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.
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"
28692 results found.
- GRB 201223A: Fermi GBM Detection
- GRB 201223A: Nanshan/NEXT early optical afterglow detection
- Swift-XRT observations of Icecube 201222A
- IceCube-201222A: No significant detection in HAWC
- IceCube-201221A: No significant detection in HAWC
- GRB 201221A: Konus-Wind detection and joint Konus-Wind + Swift-BAT spectral analysis
- GRB 201221A: REM early-time afterglow detection
- GRB 201221D: 3.6m DOT optical observations
- GRB 201221B: Insight-HXMT/HE detection
- IceCube-201221A: Upper limits from Insight-HXMT/HE observations
- GRB 201221D: SMA submm observation
- Fermi GRB 201222B: Global MASTER-Net observations report
- GRB 201221D: MMT MMIRS detection of marginally extended source
- GRB 201221D: LCOGT upper limits
- GRB 201221D: Fermi GBM detection
- GRB 201221D: Swift-BAT refined analysis
- Swift Trigger 1014012 (possible GRB 201221C) is likely not an astrophysical event
- GRB 201216A - further Swift-XRT observations
- Fermi-LAT Gamma-ray Observations of IceCube-201222A
- Fermi-LAT Gamma-ray Observations of IceCube-201221A
- IceCube-201222A: not observable by Fermi-GBM
- GRB 201221D: Archival PS1 Imaging of the Putative Host Galaxy
- Short GRB201221D: High Redshift from OSIRIS/GTC
- IceCube-201222A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- Konus-Wind detection of GRB 201221D (short)
- GRB 201221D: Swift/UVOT Upper Limits
- GRB 201221D: Lowell Discovery Telescope afterglow observations
- GRB 201221D: Swift-XRT refined Analysis
- Swift GRB 201221D: Global MASTER-Net observations report
- Fermi GRB 201221E: Global MASTER-Net observations report
- GRB 201221D: Nanshan/NEXT early optical upper limit
- GRB 201221D: candidate optical counterpart from the NOT
- GRB 201221A: Swift-BAT refined analysis
- correction to GCN 29110 - Fermi GBM Sub-Threshold Detection of GRB 201221A
- Fermi GBM Sub-Threshold Detection of GRB 201221A
- GRB 201221A: Swift/UVOT Upper Limits
- GRB 201221A: Swift-XRT refined Analysis
- IceCube-201221A: not observable by Fermi-GBM
- IceCube-201221A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- GRB 201221A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 5.7
- Swift GRB 201221A: Global MASTER-Net observations report
- Konus-Wind observation of GRB 201218A
- GRB 201209A: Mondy optical observations, afterglow confirmation
- GRB 201214A: TSHAO optical upper limit
- GRB 201214A: Swift-XRT afterglow detection
- GRB 201214A: 1.3m DFOT, optical upper limits
- IPN triangulation of GRB 201218A
- Fermi GRB 201218B: Global MASTER-Net observations report
- Fermi GRB 201218A: Global MASTER-Net observations report
- GRB201216C: No significant detection in HAWC
- GRB 201216C: Liverpool Telescope First Hour Observations
- Konus-Wind detection of GRB 201216C
- IceCube-201209A : MAXI/GSC upper limit
- GRB 201216C: Swift-BAT refined analysis
- Fermi GRB 201217A: Global MASTER-Net observations report
- 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 201216A: Swift-XRT observations
- GRB 201216C: VLT afterglow candidate discovery
- GRB 201216A: Swift ToO observations
- Fermi GRB 201216A: Global MASTER-Net observations report
- GRB 201216A: Swift/BAT-GUANO detection and arcminute 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
- 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 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: Swift ToO observations
- 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
- 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
- GRB 201209A: Swift-BAT refined analysis
- IPN triangulation of GRB 201207A
- 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
- GRB 201209A: AstroSat CZTI detection