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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"

3040 results found.

  1. GRB 190604B: Swift-XRT refined Analysis
  2. LIGO/Virgo S190602aq: No counterpart candidates in Fermi-LAT observations
  3. GRB 190531B: Swift-XRT afterglow detection
  4. GRB 190530A: Swift/UVOT Detection
  5. GRB 190530A: Swift-XRT afterglow detection
  6. IceCube-190504A: Kanata optical/NIR follow-up observations
  7. LIGO/Virgo S190521r: Coverage and upper limits from Fermi-LAT observations
  8. LIGO/Virgo S190521g: No candidate counterpart in Fermi-LAT observations
  9. LIGO/Virgo S190519bj: Fermi-LAT search for a high-energy gamma-ray counterpart
  10. GRB 190519A: Swift-XRT refined Analysis
  11. LIGO/Virgo S190426c: NICER X-ray Follow-Up of ZTF19aassfws
  12. LIGO/Virgo S190517h: Fermi-LAT search for a high-energy gamma-ray counterpart
  13. GRB 190515B: Swift-XRT refined Analysis
  14. LIGO/Virgo S190510g: Swift-XRT observations and results
  15. LIGO/Virgo S190513bm: Fermi-LAT search for a high-energy gamma-ray counterpart
  16. LIGO-Virgo S190512at: AGILE GRID observations
  17. LIGO/Virgo S190512at: Fermi-LAT search for a high-energy gamma-ray counterpart
  18. GRB 190511A: Swift-XRT refined Analysis
  19. GRB 190511A: Swift/UVOT Detection
  20. LIGO/Virgo S190510g: J-GEM optical/NIR follow-up observations
  21. LIGO/Virgo S190510g: Fermi-LAT search for a high-energy gamma-ray counterpart
  22. GRB 190501A: Swift XRT and UVOT Observations
  23. LIGO/Virgo S190503bf: Fermi-LAT search for a high-energy gamma-ray counterpart
  24. LIGO/Virgo S190425z: Insight-HXMT observation and counterpart search
  25. LIGO/Virgo S190412m: Further J-GEM optical/NIR observations
  26. LIGO/Virgo S190426c: Fermi-LAT search for a high-energy gamma-ray counterpart
  27. LIGO/Virgo S190425z: VISTA K-band observations of the Swift/UVOT Transient
  28. LIGO/Virgo S190425z : IRSF/SIRIUS NIR photometric follow-up observation of the Swift/UVOT Transient
  29. LIGO/Virgo S190425z: Swift/UVOT and XRT pre-images at the position of the potential Swift/UVOT counterpart
  30. LIGO/Virgo S190426c: Swift-XRT sources
  31. LIGO/Virgo S190425z: Fermi-LAT search for a high-energy gamma-ray counterpart
  32. LIGO/Virgo S190425z : IRSF/SIRIUS NIR photometry of ZTF19aarykkb and ZTF19aarzaod
  33. LIGO/Virgo S190421ar: Fermi-LAT search for a high-energy gamma-ray counterpart
  34. GRB 190422A: Swift-XRT refined Analysis
  35. LIGO/Virgo S190408an: INTEGRAL follow-up observations
  36. GRB 190326A: Swift XRT and UVOT follow-up observations
  37. LIGO/Virgo S190412m: Fermi-LAT search for a high-energy gamma-ray counterpart
  38. GRB 190409A: ground analysis reveals a likely spurious event
  39. LIGO/Virgo ST190408an: Fermi-LAT search for a high-energy gamma-ray counterpart
  40. GRB 190409A: Swift detection of a possible burst
  41. GRB 190404C: Swift-XRT afterglow detection
  42. GRB 190404C: Swift-XRT observations
  43. Swift GRB 190331B: Further Swift-XRT observations
  44. GRB 190331B: Swift observations of a ground-detected burst
  45. GRB 190324A: Swift-XRT refined Analysis
  46. Further Chandra observations of GW170817 ~581-583 days since merger
  47. SWIFT GRB190323.85 Global MASTER-Net observations report
  48. GRB 190320A: Swift-XRT refined Analysis
  49. GRB 190311A: Swift-XRT refined Analysis
  50. GRB 190305A: Swift-XRT afterglow detection
  51. GRB 190306A: Swift-XRT observations
  52. GRB 190305A: Swift-XRT observations
  53. GRB 190220A: Swift-XRT refined Analysis
  54. GRB 190219A: Swift-XRT refined Analysis
  55. GRB 190211A: Swift-XRT refined Analysis
  56. GRB 190203A: Swift-XRT refined Analysis
  57. GRB 190204A: Swift-XRT refined Analysis
  58. GRB 190202A: Swift-XRT refined Analysis
  59. GRB 190129B: Swift-XRT candidate afterglow detection
  60. GRB 190123A: Swift-XRT refined Analysis
  61. GRB 190114B: Swift-XRT refined Analysis
  62. GRB 190114C: Swift-XRT refined Analysis
  63. GRB 190114A: Swift-XRT refined Analysis
  64. GRB 190109B: Swift-XRT refined Analysis
  65. GRB 190109A: Swift-XRT refined Analysis
  66. GRB 190106A: Swift-XRT refined Analysis
  67. GRB 190103B: Swift-XRT refined Analysis
  68. GRB 181225A: further Swift-XRT observations
  69. GRB 181228A: Swift-XRT refined Analysis
  70. GRB 181222B: Swift follow-up observations of MASTER optical transient J204928.79+245744.0
  71. GRB 181225A: Swift observations and X-ray candidate afterglow
  72. GRB 181213A: Swift-XRT refined Analysis
  73. GRB 181203A: Swift/UVOT Upper Limits
  74. GRB 181203A: Swift-XRT refined Analysis
  75. GRB 181201A: Swift/UVOT Detection
  76. GRB 181202A: Swift-XRT refined Analysis
  77. GRB 181201A: Swift-XRT afterglow detection
  78. GRB 181126A: No Ks-band afterglow detection with Keck I
  79. GRB 181126A: Swift-XRT refined Analysis
  80. GRB 181123B: Swift-XRT refined Analysis
  81. Swift Trigger 872470: further Swift analysis
  82. GRB 181110A: Swift-XRT refined Analysis
  83. GRB 181103A: Swift-XRT refined Analysis
  84. GRB 181030A: Swift-XRT refined Analysis
  85. GRB 181022A: Swift-XRT refined Analysis
  86. GRB 181023A: Swift-XRT refined Analysis
  87. GRB 181020A: Swift-XRT refined Analysis
  88. GRB 181013A: Swift detection of a probable burst
  89. GRB 181010A: Swift-XRT refined Analysis
  90. GRB 181003A: Swift-XRT afterglow detection
  91. GRB 181002A: Swift-XRT refined Analysis
  92. GRB 180930A: Swift-XRT refined Analysis
  93. GRB 180925A: Swift-XRT refined Analysis
  94. GRB 180924A: Swift-XRT refined Analysis
  95. GRB 180914B: Swift-XRT afterglow detection
  96. GRB 180914A: Swift-XRT observations
  97. GRB 180905A: Swift-XRT refined Analysis
  98. GRB 180904A: Swift-XRT refined Analysis
  99. GRB 180829A: Swift-XRT observations
  100. GRB 180828A: Swift-XRT refined Analysis

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