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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"

36180 results found.

  1. Konus-Wind detection of GRB 260410A (short/hard)
  2. GRB 260411B: GECAM-B observation of a long burst
  3. GRB 260410A: CALET Gamma-Ray Burst Monitor detection
  4. GRB 260412A: GECAM-B observation of a long burst
  5. Fermi GRB 260412A: Global MASTER-Net observations report
  6. GRB 260412A: Fermi GBM Observation
  7. GRB 260310A / AT2026fgk: NuSTAR detection of the rebrightening
  8. GRB 260411B: Fermi-LAT detection
  9. GRB 260412A: SVOM detection of a long burst
  10. GRB 260412A: Fermi GBM Final Real-time Localization
  11. GRB 260411B: COLIBRÍ optical observations
  12. GRB 260410B: Fermi GBM Observation
  13. GRB 260411B: Ondrejov D50 optical afterglow detection
  14. GRB 260411A: SVOM/GRM observation
  15. GRB 260407B: SVOM/GRM detection of a possible magnetar X-ray burst
  16. GRB 260411B: SVOM/GRM observation of a long burst
  17. GRB 260409A: Insight-HXMT/HE detection
  18. GRB 260411B: Fermi GBM Detection
  19. GRB 260411B: GOTO optical counterpart candidate
  20. GRB 260411B: BALROG localization (Fermi Trigger 797587480 / GRB 260411337)
  21. GRB 260411B: Fermi GBM Final Real-time Localization
  22. GRB 260411A: Fermi GBM Final Real-time Localization
  23. GRB 260410A: COLIBRÍ optical upper limit
  24. GRB 260410A: Fermi GBM Observation
  25. GRB 260410B: SVOM/GRM detection of a short faint burst
  26. GRB 260410B: Fermi GBM Final Real-time Localization
  27. GRB 260410A: Fermi-LAT detection
  28. GRB 260410A: Fermi GBM Final Real-time Localization
  29. EP260321a: Chandra X-ray Non-detection
  30. GRB 260409A: Fermi GBM Final Real-time Localization
  31. GRB 260310A/AT2026fgk: Kilonova-Catcher SN peak identification
  32. GRB 260407A: GECAM-A detection
  33. GRB 260407A: Insight-HXMT/HE detection
  34. GRB 260407A: CALET Gamma-Ray Burst Monitor detection
  35. GRB 260404A: Fermi GBM Final Localization
  36. GRB 260407A: Glowbug gamma-ray detection
  37. GRB 260402A: SVOM/ECLAIRs refined analysis
  38. GRB 260310A: Continued VLA Multi-frequency Radio Observations
  39. GRB 260310A / AT2026fgk: X-ray rebrightening
  40. EP260402a / GRB 260402A: Mephisto optical upper limits
  41. EP260402a/GRB 260402A: Xinglong optical upper limit
  42. GRID detection of GRB 260401A
  43. GRB 260407A: Fermi GBM Final Real-time Localization
  44. GRB 260403A: GECAM-B observation of a long burst
  45. Fermi Gamma-ray Burst Monitor trigger 796972356/260404217 is not a GRB
  46. GRB 260330B: SVOM/VT further optical observation
  47. Fermi Gamma-ray Burst Monitor trigger 796931884/260403749 is not a GRB
  48. GRB 260330B: SVOM/ECLAIRs refined analysis
  49. GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
  50. GRB 260330B: SVOM/VT optical candidate
  51. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  52. GRB 260403A: AstroSat CZTI detection
  53. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  54. GRB 260402B: GECAM-B observation
  55. EP260402a/GRB 260402A: Jinshan near-infrared upper limit
  56. GRB 260402C: NuSTAR detection of prompt emission
  57. GRB 260402C: AstroSat CZTI detection of a long burst
  58. GRB 260403A: Fermi GBM Final Real-time Localization
  59. GRB 260402B: Fermi GBM Final Real-time Localization
  60. GRB 260402A: WINTER J-band upper limit
  61. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  62. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  63. GRB 260401A: SVOM/GRM observation
  64. GRB 260401A: GECAM-B observation
  65. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  66. GRB 260402A: Kilonova-Catcher optical upper limit
  67. GRB 260402A: MASTER optical observations
  68. GRB 260402A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  69. GRB 260402A: SVOM/MXT candidate X-ray afterglow
  70. GRB 260402A: SVOM detection of a burst
  71. Fermi GRB 260401A: Global MASTER-Net observations report
  72. GRB 260401A: Fermi GBM Observation
  73. GRB 260401A: NuSTAR detection of prompt emission
  74. GRB 260401A: CALET Gamma-Ray Burst Monitor detection
  75. GRB 260401A: MAXI/GSC detection
  76. GRB 260401A: BALROG localization (Fermi Trigger 796733611 / GRB 260401454)
  77. GRB 260401A: Fermi GBM Final Real-time Localization
  78. EP260329b: Mondy and Assy-Turgen optical upper limits
  79. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  80. EP260329b: GOTO detection of optical counterpart
  81. GRB 260330B: SVOM/VT optical upper limits
  82. Konus-Wind detection of GRB 260320A
  83. Konus-Wind detection of GRB 260316B (duplicate submission)
  84. Konus-Wind detection of GRB 260316B
  85. GRB 260321A: SVOM/ECLAIRs refined analysis
  86. EP260329b: J-band upper limits with WINTER
  87. EP260329a: J-band upper limit with WINTER
  88. GRB 260330A: Glowbug gamma-ray detection
  89. GRB 260310A: VLA Multi-frequency Radio Observations
  90. Fermi GBM Sub-Threshold Detection of GRB 260330B
  91. GRB 260330B: LCO optical upper limits
  92. GRB 260330B: SVOM detection of a burst
  93. GRB 260330A: Fermi GBM Final Real-time Localization
  94. GRB 260327A: Insight-HXMT/HE detection
  95. GRB 260326A: Insight-HXMT/HE detection
  96. GRID detection of GRB 260326A
  97. GRB 260310A: Gemini-North Spectral Confirmation of Supernova Features
  98. SMA Detection of GRB 260310A / AT 2026fgk
  99. GRB 260307B: ATCA Radio Upper Limits
  100. GRB 260327A: AstroSat CZTI detection of a long burst

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