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 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
- GRB 180728A: MASTER OT J165415.75-540239.27 is the Optical Counterpart of GRB
- GRB 180728A: Swift-XRT observations
- GRB 180728A: MASTER OT (= new object) detection
- GRB 180727A: Swift-BAT refined analysis
- GRB 180728A: Swift detection of a bright burst
- GRB 180727A: Swift-XRT refined Analysis
- GRB 180727A: Fermi GBM observation
- GRB 180727A: Swift detection of a burst
- GRB 180720B: CALET Gamma-Ray Burst Monitor detection
- NuSTAR observations of GRB 180720B
- GRB 180720B: OAJ optical observations
- GRB 180722B: Insight-HXMT/HE detection
- GRB 180724A: Insight-HXMT/HE detection
- GRB 180720B: AMI-LA 15.5 GHz observation
- GRB 180720B long follow up requested
- GRB 180723A: Fermi GBM detection
- GRB 180721A: KAIT Optical Upper Limit
- GRB 180720B: KAIT Optical Observations
- GRB 180722A: Swift-XRT observations
- GRB 180718B: Swift-XRT observations
- GRB 180718A: Swift-XRT observations
- GRB 180723A: CALET Gamma-Ray Burst Monitor detection
- GRB 180722B: CALET Gamma-Ray Burst Monitor detection
- GRB 180723.13: MASTER optical observation of the short Fermi GBM trigger number 554008254
- GRB 180722A: MASTER second inspection
- GRB 180723.76: MASTER optical observation of the bright long Fermi GBM trigger number 554062193
- GRB 180720B: D50 optical observations
- GRB 180720B: MASTER Global Net OT observations
- GRB 180721A: MITSuME Akeno optical upper limits
- GRB 180720B: REM photometry
- GRB 180720B: ISON-Castelgrande optical observations
- GRB 180720B: Testing the universality of the newly born neutron star in BdHNe
- GRB 180721A: BOOTES-5/JGT optical observations
- GRB 180720B: COATLI Optical Detection
- GRB 180720C: BOOTES-2/TELMA optical observations
- GRB 180722A: Tiled Swift observations
- GRB 180721A: Swift/UVOT Upper Limits
- GRB 180715B: AstroSat CZTI detection
- GRB 180715A: AstroSat CZTI detection
- Konus-Wind observation of GRB 180720B
- FRB 180714: MASTER optical inspection of the Fast Rado Burst Transient
- GRB 180720C: MASTER optical observation
- ANTARES neutrino Alert180713.02: MASTER optical observation
- Fermi Trigger 553879512: MASTER optical observation
- GRB 180722A: MASTER optical observation
- GRB 180722A: MAXI/GSC detection
- GRB 180720B: MITSuME Ishigaki optical observations
- GRB 180720C: Swift-XRT refined Analysis
- GRB 180711A: AstroSat CZTI detection
- GRB 180721A: Swift-BAT refined analysis
- GRB 180720C: Swift-BAT refined analysis
- GRB 180721A: Swift-XRT refined Analysis
- GRB 180720B: Swift-BAT refined analysis
- GRB 180721A: Enhanced Swift-XRT position
- GRB 180720B: VLT/X-shooter redshift
- GRB 180721A: LCO Haleakala observations
- GRB 180721A: Swift detection of a burst
- GRB 180720B: MAXI/GSC detection
- GRB 180720C: Swift/UVOT Upper Limits
- GRB 180720C: LT observations
- GRB 180720C: Fermi GBM observation
- GRB 180706A: OSN detection
- GRB 180720B: LCO optical afterglow observations
- GRB 180720C: Enhanced Swift-XRT position
- GCN 22984 was for GRB 180720B