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 161017A: Redshift from GTC
- GRB 161017A: Fermi GBM observation
- GRB 161017A: Enhanced Swift-XRT position
- GRB 161014A: Continued RATIR Optical and NIR Observations
- GRB 161015A: Swift/UVOT observations
- GRB 161017A: Swift detection of a burst with a bright optical afterglow
- GRB161017.74 MASTER-Net OT detection
- Konus-Wind observation of GRB 161015A
- GRB 161014A: VLT/X-shooter redshift confirmation
- GRB161015A: AstroSat CZTI detection
- Konus-Wind observation of GRB 161014A
- GRB 161014A: refined analysis of TSHAO optical observations
- GRB 161015A: Swift-XRT observations
- GRB 161015A: Fermi GBM detection
- GRB 161015A: Tiled Swift observations
- GRB 161015A: Fermi-LAT detection
- GRB161004A: Further analysis of the burst nature
- GRB 161014A: RATIR Optical and NIR Observations
- GRB 161014A: Fermi GBM observation
- GRB 161014A: Swift-XRT refined Analysis
- GRB 161014A: Swift-BAT refined analysis
- GRB 161014A: TNG optical observations
- GRB 161014A: AROMA-N Optical Observation
- GRB 161014A: Continued MITSuME Akeno Optical Observation
- GRB 161014A: Swift/UVOT Detection
- GRB161014A: NOT optical observations
- GRB 161014A: GTC spectroscopy
- GRB 161014A: TSHAO optical observations
- GRB 161011A: RATIR Optical and NIR Observations
- GRB 161014A: Swift-XRT and UVOT afterglow detection
- GRB 161014A: Kanata optical observation
- GRB 161014A : Xinglong TNT optical observation
- GRB161014A: optical afterglow candidate with the LCOGT-FTS
- GRB 161014A: MITSuME-Akeno optical observation
- GRB 161014A: Swift detection of a burst
- GRB 161010A: Swift/UVOT Possible Detection
- GRB 161010A: CALET Gamma-Ray Burst Monitor detection
- GRB 161011A, Swift-BAT refined analysis
- GRB 161011A: Swift burst of interest
- GRB 161011A: TSHAO afterglow candidate
- GRB 161011A: Swift/UVOT Upper Limits
- GRB 161011A: Swift-XRT refined Analysis
- Konus-Wind observation of GRB 161010A
- GRB 161011A: Enhanced Swift-XRT position
- GRB 161010A: Swift-XRT afterglow detection
- GRB 161011A: Prompt enhanced Swift-XRT position
- GRB 161011A: Swift detection of a burst
- GRB 161010A: Swift ToO observations
- GRB 161010A: a long GRB detected by INTEGRAL
- GRB 161007A: NOT optical observations
- GRB 161007A: AbAO optical observations
- GRB 161007A: Mondy optical observations
- GRB 161007A: Swift-BAT refined analysis
- GRB 161007A: Swift/UVOT Upper Limits
- GRB 161007A: Swift-XRT refined Analysis
- GRB 161007A: GTC observations
- GRB 161007A: Enhanced Swift-XRT position
- GRB 161004A: Maidanak optical observations
- GRB 161004A: refined analysis of TSHAO optical observations
- GRB 161007A: Prompt enhanced Swift-XRT position
- GRB 161007A: MASTER-net early optical observations
- GRB 161007A: Swift detection of a burst
- GRB 160821A: Maisoncelles observatory optical observations
- GRB 160925A: Kottamia R-band observation
- Konus-Wind observation of GRB 161004B
- GRB 160927A: GTC observations
- GRB 161004B: CALET Gamma-Ray Burst Monitor detection
- GRB 160927A: CALET Gamma-Ray Burst Monitor ground detection
- GRB 161004A: Swift-BAT refined analysis
- GRB 150302A: late-time imaging and optical afterglow confirmation
- GRB 161001A: IRSF upper limits
- GRB 161004B: Fermi GBM detection
- GRB 161004B: Swift/UVOT Upper Limits
- GRB161004B: AstroSat CZTI detection
- GRB 161004B: Swift-BAT refined analysis
- GRB 161004B: Swift-XRT refined Analysis
- GRB 161004A: RATIR Optical and NIR Observations
- GRB 160917B: Lomonosov BDRG gamma ray discovery
- GRB 161004B: Enhanced Swift-XRT position
- GRB 160917A: Lomonosov BDRG gamma ray detection
- GRB 160915A: Lomonosov BDRG gamma ray detection
- GRB 161004B: Prompt enhanced Swift-XRT position
- GRB 161004B: Swift detection of a burst
- GRB 161004A: SAO RAS optical upper limit
- GRB 161004A: Swift-XRT refined Analysis
- GRB 161004A: Swift/UVOT Detection
- GRB 161004A: Enhanced Swift-XRT position
- Swift Trigger 715209 is not an astrophysical event
- GRB 161004A: Bassano Bresciano Observatory upper limit
- GRB 161004A: TSHAO optical observations
- GRB 161004A: Swift detection of a burst with a possible optical counterpart
- GRB 160927A: 15 GHz upper limits from AMI
- Konus-Wind observation of GRB 161001A (short/hard ?)
- GRB 161001A: MASTER-OAFA and MASTER-SAAO early optical observations
- GRB 161001A: GROND afterglow candidate
- GRB 161001A, Swift-BAT refined analysis (likely a short GRB)
- GRB 161001A: Fermi GBM detection
- GRB 161001A: Swift-XRT refined Analysis
- GRB 161001A: X-shooter spectroscopy, candidate host galaxy and redshift
- GRB 161001A: Swift/UVOT Upper Limits