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 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
- GRB 100115A: SARA Astrometry
- GRB100115A: Revision of NOT observation
- GRB 100116A: Fermi GBM detection
- NOT observation of GRB100115A localization
- GRB 100115A: SARA Afterglow Candidate
- GRB 100115A: Swift/UVOT Upper Limits
- GRB 100115A: Swift-XRT candidate afterglow
- GRB 100115A detected in ground analysis of Swift-BAT data
- GRB 100111A: PAIRITEL NIR Upper Limits
- GRB 100111A: Swift UVOT Refined Analysis
- GRB 100111A: Swift-BAT refined analysis
- GRB 100111A: Enhanced Swift-XRT position
- GRB100111A: Swift-XRT refined analysis
- GRB 100111A: Fermi GBM observation
- GRB 100111A: NOT optical observations
- GRB 100111A: Swift detection of a burst with an optical afterglow
- Swift/BAT Detects an Outburst from XTE J1901+014
- Swift Trigger #382159 is due to XTE J1752-223
- GRB 100103A: GROND Upper Limits
- GRB 100103A: Swift-XRT team refined analysis
- GRB 100103A - UVOT-enhanced XRT position
- Konus-Wind observation of GRB 100103A
- GRB 100103A: Swift/UVOT Upper Limits
- GRB 100103A: Correction to Swift position error
- GRB 100103A: Swift/XRT position
- GRB 100103A: a long GRB detected with INTEGRAL
- Swift Trigger 381591: Retraction of Reported UVOT Source
- Swift Trigger 381591 is probably not a burst
- GRB 091231: GROND NIR observations
- Swift Trigger 381591: Uncatalogued UVOT Source
- GRB 091230: Swift/UVOT Observations
- Trigger 381591: Swift detection of a possible burst
- GRB 091230: Swift-XRT observation
- GRB 091230: GROND optical/NIR afterglow candidate
- GRB 091230: a long GRB detected by INTEGRAL
- Swift Trigger 381434 is not a GRB
- Trigger 381434: Swift detection of a possible burst
- GRB 091221 : IRSF NIR upper limit