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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"

39172 results found.

  1. Ep250125A: 1.3m DFOT optical upper limit
  2. GRB 250129A: Skynet optical observations
  3. GRB 250129A: KAIT optical observations of the rebrightening around 5.1 hours
  4. GRB 250129A: Swift-XRT refined Analysis
  5. GRB 250128B: Gemini-North optical extended source detection
  6. The EP-WXT trigger 01709131085: KAIT confirmation of the stellar flare
  7. GRB 250128B: TNG optical upper limit
  8. GRB 250129A: Swift/UVOT Detection
  9. GRB 250128B: VLT/HAWKI near-infrared observations
  10. GRB 250127A: CrAO and Terskol optical upper limits
  11. GRB 250129A: Enhanced Swift-XRT position
  12. GRB 250128B: NOT optical upper limit
  13. GRB 250128B: VLT/FORS2 optical observations
  14. GRB 250129A: REM optical/NIR afterglow detection
  15. GRB 250129A: OHP/T193 optical and spectroscopy observations
  16. GRB 250129A: Early afterglow detection by LCO.
  17. GRB 250128B: OHP/T193 optical upper limit
  18. Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
  19. GRB 250129A: LCO optical observations
  20. GRB 250129A: NOT optical observations and redshift confirmation
  21. GRB 250129A: GOTO optical observations show brightening afterglow
  22. GRB 250129A: VLT/X-shooter redshift of z = 2.151
  23. Swift GRB 250129A: Global MASTER-Net observations report
  24. GRB 250128B: Enhanced Swift-XRT position
  25. Fermi GRB 250128B: Global MASTER-Net observations report
  26. GRB 250129A: Swift detection of a burst with an optical counterpart
  27. Swift GRB 250129A: Global MASTER-Net OT detection
  28. GRB 250128B: Swift-XRT refined Analysis
  29. GRB 250128B: Fermi GBM Observation
  30. GRB 250128B: GOTO optical upper limit
  31. Swift GRB 250128B: Global MASTER-Net observations report
  32. EP250125a: Upper limits from Swift/BAT-GUANO
  33. GRB 250128B: LCO optical observations
  34. GRB 250128B: Swift detection of a short burst
  35. GRB 250128B: Fermi GBM Final Real-time Localization
  36. GRB 250127A: Swift-XRT observations
  37. GRB 250127B: DDOTI Upper Limit on the Afterglow
  38. GRB 250127A: EP-FXT afterglow detection
  39. Fermi GRB 250128A: Global MASTER-Net observations report
  40. GRB 250128A: Fermi GBM Final Real-time Localization
  41. GRB 250117A: Fermi GBM Observation
  42. Fermi GRB 250127B: Global MASTER-Net observations report
  43. Fermi-LAT Gamma-ray Observations of IceCube-250101A
  44. GRB 250127A: SVOM/VT upper limit
  45. GRB 250127B: Fermi GBM Final Real-time Localization
  46. IPN triangulation of GRB 250119C
  47. GRB 250127A: Swift ToO observations
  48. GRB 250127A: LCO optical upper limit
  49. GRB 241223A: cubesat Avion detection
  50. GRB 250127A: SVOM detection of a long burst
  51. GRB 250126A: CALET Gamma-Ray Burst Monitor detection
  52. EP250125A: Non-detection from Fermi-GBM Observations
  53. GRB 250126A: MAXI/GSC detection
  54. GRB 250126A: BALROG localization (Fermi Trigger 759560335 / GRB 250126208)
  55. GRB 250126A: Fermi GBM Final Real-time Localization
  56. GRB 250118A: Fermi GBM Observation
  57. EP250125a: REM optical counterpart detection
  58. GRB 250119C: Fermi GBM Observation
  59. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  60. GRB 250121A: CALET Gamma-Ray Burst Monitor detection
  61. EP250108a: AbAO, CMO and Terskol optical upper limits
  62. Konus-Wind detection of GRB 250118B
  63. GRB 250121A: Fermi GBM Observation
  64. IPN triangulation of GRB 250118B
  65. Konus-Wind detection of GRB 250119B
  66. IPN triangulation of GRB 250119B
  67. GRB 250122A: Fermi GBM Final Real-time Localization
  68. Improved IPN triangulation of GRB 250107C
  69. GRB 250114A: Swift-BAT refined analysis
  70. GRB 250121A: INTEGRAL/SPI-ACS detection
  71. GRB 250121A: Fermi-LAT detection
  72. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  73. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  74. GRB 250121A: Fermi GBM Final Real-time Localization
  75. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  76. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  77. GRB 250119B: Fermi GBM Observation
  78. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  79. Konus-Wind detection of GRB 250117A
  80. IPN triangulation of GRB 250117A (short)
  81. ATCA detection of possible radio counterpart to GRB 250114A
  82. GRB 250119B: INTEGRAL/SPI-ACS detection
  83. EP 250108A: Late-time optical observation by LCO
  84. GRB 250117A: SVOM/GRM observation of a short burst
  85. GRB 250119C: Fermi GBM Final Real-time Localization
  86. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  87. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  88. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  89. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  90. GRB 250117A: GECAM observation of a short burst
  91. GRB 250119B: BALROG localization (Fermi Trigger 758968026 / GRB 250119352)
  92. GRB 250119B: Fermi GBM Final Real-time Localization
  93. GRB 250119A: Fermi GBM Final Real-time Localization
  94. GRB 250118A: Fermi GBM Final Real-time Localization
  95. EP250108a / AT2025kg: VLA radio upper limit
  96. Fermi Gamma-ray Burst Monitor trigger 758829338/250117747 is not a GRB
  97. Konus-Wind detection of GRB 250116A
  98. GRB 250116A: GECAM-B detection of a long burst
  99. GRB 241217A / EP241217B: radio detection with the VLA
  100. GRB 250116A: INTEGRAL/SPI-ACS and PICsIT detection

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