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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.

Lucene Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

3035 results found.

  1. EP250428b: refined analysis of the EP-FXT follow-up observation
  2. GRB 250427A: Swift/UVOT Detection
  3. EP250427a: EP-FXT follow-up observations
  4. GRB 250427A: Swift-XRT refined Analysis
  5. GRB 250424A: Swift-XRT refined Analysis
  6. SVOM/sb25042207: XRT observations
  7. EP250421a: Swift/XRT counterpart detection
  8. GRB 250419A: Swift-XRT refined Analysis
  9. EP250416a: Swift/XRT counterpart fading
  10. EP20250416a: Swift/XRT counterpart detection
  11. SVOM/sb25041603 is not a GRB
  12. IceCube-250406A: Swift-XRT observations
  13. EP250407a: Swift-XRT observations
  14. GRB 250407A: Swift-XRT afterglow detection
  15. GRB 250331D: Swift-XRT afterglow detection
  16. EP250402a: EP-FXT follow-up observations
  17. GRB 250403A: Swift-XRT observations
  18. GRB 250402A: Swift-XRT observations
  19. GRB 250402A: refined SVOM/MXT data analysis
  20. GRB 250329B: Swift/UVOT Upper Limit
  21. GRB 250327A: Swift/UVOT Upper Limits
  22. GRB 250331D: Swift-XRT observations
  23. GRB 250331C: Swift-XRT refined Analysis
  24. GRB 250331B: Swift-XRT refined Analysis
  25. GRB 250331B: Swift-XRT refined Analysis
  26. LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
  27. GRB 250328A: Swift-XRT refined Analysis
  28. GRB 250331C: Prompt enhanced Swift-XRT position
  29. GRB 250330A: Swift-XRT afterglow detection
  30. GRB 250330A: Prompt Swift-XRT position
  31. GRB 250329B: Swift-XRT afterglow detection
  32. GRB 250329A: Swift-XRT afterglow detection
  33. GRB 250327A: SVOM/VT upper limits on the XRT position
  34. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  35. GRB 250327A: Swift-XRT refined Analysis
  36. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  37. GRB 250321B: Swift-XRT observations
  38. GRB 250322A: Swift-XRT refined Analysis
  39. FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
  40. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  41. GRB 250321A: Swift-XRT refined Analysis
  42. EP250321a: Swift-XRT detection of an X-ray source
  43. GRB 250321A: Swift-XRT localisation
  44. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  45. GRB 250317B: Swift-XRT observations
  46. GRB 250316A: Swift/UVOT Upper Limits
  47. GRB 250316A: Swift-XRT afterglow detection
  48. GRB 250316A: Swift-XRT observations
  49. GRB 250314A: Swift/UVOT Upper Limits
  50. GRB 250314A: SVOM/VT upper limit
  51. GRB 250313A: Swift-XRT observations
  52. EP250302a: Chandra X-ray Detection
  53. GRB 250312A: Swift-XRT refined Analysis
  54. GRB 250311A: Swift-XRT observations
  55. GRB 250309B: Swift-XRT refined Analysis
  56. EP250308a: Einstein Probe detection of an X-ray transient
  57. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  58. EP250304a: Swift-XRT detection of a fading X-ray source
  59. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  60. EP250302a: Swift-XRT observations of a fading X-ray source
  61. GRB 250225B: VLT/HAWKI near-infrared observations
  62. EP250225a: EP-FXT follow-up observation
  63. GRB 250221A: EP-FXT detection of the X-ray afterglow
  64. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  65. EP250220a: EP-FXT follow-up observations
  66. GRB 250221A: Swift-XRT refined Analysis
  67. GRB 250219A: Swift/UVOT Upper Limits
  68. GRB 250219A: Swift-XRT observations
  69. GRB 250217C: Swift-XRT observations
  70. GRB 250213A: Swift-XRT observations
  71. GRB 250215A: Swift/UVOT Upper Limits
  72. GRB 250215A: Swift-XRT refined Analysis
  73. EP250207B: Chandra localization of the X-ray counterpart
  74. GRB 250210A: AstroSat CZTI detection
  75. GRB 250206A: Swift-XRT observations
  76. GRB 250207B: Swift-XRT observations
  77. GRB 250207A: Swift-XRT refined Analysis
  78. GRB 250205A: Swift/XRT detection
  79. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  80. GRB 250129A: Swift-XRT refined Analysis
  81. GRB 250128B: Swift-XRT refined Analysis
  82. GRB 250127A: Swift-XRT observations
  83. GRB 250127A: EP-FXT afterglow detection
  84. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  85. GRB 250114B: Swift-XRT afterglow detection
  86. GRB 250114B: Swift-XRT observations
  87. GRB 250114A: Swift-XRT refined Analysis
  88. GRB 250106A: Swift-XRT afterglow detection
  89. GRB 250108A: Swift/XRT afterglow fading
  90. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  91. EP250108a: EP-FXT follow-up observation
  92. GRB 250108B: Swift-XRT refined Analysis
  93. GRB 250108A: Swift-XRT afterglow detection
  94. GRB 250103A: Swift-XRT afterglow detection
  95. GRB 250106A: Swift-XRT observations
  96. GRB 250103B: Swift-XRT refined Analysis
  97. GRB 250103A: Swift-XRT observations
  98. GRB 250101A: Swift-XRT refined Analysis
  99. GRB 241229A: EP-FXT X-ray afterglow confirmation
  100. GRB 241229A: Swift-XRT observations

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