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 081012: Fermi GBM detection
- GRB 081007 and GRB 081007B: Fermi GBM detection
- GRB 080430: optical observations
- GRB 081008 optical upper limit
- GRB 081012: Observations from NOT
- GRB 081012: Swift/UVOT analysis of initial observations
- GRB 081012: Swift/XRT detection
- GRB 081012, Swift-BAT refined analysis
- GRB 081012: ROTSE-III Optical Limits
- GRB 081012: Swift detection of a burst
- Revised table for GRB 081011 UVOT detections
- GRB081011: UVOT detection of an optical afterglow
- GRB 081011: Swift/XRT detection
- GRB 081011, Swift-BAT refined analysis
- GRB 081008, SMARTS optical/IR afterglow observations
- GRB 081011: Swift detection of a burst
- GRB 081007: Radio Detection
- Konus-Wind observation of GRB 081001
- GRB 081007: Rapid PROMPT Detections
- GRB 081008, Swift-BAT refined analysis
- GRB 081008: VLT redshift confirmation
- GRB 081008: Swift-XRT Refined Analysis
- GRB081008: Swift/UVOT observations
- GRB 081008: Enhanced Swift-XRT position
- GRB 081008: Gemini-South Absorption Redshiftt
- GRB 081008: VLT/FORS2 spectroscopy
- GRB 081008: Swift detection of a burst with optical afterglow
- GRB 081008: ROTSE-III Detection of Optical Counterpart
- GRB081006B: Fermi GBM detection
- GRB081006: Fermi GBM detection
- GRB081007: Swift/UVOT Observations
- GRB 081007, SMARTS optical afterglow observations
- GRB 081007, Swift-BAT refined analysis
- GRB 081007: Early RAPTOR measurements of optical counterpart
- GRB 081007: Swift-XRT Team refined analysis
- GRB 081007: Gemini-south redshift
- GRB 081007: Enhanced Swift-XRT position
- GRB 081007, Faulkes Telescope North optical observations
- GRB 081007, SMARTS optical/IR afterglow observations
- GRB 081007: REM NIR and optical counterpart
- GRB 081007: Swift detection of a burst with optical afterglow
- GRB081003C: GLAST Burst Monitor detection
- Fermi GBM detection of additional bursts from AXP 1E1547.0-5408
- INTEGRAL ToO observation of the AXP 1E 1547.0-5408
- GRB 081003B: TAROT Calern observatory optical observations
- AXP 1E 1547.0-5408: Swift/UVOT Upper Limits
- GRB 081003B: Swift-XRT upper limit
- GRB 081003A: OSN optical observations
- GRB 081001: Further observations from OSN
- AXP 1E1547.0-5408: Swift-XRT Team refined analysis
- GRB081003B: Optical limits from Spain
- GRB 081003A: Swift-XRT Team position and analysis
- Swift-BAT refined analysis of AXP 1E1547.0-5408 (Trigger 330353)
- GRB 081003B: a long GRB detected with INTEGRAL
- GRB 080928: Fermi GBM detection
- AXP 1E1547.0-5408 (SGR 1550-5418): Fermi GBM detection
- GRB 081003: A long GRB discovered by INTEGRAL
- SGR 1550-5418 = AXP 1E1547.0-5408 (Trigger 330353)
- Swift discovery of a new Soft Gamma Repeater SGR 1550-5418
- Trigger 330353: Swift detection of a Galactic short soft burst
- GRB 081001: Observations from OSN
- GRB 080925: Suzaku WAM observation of the prompt emission
- GRB 081001: Swift UVOT Observations
- GRB 081001: Swift-XRT position
- GRB081001: optical limit from ASH-Centurion
- GRB081001: SuperAGILE Localization of a long GRB
- GRB080928: redshift retraction
- GRB 080928: Watcher observations
- GRB 080927: Fermi GBM detection
- GRB 080928: VLT redshift
- GRB080928: Gemini-South Absorption Redshift
- GRB 080928: Swift-XRT refined analysis
- GRB 080928: Swift/UVOT observations
- GRB 080928, Swift-BAT final refined analysis
- GRB 080928: GROND DETECTION
- GRB 080928: Enhanced Swift-XRT position
- GRB 080928, Swift-BAT initial refined analysis
- GRB 080928A: ROTSE-III Confirmation of Optical Counterpart
- GRB 080928: Swift detection of a burst with an optical counterpart
- GRB 080925: Fermi GBM Detection
- GRB 080920: Fermi GBM detection
- GRB080922, optical upper limit
- Swift-BAT trigger 325707 is not a GRB
- Swift trigger 325707: Swift/UVOT Upper Limits
- Swift trigger 325707: Swift-XRT upper limit
- Swift detection of a possible GRB (trigger 325707)
- GRB080916A: Suzaku WAM observation of the prompt emission
- GRB 080922: Swift/UVOT Upper Limits
- GRB080922: Swift-XRT upper limit
- GRB080922: A long GRB detected by INTEGRAL
- GRB 080913B: Fermi GBM detection
- Trigger 324561: IGR J08408-4503 detected by Swift
- GRB 080916C: Fermi GBM Spectral Analysis
- GRB 080919: Swift/UVOT Refined Analysis
- GRB 080919: Swift-XRT refined analysis
- GRB 080919, Swift-BAT refined analysis
- GRB 080916C: IRSF/SIRUS NIR Observation
- GRB 080916C: GROND Confirmation of the Optical Afterglow
- GRB 080916C: GROND Confirmation of the Optical Afterglow
- GRB 080919: REM NIR observations