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"- Fermi GBM trigger 150805556 is not a GRB
- GRB 150727A: IRSF NIR observation
- GRB 150801A: Swift-XRT observations
- GRB 150801B: Swift/UVOT Upper Limits
- GRB 150801B: Swift-BAT refined analysis
- GRB 150801B: Swift-XRT refined Analysis
- GRB 150801B: Enhanced Swift-XRT position
- Fermi GBM triggers 150730606 150731173 and 150801590 are not due to GRBs
- Fermi GBM GRB Trigger 458852670: iPTF P48 Observations
- GRB 150721A (Fermi GBM Trigger 459150552): iPTF P48 Observations
- GRB 150801B: Swift detection of a burst
- GRB 150801A: Tiled Swift observations
- GRB 150801A: MAXI/GSC detection
- GRB 150724B: Swift-XRT afterglow detection
- GRB 150424A: HST imaging
- GRB150724B: Retraction of the uvot detection
- GRB 150728A: Continued RATIR Optical Observations
- GRB 150728A: TSHAO optical observations
- GRB 150728A: RATIR Optical Observations
- GRB 150727A: Continued RATIR Optical Observations - Fading
- GRB 150728A: AAO optical observations
- GRB 150728A: Swift-XRT refined Analysis
- GRB 150728A: Swift/UVOT Upper Limits
- GRB 150728A: Swift-BAT refined analysis
- GRB 150728A: FTN observations
- GRB 150727A: RATIR Optical Observations
- GRB 150728A: Enhanced Swift-XRT position
- GRB 150728A: Swift detection of a GRB
- GRB 150727A: Swift-BAT refined analysis
- GRB 150727A: Watcher optical upper limit
- GRB 150727A: Swift/UVOT Detection
- GRB 150727A: LCOGT-Cerro Tololo observations
- GRB 150727A: Swift-XRT refined Analysis
- GRB 150727A: Fermi GBM detection
- GRB 150727A: VLT/X-shooter redshift
- GRB 150727A: Enhanced Swift-XRT position
- GRB 150724B: Continued RATIR Optical Observations
- GRB 150724B: MASTER upper limit
- GRB 150727A: Swift detection of a burst with an optical counterpart
- GRB 150724B: Swift/UVOT Detection
- Konus-Wind observation of GRB 150724B
- Konus-Wind observation of GRB 150725A
- GRB 150724B: RATIR Optical Observations
- Swift Trigger 650408 is not a burst
- Swift 650221/IGR J00291+5934: Liverpool Telescope observations
- GRB 150724B: Swift-XRT observations
- GRB 150724B: Swift ToO observations
- IGR J00291+5934, Swift-BAT refined analysis
- GRB 150724B: Fermi GBM detection
- GRB 150724B: Fermi-LAT detection
- Swift Trigger 650221 / IGR J00291+5934: MASTER-IAC OT observations
- Fermi GBM trigger 150725291 is not a GRB
- GRB 150725A: MAXI/GSC detection
- Trigger 650221: Swift detection of a IGR J00291+5934
- Correction to GCN 18059: Parameterisation of Swift-XRT light curve
- GRB 150724A: Swift-XRT refined Analysis
- Swift IGR J00291+5934: MASTER Optical flare detection
- GRB 150724A: Swift/UVOT Upper Limits
- IGR J00291+5934: Swift-BAT refined analysis
- GRB 150724A: Swift-BAT refined analysis
- GRB 150724A: Enhanced Swift-XRT position
- SGR 1E 1841-045 (Swift trigger 649113): Terskol upper limit
- GRB 150724A: Prompt enhanced Swift-XRT position
- Trigger 650140: Swift detection of IGR J00291+5934
- GRB 150724A: Swift detection of a burst
- GRB 150722A: LCOGT-Sutherland observations
- GRB 150722A: Swift-BAT refined analysis
- GRB 150722A: Swift-XRT refined Analysis
- GRB 150722A: Swift/UVOT Upper Limits
- GRB 150720A: Swift/UVOT Upper Limits
- GRB 150722A: Enhanced Swift-XRT position
- GRB 150722A: Swift-XRT observations
- GRB 150722A: Swift detection of a burst
- GRB 150721A: Fermi GBM detection
- GRB 150720A: Enhanced Swift-XRT position
- GRB 150720A: Swift-XRT refined Analysis
- GRB 150720A: Swift-BAT refined analysis
- Swift Trigger 649706: a possible GRB or bright Galactic transient
- GRB 150716A: KAIT Optical Upper Limit
- GRB 150711A: Burakan-ISON optical observations
- GRB 150716A: Swift-BAT refined analysis
- GRB 150716A: Swift/UVOT Upper Limits
- GRB 150716A: Continued RATIR Optical Observations
- Swift trigger 649143 is not AX J1619.4-4945 or other astrophysical source
- GRB 150716A: Swift-XRT refined Analysis
- GRB 150716A: P60 Candidate Optical Afterglow
- GRB 150716A: RATIR Optical Observations
- GRB 150716A: Swift detection of a burst
- Fermi GBM triggers bn150715759 and bn150715817 are not due to GRBs
- Trigger 649143: Swift detection of AX J1619.4-4945
- Trigger 649113: Swift detection of SGR 1E 1841-045
- Fermi Gamma-ray Burst Monitor triggers that are not GRBs
- GRB 150710B: Swift-XRT afterglow detection
- Fermi GBM trigger 458312518/150711543 is not a GRB
- GRB 150711A: Swift-BAT refined analysis
- Konus-Wind observation of GRB 150710B
- GRB 150710B: Swift-XRT and Swift-UVOT observations
- GRB 150711A: Swift/UVOT Upper Limits
- GRB 150711A: Swift-XRT refined Analysis
- GRB 150711A: Fermi GBM detection