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 181201A: continued optical observations in SAAO and Chilesope
- GRB 181202A: RATIR Optical and NIR Observations
- Konus-Wind observation of GRB 181201A
- GRB 181203A: Enhanced Swift-XRT position
- GRB 181203A: Swift detection of a burst
- GRB 181201A: Further COATLI Optical Monitoring
- GRB 181201A: Insight-HXMT/HE detection
- GRB 181202A: Global MASTER-Net optical observations
- GRB 181202A: Swift-BAT refined analysis
- GRB 181201A: VLT/FORS2 tentative spectroscopic redshift
- GRB 181202A: Swift-XRT refined Analysis
- GRB 181201A: GROND detection of the afterglow and redshift upper limit of z < 3
- GRB 181201A: optical observations in Chilescope observatory
- GRB 181201A: Global MASTER-Net prompt optical descovery and afterglow observations
- GRB 181202A: Enhanced Swift-XRT position
- GRB 181202A: Swift detection of a burst with an optical counterpart
- GRB 181201A: COATLI Optical Detection
- GRB 181201A: Fermi-LAT detection
- GRB 181201A: Zeiss-1000/CrAO optical observations
- GRB 181201A: NOT optical observations
- GRB 181201A: optical observations in SAAO
- GRB 181201A MASTER-Net OT continued observation
- GRB 181201A: iTelescope optical afterglow detection
- GRB 181201A: Swift-XRT afterglow detection
- GRB 181201A: Swift ToO observations
- GRB 181201A: Swift-XRT afterglow
- GRB 181201A: likely Swift/XRT afterglow
- GRB 181201A MASTER-Net OT detection
- GRB 181201A: a long GRB detected by INTEGRAL
- GRB 181119A: CALET Gamma-Ray Burst Monitor detection
- GRB 181123B: ATCA 5/9 GHz rapid-response radio observation
- Short-duration GRB 181121.4: MASTER-Tavrida possible OT detection near the PGC galaxy during large Fermi error box inspection
- GRB 181127A : a long GRB detected by INTEGRAL
- GRB 181126A: Swift-BAT refined analysis
- GRB 181126A: No Ks-band afterglow detection with Keck I
- GRB 181123B: Keck further near-infrared imaging
- GRB 181126A: Swift/UVOT Upper Limits
- GRB 181126A: Swift-XRT refined Analysis
- GRB 181126A deep Gemini imaging
- GRB 181126A: Fermi GBM observation
- Konus-Wind observation of GRB 181121A
- GRB 181126A: Enhanced Swift-XRT position
- GRB 181126A: Prompt enhanced Swift-XRT position
- GRB 181126A: Swift detection of a burst
- GRB 181123B: Insight-HXMT/HE detection
- GRB 181125A: Fermi GBM observation
- GRB 181125A: Swift-BAT refined analysis
- IPN Triangulation of GRB 181121A (short)
- GRB 181125A: Swift detection of a burst
- GRB 181121A: AstroSat CZTI detection
- Swift J1858.6-0814/GRB 181123A: Swift/BAT location correction to GCN 23442
- Swift trigger 873178: GRB 181123A is Swift J1858.6-0814
- GRB 181123B: Global MASTER Net optical inspection
- GRB 181123B: Swift-BAT lag analysis and search for extended emission
- GRB 181123A, Swift-BAT refined analysis
- GRB 181123B: Keck near-infrared imaging
- GRB 181123B: Gemini-North optical detection
- GRB 181119A: AstroSat CZTI detection
- GRB 181123B: Swift/UVOT Upper Limits
- GRB 181020A: AstroSat CZTI detection
- GRB 181123B: Swift-XRT refined Analysis
- GRB 181123B: Enhanced Swift-XRT position
- GRB 181123B: Prompt enhanced Swift-XRT position
- GRB 181123B: Swift detection of a short burst
- GRB 181123A: Swift detection of a burst
- GRB 181119A: Insight-HXMT/HE detection
- GRB 181121A: AGILE/MCAL detection of a burst
- GRB 181120A: Fermi GBM observation
- GRB 181120A: Fermi-LAT detection
- Swift Trigger 872470: further Swift analysis
- Swift Trigger 872470 is probably not a GRB
- Konus-Wind observation of GRB 181110A
- GRB 181110A: optical observations in Chilescope observatory
- GROND observations of GRB181110A
- GRB 181110A: VLT/X-shooter redshift
- GRB 181110A, Swift-BAT refined analysis
- GRB 181110A: Swift/UVOT Detection
- GRB 181110A: Swift-XRT refined Analysis
- GRB 181110A: Enhanced Swift-XRT position
- GRB 181110A: optical observations from iTelescope SSO
- GRB 181110A: MITSuME Akeno optical observation
- GRB 181110A: Kanata 1.5m optical observation
- GRB 181110A: Swift detection of a burst with an optical counterpart
- Swift Trigger 871103 is not an astrophysical event
- Fermi GRB 181105.31: Global MASTER Net optical observations
- GRB 181103A: AbAO optical upper limit
- GRB 181028A: Insight-HXMT/HE detection
- GRB 181103A: MITSuME Okayama optical upper limits
- GRB 181103A: Swift/UVOT Detection
- GRB 181103A: Nanshan-1m optical upper limit
- GRB 181103A: Swift-BAT refined analysis
- GRB 181103A: Swift-XRT refined Analysis
- GRB 181103A: Enhanced Swift-XRT position
- GRB 181103A: Swift detection of a burst
- FACT follow-up of IceCube20181023A
- GRB 181030A: Swift/UVOT Detection
- GRB 181028A: CALET Gamma-Ray Burst Monitor detection
- IceCube-181031A retraction
- GRB 181030A, Swift-BAT refined analysis
- GRB 181030A: RATIR Optical and NIR Observations