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 180314B: Swift detection of a burst
- GRB 180314A: Swift-BAT refined analysis
- Swift Trigger on MAXI J1820+070
- GRB 180314A: TAROT La Silla observatory optical observations
- GRB 180314A: LCO Siding Springs observations
- GRB 180314A: Swift-XRT refined Analysis
- GRB 180314A: Fermi GBM observation
- GRB 180314A: VLT/X-shooter redshift
- GRB 180314A: Swift/UVOT Detection
- GRB 180314A: REM optical/NIR observations
- GRB 180314A: MASTER-Net OT dtetction
- GRB 180314A: Enhanced Swift-XRT position
- GRB180314A: GROND detection of the afterglow
- GRB 180314A: Swift detection of a burst with an optical counterpart
- Trigger 814090: Swift detection of MAXI J1820+070
- GRB 180305A: AstroSat CZTI detection
- GRB 180311A: Swift/UVOT Upper Limits
- GRB 180311A, Swift-BAT refined analysis
- GRB 180311A: Swift-XRT refined Analysis
- MAXI J1820+070: Swift/UVOT counterpart correction
- Swift detection of MAXI J1820+070
- GRB 180311A: Enhanced Swift-XRT position
- GRB 180311A: Prompt enhanced Swift-XRT position
- GRB 180311A: Swift detection of a burst
- GRB 180305A CALET Gamma-Ray Burst Monitor detection
- Trigger 813449: Swift detection of large burst from XTE J1701-407
- GRB 180305A: RATIR Optical Observations
- GRB 180305A: Swift/UVOT Upper Limits
- GRB 180305A: Mondy optical observations
- GRB 180305A: Swift-XRT afterglow detection
- Konus-Wind observation of GRB 180305A
- GRB 180305A: RATIR Optical Afterglow Candidate
- GRB 180305A: Swift ToO observations
- GRB 180305A: Fermi GBM detection
- GRB 180305A: Fermi-LAT detection
- GRB 180221B: Insight-HXMT/HE observation
- Fermi GBM trigger 541402602/180227234 is not a GRB
- GRB 180224A: Swift/UVOT Detection
- Konus-Wind observation of GRB 180223A
- GRB 180224A: OASDG optical observations
- IPN Triangulation of GRB 180223A (long)
- GRB 180210A: Insight-HXMT/HE observation
- Swift Trigger 811686 is probably not an astrophysical source.
- GRB 180224A: AbAO optical observations
- GRB 180224A: Swift-BAT refined analysis
- GRB 180224A: RATIR Optical Observations
- GRB 180224A: Swift-XRT refined Analysis
- GRB180224A: Global MASTER-Net bright OT detection
- GRB 180224A: Enhanced Swift-XRT position
- GRB 180224A: Swift detection of a burst with an optical counterpart
- GRB 180218A: AstroSat CZTI detection
- MAXI J1813-095 source: AbAO optical observations
- GRB 180222A: Swift/UVOT Upper Limits
- GRB 180221B CALET Gamma-Ray Burst Monitor detection
- GRB 180222A: Swift-XRT refined Analysis
- GRB 180222A: Swift-BAT refined analysis
- GRB 180222A: Enhanced Swift-XRT position
- GRB 180222A: A long GRB detected by INTEGRAL
- GRB 180222A: Swift detection of a burst
- Swift trigger 811074 (possible GRB 180221A): Swift refined analysis
- Swift Trigger 811167: Detection of MAXI J1813-095
- GRB 180205A: Mondy optical observations
- GRB 180219A CALET Gamma-Ray Burst Monitor detection
- GRB180221A: MASTER-OAFA optical observations
- Swift Trigger 811074: possible GRB 180221A
- Konus-Wind observation of GRB 180218A
- GRB 180218A CALET Gamma-Ray Burst Monitor detection
- GRB 180218A: Fermi GBM Detection
- IPN Triangulation of GRB 180218A (long/bright)
- GRB 180204A: 15 GHz upper limits from AMI
- GRB 180112A: AstroSat CZTI detection
- Fermi GBM triggers 540405116/180215689 and 540476225/180216512 are not a GRBs
- Swift J1658.2-4242: Swift BAT and XRT refined analysis
- Swift trigger 810300: MASTER-OAFA robotic report
- Swift J1658.2-4242 (trigger 810300): Swift-XRT position
- Swift Trigger 810300 is a probable new Galactic source: Swift J1658.2-4242
- Konus-Wind observation of GRB 180210A
- GRB 180205A: SEDM Observations
- GRB 180210A: Swift-XRT afterglow detection
- GRB 180210A: Tiled Swift observations
- GRB 180205A: BAO optical observations
- Retraction of Swift trigger 809374
- GRB 180210A: Swift ToO observations
- GRB 180210A: Fermi-LAT detection
- GRB 180210A: Fermi GBM detection
- Trigger 809374: Swift detection of a possible non-burst faint source
- Trigger 809217: Swift trigger on RS CVn Star HD 8357
- GRB180205A: Optical observations with DOAO 1m telescope
- GRB 180205A: AbAO optical observations
- Fermi-GBM Detection of possible burst from AXP CXOU J164710.2-455216/PSR J1647-4552
- GRB 180205A optical observations
- GRB 180202A: Insight-HXMT/HE detection
- GRB 180204A: MITSuME Okayama optical upper limits
- GRB 180205A: confirmation of Swift-BAT trigger time.
- GRB 180205A: Optical observations
- GRB 180205A: Swift/UVOT Detection
- GRB 180205A: Nanshan-1m optical observations
- GRB 180205A: Swift-XRT refined Analysis
- GRB 180205A: Swift-BAT refined analysis
- GRB 180205A: Xinglong TNT optical observation