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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"

26504 results found.

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

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