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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"
  1. GRB 190719C: Swift-BAT refined analysis
  2. GRB 190719C: Swift/UVOT Upper Limits
  3. LIGO/Virgo S190720a: No counterpart candidates in the Swift/BAT Observations
  4. GRB 190719C: Swift-XRT light-curve fit
  5. GRB 190719C: Swift-XRT refined Analysis
  6. GRB 190720A: BALROG localization (Fermi Trigger 585326534 / GRB 190720613)
  7. GRB 190720A: Fermi GBM Final Real-time Localization
  8. LIGO/Virgo S190720a: Upper limits from Fermi-GBM Observations
  9. LIGO/Virgo S190720a: Upper limits from AGILE-GRID observations
  10. LIGO/Virgo S190720a : no neutrino counterpart candidate in ANTARES search
  11. LIGO/Virgo S190720a: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  12. LIGO/Virgo S190720a: Coverage and upper limits from MAXI/GSC observations
  13. LIGO/Virgo S190718y: No counterpart candidates in CNEOST
  14. LIGO/Virgo S190720a: AGILE-MCAL observations
  15. LIGO/Virgo S190720a: Identification of a GW compact binary merger candidate
  16. LIGO/Virgo S190720a Global MASTER-Net observations report
  17. LIGO/Virgo S190720a: No counterpart candidates in HAWC observations
  18. LIGO/Virgo S190720a: Upper limits from IceCube neutrino searches
  19. Fermi trigger No 585196946 Global MASTER-Net observations report
  20. GRB 190719C: NOT candidate optical afterglow and host
  21. LIGO/Virgo S190718y: No counterpart candidates in KAIT observations
  22. LIGO/Virgo S190718y: ZTF pre-detection of MASTER candidate AT2019lly
  23. LIGO/Virgo S190718y: Analysis update
  24. GRB 190719C: Swift detection of a burst
  25. MASTER OT detection inside LIGO/Virgo S190718y error box
  26. GRB 190719C: Fermi GBM Final Real-time Localization
  27. LIGO/Virgo S190718y: Upper limits from Insight-HXMT/HE observations
  28. LIGO/Virgo S190718y: No counterpart candidates in Fermi-LAT observations
  29. GRB 190719B: a long GRB detected by INTEGRAL
  30. LIGO/Virgo S190718y: Coverage and upper limits from MAXI/GSC observations
  31. LIGO/Virgo S190718y: Upper limits from CALET observations
  32. GRB 190719A: Fermi GBM Final Real-time Localization
  33. GRB 190718A: Swift-BAT refined analysis
  34. LIGO/Virgo S190718y: No counterpart candidates in the Swift/BAT Observations
  35. LIGO/Virgo S190718y: Upper limits from Fermi-GBM Observations
  36. LIGO/Virgo S190630ag: Updated sky localization
  37. GRB 190718A: Swift-XRT refined Analysis
  38. LIGO/Virgo S190718y: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  39. LIGO/Virgo S190718y : no neutrino counterpart candidate in ANTARES search
  40. GRB 190718A: Swift/UVOT Upper Limits
  41. LIGO/Virgo S190718y Global MASTER-Net observations report
  42. LIGO/Virgo S190718y: Identification of a GW compact binary merger candidate
  43. LIGO/Virgo S190718y: Upper limits from IceCube neutrino searches
  44. GRB 190718A: FRAM-Auger optical limit
  45. GRB 190718A: Enhanced Swift-XRT position
  46. Swift GRB190718.2 Global MASTER-Net observations report
  47. GRB 190718A: Swift detection of a burst
  48. GRB 190613B: FRAM-Auger afterglow detection
  49. Fermi trigger No 585007213 Global MASTER-Net observations report
  50. GRB 190716A: BALROG localization (Fermi Trigger 585007213 / GRB 190716917)
  51. GRB 190716A: Fermi GBM Final Real-time Localization
  52. Fermi trigger No 584977168 Global MASTER-Net observations report
  53. GRB 190714A: an X-ray flare from 2E 1624.6+1504/UCAC4 525-061488
  54. Fermi trigger No 584929684 Global MASTER-Net observations report
  55. Fermi trigger No 584929684 Global MASTER-Net observations report
  56. GRB 190708B: confirmation of the X-ray afterglow
  57. IceCube-190712A: Upper limits from a search for additional neutrino events in IceCube
  58. Fermi trigger No 584804684 Global MASTER-Net observations report
  59. GRB 190714B: Fermi GBM Final Real-time Localization
  60. GRB 190714A: Tiled Swift observations
  61. GRB 190714A: MAXI/GSC detection
  62. Fermi trigger No 584710308 Global MASTER-Net observations report
  63. IceCube-190712A : Upper limits from Insight-HXMT/HE observations
  64. Fermi-LAT Gamma-ray Observations of IceCube-190712A
  65. IceCube-190712A: No neutrino counterpart candidates in ANTARES search
  66. Fermi trigger No 584637077 Global MASTER-Net observations report
  67. IceCube-190712A: Upper limits from Fermi-GBM Observations
  68. GRB 190706D: Insight-HXMT/HE detection
  69. GRB 190706C: Insight-HXMT/HE detection
  70. IceCube Alert 190712.05 Global MASTER-Net observations report
  71. IceCube-190712A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  72. IceCube-190712A - IceCube observation of a high-energy neutrino candidate event
  73. Fermi trigger No 584590606 Global MASTER-Net observations report
  74. GRB 190712A: Fermi GBM Final Real-time Localization
  75. Fermi trigger No 584583925 Global MASTER-Net observations report
  76. GRB 190708B: Swift-XRT observations
  77. LIGO/Virgo S190706ai: Upper limits from Insight-HXMT/HE observations
  78. Fermi trigger No 584465880 Global MASTER-Net observations report
  79. Fermi trigger No 584404689 Global MASTER-Net observations report
  80. LIGO/Virgo S190706ai: Updated sky localization
  81. LIGO/Virgo S190707q: Updated sky localization
  82. Konus-Wind observation of GRB 190706D
  83. LIGO/Virgo S190707q: MASTER OT seach result
  84. LIGO/Virgo S190707q: No counterpart candidates in the CNEOST
  85. LIGO/Virgo S190707q: No counterpart candidates in the Swift/BAT Observations
  86. Konus-Wind observation of GRB 190708B
  87. Konus-Wind observation of GRB 190706C
  88. GRB 190708B: Tiled Swift observations
  89. MAXI GRB190708.83 Global MASTER-Net observations report
  90. GRB 190706C: CALET Gamma-Ray Burst Monitor detection
  91. GRB 190708B: MAXI/GSC detection
  92. IPN triangulation of GRB 190706D (short)
  93. IPN triangulation of GRB 190706C (long/very bright)
  94. Fermi trigger No 584264100 Global MASTER-Net observations report
  95. LIGO/Virgo S190707q: Upper limits from CALET observations
  96. Konus-Wind observation of GRB 190704A
  97. LIGO/Virgo S190707q: No counterpart candidates in Fermi-LAT observations
  98. GRB 190708A: Fermi GBM Final Real-time Localization
  99. LIGO/Virgo S190707q: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observations
  100. LIGO/Virgo S190706ai: No counterpart candidates in KAIT observations

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