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"
6098 results found.
- LIGO/Virgo S200105ae: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- Fermi-LAT Gamma-ray Observations of IceCube-191231A
- IceCube-191231A: No significant detection in HAWC
- GRB 200101A: Fermi GBM detection
- IceCube-191231A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- GRB 191228A: Swift-XRT refined Analysis
- GRB 191227A: Fermi GBM detection
- GRB 191227A: Marginal detection by Fermi-LAT
- GRB 191221B: iTelescope T17 detection
- GRB 191221B: ALMA detection
- GRB 191221B: Swift-XRT refined Analysis
- LIGO/Virgo S191222n: No counterpart candidates in Fermi-LAT observations
- GRB 191220A: Swift-XRT refined Analysis
- GRB 191220A: SAO RAS possible OT detection
- LIGO/Virgo S191213g: Lulin Follow-up Observations of AT2019wxt
- LIGO/Virgo S191213g: Swift UVOT/XRT observations of Pan-STARRS1 candidate: PS19hgw
- LIGO/Virgo S191216ap: No candidates found in J-GEM follow-up observations of HAWC error region
- LIGO/Virgo S191213g: No candidates found in J-GEM follow-up observations
- LIGO/Virgo S191216ap and IceCube neutrino: Swift XRT sources
- LIGO/Virgo S191213g: Swift UVOT/XRT observations of three ZTF sources
- LIGO/Virgo S191215w : No significant candidates in TAROT - FRAM - GRANDMA observations.
- LIGO/Virgo G191216ap: No counterpart candidates in Fermi-LAT observations
- Fermi-LAT Gamma-ray Observations of IceCube-191215A
- LIGO/Virgo S191216ap: Identification of a GW compact binary merger candidate
- LIGO/Virgo S191215w: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S191215w: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- IceCube-191215A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- LIGO/Virgo S191213g: Lulin Follow-up Observations of ZTF19acykzsk/AT2019wqj
- LIGO/Virgo S191213g: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S191213g: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- Possible HAWC-detected GRB 191210A: Fermi-LAT Upper Limits
- Possible HAWC-detected GRB 191210A: Swift-XRT observations
- GRB 191207A: Possible GRB detected in Fermi-LAT blind search
- IceCube-191204A: No significant detection in HAWC
- Fermi-LAT Gamma-ray Observations of IceCube-191204A
- LIGO/Virgo S191205ah: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S191204r: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S191205ah: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- GRB 191130A: Swift-XRT observations
- IceCube-191204A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- LIGO/Virgo S191204r: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- GRB 191202A: Fermi-LAT detection
- GRB 191202A: Fermi GBM observation
- LIGO/Virgo S191129u: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S191129u: no INTEGRAL data available
- IceCube-191122A: No significant detection in HAWC
- Fermi-LAT Gamma-ray Observations of IceCube-191122A
- GRB 191123A: Swift-XRT refined Analysis
- GRB 191122A: Swift-XRT refined Analysis
- IceCube-191119A: No significant detection in HAWC
- Fermi-LAT Gamma-ray Observations of IceCube-191119A
- IceCube-191119A - No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- LIGO/Virgo S191110af: Upper limits from Konus-Wind observations
- LIGO/Virgo S191110af: Swift XRT observations, no secure afterglow found
- LIGO/Virgo S191110af: No counterpart candidates in INTEGRAL SPI-ACS, and IBIS prompt observation
- LIGO/Virgo S191110af: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S191110af: No counterpart candidates in INTEGRAL SPI-ACS, prompt observation
- LIGO/Virgo S191109d: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S191109d: No counterpart candidates in INTEGRAL SPI-ACS,prompt observation
- ZTF19abvizsw: Upper limits from Konus-Wind observations
- LIGO/Virgo S191105e: No counterpart candidates in Fermi-LAT observations
- GRB 191106A: Swift-XRT refined Analysis
- LIGO/Virgo S191105e: No counterpart candidates in INTEGRAL SPI-ACS and,IBIS prompt observation
- GRB 191101A: Swift/UVOT Upper Limits
- GRB 191101A: iTelescope optical limit
- GRB 191101A: Swift-XRT refined Analysis
- GRB 191031C: Swift-XRT refined Analysis
- GRB 191031D: Swift-XRT refined Analysis
- GRB 191031C: Fermi GBM detection
- GRB 191031D: Fermi GBM detection
- GRB 191031A: Fermi GBM detection
- GRB 191029A: CORRECTED Swift-XRT refined analysis
- GRB 191029A: Swift/UVOT Upper Limits
- GRB 191029A: Swift-XRT refined Analysis
- Swift Trigger 931384: possible GRB 191025A
- GRB 191024A: Swift-XRT refined Analysis
- GRB191024A: MASTER optical observation
- GRB 191019A: Nanshan-0.6m optical observations
- GRB 191019A: Swift-XRT updated analysis
- GRB 191019A: Swift-XRT refined Analysis
- Alert from the HAWC Burst Monitor HAWC-191019A
- GRB 191017B: Swift-XRT refined Analysis
- GRB 191016A: Swift-XRT afterglow detection
- GRB 191016A: Swift/UVOT Detection
- GRB 191011A: Fermi GBM observation
- GRB 191011A: Swift-XRT refined Analysis
- LIGO/Virgo S190930t: Continued Swift observations of AT2019sbk
- Fermi/GBM observation of a bright burst from magnetar SGR 1935+2154
- LIGO/Virgo S190930t: Swift XRT observations, no secure afterglow found
- LIGO/Virgo S190930t: SALT optical spectroscopy of Swift J221951-484240
- GRB 191004B: Swift-XRT refined Analysis
- GRB 191004A: Swift-XRT refined Analysis
- GRB 191001A: Swift-XRT observations
- LIGO/Virgo S190930t: Continued Swift/UVOT observations of Swift J221951-484240
- GRB 191001A: Fermi GBM observation
- IceCube-191001A: HAWC follow-up
- Fermi-LAT Gamma-ray Observations of IceCube-191001A
- LIGO/Virgo S190930t: HCT observations of ZTF19acbpsuf
- LIGO/Virgo S190930t: Lulin Follow-up Observations of AT2019rpn and AT2019rpj
- IceCube-191001A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation