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 160509A: Preliminary XRT positon
- GRB 160509A: Tiled Swift observations
- Correction to GCN 19404; GRB 160509A: MAXI/GSC detection
- GRB 160227A: MAXI/GSC detection
- GRB 160509A: Fermi-LAT prompt detection of a very bright burst
- GRB 160506A: TAROT La Silla observatory optical observations
- LIGO/Virgo G211117: Astrosat CZTI upper limits
- GRB 160506A: IRSF upper limits
- GRB 160506A: Swift-XRT refined Analysis
- GRB 160506A: Swift/UVOT Upper Limits
- GRB 160506A: Swift-BAT refined analysis
- GRB 160506A: GROND upper limits
- GRB 160506A: Enhanced Swift-XRT position
- GRB 160506A: Swift detection of a burst
- GRB 160504A: Swift-BAT refined analysis
- IceCube-160427A: iPTF Observations
- GRB 160504A: RATIR Optical and NIR Observations
- GRB 160504A: Swift/UVOT Upper Limits
- GRB160504A: Gemini NIR Observations
- GRB 160504A: Bassano Bresciano Observatory upper limits
- GRB 160504A: Swift-XRT refined Analysis
- GRB 160504A: Enhanced Swift-XRT position
- GRB 160504A: NOT upper limits
- GRB 160417A, the review of the sky area in plate archive
- GRB 160504A: TAROT Calern observatory optical observations
- GRB 160504A: Swift detection of a burst
- ICECUBE-160427A : Pan-STARRS imaging and optical transients in the field
- GRB 160503A: Fermi GBM observation
- GRB 160503A: Fermi-LAT detection
- GRB 160501A: SMARTS optical/IR observations
- VERITAS rapid follow-up observations of IceCube event 160427A
- GRB 160501A: Swift-BAT refined analysis
- GRB 160501A: GROND Upper limits
- GRB 160501A: MITSuME Okayama upper limits
- GRB 160501A: UKIRT near-IR upper limits
- GRB 160501A: Swift/UVOT Upper Limits
- GRB 160501A: Swift-XRT refined Analysis
- GRB 160501A: RATIR Optical and NIR Observations
- GRB 160501A: Enhanced Swift-XRT position
- GRB 160501A: TAROT Calern observatory optical observations
- GRB 160501A MASTER-NET early observations
- GRB 160501A: NOT optical and NIR observations
- GRB 160501A: Swift detection of a burst
- IceCube-160427A: Fermi GBM Observations
- ICECUBE-160427A neutrino candidate event: updated direction information
- MASTER search for counterpart to the IceCube event 67093193 (run 127853)
- Archival observations by HAWC of IceCube HESE event of April 27, 2016
- Fermi/LAT search for counterpart to the IceCube event 67093193 (run 127853)
- GRB 160422A: XRT Afterglow Confirmation
- LSGT observation of GRB 160425A
- GRB 160425A: Swift/UVOT Detection
- GRB 160425A: Skynet PROMPT-CTIO observations of the optical afterglow
- GRB 160425A: Swift-BAT refined analysis
- GRB 160425A: SMARTS optical/IR observations
- GRB 160325A: Skynet PROMPT-CTIO observations of the optical afterglow
- GRB 160422A: GROND NIR afterglow detection
- GRB 160425A MASTER notices: possible host galaxy in the optical error-box
- GRB 160425A VLT/X-shooter redshift
- GRB 160425A: GROND observation
- GRB 160425A: Swift-XRT refined Analysis
- GRB 160425A: Enhanced Swift-XRT position
- GRB 160422A: Swift/UVOT Afterglow Confirmation
- GRB 160422A: CALET Gamma-Ray Burst Monitor detection
- GRB 160425A : MASTER earlier optical observations
- GRB 160425A: Swift detection of an unusual burst with an optical afterglow
- Konus-Wind observation of GRB 160424A
- LIGO/Virgo G197392 / LVT151012: Identification of a GW CBC Candidate
- GRB 160424A: Fermi GBM observation
- GRB 160424A - XRT position uncertain
- GRB 160424A: Swift-BAT refined analysis
- GRB 160424A: Swift/UVOT Upper Limit
- GRB 160424A: Swift-XRT observations
- GRB 160424A: Swift detection of a burst
- GRB 160422A: Swift-XRT afterglow detection
- GRB 160422A: Swift/UVOT Candidate Afterglow
- GRB 160419A: CALET Gamma-Ray Burst Monitor detection
- GRB 160422A: Fermi GBM observation
- GRB 160422A: Swift ToO observations
- GRB 160422A: Fermi-LAT Detection
- GRB 160419A, Swift-BAT refined analysis
- GRB 160419A: Fermi GBM detection
- GRB 160419A: Swift detection of a burst
- Fermi GBM trigger 482632364/160418023 is not a GRB
- GRB 160417A: GMG observations
- GRB 160417A: Swift-BAT refined analysis
- GRB 160417A: Swift/UVOT Detection
- GRB 160417A: iTelescope T11 optical observations
- GRB 160417A: Swift-XRT refined Analysis
- GRB 160417A: MITSuME Okayama upper limits
- GRB 160417A: Enhanced Swift-XRT position
- GRB 160417A: KAIT optical afterglow confirmation
- GRB 160417A: Swift detection of a burst with an optical counterpart
- LIGO/Virgo G211117: EWE for NOWT of 12 days follow-up of northern sky
- GRB 160412A: GROND upper limits
- GRB 160411A - Gemini-S afterglow candidate
- Konus-Wind observation of GRB 160409A
- GRB 160410A: SMARTS optical/IR observations
- LIGO Virgo G211117: Additional MWA Observations
- GRB 160410A: TLS Tautenburg observations
- GRB 160412A: Swift/UVOT Upper Limits