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 101213A: Gemini-N galaxy redshift
- GRB 110106B: Fermi GBM detection
- Short GRB 110106A: MASTER OT observations
- GRB 110106B: Swift-XRT refined Analysis
- GRB 110106B: Gemini-North / WHT detection of a fading afterglow
- GRB 110106A: TNG NIR observations
- GRB 110106B Gemini-N galaxy redshift
- GRB 110106B: Liverpool Telescope observations
- GRB 110106A: ISAS-Kanazawa optical upper limit
- GRB 110106A: MITSuME Okayama optical upper limits
- GRB 110106B: WHT candidate afterglow
- GRB 110106B: Swift-BAT refined analysis
- GRB 110106B: Enhanced Swift-XRT position
- GRB 110106A: Swift/UVOT Upper Limits
- GRB 110106A: TNG redshift of the closeby galaxy
- GRB 110106A: Swift-XRT refined Analysis
- GRB110106B: Xinglong TNT upper limit
- GRB 110106A: Swift-BAT refined analysis
- GRB 110106A: Enhanced Swift-XRT position
- GRB 110106B: Swift detection of a burst
- GRB 110106A: TNG optical observations and candidate counterparts
- GRB 110106A: MASTER optical observations
- GRB 101225A: Keck redshift
- GRB110106A: Xinglong TNT upper limit
- GRB 110106A: Swift detection of a burst
- GRB 101225A: Host galaxy
- GRB 101219A: Gemini-North host redshift
- GRB 110102A: Swift-XRT refined Analysis
- GRB 101219B: After 2 weeks still detected by Swift/UVOT
- Konus-Wind observation of GRB 110102A
- GRB110102A: Swift/UVOT observations
- GRB110102A: MITSuME Okayama Optical Observation
- GRB 110102A: Fermi GBM observation
- GRB 110102A: Swift-BAT refined analysis
- GRB 110102A: Enhanced Swift-XRT position
- GRB 110102A: Swift detection of a burst with an optical detection
- GRB 101225A: optical break from NOT observation
- GRB 101225A: MMT spectroscopy
- GRB 101225A: P60 Observations
- GRB 101225A: MAXI/GSC observations
- GRB 101225A Late-time emission observed by Swift-BAT
- GRB 101225: Optical follow-up of the Christmas burst
- GRB 101225A: WHT observations
- Tentative redshift of GRB101225A (Christmas's burst) from Swift-XRT data
- GRB 101225A, Swift-BAT refined analysis
- GRB 101225A: Swift/UVOT Detection
- GRB 101225A: Swift-XRT refined Analysis
- GRB 101225A: Enhanced Swift-XRT position
- Trigger 441015 / GRB 101225A: Further NOT optical observation
- Trigger 441015 / GRB 101225A: NOT optical afterglow candidate
- GRB 101225A (Swift trigger 441015): optical upper limit
- Trigger 441015: Swift detection of a possible burst or transient
- GRB 101224A: NOT optical observation
- GRB 101224A: Pre-event imaging from DeepSky; Detection of a source in the XRT error circle
- GRB 101224A: Swift/UVOT Upper Limits
- GRB 101224A: Fermi GBM observation
- GRB 101224A: Swift-XRT refined Analysis
- GRB101224A: MITSuME Okayama optical upper limits
- GRB 101224A, Swift-BAT refined analysis
- GRB 101224A - UVOT-enhanced XRT position
- GRB 101224A: Swift detection of a short burst
- GRB 101219A: Chandra Observations
- GRB 101219B: Swift/UVOT refined analysis
- GRB 101219B: Swift-XRT refined Analysis
- GRB 101219B: Enhanced Swift-XRT position
- GRB 101219A: MITSuME Ishigakijima Optical upper limits
- GRB 101219B: GROND Detection of the Optical/NIR Afterglow
- GRB 101219B: Fermi GBM observation
- GRB 101219A: IAC80 optical observations
- GRB 101219B: Swift-BAT refined analysis
- GRB 101219A: Swift-XRT refined Analysis
- GRB 101219B: Swift detection of a burst with an optical afterglow
- GRB 101219A: Swift/UVOT Upper Limits
- GRB 101219A: GROND Upper limits
- Konus-Wind observation of short hard GRB 101219A
- GRB 101219A: Magellan NIR observations
- GRB 101219A: Further Gemini-South Imaging
- GRB 101219A: Swift-BAT refined analysis
- GRB 101219A - NOT observation - upper limit
- GRB 101219A: SARA-N Upper Limit
- GRB 101219A: Gemini-South observations
- GRB 101219A: REM optical and NIR observations
- GRB 101219A: ROTSE-III Optical Limits
- GRB 101219A: Swift detection of a short hard burst
- Request for Supernova related data for GRB 101023A
- GRB 101213A : Suzaku WAM observation of the prompt emission
- Redshift solution(s) for GRB101213A from Swift-XRT data
- Konus-Wind observation of GRB 101213A
- XRF 101117A, RIMOTS optical upper limits
- GRB 101213A: Fermi GBM observation
- GRB 101213A, Swift-BAT refined analysis
- GRB 101213A: Swift-XRT refined Analysis
- GRB 101213A: Swift/UVOT Upper Limits
- GRB 101213A: Enhanced Swift-XRT position
- GRB 101213: object within the X-ray error circle
- GRB 101213A: Swift detection of a burst
- GRB101204A: Swift/UVOT observations
- GRB 101204A: Swift-XRT refined Analysis
- GRB101204A GROND Detection of the Optical/NIR Afterglow
- GRB 101204A Afterglow Candidate, VATT Observations