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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"

3039 results found.

  1. Possible HAWC-detected GRB 191210A: Fermi-LAT Upper Limits
  2. Possible HAWC-detected GRB 191210A: Swift-XRT observations
  3. Fermi trigger No 597737032: Global MASTER-Net observations report
  4. LIGO/Virgo S191205ah: No counterpart candidates in Fermi-LAT observations
  5. LIGO/Virgo S191204r: No counterpart candidates in Fermi-LAT observations
  6. GRB 191130A: Swift-XRT observations
  7. LIGO/Virgo S191129u: No counterpart candidates in Fermi-LAT observations
  8. GRB 191123A: Swift-XRT refined Analysis
  9. GRB 191122A: Swift-XRT refined Analysis
  10. LIGO/Virgo S191110af: Swift XRT observations, no secure afterglow found
  11. LIGO/Virgo S191110af: No counterpart candidates in Fermi-LAT observations
  12. LIGO/Virgo S191109d: No counterpart candidates in Fermi-LAT observations
  13. LIGO/Virgo S191105e: No counterpart candidates in Fermi-LAT observations
  14. GRB 191106A: Swift-XRT refined Analysis
  15. GRB 191101A: Swift-XRT refined Analysis
  16. GRB 191031C: Swift-XRT refined Analysis
  17. GRB 191031D: Swift-XRT refined Analysis
  18. GRB 191029A: CORRECTED Swift-XRT refined analysis
  19. GRB 191029A: Swift/UVOT Upper Limits
  20. GRB 191029A: Swift-XRT refined Analysis
  21. Swift Trigger 931384: possible GRB 191025A
  22. GRB 191024A: Swift-XRT refined Analysis
  23. GRB 191019A: Swift-XRT updated analysis
  24. GRB 191019A: Swift-XRT refined Analysis
  25. GRB 191017B: Swift-XRT refined Analysis
  26. GRB 191016A: Swift-XRT afterglow detection
  27. GRB 191016A: Swift/UVOT Detection
  28. GRB 191011A: Swift-XRT refined Analysis
  29. LIGO/Virgo S190930t: Continued Swift observations of AT2019sbk
  30. LIGO/Virgo S190930t: Swift XRT observations, no secure afterglow found
  31. GRB 191004B: Swift-XRT refined Analysis
  32. GRB 191004A: Swift-XRT refined Analysis
  33. GRB 191001A: Swift-XRT observations
  34. LIGO/Virgo S190930t: Continued Swift/UVOT observations of Swift J221951-484240
  35. LIGO/Virgo S190930t: Transient found in Swift/UVOT counterpart search
  36. LIGO/Virgo S190930t: No counterpart candidates in Fermi-LAT observations
  37. LIGO/Virgo S190930s: No counterpart candidates in Fermi-LAT observations
  38. GRB 190926A: Swift-XRT refined Analysis
  39. LIGO/Virgo S190924h: No counterpart candidates in Fermi-LAT observations
  40. LIGO/Virgo S190923y: No counterpart candidates in Fermi-LAT observations
  41. GRB 190919B: Swift-XRT observations
  42. GRB 190919B: GROND detection of the NIR afterglow
  43. LIGO/Virgo S190915ak: No counterpart candidates in Fermi-LAT observations
  44. LIGO/Virgo S190910h: No counterpart candidates in Fermi-LAT observations
  45. LIGO/Virgo S190910d: No counterpart candidates in Fermi-LAT observations
  46. GRB 190823A: Swift-XRT afterglow detection
  47. Chandra observations of GW170817 ~740-743 days since merger
  48. LIGO/Virgo S190901ap: No counterpart candidates in Fermi-LAT observations
  49. GRB 190829A: TNG imaging of the NIR afterglow
  50. GRB 190829A: Fermi-LAT Upper Limits
  51. GRB 190829A: GROND detection of the Optical/NIR Afterglow
  52. GRB 190829A: Swift-XRT refined Analysis
  53. GRB 190828B: Swift-XRT refined Analysis
  54. GRB 190828A: Swift-XRT observations
  55. LIGO/Virgo S190828l: No counterpart candidates in Fermi-LAT observations
  56. LIGO/Virgo S190828j: No counterpart candidates in Fermi-LAT observations
  57. LIGO/Virgo S190814bv: no variation of DESGW candidates AT 2019onj and AT 2019okr from ENGRAVE VLT/HAWK-I observations, and archival detection
  58. GRB 190823A: Swift-XRT observations
  59. GRB 190816A: Swift-XRT afterglow detection
  60. GRB 190824A: Swift-XRT refined Analysis
  61. LIGO/Virgo S190814bv: GROND follow-up observations of AT2019npv
  62. LIGO/Virgo S190814bv: ENGRAVE VLT/HAWK-I observations and archival detection of the CFHT candidate
  63. GRB 190821A: Swift-XRT refined Analysis
  64. Fermi GBM-190816: No counterpart candidates in Fermi-LAT observations
  65. LIGO/Virgo S190814bv: No strong counterpart candidates in Swift/XRT observations
  66. GRB 190816A: Swift-XRT observations
  67. LIGO/Virgo S190814bv: Fermi-LAT search for a high-energy gamma-ray counterpart
  68. LIGO/Virgo S190814bv: GRAWITA TNG infrared imaging of desgw-190814e, DG19sevhc and selected galaxies
  69. LIGO/Virgo S190814bv: GRAWITA TNG infrared imaging of selected galaxies
  70. HAWC-190806A: Swift-XRT observations
  71. GRB 190804B: Swift-XRT afterglow detection
  72. GRB 190805B: Swift-XRT observations
  73. GRB 190804B: Swift-XRT observations
  74. GRB 190731A: Swift-XRT afterglow detection
  75. LIGO/Virgo S190728q: No counterpart candidates in Fermi-LAT observations
  76. LIGO/Virgo S190727h: No counterpart candidates in Fermi-LAT observations
  77. LIGO/Virgo S190718y: Swift XRT observations, 45 X-ray sources
  78. LIGO/Virgo S190720a: No counterpart candidates in Fermi-LAT observations
  79. GRB 190719C: Swift-XRT refined Analysis
  80. LIGO/Virgo S190718y: No counterpart candidates in Fermi-LAT observations
  81. GRB 190718A: Swift-XRT refined Analysis
  82. GRB 190714A: an X-ray flare from 2E 1624.6+1504/UCAC4 525-061488
  83. GRB 190708B: confirmation of the X-ray afterglow
  84. GRB 190708B: Swift-XRT observations
  85. LIGO/Virgo S190707q: No counterpart candidates in Fermi-LAT observations
  86. LIGO/Virgo S190706ai: No counterpart candidates in Fermi-LAT observations
  87. LIGO/Virgo S190701ah: No counterpart candidates in Fermi-LAT observations
  88. GRB 190706B: Swift-XRT refined Analysis
  89. GRB 190701A: Swift-XRT refined Analysis
  90. GRB 190630C: Swift-XRT refined Analysis
  91. LIGO/Virgo S190630ag: No counterpart candidates in Fermi-LAT observations
  92. GRB 190630B: Swift-XRT refined Analysis
  93. GRB 190627A: Swift-XRT refined Analysis
  94. Swift Trigger 911102 is likely not an astrophysical event
  95. GRB 190610A: Swift-XRT observations
  96. GRB 190613B: Swift-XRT refined Analysis
  97. GRB 190613A: Swift-XRT refined Analysis
  98. GRB 190611A: Swift-XRT refined Analysis
  99. Fermi trigger No 581645543 Global MASTER-Net observations report
  100. GRB 190604B: Swift-XRT refined Analysis

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