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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"

12316 results found.

  1. EP260126a: Optical upper limit with Kinder observations
  2. EP260126a: Liverpool Telescope optical upper limits
  3. EP260126a: Further NOT optical upper limits
  4. EP260126a: COLIBRÍ optical upper limits
  5. EP260126a: NOT optical observations
  6. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  7. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  8. Fermi GRB 260125B: Global MASTER-Net observations report
  9. GRB 260114A: SVOM/VT optical upper limits
  10. Swift GRB260122.97: Global MASTER-Net observations report
  11. EP260119a: Mondy and SAO RAS optical upper limits
  12. EP260119a: Xinglong optical upper limit
  13. Fermi GRB 260120C: Global MASTER-Net observations report
  14. GRB 260120B: Swift/UVOT Detection
  15. GRB 260120B: COLIBRÍ optical upper limits
  16. SVOM GRB260121.06: Global MASTER-Net observations report
  17. Swift GRB260120B: Global MASTER-Net observations report
  18. Fermi trigger No 790601190: Global MASTER-Net observations report
  19. Fermi trigger No 790570272: Global MASTER-Net observations report
  20. GRB 260114A: Swift/UVOT Upper Limits
  21. SVOM GRB260119.92: Global MASTER-Net observations report
  22. SVOM GRB260119.92: Global MASTER-Net observations report
  23. SVOM GRB260119.90: Global MASTER-Net observations report
  24. EP260119a: Global MASTER-Net observations report
  25. GRB 260117A: ZTSh optical upper limit
  26. Swift GRB260118.48: Global MASTER-Net observations report
  27. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  28. SVOM GRB260117.82: Global MASTER-Net observations report
  29. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  30. GRB 260117A: SVOM/C-GFT upper limit
  31. GRB 260117A: Swift-XRT observations
  32. EP 260116a: COLIBRÍ optical upper limit
  33. EP260116a: Liverpool Telescope upper limits
  34. EP260116A: 1.3m DFOT optical upper limit
  35. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  36. EP260116a: Global MASTER-Net observations report
  37. EP260116a: Xinglong optical upper limit
  38. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  39. IceCube Alert 260115.73: Global MASTER-Net observations report
  40. Fermi GRB 260115A: Global MASTER-Net observations report
  41. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  42. Konus-Wind detection of GRB 260114A
  43. GRB 260114A: 6 GHz VLA observations
  44. GRB 260114A : MITSuME Akeno optical upper limits
  45. GRB 260114A: COLIBRÍ optical upper limits
  46. GRB 260114A: TNG NIR upper limit
  47. GRB 260114A: NOT optical observations
  48. Konus-Wind detection of GRB 251230A / EP251230a
  49. Swift GRB 260114A: Global MASTER-Net observations report
  50. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  51. GRB 260114A: Swift detection of a short burst
  52. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  53. Swift GRB260113.43: Global MASTER-Net observations report
  54. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  55. EP260110a: TRT optical upper limits
  56. GRB 260111A: Swift-XRT observations
  57. Swift Trigger 1439093: is probably not GRB 260113A
  58. GRB 260111A: COLIBRÍ optical afterglow candidate
  59. GRB 260111A: GOTO optical upper limits
  60. GRB 251230A: Mondy Optical Observations
  61. EP260110a: SVOM/VT optical upper limits
  62. IceCube Alert 260111A: Global MASTER-Net observations report
  63. EP260110a: Global MASTER-Net observations report
  64. Fermi GRB 260111A: Global MASTER-Net observations report
  65. Swift trigger 1436759 is not an astrophysical event
  66. EP260110a: KAIT optical upper limit
  67. EP 260110a: COLIBRÍ optical observations
  68. EP260110a: SVOM/C-GFT upper limit
  69. EP260110a: BOOTES-5/JGU optical upper limit
  70. GRB 260109C: LCO optical upper limits
  71. GRB 260109C: Kilonova-Catcher optical upper limit
  72. Swift Trigger 1434591: possible GRB 260109C
  73. Swift GRB 251230A: Global MASTER-Net OT detection
  74. Fermi GRB 260107A: Global MASTER-Net observations report
  75. GRB 260102A: AbAO optical observations
  76. Fermi GRB 260105A: Global MASTER-Net observations report
  77. EP260105a: FTW optical observations
  78. EP260104a: FTW optical observations
  79. FRB 20251229A: COLIBRÍ optical upper limits
  80. Fermi GRB 260105B: Global MASTER-Net observations report
  81. EP260105a: LCO Optical Upper limit
  82. EP260104a: Global MASTER-Net observations report
  83. GRB 260101A: COLIBRÍ optical upper limits
  84. EP260105a: Global MASTER-Net observations report
  85. GRB 260104A: COLIBRÍ optical upper limits
  86. Fermi GRB 260104B: Global MASTER-Net observations report
  87. Swift GRB 260104A: Global MASTER-Net observations report
  88. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  89. GRB 260101A: Swift/UVOT Detection
  90. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  91. SVOM GRB260103.08: Global MASTER-Net observations report
  92. SVOM GRB260102A: Global MASTER-Net observations report
  93. GRB 260102A: EP-FXT follow-up observation
  94. EP260101a: Global MASTER-Net observations report
  95. GRB 260102A: LCO optical upper limits
  96. GRB 260102A: Swift-XRT observations
  97. Swift GRB 260101A: Global MASTER-Net observations report
  98. SVOM GRB251231.57: Global MASTER-Net observations report
  99. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  100. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening

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