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 200716B: BALROG localization (Fermi Trigger 616577673 / GRB 200716316)
- GRB 200716B: Fermi GBM Final Real-time Localization
- GRB 200716A: BALROG localization (Fermi Trigger 616555602 / GRB 200716060)
- GRB 200715A: Swift ToO observations
- GRB 200715A : A long GRB detected by INTEGRAL
- GRB 200716A: Fermi GBM Final Real-time Localization
- GRB 200714E: Fermi GBM observation
- GRB 200714E: Swift-XRT observations
- Fermi GRB 200714E: Global MASTER-Net observations report
- GRB 200714E: AGILE detection
- GRB 200714E: Swift ToO observations
- GRB 200714E: Swift/BAT-GUANO detection and arcminute localization
- Fermi GRB 200714D: Global MASTER-Net observations report
- Fermi GRB 200714A: Global MASTER-Net observations report
- GRB 200522A: Candidate Optical/nIR Counterpart from Gemini and HST Imaging
- GRB 200714E: BALROG localization (Fermi Trigger 616444510 / GRB 200714774)
- GRB 200714E: Fermi GBM Final Real-time Localization
- GRB 200714D: Fermi GBM Final Real-time Localization
- GRB 200713A: Swift-BAT refined analysis
- GRB 200714C: Fermi GBM Final Real-time Localization
- GRB 200711A: Insight-HXMT/HE detection
- GRB 200714B: Fermi GBM Final Real-time Localization
- GRB 200713A: Swift-XRT refined Analysis
- GRB 200714A: Fermi GBM Final Real-time Localization
- Fermi trigger No 616370565: Global MASTER-Net observations report
- GRB 200713A: Enhanced Swift-XRT position
- GRB 200713A: Swift detection of a burst
- GRB 200711A: CALET Gamma-Ray Burst Monitor detection
- GRB 200711A: AbAO optical upper limit
- GRB 200711A: Swift/UVOT Upper Limits
- GRB 200711A: Swift-BAT refined analysis
- GRB 200711A: Fermi-LAT marginal detection
- GRB 200711A: KAIT Optical Upper Limit
- GRB 200711A: Swift-XRT refined Analysis
- GRB 200711A: Fermi GBM detection
- Swift GRB 200711A: Global MASTER-Net observations report
- GRB 200711A: Swift detection of a burst
- GRB 200711A: Fermi GBM Final Real-time Localization
- Update of alert from the HAWC Burst Monitor HAWC-200709A
- GRB 200709B/HAWC-200907A: Swift-XRT further observations
- HAWC-200907A: No Neutrino Counterpart detected with ANTARES
- GRB 200710A: Fermi GBM Final Real-time Localization
- GRB 200709B: Swift-XRT observations
- GRB 200709B: Tiled Swift observations
- GRB 200709A: Fermi GBM Final Real-time Localization
- GRB 200707A: Insight-HXMT/HE detection
- GRB 200707A: Fermi GBM Final Localization
- Fermi trigger No 615741133: Global MASTER-Net observations report
- GRB 200704A: Insight-HXMT/HE detection
- GRB 200706A: Fermi GBM Final Real-time Localization
- Fermi GRB 200705A: Global MASTER-Net observations report
- Fermi-LAT-ANTARES 200407a Coincidence
- GRB 200705A: Fermi GBM Final Real-time Localization
- GRB 200703B: Insight-HXMT/HE detection
- GRB 200703B: AstroSat CZTI detection
- GRB 200703B: Fermi GBM Final Real-time Localization
- GRB 200703A: Fermi GBM Final Real-time Localization
- Fermi GRB 200702A: Global MASTER-Net observations report
- GRB 200702A: Fermi GBM Final Real-time Localization
- Trigger 980513: Swift detection of SGR Swift J1818.0-1607
- GRB 200701A: Swift-BAT refined analysis
- Fermi-GBM Sub-Threshold Detection of GRB 200701A
- GRB 200701A: Swift detection of a burst
- GRB 200630A: Swift-BAT refined analysis
- GRB 200630A: Swift/UVOT Upper Limits
- GRB 200630A: Swift-XRT refined Analysis
- GRB 200630B: Fermi GBM Final Localization
- GRB 200623A: Swift XRT further observations
- GRB 200630A: Fermi GBM detection
- GRB 200629A: AstroSat CZTI detection
- GRB 200630A: Enhanced Swift-XRT position
- GRB 200630A: Swift detection of a burst
- Fermi trigger No 615174580: Global MASTER-Net observations report
- Fermi GRB 200629A: Global MASTER-Net observations report
- GRB 200629A: Fermi GBM Final Real-time Localization
- GRB 200629A: BALROG localization (Fermi Trigger 615127794 / GRB 200629535)
- GRB 200522A: Gemini North spectroscopy of the putative host galaxy
- Konus-Wind detection of short/hard GRB 200623B
- GRB 200623A: Further MMTCam Observations of XRT Source #3
- GRB 200625A: Fermi-LAT detection is likely a flare from PKS 1127-14
- GRB 200623A: LBT optical observations
- GRB 200623A : SMA observations at Swift/XRT Source #3
- Fermi GRB 200626A: Global MASTER-Net observations report
- GRB 200625A: Swift ToO observations
- GRB 200626A: Fermi GBM Final Real-time Localization
- Fermi GRB 200625A: Global MASTER-Net observations report
- GRB 200625A: Fermi GBM Final Real-time Localization
- Updated catalog of X-ray bursts of SGR J1935+2154 from Insight-HXMT observations
- GRB 200623A: MMT observations at XRT Source #3
- GRB 200623A: Swift/UVOT Upper Limits
- IPN triangulation of GRB 200623B (short)
- GRB 200623A: Swift-XRT observations
- GRB 200623A: OAJ deep multi-color imaging, XRT #2 is pre-detected
- GRB 200623A: TNG optical observations
- GRB 200623A: AbAO afterglow candidate within XRT #2
- GRB 200623A: Fermi GBM observation
- Fermi GRB 200623B: Global MASTER-Net observations report
- GRB 200623B: Fermi GBM Final Real-time Localization
- GRB 200623A: Correction to GCN 28013
- GRB 200623A: Swift ToO observations