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 100504A: Swift detection of a burst
- Swift-BAT trigger 421072 is not astrophyical
- INTEGRAL observations of Swift GRB trigger 421072
- GRB100423A : Suzaku WAM observation of the prompt emission
- Trigger 421072: Possible Swift detection of a GRB or transient
- GRB 100420A: EVLA radio observations
- GRB 100420A: Gemini discovery of infrared afterglow
- GRB 100423A: xinglong TNT optical upper limit
- GRB 100420A: Terskol optical upper limit
- GRB 100427A: Swift XRT and UVOT Upper Limits
- GRB 100427A: Fermi GBM detection
- GRB 100424a. Radio observations
- GRB 100418A: RTT150 optical observations
- GRB 100427A detected in ground analysis of Swift BAT data
- GRB 100414A : EVLA Radio Detection
- GRB 100414A : WSRT Radio Detection
- Konus-Wind observation of GRB 100423A
- GRB 100423A: CrAO optical observations
- GRB 100418A: Terskol optical observations
- GRB 100424A: CrAO optical observations
- GRB 100424A: NIR Afterglow Confirmation
- GRB 100425A: Swift XRT refined analysis
- GRB 100424A: Gemini/NIRI H-band observations
- GRB100425A: Swift/UVOT Upper Limits
- GRB 100424A: Swift/UVOT Upper Limits
- GRB 100424A: Liverpool Telescope Upper Limits
- GRB 100425A: Enhanced Swift-XRT position
- GRB 100425A: Swift-BAT refined analysis
- GRB 100425A: VLT/X-shooter redshift
- GRB 100425A: GROND afterglow observation
- GRB 100424A: Gemini/NIRI Candidate Afterglow
- GRB 100424A: D50 optical limits
- GRB 100425A: candidate optical afterglow from the VLT
- GRB100424A: MITSuME optical upper limits
- GRB100423A: MITSuME optical upper limits
- GRB 100424A : Lulin early z'-band upper limit
- GRB 100424A: GROND Upper Limits
- GRB 100424A: PAIRITEL NIR Upper Limits
- GRB 100424A: Swift-XRT refined analysis
- GRB 100425A: Swift detection of a burst
- GRB 100424A: WHT z-band observations
- GRB 100424A: NOT optical observations
- GRB 100424A, Swift-BAT refined analysis
- GRB 100424A: Enhanced Swift-XRT position
- GRB 100424A: Prompt enhanced Swift-XRT position.
- GRB 100424A: Swift detection of a burst
- GRB 100420A: GRT Optical Observation
- GRB 100418A: ROVOR optical measurements at 35 hours
- Swift-BAT refined analysis of trigger 420256
- Swift Trigger 420256: D50 optical limits
- GRB 100418A: Possible Evidence for a Supernova
- GRB 100420A: Swift-BAT refined analysis
- GRB 100423B: Fermi GBM detection
- GRB 100423A: Swift-BAT refined analysis
- Swift Trigger 420256: IAC80 R-band observations
- Swift Trigger 420256: BOOTES-2 observations
- Swift Trigger 420256: ROTSE-III Optical Limits
- Trigger 420256: Swift detection of a possible GRB
- GRB 100423A: Skynet/PROMPT Detections
- GRB 100423A: GROND discovery of afterglow
- GRB 100423A: Swift detection of a burst
- Radio afterglow detection of GRB 100418A with the EVLA
- GRB 100414A: Radio Afterglow Detection with the Expanded VLA
- GRB 100418A: Continued PAIRITEL NIR Observations
- GRB 100418A: WSRT Radio Detection
- GRB100418A: REM possible afterglow detection
- GRB 100418A: Continuing Swift/UVOT Observations
- GRB 100418A: further GROND observations and light curve fit
- GRB 100418A: RTT150 optical observations
- GRB100420A: MITSuME optical upper limits
- GRB 100414A: CFHT optical observations
- GRB 100420A: Swift/UVOT Upper Limits
- GRB 100420A: XRT refined analysis
- GRB 100420A: Enhanced Swift-XRT position
- GRB 100418A: SARA second epoch
- GRB 100420A: SARA Upper Limits
- GRB 100418A: RTT150 observations during the optical afterglow maximum
- GRB 100418A: optical observations
- GRB 100418A: MASTER-Net optical observations
- GRB 100414A: Confirmation of the X-ray afterglow
- GRB 100418A: VLT optical observations
- GRB 100418A: SMA submm detection
- GRB 100420A: ROTSE-III Optical Limits
- GRB 100420A: Swift detection of a burst
- GRB 100418A PAIRITEL NIR Observations
- GRB 100418A: ROVOR optical afterglow detection
- GRB 100418A: Swift/UVOT Observations
- GRB 100418A: Gemini-N redshift confirmation
- GRB 100413A: GMRT observation of radio afterglow
- GRB 100418A: Swift-XRT Refined Analysis
- GRB 100418A: host galaxy detection in the SDSS
- GRB100418A: VLT/X-shooter redshift and photometry
- GRB 100418A: SARA observations
- GRB100414A: SAO RAS optical observations
- GRB 100418A: GROND observations; missing author list added
- GRB 100418A: GROND observations
- GRB 100418A: Swift-BAT refined analysis
- GRB 100418A: Enhanced Swift-XRT position
- GRB 100418A: ROTSE-III Optical Limits
- GRB 100418A: Swift detection of a burst with a possible optical afterglow