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"- Konus-Wind detection of GRB 201216C
- GRB 201218A: BALROG localization (Fermi Trigger 629957660 / GRB 201218177)
- IceCube-201209A : MAXI/GSC upper limit
- GRB 201218A: Fermi GBM Final Real-time Localization
- GRB 201216C: Swift-BAT refined analysis
- Fermi GRB 201217A: Global MASTER-Net observations report
- GRB 201217A: Fermi GBM Final Localization
- GRB 201216C: VLT X-shooter spectroscopy and potential high redshift of a VHE-emitting GRB
- GRB 201216C: Fermi-LAT upper limit
- GRB 201216C: MAGIC detection in very high energy gamma rays
- GRB 201216C: AstroSat CZTI detection
- GRB 201216C: Fermi GBM detection
- GRB 201216A: Fermi GBM detection
- GRB 201216C: Swift/UVOT Upper Limits
- GRB 201216C: FRAM-ORM afterglow confirmation
- GRB 201216A: Swift-XRT observations
- Baksan Neutrino Observatory Alert 201216.94: Global MASTER-Net observations report
- GRB 201216C: Enhanced Swift-XRT position
- GRB 201216C: VLT afterglow candidate discovery
- GRB 201216A: Swift ToO observations
- GRB 201216C: Swift-XRT observations
- GRB 201216C: Fermi GBM Final Real-time Localization
- Swift GRB201216.96: Global MASTER-Net observations report
- GRB 201216C: Swift detection of a burst
- Fermi GRB 201216A: Global MASTER-Net observations report
- GRB 201216A: Swift/BAT-GUANO detection and arcminute localization
- GRB 201216B: AGILE detection of a burst
- GRB 201216A: Fermi GBM Final Real-time Localization
- GRB 201214B: MITSuME Akeno optical upper limits
- Chandra observations of GW170817 at ~3.3 years since merger (Full report)
- GRB 201214B: Lowell Discovery Telescope optical observations
- VLA observations of GW170817 at ~3.3 years post-merger
- GRB 201214B: Swift-XRT observations
- Fermi GRB 201215A: Global MASTER-Net observations report
- GRB 201209A: Insight-HXMT/HE detection
- IceCube-201209A: Upper limits from Insight-HXMT/HE observations
- GRB 201214A: Swift-XRT observations
- GRB 201215A: BALROG localization (Fermi Trigger 629706213 / GRB 201215266)
- GRB 201215A: Fermi GBM Final Real-time Localization
- GRB 201214B: Swift BAT location of short burst
- Fermi GRB 201214B: Global MASTER-Net observations report
- GRB 201214B: Swift ToO observations
- IceCube-201209: No significant detection in HAWC
- Potential X-ray KN afterglow from Chandra observations of GW170817 ~3.3 years since merger (3 Epochs of 4)
- GRB 201214A: Mates' birthday GRB optical limit from FRAM-ORM
- GRB 201214B: Fermi GBM Final Real-time Localization
- Long-lasting X-ray emission from GW170817 detected by Chandra
- GRB 201214A: A long GRB detected by INTEGRAL
- GRB 201214A: Swift ToO observations
- Integral GRB201214.26: Global MASTER-Net observations report
- GRB 201213A: Fermi GBM Final Real-time Localization
- GRB 201015A: optical observations and supernova identification
- GRB 201203A: Zeiss-1000 (Koshka observatory) optical upper limit
- IceCube-201209A: No Candidate Counterparts from the Zwicky Transient Facility
- GRB 201203A: 1.3m DFOT, optical upper limits
- GRB 200826A: GMOS-N detected source magnitude (Correction)
- GRB 201015A: 5-GHz radio afterglow detection with the EVN
- IceCube-201209A: Upper limits from a search for additional neutrino events in IceCube
- GRB 201209A: Swift/UVOT Upper Limits
- IceCube-201209A: Upper limits from Fermi-GBM Observations
- Fermi-LAT Gamma-ray Observations of IceCube-201209A
- IceCube-201209A: No neutrino counterpart candidates in ANTARES search
- IceCube Alert 201209.43: Global MASTER-Net observations report
- GRB 201209A: Swift-BAT refined analysis
- IPN triangulation of GRB 201207A
- Chandra observations of GW170817 at ~3.3 years since merger (Observation 1 of 4)
- GRB 201208A: Swift-XRT afterglow detection
- GRB 201208A: Fermi GBM observation
- IceCube-201209A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- GRB 201208A: LCO observations
- GRB 201209A: Swift-XRT refined Analysis
- GRB 201209A: Xinglong-2.16m likely optical afterglow detection
- IceCube-201209A: IceCube observation of a high-energy neutrino candidate event
- GRB 201209A: AstroSat CZTI detection
- GRB 201207A: AGILE detection
- GRB 201209A: Enhanced Swift-XRT position
- IceCube-201130A: Optical and NIR Imaging Follow-up by Kanata Telescope
- GRB 201209A: KAIT Optical Upper Limit
- GRB 201209A: FRAM-Auger optical limit
- GRB 201209A: Swift detection of a burst
- Swift GRB201209.24: Global MASTER-Net observations report
- GRB 201208A: Fermi-LAT detection
- GRB 201208A: Swift ToO observations
- GRB 201208A: AstroSat CZTI detection
- GRB 201207A: AstroSat CZTI detection
- Fermi GRB 201208A: Global MASTER-Net observations report
- GRB 201208A: Fermi GBM Final Real-time Localization
- Fermi GRB 201207A: Global MASTER-Net observations report
- GRB 201207A: Fermi GBM Final Real-time Localization
- GRB 201203A: Swift-BAT refined analysis
- Swift follow-up observations of the flat spectrum radio quasar PMN J0206-1150 in the error region of IceCube-201130A
- GRB 201203A: GROWTH-India Telescope optical upper limit.
- GRB 201203A: MITSuME Okayama optical upper limits
- Swift GRB 201203A: Global MASTER-Net observations report
- GRB 201203A: Swift-XRT afterglow detection
- IceCube-201130A: No Candidate Counterparts from the Zwicky Transient Facility
- GRB 201203A: KAIT Optical Upper Limit
- GRB 201203A: DDOTI Observations
- GRB 201203A: FRAM-Auger optical limit
- GRB 201203A: Swift detection of a burst