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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"

26499 results found.

  1. GRB 260411B: Glowbug gamma-ray detection
  2. GRB 260415A: Insight-HXMT/HE detection
  3. EP260416a: COLIBRÍ optical counterpart candidate
  4. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
  5. EP260416a: Einstein Probe detection of an X-ray transient
  6. GOTO26djh/AT2026jpw : MASTER OT observation
  7. GOTO26djh/AT2026jpw: EP-FXT X-ray counterpart detection
  8. GOTO26djh/AT2026jpw transient: SAO RAS optical observations
  9. NOT r-band observations of the transient GOTO26djh/AT2026jpw
  10. GOTO discovery of fast-fading transient GOTO26djh/AT2026jpw, a candidate orphan afterglow
  11. GRB 260414A: Glowbug gamma-ray detection
  12. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  13. EP260321a: CMO SAI J,K observations
  14. The EP-WXT trigger 01709260122 is likely a flaring star
  15. GRB 260410A: Glowbug gamma-ray detection of a short burst
  16. The EP-WXT trigger 01709260010 is likely a flaring star
  17. GRB 260412A: Fermi GBM Observation
  18. GRB 260310A / AT2026fgk: NuSTAR detection of the rebrightening
  19. GRB 260411B: Fermi-LAT detection
  20. GRB 260412A: SVOM detection of a long burst
  21. GRB 260411B: COLIBRÍ optical observations
  22. GRB 260410B: Fermi GBM Observation
  23. GRB260411B: 3.6m DOT optical observation
  24. GRB 260411A: SVOM/GRM observation
  25. GRB 260411B: SVOM/GRM observation of a long burst
  26. GRB 260411B: Fermi GBM Detection
  27. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  28. GRB 260411B: BALROG localization (Fermi Trigger 797587480 / GRB 260411337)
  29. GRB 260410A: COLIBRÍ optical upper limit
  30. EP-WXT01709259790: Optical Upper limits with kinder observations
  31. GRB 260410A: Fermi GBM Observation
  32. The EP-WXT trigger 01709259790 is likely a flaring star
  33. EP-WXT01709259790: Xinglong optical upper limit
  34. GRB 260410A: Fermi-LAT detection
  35. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  36. GRB 260310A/AT2026fgk: Kilonova-Catcher SN peak identification
  37. The EP-WXT trigger 01709259773 is likely a flaring star
  38. EP260409a: COLIBRÍ optical upper limits
  39. EP260409a: Einstein Probe detection of an X-ray transient
  40. EP260321a: VLA radio detection
  41. GRB 260407A: Glowbug gamma-ray detection
  42. GRB 260402A: SVOM/ECLAIRs refined analysis
  43. EP260402a / GRB 260402A: Mephisto optical upper limits
  44. EP-WXT01709259586: Xinglong optical upper limit
  45. EP260403a: Mephisto optical upper limits
  46. EP260402a/GRB 260402A: Xinglong optical upper limit
  47. EP260321a: uGMRT observations
  48. EP260405a: GMOS-N optical upper limits
  49. EP260405a: Einstein Probe detection of a fast X-ray transient
  50. The EP-WXT trigger 01709259621 is likely a flaring star
  51. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  52. The EP-WXT trigger 01709259615 is likely a flaring star
  53. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  54. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  55. The EP-WXT trigger 01709259586 is likely a flaring star
  56. GRB 260330B: SVOM/VT further optical observation
  57. GRB 260330B: SVOM/ECLAIRs refined analysis
  58. EP260403a: LCO optical observations of the counterpart
  59. GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
  60. EP260403a: LCO optical counterpart detection
  61. EP260403a: COLIBRÍ optical counterpart candidate
  62. GRB 260330B: SVOM/VT optical candidate
  63. EP260403a: Einstein Probe detection of an X-ray transient
  64. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  65. GRB 260403A: AstroSat CZTI detection
  66. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  67. EP260402a/GRB 260402A: Jinshan near-infrared upper limit
  68. GRB 260402C: AstroSat CZTI detection of a long burst
  69. EP260324A / AT 2026hir: COLIBRÍ optical observations
  70. GRB 260402B: Fermi GBM Final Real-time Localization
  71. GRB 260402A: WINTER J-band upper limit
  72. GRB260402A: GROWTH-India Telescope optical upper limit
  73. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  74. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  75. GRB 260401A: SVOM/GRM observation
  76. GRB 260401A: GECAM-B observation
  77. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  78. GRB 260402A: Kilonova-Catcher optical upper limit
  79. GRB 260402A: MASTER optical observations
  80. GRB 260402A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  81. GRB 260402A: SVOM/MXT candidate X-ray afterglow
  82. GRB 260402A: SVOM detection of a burst
  83. GRB 260401A: Fermi GBM Observation
  84. EP260329b: Mondy and Assy-Turgen optical upper limits
  85. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  86. EP260321a :Xinglong optical observations
  87. EP260327a: Xinglong optical upper limit
  88. GRB 260330B: SVOM/VT optical upper limits
  89. Konus-Wind detection of GRB 260320A
  90. GRB 260321A: SVOM/ECLAIRs refined analysis
  91. EP260329b: J-band upper limits with WINTER
  92. EP260329a: J-band upper limit with WINTER
  93. GRB 260330A: Glowbug gamma-ray detection
  94. GRB 260310A: VLA Multi-frequency Radio Observations
  95. GRB 260330B: LCO optical upper limits
  96. GRB 260330B: SVOM detection of a burst
  97. EP260324a / AT2026hir: g- and r-band optical follow-up with the PKU 60cm Telescope
  98. EP260329b: refined analysis of the EP-WXT and EP-FXT observations
  99. EP260329a: COLIBRÍ optical upper limit
  100. EP260329a: EP-FXT follow up observation

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