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 201021C: VLT/X-shooter redshift
- IceCube-201021A: No neutrino counterpart candidates in ANTARES search
- GRB 201020A: VIRT optical observations
- GRB 201021C: Enhanced Swift-XRT position
- IceCube-201021A: Upper limits from Fermi-GBM Observations
- HAWC-201019A: not observable by Fermi-GBM
- GRB 201021C: MASTER optical synchronously observation
- IceCube-201021A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- Swift GRB201021.85: Global MASTER-Net observations report
- GRB 201021C: Swift detection of a burst with an optical counterpart
- HAWC-201019A: No Neutrino Counterpart detected with ANTARES
- MAXI GRB201021.68: Global MASTER-Net observations report
- GRB200826A: GMOS-N detection of a supernova bump
- GRB 201021B MAXI/GSC detection
- GRB 201020B: Mondy optical observations
- Swift-XRT observations of IceCube 201021A
- Konus-Wind detection of GRB 201020B
- IceCube Alert 201021.28: Global MASTER-Net observations report
- GRB 201015A: SAO RAS optical observations
- GRB 201020B: Swift ToO observations
- GRB 201020B: Nanshan/NEXT optical afterglow confirmation
- GRB 201020B: MASTER bright optical afterglow detection
- GRB 201020A: Redshift from GTC/OSIRIS
- GRB 201020B: Fermi-LAT detection
- IceCube-201021A: IceCube observation of a high-energy neutrino candidate event
- GRB 201020B: AGILE detection
- GRB 201020A: DOAO optical afterglow observations
- GRB 201021A: Fermi GBM Final Real-time Localization
- GRB 201020A: GROWTH-India Telescope optical observations
- GRB 201020B: Fermi GBM detection
- Alert from the HAWC Burst Monitor HAWC-201019A
- 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