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 150101B/Swift J123205.1-105602: VLT observations and redshift
- Swift detection of 4U 1700+24 (= V* V934 Her)
- GRB 150103A: MASTER optical observations
- GRB 150101B: potential host galaxy redshift by GTC
- GRB 150103A: Swift-XRT refined Analysis
- GRB 150101B: Fermi GBM detection
- GRB 150103A: Swift/UVOT Upper Limits
- GRB 150103A: Swift-BAT refined analysis
- GRB 150103A: Zadko observatory - Gingin optical observations
- GRB 150103A: Enhanced Swift-XRT position
- Swift J123205.1-105602: Magellan candidate afterglow
- GRB 150103A: Prompt enhanced Swift-XRT position
- GRB 150103A: Swift detection of a burst
- Swift J123205.1-105602: XRT and UVOT observations of soft short burst source
- Short burst found in ground analysis of Swift-BAT data
- GRB 150101A Swift-BAT refined analysis of the short hard burst
- GRB 150101A: Fermi GBM detection
- GRB 150101A: Swift-XRT refined Analysis
- GRB 150101A: Swift/UVOT Upper Limits
- GRB 150101A: Enhanced Swift-XRT position
- GRB 150101A: Swift detection of a short burst
- Konus-Wind observation of GRB 141229A
- GRB 141229A: Deep MASTER inspection
- Swift-XRT and UVOT follow-up of iPTF14jko (GRB 141230A)
- GRB 141230A: Fermi GBM detection
- GRB 141229A Swift-BAT observations
- GRB 141230A: Nanshan optical obsrvations
- GRB 141230A: iPTF Optical Observations and Candidate Afterglow iPTF14jko
- GRB 141229A: 1.23m CAHA optical observations
- GRB 141229A: Nanshan optical upper limit
- GRB 141229A: Swift-XRT observations
- Fermi GBM trigger 141229739 is not a GRB
- GRB 141229A: Fermi GBM detection
- Christmas GRB 141225A: GROND Observations
- GRB 141229A Tiled Swift observations
- GRB 141229A: MAXI/GSC detection
- GRB 141225A: MASTER-SAAO OT light curve
- GRB 141225A: MITSuME Okayama upper limits
- GRB 141225A: TAROT Calern observatory optical observations
- GRB 141225A: Swift/UVOT refined analysis
- GRB 141225A: Fermi GBM detection
- GRB 141225A: very early T60 observations
- GRB 141225A: Swift-BAT refined analysis
- GRB 141225A: Swift-XRT refined Analysis
- GRB 141225A: MASTER-SAAO first OT detection
- GRB 141225A: Nanshan very early optical observations
- GRB 141225A: Enhanced Swift-XRT position
- GRB 141225A: Redshift from OSIRIS at the 10.4m GTC
- GRB 141225A: UVOT detection
- GRB 141225A: Optical aftergow confirmation
- GRB 141225A: LT optical candidate
- GRB 141225A: 1.23m CAHA optical observations
- GRB 141225A: Swift detection of a burst
- GRB 141221A: Keck spectroscopy
- GRB 141221A: TAROT La Silla observatory optical observations
- Swift XRT and UVOT observations of GRB141222A
- Konus-Wind observation of GRB 141222A
- GRB 141222A: First MASTER-SAAO optical observation
- IPN Triangulation of GRB 141222A (very intense)
- GRB 141221A: MITSuME Akeno upper limits
- GRB 141221A: Continued Skynet PROMPT-CTIO observations
- GRB 141222A: Fermi GBM detection
- GRB 141221A: Swift/UVOT Detection
- GRB 141222A: Fermi-LAT detection
- GRB 141215A: further Swift-XRT observations and afterglow detection
- GRB 141221A: Fermi GBM observation
- GRB 141220A: MITSuME Akeno upper limits
- GRB 141221A: Swift-XRT refined Analysis
- GRB 141221A: Swift-BAT refined analysis
- GRB141221A: GROND Afterglow Detection
- GRB 141221A: Enhanced Swift-XRT position
- GRB 141221A: Skynet PROMPT-CTIO observations of the optical afterglow
- GRB 141221A: LCOGT-McDonald optical afterglow observations
- GRB141221A: REM afterglow
- Konus-Wind observation of GRB 141220A
- GRB 141221A: Swift detection of a burst with an optical counterpart
- GRB 141220A: Fermi GBM observation
- GRB 141220A: MITSuME Okayama upper limits
- GRB 141220A: Swift-XRT refined Analysis
- GRB 141220A: Swift-BAT refined analysis
- GRB 141220A: Swift/UVOT Detection
- GRB 141220A: Photometry from OSIRIS/GTC
- GRB 141220A: LT optical afterglow observations
- GRB 141220A: Redshift from OSIRIS at the 10.4m GTC
- GRB141220A: 1.23m CAHA I-band observations
- GRB 141220A: Swift detection of a burst with an optical afterglow
- Fermi Gamma-ray Burst Monitor trigger 440728127 / 141220020 is not a GRB
- IPN Triangulation of GRB 141207A
- GRB 141207A: Suzaku WAM observation of the prompt emission
- GRB 141202A: Suzaku WAM observation of the prompt emission
- GRB 141121A: Keck observations
- GRB 141215A: Swift-XRT observations
- GRB 141215A: Fermi GBM detection
- GRB 141215A Tiled Swift observations
- Konus-Wind observation of GRB 141215A
- IPN Triangulation of GRB 141215A (long/intense)
- GRB 141212A iTelescope observation
- GRB 141212A: Zadko observatory - Gingin optical observations
- GRB 141212B: MITSuME Akeno upper limits
- Konus-Wind observation of GRB 141212B