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 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
- GRB 180720B: OSN detection, fading slower?
- GRB 180720B: Swift-XRT refined Analysis
- GRB 180720B: MITSuME Akeno optical observations
- GRB 180720C: Swift detection of a burst or possible Galactic Transient
- GRB 180720B: Fermi GBM observation
- GRB 180720B : Fermi-LAT detection
- GRB 180720B : TSHAO optical observations
- GRB 180715A: MASTER optical observation
- GRB 180720B: Kanata 1.5m optical/NIR observation
- GRB 180720B: LCO Haleakala possible bright optical candidate
- Correction: Swift trigger #848890 is GRB 180720B (not GRB 180720A)
- GRB 180720A: Fermi GBM observation
- GRB 180720B: Swift detection of a burst
- GRB 180718A: MASTER optical observation
- GRB 180718B: MASTER optical observation
- AGILE/MCAL detection of GRB 180720A
- GRB180715B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 553369644)
- GRB 180715A: Gemini imaging upper limits
- GRB 180715A: Swift/UVOT Upper Limits
- Swift detects a flare from AX 1631.9-4752
- GRB 180718B: Fermi GBM detection
- GRB 180716A: CALET Gamma-Ray Burst Monitor detection
- GRB 180718A: Swift ToO observations
- GRB 180718B: Swift ToO observations
- GRB 180718B: Fermi-LAT detection
- GRB 180718A: Fermi GBM detection
- GRB 180718A short GRB detected by IPN and found in ground analysis of BAT data
- Swift Trigger 848621 is not an astrophysical event
- Trigger 848584: Swift detection of AX 1631.9-4752
- GRB 180715A: CALET Gamma-Ray Burst Monitor detection
- GRB 180715A: LCO Sutherland observations
- GRB 180715A: COATLI Optical Observations
- GRB 180715A: Swift-XRT observations
- GRB 180715A: Fermi GBM detection
- GRB 180715A: Swift-BAT refined analysis
- GRB 180715A: GOTO optical limits
- GRB 180715A: LCO Sutherland possible optical candidate
- GRB 180715A: Swift-XRT observations
- GRB 180715A: Swift detection of a short hard burst