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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"

6094 results found.

  1. EP250508a: Gemini NIR upper limits
  2. GRB 250510B: Fermi GBM Observation
  3. GRB 250510A: Swift-XRT observations
  4. GRB 250509A: Fermi GBM Observation
  5. IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
  6. GRB 250509A: Swift-XRT refined Analysis
  7. GRB 250506A: Swift-XRT afterglow detection
  8. GRB 250507A: Swift-XRT refined Analysis
  9. GRB 250506A: Swift/UVOT Upper Limits
  10. EP#01709175213/IGR J19566+0326: Swift-XRT detection
  11. GRB 250507A: refined SVOM/MXT data analysis
  12. GRB 250506A: Swift-XRT observations
  13. Fermi-LAT Gamma-ray Observations of IceCube-250506A
  14. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  15. GRB 250506A: Mephisto optical upper limits
  16. GRB 250430A: Konus-Wind detection and joint Konus-Wind+Swift-BAT spectral analysis
  17. GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
  18. GRB 250506A: Fermi GBM Observation
  19. GRB 250506A: Swift XRT observations and possible counterpart detection
  20. GRB 250504A: Swift-XRT refined Analysis
  21. GRB 250504A: Fermi GBM Observation
  22. GRB 250502A: Swift-XRT afterglow detection
  23. GRB 250502A: LCO optical counterpart detection
  24. Fermi-LAT Gamma-ray Observations of IceCube-250429A
  25. GRB 250430A: Swift-XRT refined Analysis
  26. GRB 250430A: Optical Observations via Virtual Telescope Project, Italy
  27. GRB 250430A: NUTTelA-TAO Early Measurements
  28. EP250428b: refined analysis of the EP-FXT follow-up observation
  29. EP250428b: SAO RAS optical upper limit
  30. GRB 250427A: Swift/UVOT Detection
  31. Fermi-LAT Gamma-ray Observations of IceCube-250426A
  32. EP250427a: EP-FXT follow-up observations
  33. GRB 250427A: Swift-XRT refined Analysis
  34. Konus-Wind detection of GRB 250424A
  35. Fermi-LAT gamma-ray observations of IceCube-250421A
  36. GRB 250424A: Swift-XRT refined Analysis
  37. GRB 250424A: VLT/X-shooter spectroscopic redshift z = 0.310
  38. SVOM/sb25042207: XRT observations
  39. GRB 250419A: Optical Observations via Virtual Telescope Project
  40. EP250421a: Swift/XRT counterpart detection
  41. EP250421a: Mephisto optical counterpart confirmation
  42. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  43. GRB 250419A: LCO optical afterglow multi-band observations
  44. Fermi-LAT Gamma-ray Observations of IceCube-250416A
  45. GRB 250407A: rest-frame energetics from Konus-Wind observation
  46. GRB 250419A: Swift-XRT refined Analysis
  47. EP250416a: Swift/XRT counterpart fading
  48. Konus-Wind detection of GRB 250403A
  49. EP20250416a: Swift/XRT counterpart detection
  50. SVOM/sb25041603 is not a GRB
  51. EP250227a: Further NOT optical observations
  52. IceCube-250406A: Swift-XRT observations
  53. GRB 250407A: LCO detection of a fading optical counterpart
  54. Fermi-LAT gamma-ray observations of IceCube-250406A
  55. EP250407a: Swift-XRT observations
  56. GRB 250407A: Fermi GBM Detection
  57. GRB 250407A: Swift-XRT afterglow detection
  58. Konus-Wind detection of GRB 250404A / EP250404a
  59. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  60. GRB 250331D: Swift-XRT afterglow detection
  61. EP250404a: LCO optical counterpart detection
  62. EP250404a: Xinglong decaying optical counterpart
  63. GRB 250404A: Fermi GBM Detection
  64. GRB 250403A: Fermi GBM observations
  65. EP250404a: Nanshan/HMT optical counterpart detection
  66. EP250402a: Optical upper limit with Kinder observations
  67. GRB 250403A: LCO optical counterpart detection
  68. EP250402a: EP-FXT follow-up observations
  69. GRB 250403A: Swift-XRT observations
  70. GRB 250402A: Fermi GBM Observation
  71. GRB 250402A: Swift-XRT observations
  72. GRB 250402A: LCO optical counterpart detection
  73. GRB 250402A: refined SVOM/MXT data analysis
  74. GRB 250329B: Swift/UVOT Upper Limit
  75. GRB 250327A: Swift/UVOT Upper Limits
  76. GRB 250331D: Fermi GBM observation
  77. GRB 250331D: Swift-XRT observations
  78. GRB 250331C: Swift-XRT refined Analysis
  79. GRB 250331B: Swift-XRT refined Analysis
  80. GRB 250331B: Swift-XRT refined Analysis
  81. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  82. Konus-Wind detection of GRB 250327B
  83. LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
  84. GRB 250328A: Swift-XRT refined Analysis
  85. Fermi-LAT gamma-ray observations of IceCube-250330A
  86. GRB 250330A: Fermi GBM Observation
  87. GRB 250331C: Prompt enhanced Swift-XRT position
  88. GRB 250330A: Swift-XRT afterglow detection
  89. GRB 250330A: Prompt Swift-XRT position
  90. GRB 250329B: Swift-XRT afterglow detection
  91. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  92. GRB 250329A: Swift-XRT afterglow detection
  93. GRB 250329A: Fading optical counterpart detection by LCO.
  94. GRB 250327B: LCO optical counterpart detection
  95. GRB 250327B: CrAO and SAO RAS Optical Observations
  96. GRB 250327B: further optical observations by LCOGT
  97. GRB 250327A: SVOM/VT upper limits on the XRT position
  98. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  99. GRB 250327A: Swift-XRT refined Analysis
  100. GRB 250327B: SVOM detection of a burst

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