GCN Circulars
GCN Circulars are rapid bulletins submitted by and distributed to the community. 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 201020A: CrAO/ZTSH optical observations
- GRB 201020A: Swift-XRT refined Analysis
- GRB 201020A: Fermi GBM observation
- GRB 201020A: Swift-BAT refined analysis
- Fermi GRB 201020B: Global MASTER-Net observations report
- GRB 201020A: Assy optical observations
- GRB 201020B: Fermi GBM Final Real-time Localization
- GRB 201020A: Nanshan/NEXT optical observations
- Swift GRB 201020A: Global MASTER-Net observations report
- GRB 201014A: SAO RAS optical observations
- GRB 201020A: Enhanced Swift-XRT position
- GRB 201020A: MITSuME Akeno optical observation
- GRB 201020A: Swift detection of a burst with an optical counterpart.
- GRB 201019B: AstroSat CZTI detection
- GRB 201016A: Insight-HXMT/HE detection
- GRB 201017A iTelescope observation
- GRB 201017A: SAO RAS optical observations
- GRB 201017A: GROWTH-India optical upper limit
- GRB 201019B: Fermi GBM correction to GCN 28687
- GRB 201014A: 3.6m DOT Optical Observations
- GRB 201015A: 6 GHz VLA radio afterglow candidate detection
- GRB 201019A: Fermi GBM Final Real-time Localization
- GRB 201013A: 3.6m DOT Optical Observations
- GRB 201014A: MMT afterglow detection
- GRB 201017A: MITSuME Akeno optical upper limits
- GRB 201019A: Fermi GBM Final Real-time Localization
- GRB 201017A: Swift-BAT refined analysis
- GRB 201015A: GROWTH-India Telescope (GIT) upper limit
- GRB 201015A: HCT optical photometric follow-up
- GRB 201017A: Assy and Mondy optical observations, possible afterglow detection
- GRB 201017A: Swift-XRT refined Analysis
- GRB 201015A: Xinglong-2.16m optical observations
- GRB 201015A: MMT afterglow imaging
- GRB 201017A: Fermi GBM detection
- GRB 201015A NUTTelA-TAO / BSTI Early Measurements (Preliminary)
- GRB 201015A: Assy and Mondy optical observations
- GRB 201017A: Xinglong TNT upper limit
- GRB 201017A: Enhanced Swift-XRT position
- Trigger 1000631: Swift detection of Cen X-3
- GRB 201015A: classification as long GRB
- Swift GRB 201017A: Global MASTER-Net observations report
- GRB 201017A: Swift detection of a burst
- GRB 201017A: Fermi GBM Final Real-time Localization
- GRB 201015A: FRAM-ORM afterglow detection
- Fermi GBM Sub-Threshold Detection of GRB 201015A
- GRB 201015A: Swift/UVOT Detection
- GRB 201015A: redshift confirmation
- GRB 201015A: Swift-XRT refined Analysis
- MAGIC observations of GRB 201015A: hint of very high energy gamma-ray signal
- GRB 201015A: Swift-BAT refined analysis (a soft short pulse with a tail emission)
- IceCube-201014A: No significant detection in HAWC
- GRB 201015A: CrAO/ZTSH optical observations
- GRB 201014A: Nanshan/NEXT optical observations
- GRB 201014A: Lowell Discovery Telescope afterglow imaging
- GRB201015A: Nanshan/NEXT early optical observations
- Konus-Wind observation of GRB 201013A
- GRB 201016A: AstroSat CZTI detection
- GRB 201014A: Redshift from GTC/OSIRIS
- GRB 201015A: Redshift from GTC/OSIRIS
- GRB 201008A: Swift-XRT afterglow detection
- GRB 201015A: Enhanced Swift-XRT position
- GRB 201016A: Fermi GBM detection
- GRB 201015A: BOOTES-1 early optical afterglow detection
- GRB 201014A: Swift/UVOT Upper Limits
- Fermi GRB 201016B: Global MASTER-Net observations report
- GRB 201016B: BALROG localization (Fermi Trigger 624510986 / GRB 201016136)
- GRB 201016A: BALROG localization (Fermi Trigger 624500874 / GRB 201016019)
- GRB 201016B: Fermi GBM Final Real-time Localization
- GRB 201015A: GOTO confirmation of afterglow detection
- GRB 201014A: Swift-XRT refined Analysis
- GRB 201015A: NOT optical afterglow confirmation
- GRB 201016A: Fermi GBM Final Real-time Localization
- GRB 201015A: Swift-XRT observations
- Swift GRB 201015A: Global MASTER-Net observations report
- Swift GRB201015.95: Global MASTER-Net OT detection
- GRB 201015A: Swift detection of a burst
- IceCube-201014A: Upper limits from a search for additional neutrino events in IceCube
- GRB 201014A: BOOTES-1 and -2 early optical upper limits
- GRB 201014A: Swift-BAT refined analysis
- GRB 201014A (Swift trigger =1000255): CrAO/ZTSH optical afterglow discovery
- IceCube Alert 201014.09: Global MASTER-Net observations report
- Swift-BAT trigger 1000255: XRT afterglow detection of GRB 201014A
- GRB 201013A: Insight-HXMT/HE detection
- IceCube-201014A: No neutrino counterpart candidates in ANTARES search
- Swift Trigger 1000255 is probably not a GRB
- Fermi-LAT Gamma-ray Observations of IceCube-201014A
- GRB 201013A: TSHAO and AbAO optical observations, afterglow confirmation
- GRB 201013A: AstroSat CZTI detection
- IceCube-201014A: Not observable by GBM
- GRB 201013A: CALET Gamma-Ray Burst Monitor detection
- IceCube-201014A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- IceCube-201014A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 201013A: FRAM-ORM possible afterglow candidate
- GRB 201013A: Swift-BAT refined analysis
- GRB 201013A: Swift/UVOT Upper Limits
- Swift GRB 201013A: Global MASTER-Net observations report
- GRB 201013A: Swift-XRT refined Analysis
- SGR 1830-0645: Swift/UVOT Upper Limits
- IceCube-201007A: No candidate counterparts from the Zwicky Transient Facility
- GRB 201013A: Enhanced Swift-XRT position