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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.

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').
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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

7450 results found.

  1. IceCube-200120A: IceCube observation of a high-energy neutrino candidate event
  2. LIGO/Virgo S200115j: No counterpart detection within possible host galaxies observed by the GRAWITA-Savelli telescope
  3. GRB 200115A: Mondy optical observations and correction to GCN 26790
  4. IceCube-200117A: One Additional Candidate Counterpart from the Zwicky Transient Facility
  5. IceCube-200117A: Candidate Counterpart from the Zwicky Transient Facility
  6. IceCube-200117A: No Neutrino Counterpart in ANTARES data
  7. LIGO/Virgo S200115j: Updated Sky Localization and source properties
  8. LIGO/Virgo S200114f: More candidates from the Zwicky Transient Facility
  9. IceCube-200117A: Upper limits from Fermi-GBM Observations
  10. IceCube-200117A: IceCube observation of a high-energy neutrino candidate event
  11. LIGO/Virgo S200115j: Upper limits from CALET observations.
  12. LIGO/Virgo S200114f: ZTF Forced Photometry of the Swift Source S200114f_X2
  13. LIGO/Virgo S200115j: No notable candidates in GOTO imaging
  14. LIGO/Virgo S200114f: Possible X-ray transient
  15. GRB 200115A: Mondy optical afterglow candidate
  16. LIGO/Virgo S200115j: No neutrino candidates at Pierre Auger Observatory
  17. LIGO/Virgo S200115j: no counterpart candidate in SVOM/GWAC observations
  18. LIGO/Virgo S200116ah: Retraction of GW compact binary merger candidate
  19. LIGO/Virgo S200115j High Rank XRT sources are spurious
  20. LIGO/Virgo S200115j: Upper limits from Fermi-GBM Observations
  21. LIGO/Virgo S200115j: upper limits from AGILE/GRID observations
  22. LIGO/Virgo S200115j : no neutrino counterpart candidate in ANTARES search
  23. LIGO/Virgo S200114f: Upper limits from CALET observations.
  24. LIGO/Virgo S200115j: Identification of a GW compact binary merger candidate
  25. LIGO/Virgo S200115j: No counterpart candidates in HAWC observations
  26. LIGO/Virgo S200115j: Upper limits from IceCube neutrino searches
  27. LIGO/Virgo S200114f: Constraints on a CCSN origin from KM3NeT MeV neutrino search.
  28. LIGO/Virgo S200114f: SAGUARO previous detection of ZTF candidate ZTF20aafeaqk (AT2020vx)
  29. LIGO/Virgo S200114f: upper limits from AGILE-GRID observations
  30. IceCube-200109A: Candidate Counterparts from the Zwicky Transient Facility
  31. LIGO/Virgo S200114f : no neutrino counterpart candidate in ANTARES search
  32. LIGO/Virgo S200114f: Upper limits from Fermi-GBM Observations
  33. LIGO/Virgo S200114f: Identification of a GW unmodeled transient candidate
  34. LIGO/Virgo S200114f: No counterpart candidates in HAWC observations
  35. LIGO/Virgo S200114f: Upper limits from IceCube neutrino searches
  36. LIGO/Virgo S200112r: upper limits from AGILE/GRID observations
  37. LIGO/Virgo S200112r: No counterpart candidates in HAWC observations
  38. LIGO/Virgo S200112r : no neutrino counterpart candidate in ANTARES search
  39. LIGO/Virgo S200112r: Upper limits from IceCube neutrino searches
  40. LIGO/Virgo S200112r: Identification of a GW compact binary merger candidate
  41. IceCube-200109A: Swift-XRT and UVoT Follow-up Observations
  42. IceCube-200109A: Upper limits from Fermi-GBM Observations
  43. IceCube-200109A: IceCube observation of a high-energy neutrino candidate event
  44. LIGO/Virgo S200105ae: Updated Sky Localization and EM-Bright Probabilities
  45. LIGO/Virgo S200105ae: Gaia Photometric Alerts transient candidate
  46. GRB 200109A: Swift detection of a burst
  47. LIGO/Virgo S200105ae: GW data still under study
  48. LIGO/Virgo S200105ae: Candidates from the Zwicky Transient Facility
  49. Fermi-LAT Gamma-ray Observations of IceCube-200107A
  50. LIGO/Virgo S200108v: Retraction of GW compact binary merger candidate
  51. GRB 200107B: Swift detection of a burst
  52. LIGO/Virgo S200105ae: Further study ongoing for GW compact binary merger candidate
  53. IceCube-200107A: Upper limits from Fermi-GBM Observations
  54. IceCube-200107A: IceCube observation of a high-energy neutrino candidate event
  55. LIGO/Virgo S200105ae: AstroSat CZTI upper limits
  56. LIGO/Virgo S200105ae: No counterpart candidates in HAWC observations
  57. LIGO/Virgo S200105ae: Upper limits from IceCube neutrino searches
  58. LIGO/Virgo S200105ae: Upper limits from Fermi-GBM Observations
  59. LIGO/Virgo S200105ae : no neutrino counterpart candidate in ANTARES search
  60. LIGO/Virgo S200105ae: We have issued GCN Notices to support automated processing
  61. S200106au and S200106av: Retraction of GW compact binary merger candidates
  62. LIGO/Virgo S200105ae: A subthreshold GW compact binary merger candidate
  63. IceCube-191231A: No Neutrino Counterpart in ANTARES data
  64. IceCube-191231A: Upper limits from Fermi-GBM Observations
  65. IceCube-191231A: IceCube observation of a high-energy neutrino candidate event
  66. LIGO/Virgo S191216ap: Two candidate counterparts from UKIRT/WFCAM z-band observations
  67. GRB 191228A: Swift detection of a burst
  68. LIGO/Virgo S191213g: AT2019wxt 10.4m GTC further spectroscopy
  69. LIGO/Virgo S191225aq: Retraction of GW compact binary merger candidate
  70. LIGO/Virgo S191213g: Pan-STARRS monitoring shows PS19hgw (AT2019wxt) to be fading quickly
  71. LIGO/Virgo S191222n: Updated Sky Localization
  72. LIGO/Virgo S191222n: no counterpart candidate in SVOM/GWAC observations
  73. LIGO/Virgo S191216ap: Updated Source Classification
  74. LIGO/Virgo S191216ap: Upper limits from Insight-HXMT/HE observations
  75. GRB 191221B: Zadko observatory - Gingin optical observations
  76. LIGO/Virgo S191222n : no neutrino counterpart candidate in ANTARES search
  77. LIGO/Virgo S191222n: upper limits from AGILE-GRID observations
  78. LIGO/Virgo S191222n: No counterpart candidates in HAWC observations
  79. LIGO/Virgo S191222n: Identification of a GW compact binary merger candidate
  80. LIGO/Virgo S191222n: Upper limits from IceCube neutrino searches
  81. GRB 191221B: Swift detection of a burst and a very bright optical candidate
  82. GRB 191220A: AbAO optical observations
  83. LIGO/Virgo S191215w: Updated Sky Localization
  84. GRB 191220A: Swift detection of a burst
  85. LIGO/Virgo S191220af: Retraction of GW compact binary merger candidate
  86. LIGO/Virgo S191216ap: AstroSat CZTI upper limits
  87. LIGO/Virgo S191216ap: Subaru/Hyper Suprime-Cam observations of GW+IceCube+HAWC error region
  88. LIGO/Virgo S191213g: LBT spectrum of AT2019wxt (PS19hgw) reveals a type IIb supernova
  89. LIGO/Virgo S191216ap: UPDATED list of galaxies coincident with LIGO/Virgo LALInference skymap and HAWC positions
  90. LIGO/Virgo S191216ap: Updated Sky Localization
  91. LIGO/Virgo S191213g: Swift UVOT/XRT observations of Pan-STARRS1 candidate: PS19hgw
  92. LIGO/Virgo S191213g: MASTER observation of AT2019wxt (PS19hgw)
  93. LIGO/Virgo S191216ap: No candidates found in J-GEM follow-up observations of HAWC error region
  94. LIGO/VIRGO S191213g: ePESSTO+ spectroscopy of AT2019wxt (PS19hgw)
  95. LIGO/Virgo S191213g: HCT spectroscopy of PS19hgw / AT2019wxt
  96. LIGO/Virgo S191213g: No counterpart candidate in the NOWT observations
  97. LIGO/Virgo S191216ap: No candidates found in CHES observations of HAWC error region
  98. LIGO/Virgo S191216ap and IceCube neutrino: no counterpart candidates from AGILE-GRID observations
  99. LIGO/Virgo S191213g: Pan-STARRS1 discovery of a potential optical counterpart
  100. LIGO/Virgo S191216ap: GRAWITA Loiano observations of HAWC error region

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