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 140610A: Swift-XRT refined Analysis
- GRB 140606B / iPTF 14bfu: MOSFIRE NIR imaging
- GRB 140611A Detection of a source in BAT ground analysis
- GRB 140610A: Fermi GBM Detection
- IPN Triangulation of GRB 140611A (short/hard)
- GRB 140610A: RATIR Optical and NIR Observations
- GRB 140610A: Swift-BAT refined analysis
- GRB 140610A: MASTER optical observations
- GRB 140610A: Swift/UVOT Upper Limits
- Konus-Wind observation of GRB 140610A
- Swift/XRT returns to normal observing
- GRB140606B: DCT time of observation correction
- GRB 140610A: Swift-XRT observations
- GRB 140610A: Swift detection of a burst
- Konus-Wind observation of GRB 140606B
- GRB 140606B: Swift XRT refined analysis
- GRB 140521A: AAO optical upper limit
- GRB 140606A: AAO optical upper limit
- GRB 140607A: Swift-BAT refined analysis
- IPN Triangulation of GRB 140606B
- GRB 140606B: Swift/UVOT Upper Limits
- GRB140606B/iPTF14bfu: Discovery Channel Telescope Optical Detection
- GRB 140606B: Swift XRT position
- GRB 140606B / Fermi 432717114 / iPTF 14bfu: Keck redshift
- GRB 140607A: Swift detection of a burst
- GRB 140606B: Fermi GBM detection
- Fermi 423717114: Additional P48 and P60 observations
- GRB 140606A: BOOTES-2 optical upper limit
- Fermi423717114: iPTF optical transient candidates
- GRB 140606A: Nanshan optical upper limit
- GRB 140606A: Swift/UVOT Upper Limits
- GRB 140606A: Swift-XRT upper limits
- Swift XRT status update
- Swift Trigger 600914 is noise
- GRB 140606A: Swift-BAT refined analysis
- GRB 140606A: Swift detection of a short hard burst
- Swift Trigger 600914 is probably a noise fluctuation
- Konus-Wind observation of GRB 140604A
- IPN Triangulation of GRB 140604A (short/hard)
- Swift XRT is off-line
- GRB 140523A: further Swift-XRT observations
- GRB 140528A: Fermi GBM Detection
- GRB 140529A BAT refined analysis
- Konus-Wind observation of GRB 140529A
- Konus-Wind observation of GRB 140528A
- GRB 140529A: Swift/UVOT Upper Limits
- GRB 140529A: Swift-XRT afterglow detection.
- GRB 140408A: Withdrawal of afterglow candidate
- GRB 140529A found in ground analysis of BAT slew data
- IPN Triangulation of GRB 140528A
- Chandra late-time observations of GRB140515A
- Swift Trigger 600114 in M31: UVOT Observations
- Swift trigger 600114 is not an outbursting X-ray source
- Swift Trigger 600114: Optical spectroscopy from GTC
- Swift Trigger 600114: Preliminary BAT analysis
- Swift Trigger 600114 in M31: Archival and Prompt UVOT Imaging
- Swift detection of a bright X-ray source in M31
- Fermi GBM trigger 422752719/ 140525971 is not a GRB
- Swift detection of SFXT IGR J17544-2619
- GRB 140523A: NOT observation
- Konus-Wind observation of GRB 140523A
- IPN Triangulation of GRB 140523A
- GRB 140523A: Nanshan optical upper limit
- Swift trigger 599860 probably not real
- GRB 140523A: possible X-ray afterglow candidate from tiled Swift/XRT observations
- GRB 140523A Tiled Swift observations
- GRB 140523A: Fermi-LAT detection
- GRB 140523A: Fermi GBM detection
- GRB 140521A : Xinglong TNT upper limit
- GRB 140521A: Fermi GBM Detection
- GRB 140423A: TShAO optical observations
- GRB 140521A: AAO optical observations
- GRB 140521A: Swift-BAT refined analysis
- GRB 140521A: AROMA-N Optical Observation
- GRB 140521A: MITSuME Okayama upper limits
- GRB 140516A: further Swift-XRT analysis
- GRB 140521A: MASTER optical observations
- GRB 140521A: Swift detection of a burst
- GRB 140512A: Redshift from NOT
- GRB 140518A: T100 observations
- GRB 140518A: Continued RATIR Optical and NIR Observations
- GRB 140512A: MASTER prompt and afterglow optical observations
- GRB 140518A, Swift-BAT refined analysis
- GRB 140518A: Swift-XRT refined Analysis
- GRB 140518A: Skynet GORT Detections of the Optical Afterglow
- GRB 140518A: Swift/UVOT Upper Limits
- GRB 140518A: RATIR Optical and NIR Observations
- GRB 140518A: Gemini-N redshift
- GRB 140518A: P60 i-/z-band detections
- GRB 140518A: KAIT optical candidate
- GRB 140518A: Swift detection of a burst
- GRB 140516A: RATIR Optical and NIR Observations
- GRB 140516A: Subaru NIR imaging observations
- GRB 140516A: 6 GHz upper limit
- GRB 140516A: Gemini-North limit on an optical afterglow
- GRB 140516A: Swift/UVOT Upper Limits
- GRB 140516A: Swift-BAT refined analysis
- GRB 140516A: Swift-XRT refined Analysis
- GRB 140516A: NOT optical observations
- GRB 140516A: Enhanced Swift-XRT position