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"28724 results found.
- GRB 211023A: BTA spectroscopic redshift
- GRB 211106A: Swift ToO observations
- GRB 211106A: Swift/BAT-GUANO candidate arcminute localization of a short burst
- GRB 211105A: MASTER optical inspection
- GRB 211105A: Swift/BAT-GUANO detection outside the coded FOV
- GRB 211023A: optical detection by SBT in Ondrejov
- GRB 211023A: continued 1.3m DFOT Optical Observations and possible jet break
- GRB 211023B: Subaru optical observation
- GRB 211024A: MITSuME Akeno optical observation
- GCN Viewer Now Available
- GRB 211102B: GECAM detection
- Fermi GRB 211102A: Global MASTER-Net observations report
- GRB 211023B: MITSuME Akeno optical upper limits
- GRB 211024B: Optical afterglow observation by Ondrejov D50
- GRB 211024A: 1.3m DFOT observations
- Fermi GRB 211031A: Global MASTER-Net observations report
- IPN triangulation of GRB 211022A
- GRB 211023A: 1.3m DFOT Optical Observations
- Konus-Wind detection of GRB 211023A
- GRB 2121023B: 6 GHz VLA radio upper limit
- GRB 211023A: Terskol optical observations
- AMON NuEm-211020A: No Candidate Counterparts from Swift-XRT follow up observations
- GRB 211023A: continued Mondy optical observations
- GRB 211024A: Swift-XRT source 4 is not an afterglow.
- GRB 211023B: NUTTelA-TAO / BSTI Early Optical Limits (Preliminary)
- Fermi GRB 211027A: Global MASTER-Net observations report
- GRB 211024A: Possible afterglow candidate from GIT
- GRB 211024A: Swift-XRT observations
- GRB 211024A: Fermi GBM detection
- GRB 211018A: Swift-XRT observations
- GRB 211025A: Optical Afterglow Detection
- GRB211023A: optical afterglow detection from Konkoly Observatory
- GRB 211024A: Swift ToO observations
- GRB 211024A: Swift/BAT-GUANO detection and candidate arcminute localization of a short burst
- GRB 211024B: Swift/UVOT detection
- GRB 211023A: Mondy optical observations
- GRB 211023B: Mondy optical afterglow confirmation
- GRB 211023B: Gemini-North Optical Observations
- Swift GRB 211025A: Global MASTER-Net observations report
- GRB 211023B: LDT Optical Afterglow Detection
- Correction to GCN 30965: GRB 211023A: Fermi GBM detection
- GRB 211025A: Swift-BAT refined analysis
- GRB 211025A: Swift-XRT refined Analysis
- GRB 211024B: CAHA 2.2m Detection; ultra-long GRB?
- GRB 211024B: Swift-XRT refined Analysis
- IPN Triangulation of GRB 211019A
- Possible Short GRB 211023B: CAHA 2.2m Detection
- GRB 211025A: Swift/UVOT Detection
- GRB 211023A: 1.5m OSN optical observation
- GRB 211024B: Swift-BAT refined analysis
- GRB 210610B: Sintesz-Newton/CrAO optical observations
- GRB 211024B: Nanshan/NEXT optical afterglow detection
- GRB 210919A: FORS2/VLT observations
- GRB 211023A: OAJ Bright Afterglow Confirmation
- Swift GRB 211024B: Global MASTER-Net observations report
- GRB 211023B: Swift-BAT refined analysis
- Fermi-LAT Gamma-ray Observations of IceCube-211023A
- GRB 211023A: MASTER OT J045237.07+851925.2 - optical counterpart discovery
- GRB 211023B: Swift/UVOT Detection
- GRB 211024A: GECAM detection
- GRB 211023B: RATIR Optical and NIR Upper Limits
- GRB 211023B: TSHAO optical observation
- IceCube-211023A: No neutrino counterpart detected with ANTARES
- Fermi GRB 211023A: Global MASTER-Net observations report
- GRB 211023A: AGILE detection
- GRB 211022A: AstroSat CZTI detection
- GRB 211023B: Swift-XRT refined Analysis
- GRB 211023A: Fermi GBM detection
- Swift GRB 211023B: Global MASTER-Net observations report
- Fermi GRB 211024A: Global MASTER-Net observations report
- GRB 211023A: Fermi-LAT detection
- IPN Triangulation of GRB 210927B
- GRB 211018A: Swift ToO observations
- GRB 211018A: Fermi GBM observation
- GRB 211019A: Detection by GRBAlpha
- GRB 211018A: Detection by GRBAlpha
- Fermi GRB 211019A: Global MASTER-Net observations report
- IceCube-210922A: Hard X-ray flux limit for JCMT/SCUBA2 source from NuSTAR observations
- Swift trigger 1078701: MITSuME Akeno optical upper limits
- GRB 210919A: LDT optical observations and candidate host galaxies
- Swift Trigger 1078701: Mondy, CrAO, AbAO observations, possible optical counterpart
- IceCube-20210922A: DESNU Optical counterpart candidate from 5 nights of DECam observations
- IceCube-210922A: DESI Observations
- Konus-Wind detection of GRB 210928A
- Correction to GCN 30915: GRB 210928A: Swift-XRT analysis
- GRB 210928A: Kinder SLT-40cm optical limits
- GRB 210930A: Swift-BAT refined analysis
- GRB 210928A: Swift-XRT analysis (replaces GCN 30914)
- GRB 210928A: Fermi GBM observation
- Swift GRB211001.03 / trigger 1076121 : MASTER OT retraction
- GRB 210927A: GIT optical follow-up of ZTF21acdwctm.
- GRB 210930A: Swift/UVOT Upper Limits
- GRB 210930A: Swift-XRT refined Analysis
- Swift GRB 210930A: Global MASTER-Net observations report
- Fermi GRB 210929B: Global MASTER-Net observations report
- GRB 210927A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 654396242)
- GRB 210925B: AstroSat CZTI detection
- IceCube-210922A: SMA observation for the JCMT candidate
- IPN triangulation of GRB 210925B
- GRB 210926A: AstroSat CZTI detection