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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"

6098 results found.

  1. LIGO/Virgo S200105ae: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  2. Fermi-LAT Gamma-ray Observations of IceCube-191231A
  3. IceCube-191231A: No significant detection in HAWC
  4. GRB 200101A: Fermi GBM detection
  5. IceCube-191231A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  6. GRB 191228A: Swift-XRT refined Analysis
  7. GRB 191227A: Fermi GBM detection
  8. GRB 191227A: Marginal detection by Fermi-LAT
  9. GRB 191221B: iTelescope T17 detection
  10. GRB 191221B: ALMA detection
  11. GRB 191221B: Swift-XRT refined Analysis
  12. LIGO/Virgo S191222n: No counterpart candidates in Fermi-LAT observations
  13. GRB 191220A: Swift-XRT refined Analysis
  14. GRB 191220A: SAO RAS possible OT detection
  15. LIGO/Virgo S191213g: Lulin Follow-up Observations of AT2019wxt
  16. LIGO/Virgo S191213g: Swift UVOT/XRT observations of Pan-STARRS1 candidate: PS19hgw
  17. LIGO/Virgo S191216ap: No candidates found in J-GEM follow-up observations of HAWC error region
  18. LIGO/Virgo S191213g: No candidates found in J-GEM follow-up observations
  19. LIGO/Virgo S191216ap and IceCube neutrino: Swift XRT sources
  20. LIGO/Virgo S191213g: Swift UVOT/XRT observations of three ZTF sources
  21. LIGO/Virgo S191215w : No significant candidates in TAROT - FRAM - GRANDMA observations.
  22. LIGO/Virgo G191216ap: No counterpart candidates in Fermi-LAT observations
  23. Fermi-LAT Gamma-ray Observations of IceCube-191215A
  24. LIGO/Virgo S191216ap: Identification of a GW compact binary merger candidate
  25. LIGO/Virgo S191215w: No counterpart candidates in Fermi-LAT observations
  26. LIGO/Virgo S191215w: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  27. IceCube-191215A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  28. LIGO/Virgo S191213g: Lulin Follow-up Observations of ZTF19acykzsk/AT2019wqj
  29. LIGO/Virgo S191213g: No counterpart candidates in Fermi-LAT observations
  30. LIGO/Virgo S191213g: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  31. Possible HAWC-detected GRB 191210A: Fermi-LAT Upper Limits
  32. Possible HAWC-detected GRB 191210A: Swift-XRT observations
  33. GRB 191207A: Possible GRB detected in Fermi-LAT blind search
  34. IceCube-191204A: No significant detection in HAWC
  35. Fermi-LAT Gamma-ray Observations of IceCube-191204A
  36. LIGO/Virgo S191205ah: No counterpart candidates in Fermi-LAT observations
  37. LIGO/Virgo S191204r: No counterpart candidates in Fermi-LAT observations
  38. LIGO/Virgo S191205ah: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  39. GRB 191130A: Swift-XRT observations
  40. IceCube-191204A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  41. LIGO/Virgo S191204r: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  42. GRB 191202A: Fermi-LAT detection
  43. GRB 191202A: Fermi GBM observation
  44. LIGO/Virgo S191129u: No counterpart candidates in Fermi-LAT observations
  45. LIGO/Virgo S191129u: no INTEGRAL data available
  46. IceCube-191122A: No significant detection in HAWC
  47. Fermi-LAT Gamma-ray Observations of IceCube-191122A
  48. GRB 191123A: Swift-XRT refined Analysis
  49. GRB 191122A: Swift-XRT refined Analysis
  50. IceCube-191119A: No significant detection in HAWC
  51. Fermi-LAT Gamma-ray Observations of IceCube-191119A
  52. IceCube-191119A - No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  53. LIGO/Virgo S191110af: Upper limits from Konus-Wind observations
  54. LIGO/Virgo S191110af: Swift XRT observations, no secure afterglow found
  55. LIGO/Virgo S191110af: No counterpart candidates in INTEGRAL SPI-ACS, and IBIS prompt observation
  56. LIGO/Virgo S191110af: No counterpart candidates in Fermi-LAT observations
  57. LIGO/Virgo S191110af: No counterpart candidates in INTEGRAL SPI-ACS, prompt observation
  58. LIGO/Virgo S191109d: No counterpart candidates in Fermi-LAT observations
  59. LIGO/Virgo S191109d: No counterpart candidates in INTEGRAL SPI-ACS,prompt observation
  60. ZTF19abvizsw: Upper limits from Konus-Wind observations
  61. LIGO/Virgo S191105e: No counterpart candidates in Fermi-LAT observations
  62. GRB 191106A: Swift-XRT refined Analysis
  63. LIGO/Virgo S191105e: No counterpart candidates in INTEGRAL SPI-ACS and,IBIS prompt observation
  64. GRB 191101A: Swift/UVOT Upper Limits
  65. GRB 191101A: iTelescope optical limit
  66. GRB 191101A: Swift-XRT refined Analysis
  67. GRB 191031C: Swift-XRT refined Analysis
  68. GRB 191031D: Swift-XRT refined Analysis
  69. GRB 191031C: Fermi GBM detection
  70. GRB 191031D: Fermi GBM detection
  71. GRB 191031A: Fermi GBM detection
  72. GRB 191029A: CORRECTED Swift-XRT refined analysis
  73. GRB 191029A: Swift/UVOT Upper Limits
  74. GRB 191029A: Swift-XRT refined Analysis
  75. Swift Trigger 931384: possible GRB 191025A
  76. GRB 191024A: Swift-XRT refined Analysis
  77. GRB191024A: MASTER optical observation
  78. GRB 191019A: Nanshan-0.6m optical observations
  79. GRB 191019A: Swift-XRT updated analysis
  80. GRB 191019A: Swift-XRT refined Analysis
  81. Alert from the HAWC Burst Monitor HAWC-191019A
  82. GRB 191017B: Swift-XRT refined Analysis
  83. GRB 191016A: Swift-XRT afterglow detection
  84. GRB 191016A: Swift/UVOT Detection
  85. GRB 191011A: Fermi GBM observation
  86. GRB 191011A: Swift-XRT refined Analysis
  87. LIGO/Virgo S190930t: Continued Swift observations of AT2019sbk
  88. Fermi/GBM observation of a bright burst from magnetar SGR 1935+2154
  89. LIGO/Virgo S190930t: Swift XRT observations, no secure afterglow found
  90. LIGO/Virgo S190930t: SALT optical spectroscopy of Swift J221951-484240
  91. GRB 191004B: Swift-XRT refined Analysis
  92. GRB 191004A: Swift-XRT refined Analysis
  93. GRB 191001A: Swift-XRT observations
  94. LIGO/Virgo S190930t: Continued Swift/UVOT observations of Swift J221951-484240
  95. GRB 191001A: Fermi GBM observation
  96. IceCube-191001A: HAWC follow-up
  97. Fermi-LAT Gamma-ray Observations of IceCube-191001A
  98. LIGO/Virgo S190930t: HCT observations of ZTF19acbpsuf
  99. LIGO/Virgo S190930t: Lulin Follow-up Observations of AT2019rpn and AT2019rpj
  100. IceCube-191001A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation

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