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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').
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.

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

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