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"- SGR 1E 1841-045: early optical limit by "Pi of the Sky"
- SGR 1E 1841-045: Swift-BAT refined analysis
- SGR 1E 1841-045: Swift detection of a soft gamma repeater burst
- GRB 110625A: Suzaku WAM observation of the prompt emission
- Swift J185003.2-005627: 1.23m CAHA and BOOTES-3 observations
- GRB 110625A: Fermi GBM and LAT observations
- GRB 110625A: Swift/UVOT Upper Limits
- GRB 110625A: 1.23m CAHA I-band observations
- GRB 110625A: Fermi LAT detection
- GRB 110625A: GROND detection of a source inside the XRT error circle
- GRB 110625A: NIR Source
- GRB 110625A: Konkoly observations
- Konus-Wind observation of GRB 110625A
- GRB 110625A: Swift-XRT refined Analysis
- GRB 110625A: Swift-BAT refined analysis
- Swift J185003.2-005627: NIR Observation
- GRB 110625A: ROTSE-III Optical Limits
- GRB 110625A: Swift detection of a burst
- Swift J185003.2-005627: Swift-XRT/UVOT refined analysis
- Swift J185003.2-005627: Swift-BAT refined analysis
- Swift J185003.2-005627: TAROT La Silla observatory optical observations
- Swift J185003.2-005627: TAROT Calern observatory optical observations
- Swift J185003.2-005627: Swift detection of a burst from a new Galactic transient
- SGR 1E 1841-045: Swift-BAT refined analysis
- GRB 110618A: SMARTS optical observations
- GRB 110604A: final update on Swift-XRT observations
- SGR 1E 1841-045: Swift detection of a soft gamma repeater burst
- Konus-Wind observation of GRB 110618A
- IPN triangulation of GRB110618A (long duration, extremely intense)
- Fermi Gamma-ray Burst Monitor trigger 110621949 is not a GRB
- GRB 110604A: Suzaku WAM observation of the prompt emission
- GRB 110610A: Suzaku WAM observation of the prompt emission
- GRB 110610A: Fermi GBM detection
- GRB 110610A: 1.23m CAHA optical observations
- GRB 110610A: Swift-XRT refined Analysis
- GRB 110610A: Swift/UVOT Upper Limits
- GRB 110610A: Enhanced Swift-XRT position
- GRB 110610A: Swift-BAT refined analysis
- Swift detection of the X-ray afterglow of GRB 110604A
- GRB 110610A: MASTER-NET optical observations
- GRB 110610A: Swift detection of a burst
- Konus-Wind observation of GRB 110604A
- GRB 110604A Detection by IPN Spacecraft and Swift-BAT
- GRB 110530A: optical observations in Mondy observatory
- GRB 110529A: Suzaku WAM observation of the prompt emission
- GMRT detection of GRB 110328A
- GRB 110530A: optical observations at Mt. Terskol, second epoch
- GRB 110530A: Swift-XRT refined Analysis
- GRB 110530A: Swift/UVOT Detection of a Fading Afterglow
- GRB 110530A: Xinglong TNT observation
- GRB 110530A: Enhanced Swift-XRT position
- GRB 110530A: NOT optical observations
- GRB110530A: MITSuME Okayama Optical Observation
- GRB 110530A: optical observations at Mt. Terskol
- GRB 110530A: Correction to GCN Circ 12050
- GRB 110530A: MASTER OT observations
- GRB 110530A: Swift-BAT refined analysis
- GRB 110530A: MITSuME Akeno Optical Observation
- GRB 110529A: Fermi GBM detection
- GRB 110530A: Swift detection of a burst with an optical afterglow
- Konus-Wind observation of GRB 110529A
- LAT Observations of GRB110529A
- EVLA afterglow limits on the high z GRB090429B
- Fermi Gamma-ray Burst Monitor trigger 328195911 is not a GRB
- Swift J1644+57/GRB 110328A, Additional HST Observations
- GRB 110521A: MASTER prompt optical limit
- GRB 110521A: Swift/UVOT Upper Limits
- GRB 110521A: Swift-XRT refined analysis
- GRB 110520A: NOT optical follow-ups
- GRB 110521A - NOT optical observation
- GRB 110521A: Swift-BAT refined analysis
- GRB 110521A: Enhanced Swift-XRT position
- GRB 110521A: MASTER synchronous and early optical observations limit
- Swift/UVOT observations of GRB110520A
- GRB 110521A: Swift detection of a burst
- GRB 110520A: Swift-BAT refined analysis
- GRB 110520A: IAC80 I-band observations
- GRB 110520A: Swift-XRT refined Analysis
- GRB 110520A: Enhanced Swift-XRT position
- GRB 110520A: WHT IR observations
- GRB 110520A - NOT optical observation
- GRB 110520A: Skynet/DAO optical observations
- GRB 110520A: Liverpool Telescope Observations
- GRB 110520A: TAROT Calern observatory optical observations
- GRB 110520A: MASTER-NET optical observations
- GRB 110520A: Swift detection of a burst
- Konus-Wind observation of GRB 110518A
- IPN localization of bright GRB 110518A
- Radio observations of GRB 110428A with the EVLA
- GRB 110519A, Swift-BAT refined analysis
- GRB 110519A: Swift detection of a burst
- GRB 110503A optical observation
- GRB 110426A: Fermi GBM detection
- GRB 110428A: Fermi-GBM observation
- GRB 110503A: TAROT Calern observatory optical observations
- GRB 110503A: Jet Break seen from TLS
- GRB 110503A optical observations
- Konus-Wind observation of GRB 110503A
- GRB 110422A: MASTER first 30 min OT light curve
- GRB 110422A: Herschel FIR observation preliminary report