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 171222A: Swift/UVOT Upper Limits
- GRB 171222A: Nanshan-1m optical afterglow detection
- GRB 171222A: MASTER-Net OT observations
- GRB 171222A: Redshift from 10.4m GTC/OSIRIS
- GRB 171222A: Swift-XRT refined Analysis
- GRB 171205A: SMARTS optical/IR supernova monitoring
- GRB 171222A: NOT Optical Afterglow
- GRB 171216B CALET Gamma-Ray Burst Monitor detection
- GRB 171210A CALET Gamma-Ray Burst Monitor detection
- GRB 171222A: Enhanced Swift-XRT position
- GRB 171222A: Swift detection of a burst
- GMRT Radio detection of GRB 171205A
- IPN Triangulation of GRB 171216B
- GRB 171216A: Swift/UVOT Upper Limits
- GRB 171210A: Further Swift-XRT observations
- GRB 171216A: Swift-XRT refined Analysis
- GRB 171216A: Swift-BAT refined analysis
- GRB 171205A: RATAN observations
- GRB 171216A: Enhanced Swift-XRT position
- GRB 171216A: Swift detection of a burst
- Swift Trigger 797070: KAIT Optical Observations
- Swift Trigger 797070 is probably not a GRB
- GRB 171212A/Swift J1935.7+2036: Swift-BAT refined analysis
- GRB 171205A: ALMA observations
- GRB 171212A: Swift-XRT refined Analysis
- GRB 171211A iTelescope observation
- GRB 171212B: Fermi GBM observation
- GRB 171212A/Swift J1935.7+2036: Swift/UVOT Upper Limits
- GRB 171212B: Fermi-LAT detection
- GRB 171212A/Swift J1935.7+2036: TSHAO optical observations
- GRB 171212A: Enhanced Swift-XRT position
- Konus-Wind observation of GRB 171210A
- GRB 171212A: Swift detection of a burst or a Galactic transient
- GRB 171205A: JCMT SCUBA-2 sub-mm observations
- GRB 171211A: Swift-BAT refined analysis
- GRB 171211A: Swift-XRT refined Analysis
- GRB 171211A: Swift/UVOT Upper Limits
- GRB 171210A: MASTER-Net optical observations
- GRB 171209A: MASTER-Net optical observations
- GRB 171211A: Enhanced Swift-XRT position
- GRB 171210A: Swift-XRT and UVOT observations
- GRB 171211A: Swift detection of a possibly short burst
- GRB 171210A: Fermi GBM detection
- GRB 171210A: Swift ToO observations
- Correction to GCN 22184: GRB 171205A: Swift-BAT refined analysis
- GRB 171209A: Lulin 1m telescope observations
- GRB 171209A: Swift-BAT refined analysis
- GRB 171210A: Fermi-LAT detection
- Konus-Wind observation of GRB 171205A
- GRB 171205A: MASTER-Net OT recent photometry
- GRB 171205A: iTelescope optical observations
- GRB 171205A: Mondy optical observations
- GRB 171205A: SAO-RAS optical observations
- GMRT upper limit on GRB 171205A
- GRB 171209A: Swift/UVOT Analysis of the burst
- Swift trigger 796115 is not astrophysical
- GRB 171209A: Swift-XRT refined Analysis
- GRB 171209A: Enhanced Swift-XRT position
- Swift Trigger 796115 is probably not a GRB
- GRB 171205A: VLA detection
- GRB 171205A: UKIRT near-IR observations
- GRB 171209A: LCO 1-m telescope observations
- GRB 171209A: Swift detection of a burst
- Swift Trigger 796098 is probably a noise peak near M31
- LIGO/Virgo GW170817: X-ray observations confirm prediction made from radio data
- GRB 171124A CALET Gamma-Ray Burst Monitor detection
- GRB 171120A CALET Gamma-Ray Burst Monitor detection
- GRB 171106A CALET Gamma-Ray Burst Monitor detection
- LIGO/Virgo GW170817: Further Hubble Space Telescope observations
- LIGO/Virgo G298048: Brightening X-ray Emission from GW170817/GRB170817A/SSS17a
- GRB 171205A: TSHAO optical observations
- GRB 171205A: Detection of the emerging SN
- LIGO/Virgo GW170817: Chandra X-ray brightening of the counterpart 108 days since merger
- GRB 171205A: Continued Swift/UVOT Observations
- LIGO/Virgo G298048: Late-time detection of the X-ray afterglow with Chandra
- Fermi GBM trigger 534174346/171205573 is not a GRB
- GRB 171205A: MASTER-SAAO optical observations of unusual OT
- GRB 171205A: GROND observations of the optical/NIR transient
- GRB 171205A: LCO 1-m telescope observations
- GRB171205A hyperluminal radio afterglow?
- GRB 171205A: GMG observations (2nd night)
- GRB 171205A: Host galaxy photometric properties
- GRB 171205A: CHILESCOPE optical observations
- GRB 171205A: SMARTS optical/IR afterglow observations
- Possible blackbody component in the X-ray spectrum of GRB171205A
- GRB 171205A: GOTO detection of the optical counterpart
- GRB 171205A: TNG NIR detections
- GRB 171205A: LSGT optical afterglow follow-up observation
- GRB 171205A: NOEMA detection of a bright mm afterglow
- GRB 171205A: GMG observation
- Fermi Gamma-ray Burst Monitor trigger 534174346/171205573 is not a GRB
- GRB 171205A: Swift-BAT refined analysis
- GRB 171205A: Swift-XRT refined Analysis
- GRB 171205A: RATIR Optical and NIR Observations
- GRB 171205A: Swift/UVOT Detection
- GRB 171205A: VLT/X-shooter optical counterpart and spectroscopic observations
- GRB 171205A: Enhanced Swift-XRT position
- GRB 171205A: Likely association with low-z spiral galaxy
- GRB 171205A: Swift detection of a burst
- GRB 171126A: AstroSat CZTI detection