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"7449 results found.
- LIGO/Virgo S200115j: No counterpart detection within possible host galaxies observed by the GRAWITA-Savelli telescope
- GRB 200115A: Mondy optical observations and correction to GCN 26790
- IceCube-200117A: One Additional Candidate Counterpart from the Zwicky Transient Facility
- IceCube-200117A: Candidate Counterpart from the Zwicky Transient Facility
- IceCube-200117A: No Neutrino Counterpart in ANTARES data
- LIGO/Virgo S200115j: Updated Sky Localization and source properties
- LIGO/Virgo S200114f: More candidates from the Zwicky Transient Facility
- IceCube-200117A: Upper limits from Fermi-GBM Observations
- IceCube-200117A: IceCube observation of a high-energy neutrino candidate event
- LIGO/Virgo S200115j: Upper limits from CALET observations.
- LIGO/Virgo S200114f: ZTF Forced Photometry of the Swift Source S200114f_X2
- LIGO/Virgo S200115j: No notable candidates in GOTO imaging
- LIGO/Virgo S200114f: Possible X-ray transient
- GRB 200115A: Mondy optical afterglow candidate
- LIGO/Virgo S200115j: No neutrino candidates at Pierre Auger Observatory
- LIGO/Virgo S200115j: no counterpart candidate in SVOM/GWAC observations
- LIGO/Virgo S200116ah: Retraction of GW compact binary merger candidate
- LIGO/Virgo S200115j High Rank XRT sources are spurious
- LIGO/Virgo S200115j: Upper limits from Fermi-GBM Observations
- LIGO/Virgo S200115j: upper limits from AGILE/GRID observations
- LIGO/Virgo S200115j : no neutrino counterpart candidate in ANTARES search
- LIGO/Virgo S200114f: Upper limits from CALET observations.
- LIGO/Virgo S200115j: Identification of a GW compact binary merger candidate
- LIGO/Virgo S200115j: No counterpart candidates in HAWC observations
- LIGO/Virgo S200115j: Upper limits from IceCube neutrino searches
- LIGO/Virgo S200114f: Constraints on a CCSN origin from KM3NeT MeV neutrino search.
- LIGO/Virgo S200114f: SAGUARO previous detection of ZTF candidate ZTF20aafeaqk (AT2020vx)
- LIGO/Virgo S200114f: upper limits from AGILE-GRID observations
- IceCube-200109A: Candidate Counterparts from the Zwicky Transient Facility
- LIGO/Virgo S200114f : no neutrino counterpart candidate in ANTARES search
- LIGO/Virgo S200114f: Upper limits from Fermi-GBM Observations
- LIGO/Virgo S200114f: Identification of a GW unmodeled transient candidate
- LIGO/Virgo S200114f: No counterpart candidates in HAWC observations
- LIGO/Virgo S200114f: Upper limits from IceCube neutrino searches
- LIGO/Virgo S200112r: upper limits from AGILE/GRID observations
- LIGO/Virgo S200112r: No counterpart candidates in HAWC observations
- LIGO/Virgo S200112r : no neutrino counterpart candidate in ANTARES search
- LIGO/Virgo S200112r: Upper limits from IceCube neutrino searches
- LIGO/Virgo S200112r: Identification of a GW compact binary merger candidate
- IceCube-200109A: Swift-XRT and UVoT Follow-up Observations
- IceCube-200109A: Upper limits from Fermi-GBM Observations
- IceCube-200109A: IceCube observation of a high-energy neutrino candidate event
- LIGO/Virgo S200105ae: Updated Sky Localization and EM-Bright Probabilities
- LIGO/Virgo S200105ae: Gaia Photometric Alerts transient candidate
- GRB 200109A: Swift detection of a burst
- LIGO/Virgo S200105ae: GW data still under study
- LIGO/Virgo S200105ae: Candidates from the Zwicky Transient Facility
- Fermi-LAT Gamma-ray Observations of IceCube-200107A
- LIGO/Virgo S200108v: Retraction of GW compact binary merger candidate
- GRB 200107B: Swift detection of a burst
- LIGO/Virgo S200105ae: Further study ongoing for GW compact binary merger candidate
- IceCube-200107A: Upper limits from Fermi-GBM Observations
- IceCube-200107A: IceCube observation of a high-energy neutrino candidate event
- LIGO/Virgo S200105ae: AstroSat CZTI upper limits
- LIGO/Virgo S200105ae: No counterpart candidates in HAWC observations
- LIGO/Virgo S200105ae: Upper limits from IceCube neutrino searches
- LIGO/Virgo S200105ae: Upper limits from Fermi-GBM Observations
- LIGO/Virgo S200105ae : no neutrino counterpart candidate in ANTARES search
- LIGO/Virgo S200105ae: We have issued GCN Notices to support automated processing
- S200106au and S200106av: Retraction of GW compact binary merger candidates
- LIGO/Virgo S200105ae: A subthreshold GW compact binary merger candidate
- IceCube-191231A: No Neutrino Counterpart in ANTARES data
- IceCube-191231A: Upper limits from Fermi-GBM Observations
- IceCube-191231A: IceCube observation of a high-energy neutrino candidate event
- LIGO/Virgo S191216ap: Two candidate counterparts from UKIRT/WFCAM z-band observations
- GRB 191228A: Swift detection of a burst
- LIGO/Virgo S191213g: AT2019wxt 10.4m GTC further spectroscopy
- LIGO/Virgo S191225aq: Retraction of GW compact binary merger candidate
- LIGO/Virgo S191213g: Pan-STARRS monitoring shows PS19hgw (AT2019wxt) to be fading quickly
- LIGO/Virgo S191222n: Updated Sky Localization
- LIGO/Virgo S191222n: no counterpart candidate in SVOM/GWAC observations
- LIGO/Virgo S191216ap: Updated Source Classification
- LIGO/Virgo S191216ap: Upper limits from Insight-HXMT/HE observations
- GRB 191221B: Zadko observatory - Gingin optical observations
- LIGO/Virgo S191222n : no neutrino counterpart candidate in ANTARES search
- LIGO/Virgo S191222n: upper limits from AGILE-GRID observations
- LIGO/Virgo S191222n: No counterpart candidates in HAWC observations
- LIGO/Virgo S191222n: Identification of a GW compact binary merger candidate
- LIGO/Virgo S191222n: Upper limits from IceCube neutrino searches
- GRB 191221B: Swift detection of a burst and a very bright optical candidate
- GRB 191220A: AbAO optical observations
- LIGO/Virgo S191215w: Updated Sky Localization
- GRB 191220A: Swift detection of a burst
- LIGO/Virgo S191220af: Retraction of GW compact binary merger candidate
- LIGO/Virgo S191216ap: AstroSat CZTI upper limits
- LIGO/Virgo S191216ap: Subaru/Hyper Suprime-Cam observations of GW+IceCube+HAWC error region
- LIGO/Virgo S191213g: LBT spectrum of AT2019wxt (PS19hgw) reveals a type IIb supernova
- LIGO/Virgo S191216ap: UPDATED list of galaxies coincident with LIGO/Virgo LALInference skymap and HAWC positions
- LIGO/Virgo S191216ap: Updated Sky Localization
- LIGO/Virgo S191213g: Swift UVOT/XRT observations of Pan-STARRS1 candidate: PS19hgw
- LIGO/Virgo S191213g: MASTER observation of AT2019wxt (PS19hgw)
- LIGO/Virgo S191216ap: No candidates found in J-GEM follow-up observations of HAWC error region
- LIGO/VIRGO S191213g: ePESSTO+ spectroscopy of AT2019wxt (PS19hgw)
- LIGO/Virgo S191213g: HCT spectroscopy of PS19hgw / AT2019wxt
- LIGO/Virgo S191213g: No counterpart candidate in the NOWT observations
- LIGO/Virgo S191216ap: No candidates found in CHES observations of HAWC error region
- LIGO/Virgo S191216ap and IceCube neutrino: no counterpart candidates from AGILE-GRID observations
- LIGO/Virgo S191213g: Pan-STARRS1 discovery of a potential optical counterpart
- LIGO/Virgo S191216ap: GRAWITA Loiano observations of HAWC error region
- LIGO/Virgo S191216ap: CORRECTED list of galaxies coincident with LIGO/Virgo and HAWC positions