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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"

4055 results found.

  1. LIGO/Virgo S200105ae: Upper limits from Fermi-GBM Observations
  2. LIGO/Virgo S200105ae: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  3. LIGO/Virgo S200105ae : no neutrino counterpart candidate in ANTARES search
  4. LIGO/Virgo S200105ae: We have issued GCN Notices to support automated processing
  5. S200106au and S200106av: Retraction of GW compact binary merger candidates
  6. LIGO/Virgo S200105ae: A subthreshold GW compact binary merger candidate
  7. IPN triangulation of GRB 191227B (short)
  8. LIGO/Virgo S191216ap: Two candidate counterparts from UKIRT/WFCAM z-band observations
  9. LIGO/Virgo S191222n: No transient candidates in CALET observations
  10. LIGO/Virgo S191213g: AT2019wxt 10.4m GTC further spectroscopy
  11. LIGO/Virgo S191225aq: Retraction of GW compact binary merger candidate
  12. LIGO/Virgo S191225aq: Global MASTER-Net observations report
  13. LIGO/Virgo S191205ah: MASTER OT detection
  14. LIGO/Virgo S191213g: Pan-STARRS monitoring shows PS19hgw (AT2019wxt) to be fading quickly
  15. LIGO/Virgo S191222n : No significant candidates in FRAM-TAROT-GRANDMA observations
  16. LIGO/Virgo S191222n: Updated Sky Localization
  17. LIGO/Virgo S191222n: no counterpart candidate in SVOM/GWAC observations
  18. LIGO/Virgo S191216ap: Updated Source Classification
  19. LIGO/Virgo S191216ap: Upper limits from Insight-HXMT/HE observations
  20. LIGO/Virgo S191216ap: No significant candidates found in Pan-STARRS observations
  21. LIGO/Virgo S191213g : No significant candidates found in GRANDMA citizen science observations
  22. LIGO/Virgo S191222n: no counterpart candidates in the Swift/BAT observations
  23. LIGO/Virgo S191222n: No counterpart candidates in Fermi-LAT observations
  24. LIGO/Virgo S191222n: not observable by Fermi-GBM
  25. LIGO/Virgo S191222n : no neutrino counterpart candidate in ANTARES search
  26. LIGO/Virgo S191222n: upper limits from AGILE-GRID observations
  27. LIGO/Virgo S191222n: upper limits from AGILE/MCAL observations
  28. LIGO/Virgo S191222n: Coverage and upper limits from MAXI/GSC observations
  29. LIGO/Virgo S191222n: INTEGRAL was inactive at the time of the event
  30. LIGO/Virgo S191222n: No counterpart candidates in HAWC observations
  31. LIGO/Virgo S191222n: Identification of a GW compact binary merger candidate
  32. LIGO/Virgo S191222n: Upper limits from IceCube neutrino searches
  33. LIGO/Virgo S191222n: Global MASTER-Net observations report
  34. LIGO/Virgo S191216ap: VLA/JAGWAR radio monitoring of the 1-sigma HAWC region
  35. LIGO/Virgo S191216ap: No radio candidates so far in the VLA/JAGWAR galaxy targeted search
  36. LIGO/Virgo S191216ap: MASTER optical observation
  37. LIGO/Virgo S191216ap : No significant candidates in FRAM-TAROT-GRANDMA observations
  38. LIGO/Virgo S191213g: VLA follow-up of AT2019wxt/PS19hg
  39. LIGO/Virgo S191213g: AT2019wxt 10.4m GTC spectroscopy
  40. LIGO/Virgo S191213g : SAO 1-m optical observation of AT2019wxt (PS19hgw)
  41. LIGO/Virgo S191215w: Updated Sky Localization
  42. LIGO/Virgo S191213g: DCT observation of AT2019wxt
  43. LIGO/Virgo S191220af: Retraction of GW compact binary merger candidate
  44. LIGO/Virgo S191220af: Global MASTER-Net observations report
  45. LIGO/Virgo S191216ap: AstroSat CZTI upper limits
  46. LIGO/Virgo S191213g: YAHPT Observations of AT2019wxt(PS19hgw)
  47. LIGO/Virgo S191216ap: Subaru/Hyper Suprime-Cam observations of GW+IceCube+HAWC error region
  48. LIGO/Virgo S191213g: LBT spectrum of AT2019wxt (PS19hgw) reveals a type IIb supernova
  49. LIGO/Virgo S191216ap: UPDATED list of galaxies coincident with LIGO/Virgo LALInference skymap and HAWC positions
  50. LIGO/Virgo S191216ap: Updated Sky Localization
  51. LIGO/Virgo S191213g: VLT spectrum of AT2019wxt (PS19hgw) - a probable Ib supernova
  52. LIGO/Virgo S191213g: Lulin Follow-up Observations of AT2019wxt
  53. LIGO/Virgo S191205ah: AT2019wmy 10.4m GTC spectroscopy
  54. LIGO/Virgo S191213g: Swift UVOT/XRT observations of Pan-STARRS1 candidate: PS19hgw
  55. LIGO/Virgo S191213g: Palomar 60-inch imaging of AT2019wxt
  56. LIGO/Virgo S191213g: GRAWITA TNG NIR imaging of AT2019wxt (PS19hgw)
  57. LIGO/Virgo S191216ap, Swift XRT observations: 16 X-ray sources in the HAWC error region search
  58. LIGO/Virgo S191213g: MASTER observation of AT2019wxt (PS19hgw)
  59. LIGO/Virgo S191216ap: No candidates found in J-GEM follow-up observations of HAWC error region
  60. LIGO/VIRGO S191213g: ePESSTO+ spectroscopy of AT2019wxt (PS19hgw)
  61. LIGO/VIRGO S191213g: LT spectroscopy of AT2019wxt (PS19hgw)
  62. LIGO/Virgo S191213g: AT2019wnh, AT2019wnk and AT2019wrt 10.4m GTC spectroscopy
  63. LIGO/Virgo S191213g: NOT optical spectroscopy of AT2019wxt (PS19hgw)
  64. LIGO/Virgo S191213g: HCT spectroscopy of PS19hgw / AT2019wxt
  65. LIGO/Virgo S191216ap: Correction to GCN 26488 (NOWT observations)
  66. LIGO/Virgo S191213g: No counterpart candidate in the NOWT observations
  67. LIGO/Virgo S191216ap: No candidates found in CHES observations of HAWC error region
  68. LIGO/Virgo S191216ap and IceCube neutrino: no counterpart candidates from AGILE-GRID observations
  69. LIGO/Virgo S191213g: Pan-STARRS1 discovery of a potential optical counterpart
  70. LIGO/Virgo S191216ap: GRAWITA Loiano observations of HAWC error region
  71. LIGO/Virgo S191216ap: No transient candidates in CALET observations
  72. LIGO/Virgo S191216ap: CORRECTED list of galaxies coincident with LIGO/Virgo and HAWC positions
  73. LIGO/Virgo S191216ap: Nanshan follow-up observations
  74. LIGO/Virgo S191213g: No candidates found in J-GEM follow-up observations
  75. LIGO/Virgo S191216ap: galaxies consistent with GW + Neutrino + HAWC position
  76. LIGO/Virgo S191216ap and IceCube neutrino: Swift XRT sources
  77. LIGO/Virgo S191216ap: IceCube event: MASTER OF detection in GW and Neutrino error field
  78. LIGO/Virgo S191216ap: No significant counterpart candidates in SAGUARO observations
  79. LIGO/Virgo S191216ap: HAWC gamma-ray sub-threshold event coincident with LIGO/Virgo and IceCube localizations
  80. LIGO/Virgo S191213g: Swift UVOT/XRT observations of three ZTF sources
  81. LIGO/Virgo S191213g: MASTER OT J064855.37-055545.7 is a dwarf nova
  82. LIGO/Virgo S191215w : No significant candidates in TAROT - FRAM - GRANDMA observations.
  83. LIGO/Virgo G191216ap: No counterpart candidates in Fermi-LAT observations
  84. LIGO/Virgo S191213g: MASTER OT detection in BNS error-box
  85. LIGO/Virgo S191216ap: no counterpart candidates in the Swift/BAT observations
  86. LIGO/Virgo S191215w: No transient candidates in CALET observations
  87. LIGO/Virgo S191216ap: No Candidates from the Zwicky Transient Facility
  88. LIGO/Virgo S191216ap: Correction to GCN 26460 (IceCube event coincident with GW event)
  89. LIGO/Virgo S191216ap: Coverage and upper limits from MAXI/GSC observations
  90. LIGO/Virgo S191216ap: Upper limits from Fermi-GBM Observations
  91. LIGO/Virgo S191216ap: 1 counterpart neutrino candidate from IceCube neutrino searches
  92. LIGO/Virgo S191216ap : no neutrino counterpart candidate in ANTARES search
  93. LIGO/Virgo S191216ap: Global MASTER-Net observations report
  94. LIGO/Virgo S191216ap: no INTEGRAL observation
  95. LIGO/Virgo S191216ap: No counterpart candidates in HAWC observations
  96. LIGO/Virgo S191216ap: Identification of a GW compact binary merger candidate
  97. LIGO/Virgo S191215w: no counterpart candidates in the Swift/BAT observations
  98. LIGO/Virgo S191215w: No counterpart candidates in Fermi-LAT observations
  99. UKIRT photometry of ZTF19acyldun/AT 2019wrt
  100. LIGO/Virgo S191215w: AstroSat CZTI upper limits

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