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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"

32508 results found.

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

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