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 170207A: AstroSat CZTI detection
- Konus-Wind observation of GRB 170208A
- GRB 170208B: GROND observations
- GRB 170206C: POLAR Observation
- GRB 170208B: NOT upper limits
- GRB 170208B: Swift-XRT refined Analysis
- GRB 170208B: Etelman observatory optical observations
- GRB 170208B: Enhanced Swift-XRT position
- GRB 170208A: Enhanced Swift-XRT position
- GRB 170208A: Fermi GBM Detection
- GRB 170208B: Swift detection of a burst
- GRB 170208A: Swift detection of a burst
- GRB 170207A: Fermi GBM observation
- Konus-Wind observation of GRB 170207A
- IPN Triangulation of GRB 170207A (long/very bright)
- LIGO/Virgo G270580: Gemini-South Spectroscopic Classification of Optical Transients
- GRB 170206B: Swift/UVOT Upper Limits
- Konus-Wind observation of GRB 170206A
- GRB 170206A: POLAR observation
- IPN Triangulation of GRB 170206A (short/hard)
- GRB 170206B: Swift-BAT refined analysis
- LIGO/Virgo G270580: ANTARES upper limits
- GRB 170206B: Swift-XRT refined Analysis
- GRB 170206B: Enhanced Swift-XRT position
- GRB 170206B: Swift detection of a burst
- GRB 170206A: Fermi-LAT detection
- GRB 170206A: Fermi GBM observation
- GRB 170205A: Swift/UVOT Detection of a Fading Afterglow
- Konus-Wind observation of GRB 170205A
- GRB 170205A: Swift-BAT refined analysis
- GRB 170205A: NOT afterglow observations
- GRB 170205A: Swift-XRT refined Analysis
- GRB 170205A: Enhanced Swift-XRT position
- GRB 170205A: RATIR Optical and NIR Observations
- Fermi GBM trigger 508010837/170205755 is not a GRB
- Fermi GBM trigger 507959893/170205165 is not a GRB
- GRB 170202A: SMARTS optical/IR afterglow observations
- GRB 170205A: LCO FTN observations
- Konus-Wind observation of GRB 170202A
- GRB 170205A: Swift detection of a burst with an optical counterpart
- GRB 170202B POLAR Observation
- GRB 170202A: SQUEAN Observation (2nd night)
- GRB 170131A: POLAR Observation
- GRB 170202A: Zadko observatory - Gingin optical observations
- GRB 170202A: Etelman Observatory optical observations
- GRB 170203A: Swift-BAT refined analysis
- GRB 170202A: Swift-BAT refined analysis
- GRB 170202A: RATIR Optical and NIR Observations
- GRB 170202A: SQUEAN Observation
- GRB 170202A: LCO FTN observations
- GRB 170202A: Swift-XRT refined Analysis
- GRB 170202A: T100 observations
- GRB 170202A VLT/X-shooter redshift [minor correction]
- GRB 170202A: Xinglong 2.16m photometry and spectroscopic redshift
- GRB 170202A: Swift/UVOT Detection
- GRB 170202A: Enhanced Swift-XRT position
- GRB 170202A: MITSuME Akeno Optical Observation
- GRB 170202A: Redshift from OSIRIS/GTC
- GRB 170203A: Swift detection of a burst
- GRB 170202A: NOT afterglow observations
- GRB 170202A: Kanata optical and infrared observations
- GRB 170202A: Zadko observatory - Gingin optical observations
- GRB 170202A: LCO Sutherland observations
- GRB 170202A: MASTGlobal ER-Net bright OT nonmonotonic light curve
- GRB 170202A: Mini-MegaTORTORA upper limits
- GRB 170202A : Xinglong TNT optical observation
- GRB 170202A: Swift detection of a burst with an optical afterglow
- GRB 170131A: Swift/UVOT Upper Limits
- GRB 170131A: Swift-XRT observations
- GRB 170131A: Fermi GBM observation
- GRB 170131A: Swift ToO observations
- GRB 170131A detected in Swift/BAT ground processing
- LIGO/Virgo G270580: Las Cumbres Observatory Follow-up Observations
- GRB 170130A: POLAR Observation
- Konus-Wind observation of GRB 170127C (short/hard GRB with extended emission)
- GRB 170127B: Swift-BAT refined analysis
- GRB 170127A: Swift-BAT refined analysis
- GRB 170127C: Swift-XRT observations
- GRB 170127C: POLAR Observation
- GRB 170127A: GROND Upper limits
- GRB 170127C: AstroSat CZTI detection
- GRB 170127B: Swift-XRT refined Analysis
- GRB 170124A: POLAR Observation
- GRB 170127A: Swift-XRT refined Analysis
- GRB 170126A, Swift-BAT refined analysis
- GRB 170124A: CALET Gamma-Ray Burst Monitor detection
- Swift Trigger 735413 is not an astrophysical event
- GRB 170127B: Swift/UVOT Upper Limits
- LIGO/Virgo G268556: FLOYDS Spectrum of iPTF17cf/PS17fr Favors an AGN Classification
- GRB 170127A: Swift/UVOT Upper Limits
- GRB 170127B: Fermi GBM observation
- GRB 170127B: Enhanced Swift-XRT position
- GRB 170127B: NOT r-band upper limits
- GRB 170127A: Enhanced Swift-XRT position
- Konus-Wind observation of GRB 170126A
- GRB 170127C: Tiled Swift observations
- GRB 170127C (Fermi/GBM trigger 507173752): AGILE analysis
- GRB 170127C: Fermi-LAT detection
- GRB 170127C: Fermi GBM detection
- LIGO/Virgo G270580: HAWC follow-up observations