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"7293 results found.
- GRB 100316A: Swift/UVOT Observations
- IBAS Alert 5992 is not a GRB, but XTE J1855-026
- GRB 100305A: Swift/UVOT Upper Limits
- GRB 100305A: Gemini-N OT candidate
- GRB 100305A: P60 Observations
- GRB 100305A: Swift detection of a burst
- GRB 100302A: Optical observations at Crni Vrh
- GRB 1000302A : A possible afterglow candidate
- GRB 100302A: Swift detection of a burst
- GRB 100219A: VLT/X-shooter redshift
- GRB 100219A: Swift/UVOT Detection of the Optical Afterglow
- GRB 100219A: Pre-explosion imaging and host candidate
- GRB 100219A: Swift detection of a burst
- GRB 100213B: Swift detection of a burst
- GRB 100213A: Swift detection of a burst
- GRB 100212A: LOAO R-band Detection/V-band Observation
- GRB 100212A: candidate optical afterglow
- GRB 100212A: Swift detection of a burst
- GRB 100205A: Keck limits on an underlying host galaxy
- GRB 100205A: BOAO/LOAO zYJK observation
- GRB 100206A: Gemini-North observations
- GRB 100206A: Swift/UVOT Upper Limits
- GRB 100206A: PAIRITEL Photometry of Host Candidate
- GRB 100206A - Keck/LRIS Spectroscopy
- GRB 100206A: WHT candidate afterglow
- GRB 100206A: optical observations from Southern Spain
- GRB 100205A: GROND upper limits
- GRB 100206A: Pre-explosion imaging and host candidate
- GRB 100206A: Swift detection of a short hard burst
- GRB 100205A: Gemini-N + NIRI photometry
- GRB 100205A Gemini-North IR afterglow candidate
- GRB 100205A: Swift detection of a burst
- Short X-ray Transient detected by MAXI/GSC
- GRB 100117A: candidate optical afterglow
- GRB 100117A: Optical object inside the revised XRT error circle
- GRB 100117A: Gemini South Imaging and CFHT Pre-Explosion Images
- GRB 100117A: Swift detection of a short hard burst
- GRB 100115A: Gemini-N photometry
- GRB 100115A: SARA Astrometry
- NOT observation of GRB100115A localization
- GRB 100115A: SARA Afterglow Candidate
- GRB 100115A: Swift/UVOT Upper Limits
- GRB 100115A: Swift-XRT candidate afterglow
- GRB 100111A: Swift detection of a burst with an optical afterglow
- GRB 100103A: Swift/UVOT Upper Limits
- GRB 091231: GROND NIR observations
- Trigger 381591: Swift detection of a possible burst
- GRB 091230: Swift-XRT observation
- GRB 091230: GROND optical/NIR afterglow candidate
- Trigger 381434: Swift detection of a possible burst
- GRB 091221: ROTSE-III Detection of Optical Counterpart
- GRB 091221: Swift detection of a burst
- Swift trigger 379449 (possible GRB) is not a burst
- Trigger 379449: Swift detection of a possible burst
- GRB 091208B: Swift detection of a burst with an optical afterglow
- GRB 091202: GTC & CAHA optical/nIR afterglow candidate
- Swift trigger 377436 (possible GRB 091130A) is not a burst
- GRB 091130B: Swift detection of a burst
- GRB 091127 : GROND observations
- GRB 091127: Swift/UVOT Detection of an Optical Afterglow
- GRB 091127: Liverpool Telescope afterglow candidate
- GRB091117: Gemini South Observations
- GRB 091109B: Swift detection of a short burst
- GRB 091109: Faulkes Telescope South observations
- GRB 091109: Swift detection of a burst with optical afterglow
- GRB 091104: Swift detection of a burst
- GRB 091102 : Faulkes Telescope South Upper Limits
- GRB 091102: GROND Upper Limits
- GRB 091102: Swift/XRT localization
- GRB 091102: Swift/UVOT Finding Chart Observation
- GRB 091024: optical observations
- GRB 091029: Swift detection of a burst with an optical counterpart
- GRB 091026: Swift detection of a Gamma Ray Burst
- GRB 091024: Swift-XRT team refined analysis
- GRB 091024: Faulkes Telescope North Afterglow Candidate
- GRB 090926A: Late-time Gemini South Observations and Possible Jet Break
- GRB 091020: Swift detection of a burst with an optical afterglow
- GRB 091018: miniTAO/ANIR Observations
- GRB 091018 : Faulkes Telescope South Observations
- GRB 091018: GROND observations
- GRB 091018: ROTSE-III Detection of Optical Counterpart
- GRB 091018: Swift detection of a burst with optical afterglow
- GRB 091003: Possible Supernova Component
- GRB 091010: optical obsevation
- GRB 091010: optical afterglow candidate rejection
- GRB 091010: Faulkes Telescope North observations
- GRB 091010: Enhanced XRT position
- GRB 091010 optical upper limits
- GRB 091010: GROND afterglow candidate
- GRB 091003: Swift UVOT Detection of a Candidate UV Afterglow
- GRB 090929B: Gemini-N upper limits
- GRB 090929B: Swift detection of a burst
- GRB 090927: Faulkes Telescope South Detection of the Optical Afterglow
- GRB 090926B: VLT spectroscopy
- GRB 090927: Swift/UVOT detection of an optical afterglow
- GRB 090926A: Swift/UVOT detection of an optical afterglow
- GRB 090926B: Swift detection of a burst
- GRB 090915: SARA detection of afterglow candidate
- GRB 090912: optical observation
- GRB 090915: Swift/UVOT detection of an optical afterglow candidate