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 090419: Enhanced Swift-XRT position
- GRB 090418: Swift XRT refined analysis
- GRB 090418A: ROTSE-III Refined Analysis
- GRB 090419: Swift detection of a burst
- VLA observations of short burst GRB 090417A
- GRB 090418B: Detection of a bright burst from Swift-BAT slew data
- GRB 090417B: Gemini imaging
- GRB 090418: Swift-BAT refined analysis
- GRB 090417B: Galaxy redshift
- GRB 090417B: Swift-XRT refined analysis
- GRB 090418: Enhanced Swift-XRT position
- GRB 090417B: Swift-BAT further refined analysis
- GRB 090418: PAIRITEL NIR detection
- GRB 090418 Lick Redshift
- GRB 090418: ROTSE-III Confirmation of Optical Counterpart
- GRB 090418: Swift detection of a burst with optical afterglow
- GRB 090418 OA candidate
- GRB 090411B: Suzaku WAM observation of the prompt emission
- GRB 090411A: Suzaku WAM observation of the prompt emission
- GRB 090417B: Subaru NIR Observations
- GRB 090417B: Liverpool Telescope observations
- GRB 090417B: MITSuME Okayama optical upper limits
- GRB090417B: Xinglong TNT optical upper limit
- GRB 090417B: optical observations
- GRB090417B: optical observations
- GRB 090417B: Swift-BAT refined analysis
- GRB 090417A: Swift-BAT refined analysis
- GRB 090417A: Early-type nature of the putative host
- GRB 090417A: nearby galaxy redshift
- GRB 090417B: Swift detection of a burst
- GRB 090417: 2MASS galaxy within BAT Localization
- GRB 090417: Swift detection of a short burst
- GRB 090412: Fermi GBM detection
- GRB 090411B: Fermi GBM detection
- GRB 090411A: Fermi GBM detection
- GRB 090410: Suzaku WAM observation of the prompt emission
- GRB 090410: GROND upper limits
- Fermi GBM trigger 261106787 is not a GRB
- GRB 090410: MITSuME optical upper limits
- GRB 090408b: IPN Triangulation
- GRB 090328b: IPN Triangulation
- GRB 090410: Swift-BAT refined analysis
- GRB 090410: Swift detection of a burst
- Konus-Wind and Konus-RF observations of GRB 090408b
- GRB090408 : TAOS optical observations
- GRB 090409: Fermi GBM detection
- Swift-BAT Trigger 348781 is not a GRB
- Swift-BAT Trigger 348720 is not a GRB
- GRB 090406: pseudo-z= 0.91 from prompt emission spectrum
- GRB090408, RIMOTS optical upper limits
- GRB 090408: Xinglong TNT optical Upper Limit
- Swift-BAT trigger 348781: almost certainly not a burst
- Fermi GBM Detection of a weak source
- GRB 090408B: MASTER II-Kourovka optical observations
- GRB 090408: Swift detection of a burst
- GRB 090407: GROND upper limits
- GRB 090407: VLT observations
- GRB 090407: Swift-XRT refined analysis
- GRB 090407: Swift UVOT Upper Limits
- GRB 090407: Enhanced Swift-XRT position
- GRB 090407: Swift-BAT refined analysis
- Konus-Wind and Konus-RF observations of GRB 090406
- GRB 090407: ROTSE-III Optical Limits
- GRB 090407: Swift detection of a burst
- GRB 090404: millimeter detection
- GRB 090404: nIR observations at Calar Alto
- GRB 090405: Fermi GBM Detection
- GRB 090403: Fermi GBM detection
- GRB 090404: GROND upper limits
- GRB 090404: further NOT observations
- Swift/UVOT observations of GRB090404
- GRB 090404: NOT observations
- GRB 090404: optical observations at BOOTES-3 and 1.5-m OSN
- GRB 090404: Swift-XRT Team refined analysis
- GRB 090404: Xinglong TNT optical Upper Limit
- GRB 090404: Swift-BAT refined analysis
- GRB 090404: Enhanced Swift-XRT position
- Fermi Gamma-ray Burst Monitor trigger 260428446 is not a GRB
- GRB 090404: Swift detection of a burst
- GRB 090401A: Suzaku WAM observation of the prompt emission
- GRB 090401B: Suzaku WAM observation of the prompt emission
- Konus-Wind observation of GRB 090401B
- GRB 090401B: Xinglong TNT optical Upper Limit
- GRB 090401B: VLA radio upper limit
- GRB 090401B: Upper limits of MITSuME optical observation
- GRB090401B, RIMOTS optical upper limits
- GRB 090401B: NOT optical observations
- GRB 090328: Fermi-LAT refined analysis
- Swift/UVOT observations of GRB090401B
- GRB 090401B: AGILE refined analysis
- Swift/UVOT observations of GRB090401B
- GRB 090401B: Swift XRT Refined Analysis
- GRB 090331: Fermi GBM detection
- Konus-Wind observation of GRB 090401A
- GRB 090401B: Enhanced Swift-XRT position
- AGILE Gamma-ray detection of GRB 090401B
- GRB 090401B: Swift-BAT refined analysis
- Swift/UVOT detection of GRB090401B
- GRB 090401B: Swift detection of a burst
- GRB 090328B: MASTER-Irkutsk prompt optical short burst observations