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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. EP250404a: LAST detection of optical counterpart
  2. EP250404a: BOOTES-4/JGT optical afterglow detection
  3. EP250404a: Einstein Probe detection of an X-ray transient
  4. GRB 250402A: EP-FXT afterglow detection
  5. EP250402a: EP-FXT follow-up observations
  6. The EP-WXT trigger 01709133862 is a flaring star
  7. EP250402a: Einstein Probe detection of a fast X-ray transient
  8. FRB 20250316A: FTW optical observations
  9. FRB 20250316A: The sub-arcsecond localization of FRB 20250316A using CHIME/FRB Outriggers coincides with reported X-ray counterparts
  10. The EP-WXT trigger 01709133021 (designated as EP250324a) is not a real source
  11. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  12. FRB 250316A: COLIBRÍ/DDRAGO Optical follow up of the X ray source EP J120944.2+585060
  13. FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
  14. FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
  15. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  16. EP250321a: KAIT optical observations
  17. EP250321a: WFST optical observations
  18. EP 250321A: Optical counterpart detection by LCO.
  19. EP250321a: Swift-XRT detection of an X-ray source
  20. EP250321a: VLT/X-shooter redshift z = 4.368
  21. EP250321a: BOOTES-5/JGT optical afterglow detection
  22. EP250321a: Einstein Probe detection of an X-ray transient
  23. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  24. The EP-WXT trigger 01709132801 is likely a flaring star
  25. GRB 250314A: EP-FXT afterglow detection
  26. EP250315a: refined analysis of the EP-WXT and EP-FXT observations
  27. EP250315a: Einstein Probe detection of an X-ray transient
  28. EP250311a/GRB 250311A: Correction to EP-WXT detection time
  29. The EP-WXT trigger 01709132551 is not a real source
  30. EP250311a/GRB 250311A: EP-FXT follow-up observation
  31. EP250311a/GRB 250311A: EP-WXT detection
  32. The EP-WXT trigger 01709132425 is not a real source
  33. EP250308a: GSP optical upper limit
  34. EP250308a: Einstein Probe detection of an X-ray transient
  35. The EP-WXT trigger 01709132387 is likely a flaring star
  36. The EP-WXT trigger 01709132323 is likely a flaring star
  37. EP 250304A: Optical counterpart detection by LCO
  38. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  39. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  40. EP250304a: Swift-XRT detection of a fading X-ray source
  41. EP250304a: Einstein Probe detection of an X-ray transient
  42. The EP-WXT trigger 01709132212 is not a real source
  43. EP250302a: Swift/UVOT detection
  44. EP250302a: NUTTelA-TAO Early Measurments
  45. EP250302a: Einstein Probe detection of an X-ray transient
  46. EP250302a: SVOM/C-GFT optical observations
  47. EP250302a: Montarrenti Observatory optical detection
  48. EP250302a: Nanshan/HMT optical counterpart detection
  49. The EP-WXT trigger 01709132140 is likely a flaring star
  50. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  51. EP250227a: Einstein Probe detected of a fast X-ray transient
  52. EP250228a: updates on the EP observations
  53. EP250225a: EP-FXT follow-up observation
  54. EP250228a: Swift/XRT localisation
  55. EP250228a: Einstein Probe detection of an X-ray transient
  56. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  57. GRB 250221A: EP-FXT detection of the X-ray afterglow
  58. EP250226a/GRB 250226A: GSP detects optical counterpart
  59. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  60. EP250225a: GSP optical upper limit
  61. EP250225a: Einstein Probe detected of a fast X-ray transient
  62. GRB 250219A: EP-FXT afterglow detection
  63. EP250223a: refined analysis of the EP-WXT and FXT observations
  64. The EP-WXT trigger 01709131882 is likely a flaring star
  65. EP250223a: Swift/XRT localization
  66. EP250223a: Einstein Probe detection of an X-ray transient
  67. EP250220a: EP-FXT follow-up observations
  68. EP250220a: EP-WXT detection of a fast X-ray transient
  69. GRB 250215A / EP250215A: Encouraging Follow-up Observations of a BdHN I with a Rest-Frame Duration 2.3 s at z=4.61
  70. The EP-WXT trigger 01709131775 is likely a flaring star
  71. GRB 250215A / EP250215a: LCO detection of the afterglow
  72. GRB 250215A: Swift/UVOT Upper Limits
  73. GRB 250215A: Swift-XRT refined Analysis
  74. EP250215A/GRB 250215A: INTEGRAL SPI-ACS detection
  75. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  76. EP250207b: VLA radio upper limits
  77. EP250212a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  78. EP250207b: Liverpool Telescope possible optical counterpart
  79. EP250207b: Gemini GMOS-N z-band observations
  80. EP250207b: a new X-ray transient detected by Einstein Probe
  81. EP250207a: EP-WXT detection and XRT follow-up observation
  82. The EP-WXT trigger 01709131347 is likely a flaring star
  83. The EP-WXT trigger 01709131332 is likely a flaring star
  84. The EP-WXT trigger 01709131290 is likely a flaring star
  85. GRB 250205A: REM NIR upper limit
  86. EP250205a/GRB 250205A: correction to the source localization
  87. EP250205a/GRB 250205A: Einstein Probe observation
  88. The EP-WXT trigger 01709131196 is likely a flaring star
  89. The EP-WXT trigger 01709131153 is not a real source
  90. EP250108A / SN 2025kg: Upper limits from a neutrino search with IceCube
  91. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  92. The EP-WXT trigger 01709131085 is likely a flaring star
  93. GRB 250127A: Swift-XRT observations
  94. GRB 250127A: EP-FXT afterglow detection
  95. EP250108a / SN 2025kg: Refined Analysis of EP-WXT Detection
  96. EP250125a: REM optical counterpart detection
  97. EP250125a: Swift/XRT detection of a fading counterpart
  98. EP250125a: a new X-ray transient detected by Einstein Probe
  99. The EP-WXT trigger 01709130758 is a false trigger
  100. EP250108a/AT2025kg: 1.3m DFOT Optical observations

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