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"- Fermi-GBM detection of a Solar Flare
- Fermi Detection of GRB 081102
- GRB 081104 : Faulkes Telescope South observations
- GRB 081104: Swift-XRT position
- GRB 081104: Swift detection of a burst
- Radio observation of GRB 080130 with ATCA
- GRB 081102: MASTER prompt optical limit
- GRB 081102: Swift-XRT refined analysis
- GRB 081102: Swift/UVOT refined analysis
- GRB 081102: Swift-BAT refined analysis
- GRB 081102: Enhanced Swift-XRT position
- Radio observation of GRB 080218b with ATCA
- Radio observation of GRB 080229a with ATCA
- GRB 081102: MASTER VWF promt observation
- GRB 081102: OPTIMA-Burst optical upper limit
- GRB 081102: Swift detection of a burst
- SGR 0501+4516: optical observations in August
- GRB 081101 (or SGR 0623-0006 ): Fermi GBM detection
- SGR 0623-0006 or GRB 081101: Swift-XRT refined analysis
- SGR 0623-0006 or GRB 081101: Swift-BAT/-XRT refined analysis
- Swift-BAT triggered on a probable GRB 081101 (trigger=333320)
- GRB 081024B: BTA deep optical observations
- GRB 081028: CrAO optical observations
- GRB 081024B: new Swift-XRT observations
- Radio observation of GRB 080229b with ATCA
- GRB 081029, SMARTS optical/IR afterglow observations
- GRB 081024B: VLA radio observation
- GRB 081029: UVOT Detection of the Optical Afterglow
- GRB 081029: PROMPT Detections
- GRB 081029: Redshift Confirmation from Gemini-South
- GRB 081029: Swift-BAT refined analysis
- GRB081029: Swift XRT refined analysis
- GRB 081025: Suzaku WAM observation of the prompt emission
- GRB 081024B: Suzaku WAM observation of the prompt emission
- GRB 081029: Enhanced Swift-XRT position
- GRB 081028: GROND Confirmation of the Optical/NIR Afterglow
- GRB 081029: REM observations
- Radio observation of GRB 080303 with ATCA
- Radio observation of GRB 080411 with ATCA
- GRB 081029: UVES/VLT Absorption Redshift
- GRB 081029: GROND Detection of the Optical/NIR Afterglow
- GRB 081029: ROTSE-III Detection of Optical Counterpart
- GRB 081029: Swift detection of a burst
- GRB 081028: Magellan redshift
- GRB 081028B: Fermi GBM detection
- GRB 081021: Fermi GBM detection
- GRB081028: UVOT detection of a brightening afterglow
- Swift UVOT observations of GRB081028
- GRB 081028: Swift-XRT refined analysis
- GRB 081028, Swift-BAT refined analysis
- GRB 081028: Enhanced Swift-XRT position
- GRB 081028: TAROT Calern observatory optical observations
- GRB 081028: optical observations at the NOT
- GRB 081028: GROND Detection of the Optical/NIR Afterglow Candidate
- Fermi LAT/GBM short-hard GRB 081024B: Possible TLS Afterglow (Corrected)
- Fermi LAT/GBM short-hard GRB 081024B: Possible TLS Afterglow
- GRB 081028: Swift detection of a burst
- GRB 081025: TLS upper limits
- GRB 081024: No radio detection with the VLA
- GRB081025: RTT150 optical observations
- GRB081024B: P200 Observations
- GRB 081024B: Swift-XRT further observations
- GRB 081025 BAT refined analysis
- Swift UVOT observations of GRB081025
- Swift UVOT observations of GRB081024B
- Konus-Wind observation of GRB 081025
- GRB 081025: Swift-XRT position
- GRB 081024B: Swift-XRT observations
- GRB 081025: Burst detection from Swift-BAT slew data
- GRB 081024B: Fermi Gamma-ray Burst Monitor detection
- Fermi-LAT observation of GRB 081024B
- Swift UVOT observations of GRB 081024
- GRB 081024: Swift-XRT refined analysis
- GRB 081024, Swift-BAT refined analysis
- GRB 081024: Enhanced Swift-XRT position
- GRB 081024: Faulkes Telescope North optical observations
- GRB 081024: KAIT Optical Limits
- GRB 081024: Early Super-LOTIS Observations
- GRB 081024A: ROTSE-III Optical Limits
- GRB 081024: Swift detection of a burst
- GRB 081022, Swift-BAT refined analysis
- GRB 081016A: Swift-XRT refined analysis
- GRB 081022: Swift detection of a burst
- GRB 081012: Swift-XRT Refined Analysis
- Swift trigger 332287 is not a GRB
- Swift detection of a possible burst (trigger 332287)
- GRB 081012 - Enhanced Swift XRT position
- GRB 081017, Swift-BAT refined analysis
- GRB 081017: REM early observations
- GRB 081017: Swift detection of a burst
- GRB 081016B, Swift-BAT refined analysis
- GRB 081016B: Swift/UVOT Upper Limits
- GRB 081011: Swift XRT refined analysis
- GRB 081016B: Swift-XRT Team refined Analysis
- GRB 081016B: Enhanced Swift-XRT position
- GRB 081016B: ROTSE-III Optical Limits
- GRB 081016B: Swift detection of a burst
- GRB 081011: Enhanced Swift-XRT position
- GRB 081016: Swift-XRT candidate afterglow detection
- Swift detection of flare on CC Eri