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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"

3400 results found.

  1. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  2. GRB 250321B: Swift-XRT observations
  3. GRB 250322A: Swift-XRT refined Analysis
  4. FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
  5. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  6. GRB 250321A: Swift-XRT refined Analysis
  7. EP250321a: Swift-XRT detection of an X-ray source
  8. GRB 250321A: Swift-XRT localisation
  9. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  10. GRB 250317B: Swift-XRT observations
  11. GRB 250316A: Swift/UVOT Upper Limits
  12. GRB 250316A: Swift-XRT afterglow detection
  13. GRB 250316A: Swift-XRT observations
  14. GRB 250314A: Swift/UVOT Upper Limits
  15. GRB 250314A: SVOM/VT upper limit
  16. GRB 250313A: Swift-XRT observations
  17. EP250302a: Chandra X-ray Detection
  18. GRB 250312A: Swift-XRT refined Analysis
  19. GRB 250311A: Swift-XRT observations
  20. GRB 250309B: Swift-XRT refined Analysis
  21. EP250308a: Einstein Probe detection of an X-ray transient
  22. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  23. EP250304a: Swift-XRT detection of a fading X-ray source
  24. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  25. EP250302a: Swift-XRT observations of a fading X-ray source
  26. GRB 250225B: VLT/HAWKI near-infrared observations
  27. EP250225a: EP-FXT follow-up observation
  28. GRB 250221A: EP-FXT detection of the X-ray afterglow
  29. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  30. EP250220a: EP-FXT follow-up observations
  31. GRB 250221A: Swift-XRT refined Analysis
  32. GRB 250219A: Swift/UVOT Upper Limits
  33. GRB 250219A: Swift-XRT observations
  34. GRB 250217C: Swift-XRT observations
  35. GRB 250213A: Swift-XRT observations
  36. GRB 250215A: Swift/UVOT Upper Limits
  37. GRB 250215A: Swift-XRT refined Analysis
  38. EP250207B: Chandra localization of the X-ray counterpart
  39. GRB 250210A: AstroSat CZTI detection
  40. GRB 250206A: Swift-XRT observations
  41. GRB 250207B: Swift-XRT observations
  42. GRB 250207A: Swift-XRT refined Analysis
  43. GRB 250205A: Swift/XRT detection
  44. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  45. GRB 250129A: Swift-XRT refined Analysis
  46. GRB 250128B: Swift-XRT refined Analysis
  47. GRB 250127A: Swift-XRT observations
  48. GRB 250127A: EP-FXT afterglow detection
  49. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  50. GRB 250114B: Swift-XRT afterglow detection
  51. GRB 250114B: Swift-XRT observations
  52. GRB 250114A: Swift-XRT refined Analysis
  53. GRB 250106A: Swift-XRT afterglow detection
  54. GRB 250108A: Swift/XRT afterglow fading
  55. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  56. EP250108a: EP-FXT follow-up observation
  57. GRB 250108B: Swift-XRT refined Analysis
  58. GRB 250108A: Swift-XRT afterglow detection
  59. GRB 250103A: Swift-XRT afterglow detection
  60. GRB 250106A: Swift-XRT observations
  61. GRB 250103B: Swift-XRT refined Analysis
  62. GRB 250103A: Swift-XRT observations
  63. GRB 250101A: Swift-XRT refined Analysis
  64. GRB 241229A: EP-FXT X-ray afterglow confirmation
  65. GRB 241229A: Swift-XRT observations
  66. GRB 241229A: EP-FXT afterglow candidates
  67. GRB 241228B: Swift-XRT afterglow detection
  68. GRB 241229B: Swift-XRT refined Analysis
  69. GRB 241228A: Swift-XRT refined Analysis
  70. GRB 241223A: Swift-XRT observations
  71. EP 241217a: NIR detection with P200/WIRC
  72. GRB 241217A: refined SVOM/MXT data analysis. Long lasting X-ray emission.
  73. GRB 241218A: Swift-XRT refined Analysis
  74. GRB 241217A: Swift-XRT afterglow detection
  75. EP241217a: Swift-XRT Detection
  76. GRB 241212A: Swift-XRT observations
  77. GRB 241213B: Swift-XRT observations
  78. GRB 241213A: Swift-XRT refined Analysis
  79. EP241213a: EP detection of An X-ray Transient
  80. GRB 241209A: Chandra X-ray Detection
  81. GRB 241209B: Swift-XRT afterglow detection
  82. GRB 241209A: Swift-XRT refined Analysis
  83. EP241208a: EP-FXT follow-up observations
  84. GRB 241209D: Swift-XRT refined Analysis
  85. GRB 241209A: VLT/HAWK-I near-IR counterpart candidate
  86. AT2024adec: X-ray Upper Limits from EP-FXT Observation
  87. EP241201a: EP-FXT follow-up observations
  88. Fermi trigger No 754701230: Global MASTER-Net observations report
  89. Swift-XRT observations of IceCube -241127A
  90. GRB 241128A: Swift-XRT refined Analysis
  91. GRB 241128A: Swift-XRT afterglow detection
  92. GRB 241127A: Swift-XRT refined Analysis
  93. LIGO/Virgo/KAGRA S241125n: Swift-UVOT Upper Limits
  94. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations
  95. LIGO/Virgo S241125n: Swift XRT observations, 5 X-ray sources
  96. GRB 241115A: Swift-XRT afterglow detection
  97. GRB 241113B: Swift-XRT observations
  98. GRB 241113A: Swift-XRT refined Analysis
  99. GRB 241112B: Swift-XRT afterglow detection
  100. GRB 241108A: Swift-XRT observations

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