732: Identification of a GW Binary Merger Candidate
- GRB 170607A: Swift/UVOT Detection
- GRB 170607A: MASTER-Tavrida early OT observations
- GRB 170607A: Fermi GBM observation
- GRB 170607A: NOT optical afterglow detection
- GRB 170607A: Swift-XRT refined Analysis
- GRB 170607A: Enhanced Swift-XRT position
- GRB 170607A: Swift detection of a burst with a bright optical counterpart
- GRB 170526A: 15 GHz upper limits from AMI
- GRB 170524A: 15 GHz upper limits from AMI
- GRB 170519A: 15 GHz upper limits from AMI
- GRB 170531B: Zeiss-1000/CrAO optical observations
- GRB 170531B: WHT spectroscopy
- GRB 170519A: TShAO and AbAO optical observations
- GRB 170604A: Swift/UVOT Observations
- GRB 170519A: Mondy optical observations
- GRB 170529A: AstroSat CZTI detection
- GRB 170604A: RATIR Optical and NIR Observations
- GRB 170604A: AbAO optical observations
- Swift trigger 755873: Swift BAT and XRT refined analysis
- GRB 170522A: confirmation of the X-ray afterglow
- GROND observations of GRB170604A
- Swift Trigger 755873: MASTER Net optical observations
- GRB 170604A: Swift-XRT refined Analysis
- GRB 170604A: GTC spectroscopic redshift
- GRB 170604A: Enhanced Swift-XRT position
- GRB 170604A: Swift-BAT refined analysis
- Swift Trigger 755873: D50 optical limits
- Swift Trigger 755873: a possible GRB
- GRB 170604A: optical observations
- GRB 170604A: Swift detection of a burst
- Trigger 755848: Swift spurious trigger on Cen X-3
- GRB 170531B: ISON/Terskol optical observations
- GRB 170531B: Swift/UVOT Detection
- GRB 170531B: SMARTS optical/IR observations
- GRB 170531B: Swift-BAT refined analysis
- GRB 170531A: Swift/UVOT Upper Limits
- GRB 170531B: LCO observations
- GRB 170531B: Swift-XRT refined Analysis
- GRB 170531A: MASTER Net job
- GRB 170531A: Swift-XRT refined Analysis
- GRB 170531B: MASTER Net optical counterpart refind position and magnitude
- GROND observations of GRB 170531B
- GRB 170531B: Redshift from GTC/OSIRIS
- GRB 170531A: ePESSTO NTT observations
- GRB 170531B: Enhanced Swift-XRT position
- GRB 170531B: CrAO confirmation of the afterglow
- GRB 170531B: MASTER Net OT detection
- GRB 170531A: Swift/UVOT Observations
- GRB 170531B: Swift detection of a burst
- GRB 170531A: Swift detection of a burst
- GRB 170519A: CrAO optical observations
- GRB 170524B: Swift-UVOT/XRT Confirmation of Afterglow
- Konus-Wind observation of GRB 170529A
- Konus-Wind observation of GRB 170527A
- IPN Triangulation of GRB 170529A (long)
- IPN Triangulation of GRB 170527A
- GRB 170511A: AstroSat CZTI detection
- GRB 170519A: ISON/Multa optical observations
- GRB 170511A: Fermi GBM observation
- LIGO/Virgo G268556: optical observations and classification of Pan-STARRS1 transients
- LIGO/Virgo G268556: BSA radio observations at 110 MHz
- LIGO/Virgo G268556/GW170104: Konus-Wind observations
- GRB 170527A: Fermi GBM detection
- GRB 170526A, Swift-BAT refined analysis
- GRB 170526A: Swift/UVOT Upper Limits
- GRB 170526A: Swift-XRT refined Analysis
- LIGO/Virgo G268556: VERITAS Very-High-Energy Gamma-Ray Observations
- GRB 170524A: RATIR Optical and NIR Observations
- GRB 170526A: Enhanced Swift-XRT position
- GRB 170524B: Swift-XRT observations
- GRB 170526A: Swift detection of a burst
- Konus-Wind observation of GRB 170524B
- GRB 170524B: MASTER-OAFA observations
- GRB 170511A CALET Gamma-Ray Burst Monitor detection
- GRB 170524A: TSHAO and CrAO optical observations
- GRB 170524B: Swift ToO observations
- GRB 170524A: Swift-BAT refined analysis
- GRB 170524B: Swift detection of a burst
- GRB 170524A: Swift/UVOT Upper Limits
- GRB 170524A: D50 optical observation and limit
- GRB 170524A: Swift-XRT refined Analysis
- IPN Triangulation of GRB 170522A
- GRB 170511A: MAXI/GSC detection
- GRB 170524A: Enhanced Swift-XRT position
- GRB 170524A: Swift detection of a burst (or possible new SGR)
- GRB 170522A: LCO McDonald observations
- GRB 170522A: Swift-XRT observations
- GRB 170522A: Global MASTER-Net job
- Konus-Wind observation of GRB 170522B
- IPN Triangulation of GRB 170522B (long/intense)
- Konus-Wind observation of GRB 170522A
- GRB 170522A: Tiled Swift observations
- GRB 170522A: Fermi-LAT detection
- GRB 170522A: Fermi GBM detection
- GRB 170514A CALET Gamma-Ray Burst Monitor detection
- GRB 170519A: MITSuME Akeno Optical Observation
- GRB 170519A: Watcher optical observations