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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').
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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.

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subject:"Swift"
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submitter:"Judith Racusin"

752 results found.

  1. GRB 250421A: AstroSat CZTI detection
  2. IPN triangulation of GRB 250406B (short/hard)
  3. Konus-Wind detection of GRB 250404A / EP250404a
  4. LIGO/Virgo/KAGRA S250331o: Identification of a GW compact binary merger candidate
  5. LIGO/Virgo/KAGRA S250328ae: Identification of a GW compact binary merger candidate
  6. GRB 250327B: Las Cumbres optical counterpart detection
  7. IPN triangulation of GRB 250322B
  8. LIGO/Virgo/KAGRA S250326y: Identification of a GW compact binary merger candidate
  9. LIGO/Virgo/KAGRA S250319bu: Identification of a GW compact binary merger candidate
  10. GRB 250312B: Fermi GBM Observation
  11. GRB 250312B: Fermi GBM Final Localization
  12. IPN triangulation of GRB 250308A (short)
  13. IPN triangulation of GRB 250309B
  14. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  15. IPN triangulation of GRB 250217C (short)
  16. LIGO/Virgo/KAGRA S250211be: Identification of a GW compact binary merger candidate
  17. LIGO/Virgo/KAGRA S250211aa: Identification of a GW compact binary merger candidate
  18. LIGO/Virgo/KAGRA S250208ad: Identification of a GW compact binary merger candidate
  19. LIGO/Virgo/KAGRA S250207bg: Identification of a GW compact binary merger candidate
  20. GRB 250205A: Fermi GBM Observation
  21. LIGO/Virgo/KAGRA S250205ee: Identification of a GW compact binary merger candidate
  22. IPN triangulation of GRB 250201A
  23. LIGO/Virgo/KAGRA S250205bk: Identification of a GW compact binary merger candidate
  24. LIGO/Virgo/KAGRA S250204ax: Identification of a GW compact binary merger candidate
  25. LIGO/Virgo/KAGRA S250202cu: Identification of a GW compact binary merger candidate
  26. IPN triangulation of GRB 250118B
  27. IPN triangulation of GRB 250119B
  28. Improved IPN triangulation of GRB 250107C
  29. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  30. LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
  31. LIGO/Virgo/KAGRA S250119ag: Identification of a GW compact binary merger candidate
  32. LIGO/Virgo/KAGRA S250118dp: Identification of a GW compact binary merger candidate
  33. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  34. LIGO/Virgo/KAGRA S250118t: Identification of a GW compact binary merger candidate
  35. IPN triangulation of GRB 250113A
  36. LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
  37. IPN triangulation of GRB 250107D (short/hard)
  38. LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
  39. LIGO/Virgo/KAGRA S250108eo: Identification of a GW compact binary merger candidate
  40. LIGO/Virgo/KAGRA S250104v: Identification of a GW compact binary merger candidate
  41. LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate
  42. LIGO/Virgo/KAGRA S241225v: Identification of a GW compact binary merger candidate
  43. LIGO/Virgo/KAGRA S241210fu: Identification of a GW compact binary merger candidate
  44. LIGO/Virgo/KAGRA S241210cw: Identification of a GW compact binary merger candidate
  45. LIGO/Virgo/KAGRA S241201ac: Identification of a GW compact binary merger candidate
  46. IPN triangulation of GRB 241128B
  47. LIGO/Virgo/KAGRA S241130be: Identification of a GW compact binary merger candidate
  48. LIGO/Virgo/KAGRA S241130n: Identification of a GW compact binary merger candidate
  49. LIGO/Virgo/KAGRA S241129aa: Identification of a GW compact binary merger candidate
  50. LIGO/Virgo/KAGRA S241127aj: Updated Sky localization
  51. GRB 241127A: Swift detection of a burst with an optical counterpart
  52. LIGO/Virgo/KAGRA S241127aj: Identification of a GW compact binary merger candidate
  53. LIGO/Virgo/KAGRA S241125n: Identification of a GW compact binary merger candidate
  54. IPN triangulation of GRB 241117A
  55. LIGO/Virgo/KAGRA S241116cq: Identification of a GW compact binary merger candidate
  56. LIGO/Virgo/KAGRA S241114y: Identification of a GW compact binary merger candidate
  57. Fermi trigger No 753166198: Global MASTER-Net observations report
  58. LIGO/Virgo/KAGRA S241111bn: Identification of a GW compact binary merger candidate
  59. IPN triangulation of GRB 241107A (short/hard)
  60. S241102cy: Identification of a GW compact binary merger candidate
  61. LIGO/Virgo/KAGRA S241102br: Identification of a GW compact binary merger candidate
  62. GRB 241030A: Swift-BAT refined analysis
  63. IPN triangulation of GRB 241022A (short/hard)
  64. IPN triangulation of GRB 241021A (long)
  65. GRB 241010A: Swift detection of a burst with an optical counterpart
  66. LIGO/Virgo/KAGRA S241009em: Identification of a GW compact binary merger candidate
  67. LIGO/Virgo/KAGRA S241009an: Identification of a GW compact binary merger candidate
  68. LIGO/Virgo/KAGRA S241007bw: Identification of a GW compact binary merger candidate
  69. LIGO/Virgo/KAGRA S241006k: Identification of a GW compact binary merger candidate
  70. IPN triangulation of GRB 240930B / EP 240930a
  71. LIGO/Virgo/KAGRA S240930du: Identification of a GW compact binary merger candidate
  72. IPN triangulation of GRB 240926A
  73. LIGO/Virgo/KAGRA S240930aa: Identification of a GW compact binary merger candidate
  74. LIGO/Virgo/KAGRA S240925n: Identification of a GW compact binary merger candidate
  75. IPN triangulation of GRB 240918B
  76. LIGO/Virgo/KAGRA S240924a: Identification of a GW compact binary merger candidate
  77. LIGO/Virgo/KAGRA S240923ct: Identification of a GW compact binary merger candidate
  78. LIGO/Virgo/KAGRA S240922df: Identification of a GW compact binary merger candidate
  79. LIGO/Virgo/KAGRA S240920dw: Identification of a GW compact binary merger candidate
  80. LIGO/Virgo/KAGRA S240920bz: Identification of a GW compact binary merger candidate
  81. LIGO/Virgo/KAGRA S240919bn: Identification of a GW compact binary merger candidate
  82. IPN triangulation of GRB 240913C / EP 240913a
  83. LIGO/Virgo/KAGRA S240916ar: Identification of a GW compact binary merger candidate
  84. LIGO/Virgo/KAGRA S240915b: Identification of a GW compact binary merger candidate
  85. IPN triangulation of GRB 240810A (short)
  86. GRB 240807B: AstroSat CZTI detection of a short burst
  87. Improved IPN triangulation of GRB 240802A / EP 240802a
  88. GRB 240805A: Swift/UVOT Upper Limits
  89. IPN triangulation of GRB 240715A (short)
  90. GRB 240712A: Swift detection of a burst
  91. IPN triangulation of GRB 240627A
  92. IPN triangulation of GRB 240619C
  93. IPN triangulation of GRB 240615A (short)
  94. GRB 240615A: Fermi GBM Observation
  95. IPN triangulation of GRB 240607A
  96. IPN triangulation of GRB 240603A
  97. IPN triangulation of the initial episode of GRB 240529A
  98. IPN triangulation of GRB 240504A
  99. IPN triangulation of GRB 240501B and GRB 240501A - possible episodes of ultra long GRB
  100. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration

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