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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"
body:"GRB"
submitter:"Judith Racusin"

1094 results found.

  1. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  2. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  3. EP250704a / GRB250704B: Swift-XRT counterpart detection
  4. EP250702a: WFST optical observations
  5. EP250704a: Einstein Probe detection of an X-ray transient
  6. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  7. GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
  8. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  9. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  10. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  11. GRB 250628B: EP-FXT counterpart detection
  12. The EP-WXT trigger 01709179435 is likely a new outburst of the CV SS Cyg
  13. The EP-WXT trigger 01709179396 is likely a flaring star CSTAR 38580
  14. The EP-WXT trigger 01709179071 is likely a flaring star
  15. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  16. The EP-WXT trigger 01709178990 is likely a flaring star
  17. EP#01709178975: Swift-XRT counterpart detection
  18. The EP-WXT trigger 01709178975 is likely a flaring star
  19. GRB 250615A / EP250615a: AstroSat CZTI detection
  20. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  21. The EP-WXT trigger 01709178875 is likely a flaring star
  22. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  23. sb25061207: EP-FXT follow-up observation and afterglow candidate
  24. EP 250612a: AST3-3 Yaoan Optical Observation
  25. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  26. EP250612a: Einstein Probe detection of an X-ray transient
  27. EP250610a: continuous follow-up observations with EP-FXT
  28. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  29. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  30. EP250610a: Swift-XRT counterpart detection
  31. EP250610a: Einstein Probe detection of an X-ray transient
  32. The EP-WXT trigger 01709178283 is likely a flaring star
  33. The EP-WXT trigger 01709178244 is likely a flaring star
  34. The EP-WXT trigger 01709178069 is likely a flaring star
  35. The EP-WXT trigger 01709177873 is likely a flaring star
  36. The EP-WXT trigger 01709177837 is likely a flaring star
  37. GRB 250601A: EP-FXT follow-up observation and afterglow candidates
  38. EP#01709177494: SVOM/VT optical observations
  39. EP#01709177494: Swift-XRT counterpart detection of known source
  40. GRB 250530A: EP-FXT counterpart detection
  41. EP J1350.0-8622: EP-FXT follow-up observation
  42. The EP-WXT trigger 01709177124 is likely a flaring star
  43. EP250526a: refined analysis of the EP-WXT and EP-FXT observations
  44. EP250526a: Einstein Probe detection of a fast X-ray transient
  45. EP J1350.0-8622: BOOTES-6/DPRT optical upper limit
  46. EP J1350.0-8622: Einstein Probe detection of an X-ray transient candidate
  47. EP-WXT trigger 01709176712: SVOM/C-GFT observations of blue-to-red color variation
  48. The EP-WXT trigger 01709176712 is likely a flaring star
  49. The EP-WXT trigger 01709176612: refined analysis of the EP-FXT observation
  50. GRB 250521B: EP-FXT follow-up observation and afterglow candidates
  51. EP#01709176612: Swift-XRT counterpart detection of flaring star
  52. The EP-WXT trigger 01709176612 is likely a flaring star
  53. EP250427a/GRB250427A: VLA Detection of Radio Counterpart
  54. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  55. GRB 250512B / EP250512a: SVOM/GRM analysis
  56. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  57. GRB 250512B/EP250512a:SVOM/VT bright optical counterpart
  58. GRB 250512B: SVOM detection of a burst
  59. EP250512a: Einstein Probe detection of an X-ray transient
  60. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  61. EP250511a: SVOM/VT optical candidate comfirmation
  62. EP250511a: Einstein Probe detection of an X-ray transient
  63. GRB 250510A: follow-up observation with EP-FXT
  64. EP250508a: follow-up observation with EP-FXT
  65. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  66. EP250508a: Einstein Probe detection of an X-ray transient
  67. GRB 250507A: follow-up observation with EP-FXT
  68. EP#01709175213/IGR J19566+0326: Swift-XRT detection
  69. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  70. SVOM/sb25050601: EP-FXT observations
  71. SVOM/sb25043004: EP-FXT observations
  72. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  73. EP 250427A: Optical counterpart detection by LCO.
  74. EP250428b: refined analysis of the EP-FXT follow-up observation
  75. EP250428b: SVOM/VT upper limit
  76. GRB 250427A: Swift/UVOT Detection
  77. EP250428b: Einstein Probe detection of a fast X-ray transient
  78. EP250427a: EP-FXT follow-up observations
  79. EP250427a: LT optical counterpart detection
  80. GRB 250427A: Swift-XRT refined Analysis
  81. EP250427a: Einstein Probe detection of a fast X-ray transient
  82. EP250416a / GRB 250416C: Gemini GMOS-S likely host galaxy redshift z = 0.963
  83. EP250421a: Einstein Probe detection of an X-ray transient
  84. EP250416a: refined EP-WXT and EP-FXT analysis
  85. EP250416a: Gemini South-GMOS optical counterpart
  86. EP250416a: GSP optical upper limit
  87. EP250416a: Einstein Probe detection of an X-ray transient
  88. EP250304a: ATCA radio observations
  89. EP250404a: Nanshan 0.43m Telescope optical observatios
  90. EP250407a: Swift-XRT observations
  91. GRB 250407A: EP-WXT afterglow detection
  92. EP250407a: EP-WXT detection of a fast X-ray transient
  93. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  94. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  95. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  96. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  97. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  98. EP250402a: Optical upper limit with PD 1.3m observations
  99. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  100. EP250404a: Seimei/TriCCS optical counterpart detection

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