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 180818B: Enhanced Swift-XRT position
- GRB 180818A: Swift/UVOT Upper Limits
- GRB 180818B: Swift detection of a burst
- GRB 180818A: Swift-XRT refined Analysis
- GRB 180818A: Enhanced Swift-XRT position
- GRB 180818A: Swift detection of a burst
- Swift Trigger 853790 is probably not an astrophysical source
- GRB 180809B: AstroSat CZTI detection
- GRB 180728A: MASTER early polarization and 19 days monitoring
- GRB 180728A: discovery of the associated supernova
- GRB 180809A: further Swift/XRT observations
- Correction: Chandra X-ray observations of GW170817 at 1 year post-merger: increasingly rapid fading
- LIGO/Virgo GW170817: A steep decline in the radio light curve and prediction for the X-rays
- GRB 180812A: Swift/UVOT Detection
- Chandra X-ray observations of GW170817 at 1 year post-merger: increasingly rapid fading
- GRB 180812A: Swift-BAT refined analysis
- GRB 180812A: Fermi GBM detection
- GRB 180812A: Swift-XRT refined Analysis
- GRB 180809B: ePESSTO NTT NIR observations
- GRB 180812A: COATLI Detection and Light Curve
- GRB 180812A: Enhanced Swift-XRT position
- GRB 180812A: BOOTES-5/JGT optical afterglow detection
- GRB 180812A: Swift detection of a burst
- Konus-Wind observation of GRB 180809B
- GRB180809B TUG T60 observations
- MASTER: OT detection during two Fermi GBM triggers (555263883 and 555263883) error boxes inspection in 22.5 mag SDSS galaxy direction
- GRB 180809B: Swift-XRT refined Analysis
- GRB 180809B: CrAO optical observations
- GRB 180809B, Swift-BAT refined analysis
- GRB 180806A: AstroSat CZTI detection
- Swift Trigger 852625: Swift/BAT/XRT/UVOT observations
- GRB 180809B: Swift/UVOT Detection
- Konus-Wind observation of GRB 180806A
- GRB 180809A: Fermi GBM observation
- GRB 180809A: CALET Gamma-Ray Burst Monitor detection
- GRB 180809B: CALET Gamma-Ray Burst Monitor detection
- Swift Trigger 852625: a possible GRB
- GRB 180809B: VLT optical upper limits
- GRB180809B: MASTER Triple Independent Automatic OT Detection
- GRB 180809B: LCO Sutherland observations
- GRB 180809B: GROND Detection of the NIR Afterglow
- GRB 180809B: RATIR Optical Observations and Confirmation of Rapid Fading
- GRB180809B: MASTER OT observation
- GRB 180805B: Teide LCO optical observations
- GRB 180809A: iTelescope optical limit
- GRB 180809A: Swift-XRT afterglow detection
- GRB 180809B: Swift detection of a burst with an optical afterglow
- GRB 180809A: Tiled Swift observations
- GRB 180809A: MAXI/GSC detection
- GRB 180728A: AstroSat CZTI detection
- GRB180806A: correction to Circular 23097
- GRB 180724A: AstroSat CZTI detection
- GRB 180723A: AstroSat CZTI detection
- GRB 180806A: NOT optical observations
- GRB 180806A: Swift-XRT afterglow detection
- GRB 180806A/180806.98: RATIR Optical Observations of MASTER OT J004613.05+242014.1
- GRB 180806A: Fermi GBM detection
- GRB 180806A/180806.94: Refined COATLI Photometry of MASTER OT J004613.05+242014.1
- GRB 180806A: Swift ToO observations
- GRB 180806.94: COATLI Detection of MASTER OT J004613.05+242014.1 and Confirmation of Fading
- GRB 180806.94: MASTER possible OT detection in Fermi GMB trigger 555287944 error box
- GRB 180805B: ESO/NTT optical observations
- GRB 180805B: COATLI Optical Observations
- GRB 180805B: 1.5m OSN I-band observation
- GRB 180805B: GOTO optical limits
- GRB 180805B: VLT optical and near-infrared observations
- GRB 180805B: MASTER optical late inspection short GRB with extended emission
- GRB 180805A: Swift-XRT refined Analysis
- GRB 180805B: Swift-XRT refined Analysis
- GRB 180805B: Swift-BAT refined analysis (short GRB with extended emission)
- GRB 180805A: Swift-BAT refined analysis
- GRB 180805B: Swift/UVOT Upper Limits
- GRB 180805B: Fermi GBM detection
- GRB 180805B: Enhanced Swift-XRT position
- GRB 180805B: Swift detection of a burst
- GRB 180805A: Enhanced Swift-XRT position
- GRB 180805A: Swift detection of a burst
- GMRT radio detection of GRB 180720B
- GRB 180727A: Swift/BAT spectral lag result
- Fermi Trigger 554765006: MASTER optical inspection
- FRB 180725A: MASTER optical observations of the Fast Radio Burst error box
- GRB 180728B: GOTO optical search over IPN region
- Fermi GBM trigger 554730582/180731493 is not a GRB
- GRB 180728A: No evidence of SN in early VLT/X-shooter spectra
- GRB 180728A: A long GRB of the X-ray flash (XRF) subclass, expecting supernova appearance
- GRB 180728B: MASTER optical observations short GRB IPN error box
- GRB 180728A: Swift/UVOT Detection
- GRB 180701A/MAXI J2119-045: CALET Gamma-Ray Burst Monitor data search
- GRB 180727A: Swift/UVOT Upper Limits
- Konus-Wind observation of the bright nearby GRB 180728A
- Konus-Wind observation of GRB 180728B
- GRB 180715A: CALET CAL gamma-ray analysis
- GRB 180703B: CALET CAL gamma-ray analysis
- GRB 180728B: Fermi GBM detection
- IPN Triangulation of GRB 180728B (short)
- GRB 180728A: VLT/X-shooter redshift of a nearby energetic GRB
- GRB 180728A: Swift-BAT refined analysis
- GRB 180728A: Fermi GBM observation
- GRB 180728A: Swift-XRT refined Analysis
- GRB 180728A: Enhanced Swift-XRT position