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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"

32510 results found.

  1. Fermi GRB 260417A: Global MASTER-Net observations report
  2. Konus-Wind detection of GRB 260411B
  3. GRB 260417A: AstroSat CZTI detection
  4. IPN triangulation of GRB 260411B
  5. EP260416a: LCO observations confirm end of flaring phase
  6. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  7. EP260417a: TRT optical counterpart detection
  8. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  9. EP-WXT trigger 01709259586: KAIT optical observations
  10. EP260416a: KAIT optical upper limit
  11. GRB 260414A: Insight-HXMT/HE detection
  12. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  13. EP260416a: WFST optical observations and rebrightening
  14. GOTO26djh/AT2026jpw: ZTSh R,I bands observations of the transient
  15. EP260416a: SVOM/VT optical observation
  16. GOTO26djh/AT2026jpw: SVOM/VT optical observation
  17. GRB 260415B: Glowbug gamma-ray detection
  18. GRB 260411B: Glowbug gamma-ray detection
  19. GRB 260415A: Insight-HXMT/HE detection
  20. EP260416a: COLIBRÍ optical counterpart candidate
  21. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
  22. EP260416a: Global MASTER-Net observations report
  23. GOTO26djh/AT2026jpw : MASTER OT observation
  24. GOTO26djh/AT2026jpw: EP-FXT X-ray counterpart detection
  25. GOTO26djh/AT2026jpw transient: SAO RAS optical observations
  26. NOT r-band observations of the transient GOTO26djh/AT2026jpw
  27. GRB 260415B: NuSTAR detection of long prompt emission
  28. GRB 260414A: Glowbug gamma-ray detection
  29. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  30. EP260321a: CMO SAI J,K observations
  31. GRB 260412A: Insight-HXMT/HE detection
  32. Fermi GRB 260413A: Global MASTER-Net observations report
  33. GRB 260410A: Glowbug gamma-ray detection of a short burst
  34. GRB 260410B: Insight-HXMT/HE detection
  35. GRB 260410A: Insight-HXMT/HE detection
  36. Konus-Wind detection of GRB 260410A (short/hard)
  37. GRB 260411B: GECAM-B observation of a long burst
  38. EP260321a: SVOM/VT optical observations and color changes around peak
  39. GRB 260410A: CALET Gamma-Ray Burst Monitor detection
  40. GRB 260412A: GECAM-B observation of a long burst
  41. Fermi GRB 260412A: Global MASTER-Net observations report
  42. GRB 260412A: Fermi GBM Observation
  43. GRB 260310A / AT2026fgk: NuSTAR detection of the rebrightening
  44. GRB 260411B: Fermi-LAT detection
  45. GRB 260412A: SVOM detection of a long burst
  46. GRB 260411B: COLIBRÍ optical observations
  47. GRB 260410B: Fermi GBM Observation
  48. GRB 260411B: Ondrejov D50 optical afterglow detection
  49. GRB260411B: 3.6m DOT optical observation
  50. GRB 260411A: SVOM/GRM observation
  51. GRB 260411B: SVOM/GRM observation of a long burst
  52. GRB 260409A: Insight-HXMT/HE detection
  53. GRB 260411B: Fermi GBM Detection
  54. GRB 260411B: GOTO optical counterpart candidate
  55. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  56. GRB 260410A: COLIBRÍ optical upper limit
  57. EP-WXT01709259790: Optical Upper limits with kinder observations
  58. GRB 260410A: Fermi GBM Observation
  59. GRB 260410B: SVOM/GRM detection of a short faint burst
  60. GRB 260410A: Fermi-LAT detection
  61. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  62. EP260321a: Chandra X-ray Non-detection
  63. GRB 260310A/AT2026fgk: Kilonova-Catcher SN peak identification
  64. GRB 260407A: GECAM-A detection
  65. GRB 260407A: Insight-HXMT/HE detection
  66. EP260409a: SVOM/VT optical upper limits
  67. EP260409a: COLIBRÍ optical upper limits
  68. GRB 260407A: CALET Gamma-Ray Burst Monitor detection
  69. EP260409a: Global MASTER-Net observations report
  70. EP260321a: VLA radio detection
  71. GRB 260407A: Glowbug gamma-ray detection
  72. GRB 260402A: SVOM/ECLAIRs refined analysis
  73. GRB 260310A: Continued VLA Multi-frequency Radio Observations
  74. GRB 260310A / AT2026fgk: X-ray rebrightening
  75. EP260402a / GRB 260402A: Mephisto optical upper limits
  76. EP-WXT01709259586: Xinglong optical upper limit
  77. EP260403a: Mephisto optical upper limits
  78. EP260402a/GRB 260402A: Xinglong optical upper limit
  79. EP260321a: Upper limits from VLA radio observations
  80. GRID detection of GRB 260401A
  81. EP260321a: uGMRT observations
  82. EP260405a: GMOS-N optical upper limits
  83. EP260405a: SVOM/VT optical upper limits
  84. EP260405a: Global MASTER-Net observations report
  85. EP260405a: Einstein Probe detection of a fast X-ray transient
  86. GRB 260403A: GECAM-B observation of a long burst
  87. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  88. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  89. GRB 260330B: SVOM/VT further optical observation
  90. GRB 260330B: SVOM/ECLAIRs refined analysis
  91. EP260403a: LCO optical observations of the counterpart
  92. GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
  93. EP260403a: LCO optical counterpart detection
  94. EP260403a: COLIBRÍ optical counterpart candidate
  95. GRB 260330B: SVOM/VT optical candidate
  96. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  97. GRB 260403A: AstroSat CZTI detection
  98. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  99. GRB 260402B: GECAM-B observation
  100. EP260402a/GRB 260402A: Jinshan near-infrared upper limit

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