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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"

32513 results found.

  1. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  2. EP260416a: NOT tentative spectroscopic redshift of z =1.909
  3. EP260416a: GMG Optical Observation
  4. Fermi GRB 260417A: Global MASTER-Net observations report
  5. Konus-Wind detection of GRB 260411B
  6. GRB 260417A: AstroSat CZTI detection
  7. IPN triangulation of GRB 260411B
  8. EP260416a: LCO observations confirm end of flaring phase
  9. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  10. EP260417a: TRT optical counterpart detection
  11. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  12. EP-WXT trigger 01709259586: KAIT optical observations
  13. EP260416a: KAIT optical upper limit
  14. GRB 260414A: Insight-HXMT/HE detection
  15. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  16. EP260416a: WFST optical observations and rebrightening
  17. GOTO26djh/AT2026jpw: ZTSh R,I bands observations of the transient
  18. EP260416a: SVOM/VT optical observation
  19. GOTO26djh/AT2026jpw: SVOM/VT optical observation
  20. GRB 260415B: Glowbug gamma-ray detection
  21. GRB 260411B: Glowbug gamma-ray detection
  22. GRB 260415A: Insight-HXMT/HE detection
  23. EP260416a: COLIBRÍ optical counterpart candidate
  24. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
  25. EP260416a: Global MASTER-Net observations report
  26. GOTO26djh/AT2026jpw : MASTER OT observation
  27. GOTO26djh/AT2026jpw: EP-FXT X-ray counterpart detection
  28. GOTO26djh/AT2026jpw transient: SAO RAS optical observations
  29. NOT r-band observations of the transient GOTO26djh/AT2026jpw
  30. GRB 260415B: NuSTAR detection of long prompt emission
  31. GRB 260414A: Glowbug gamma-ray detection
  32. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  33. EP260321a: CMO SAI J,K observations
  34. GRB 260412A: Insight-HXMT/HE detection
  35. Fermi GRB 260413A: Global MASTER-Net observations report
  36. GRB 260410A: Glowbug gamma-ray detection of a short burst
  37. GRB 260410B: Insight-HXMT/HE detection
  38. GRB 260410A: Insight-HXMT/HE detection
  39. Konus-Wind detection of GRB 260410A (short/hard)
  40. GRB 260411B: GECAM-B observation of a long burst
  41. EP260321a: SVOM/VT optical observations and color changes around peak
  42. GRB 260410A: CALET Gamma-Ray Burst Monitor detection
  43. GRB 260412A: GECAM-B observation of a long burst
  44. Fermi GRB 260412A: Global MASTER-Net observations report
  45. GRB 260412A: Fermi GBM Observation
  46. GRB 260310A / AT2026fgk: NuSTAR detection of the rebrightening
  47. GRB 260411B: Fermi-LAT detection
  48. GRB 260412A: SVOM detection of a long burst
  49. GRB 260411B: COLIBRÍ optical observations
  50. GRB 260410B: Fermi GBM Observation
  51. GRB 260411B: Ondrejov D50 optical afterglow detection
  52. GRB260411B: 3.6m DOT optical observation
  53. GRB 260411A: SVOM/GRM observation
  54. GRB 260411B: SVOM/GRM observation of a long burst
  55. GRB 260409A: Insight-HXMT/HE detection
  56. GRB 260411B: Fermi GBM Detection
  57. GRB 260411B: GOTO optical counterpart candidate
  58. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  59. GRB 260410A: COLIBRÍ optical upper limit
  60. EP-WXT01709259790: Optical Upper limits with kinder observations
  61. GRB 260410A: Fermi GBM Observation
  62. GRB 260410B: SVOM/GRM detection of a short faint burst
  63. GRB 260410A: Fermi-LAT detection
  64. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  65. EP260321a: Chandra X-ray Non-detection
  66. GRB 260310A/AT2026fgk: Kilonova-Catcher SN peak identification
  67. GRB 260407A: GECAM-A detection
  68. GRB 260407A: Insight-HXMT/HE detection
  69. EP260409a: SVOM/VT optical upper limits
  70. EP260409a: COLIBRÍ optical upper limits
  71. GRB 260407A: CALET Gamma-Ray Burst Monitor detection
  72. EP260409a: Global MASTER-Net observations report
  73. EP260321a: VLA radio detection
  74. GRB 260407A: Glowbug gamma-ray detection
  75. GRB 260402A: SVOM/ECLAIRs refined analysis
  76. GRB 260310A: Continued VLA Multi-frequency Radio Observations
  77. GRB 260310A / AT2026fgk: X-ray rebrightening
  78. EP260402a / GRB 260402A: Mephisto optical upper limits
  79. EP-WXT01709259586: Xinglong optical upper limit
  80. EP260403a: Mephisto optical upper limits
  81. EP260402a/GRB 260402A: Xinglong optical upper limit
  82. EP260321a: Upper limits from VLA radio observations
  83. GRID detection of GRB 260401A
  84. EP260321a: uGMRT observations
  85. EP260405a: GMOS-N optical upper limits
  86. EP260405a: SVOM/VT optical upper limits
  87. EP260405a: Global MASTER-Net observations report
  88. EP260405a: Einstein Probe detection of a fast X-ray transient
  89. GRB 260403A: GECAM-B observation of a long burst
  90. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  91. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  92. GRB 260330B: SVOM/VT further optical observation
  93. GRB 260330B: SVOM/ECLAIRs refined analysis
  94. EP260403a: LCO optical observations of the counterpart
  95. GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
  96. EP260403a: LCO optical counterpart detection
  97. EP260403a: COLIBRÍ optical counterpart candidate
  98. GRB 260330B: SVOM/VT optical candidate
  99. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  100. GRB 260403A: AstroSat CZTI detection

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