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 100219A: Swift/UVOT Detection of a Source near the XRT Position
- GRB 100218A : Fermi GBM detection
- GRB 100219A: Swift detection of a burst
- GRB 100216A: Keck imaging
- GRB 100216A Short, hard GRB detected in ground analysis of Swift-BAT data
- GRB 100213A: Swift-BAT lag analysis indicates probably SHB
- GRB 100213B: GRT Optical Observation
- GRB 100213A: GRT Optical Observation
- GRB 100213A: Swift-BAT refined analysis
- GRB 100213B: Enhanced Swift-XRT position
- GRB 100213B: Gemini-N Observations
- GRB 100213B: Swift/UVOT Upper Limits
- GRB 100213A: Swift/UVOT Upper Limits
- GRB 100213B: PAIRITEL NIR Upper Limits
- GRB 100213A: Enhanced Swift-XRT position
- GRB 100213B: Swift-BAT refined analysis
- GRB 100213B: Swift XRT refined analysis
- GRB 100213A: SARA observations
- GRB 100213A: Swift XRT refined analysis
- GRB 100213B: NOT optical observations
- GRB 100213B: Swift detection of a burst
- GRB 100213A: Swift detection of a burst
- GRB 100206A: Second epoch Gemini-north observations and afterglow limits
- Swift/UVOT observations of GRB100212A - correction of the name of the burst
- Swift/UVOT observations of GRB120212A
- GRB 100212A: LOAO R-band Detection/V-band Observation
- GRB 100212A: Fermi GBM detection
- GRB 100212A: Swift XRT refined analysis
- GRB 100212A: Swift-BAT refined analysis
- GRB 100212A: Enhanced Swift-XRT position
- GRB 100212A: candidate optical afterglow
- GRB 100212A: Swift detection of a burst
- GRB 091127: Detection of a Supernova
- GRB 100205A: Keck limits on an underlying host galaxy
- GRB 100205A: BOAO/LOAO zYJK observation
- GRB 100205B: Fermi GBM detection
- GRB 100206A: GROND upper limits
- GRB 100206A: Gemini-North observations
- GRB 100206A: Swift/UVOT Upper Limits
- GRB 100131A: MASTER-Net optical alert observations
- GRB 100206A: YNAO-GMG observations
- GRB 100206A: MASTER-Net optical alert observations
- GRB 100206A: PAIRITEL Photometry of Host Candidate
- GRB 100206A - Keck/LRIS Spectroscopy
- GRB100206: MITSuME optical upper limits
- GRB 100206A: NOT NIR observations
- GRB 100206A: WHT candidate afterglow
- GRB 100206A, RIMOTS optical upper limits
- GRB 100206A: optical observations from Southern Spain
- GRB 100205A: GROND upper limits
- GRB 100206A: Swift-XRT refined analysis
- GRB 100206A: Fermi GBM observation
- GRB 100206A: Optical limit
- GRB 100206A: Swift-BAT refined analysis
- GRB 100206A: Enhanced Swift-XRT position
- GRB 100206A: Pre-explosion imaging and host candidate
- GRB 100206A: Swift detection of a short hard burst
- GRB100205A: CFHT z'-band observation
- GRB 100205A: Gemini-N + NIRI photometry
- GRB 100130B: Fermi GBM detection
- GRB 100113A: Fermi GBM detection
- GRB 100205A: Swift-BAT refined analysis
- GRB 100205A: Swift UVOT upper limits
- GRB 100205A: Swift XRT refined analysis
- GRB 100203A: Swift XRT and UVOT refined analyses
- GRB 100205A: Enhanced Swift-XRT position
- GRB 100205A Gemini-North IR afterglow candidate
- GRB 100205A: Gemini-South Observations
- GRB 100205A: Super-LOTIS early observations
- GRB 100131A: Suzaku WAM observation of the prompt emission
- GRB 100205A: NOT optical observations
- GRB 100205A: Swift detection of a burst
- GRB 100203A Detected in Ground Analysis of BAT Data
- Short X-ray Transient detected by MAXI/GSC
- GRB 100131A: Fermi GBM detection
- GRB 100119A: Suzaku WAM observation of the prompt emission
- Konus-Wind observation of GRB 100119A
- GRB 100122A: Fermi GBM detection
- GRB 100122A: MASTER-Net optical observations
- GRB 100116A: Suzaku WAM observation of the prompt emission
- GRB 100115A: Swift-XRT refined analysis
- GRB 100119A: Swift-BAT refined analysis
- GRB091109A: VLT/FORS2 spectroscopic redshift
- GRB 100117A: candidate optical afterglow
- GRB 100119A: Swift detection of a burst
- Konus-Wind observation of GRB 100116A
- GRB 100117A: Gemini North spectroscopy
- GRB 100117A: Fermi GBM detection
- Swift/UVOT refined analysis of GRB100117A
- GRB 100117A: Optical object inside the revised XRT error circle
- GRB 100117A: Swift-XRT refined analysis
- GRB 100117A: Gemini-North upper limit
- GRB 100117A: Magellan IMACS imaging
- GRB 100117A: Gemini South Imaging and CFHT Pre-Explosion Images
- GRB 100117A: Swift-BAT refined analysis
- GRB100117A: Possible afterglow from NOT observation
- GRB 100117A: Swift detection of a short hard burst
- GRB 100115A: Gemini-N photometry
- GRB 100115A: Enhanced Swift-XRT position
- GRB 100116A: Fermi LAT detection