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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"

15252 results found.

  1. GRB 260421B: SVOM detection of a long burst
  2. EP260416a: Optical follow-up observations with Kinder
  3. GRB 260417A: SVOM/GRM observation
  4. EP260417a: GROWTH-India Telescope optical upper limit
  5. EP260417b: GROWTH-India Telescope optical upper limit
  6. EP260416a: VLT/FORS2 spectroscopic redshift confirmation
  7. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  8. Konus-Wind detection of GRB 260411B
  9. GRB 260417A: AstroSat CZTI detection
  10. IPN triangulation of GRB 260411B
  11. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  12. EP260416a: KAIT optical upper limit
  13. GRB 260414A: Insight-HXMT/HE detection
  14. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  15. EP260416a: WFST optical observations and rebrightening
  16. EP260416a: SVOM/VT optical observation
  17. GRB 260411B: Glowbug gamma-ray detection
  18. GRB 260415A: Insight-HXMT/HE detection
  19. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
  20. GOTO26djh/AT2026jpw: EP-FXT X-ray counterpart detection
  21. GOTO discovery of fast-fading transient GOTO26djh/AT2026jpw, a candidate orphan afterglow
  22. GRB 260414A: Glowbug gamma-ray detection
  23. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  24. EP260321a: CMO SAI J,K observations
  25. GRB 260412A: Insight-HXMT/HE detection
  26. GRB 260410B: Insight-HXMT/HE detection
  27. GRB 260410A: Insight-HXMT/HE detection
  28. Konus-Wind detection of GRB 260410A (short/hard)
  29. GRB 260411B: GECAM-B observation of a long burst
  30. GRB 260412A: GECAM-B observation of a long burst
  31. GRB 260412A: Fermi GBM Observation
  32. GRB 260310A / AT2026fgk: NuSTAR detection of the rebrightening
  33. GRB 260411B: Fermi-LAT detection
  34. GRB 260412A: SVOM detection of a long burst
  35. GRB 260411B: COLIBRÍ optical observations
  36. GRB 260410B: Fermi GBM Observation
  37. GRB 260411A: SVOM/GRM observation
  38. GRB 260407B: SVOM/GRM detection of a possible magnetar X-ray burst
  39. GRB 260411B: SVOM/GRM observation of a long burst
  40. GRB 260409A: Insight-HXMT/HE detection
  41. GRB 260411B: Fermi GBM Detection
  42. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  43. EP-WXT01709259790: Optical Upper limits with kinder observations
  44. GRB 260410A: Fermi GBM Observation
  45. GRB 260410B: SVOM/GRM detection of a short faint burst
  46. GRB 260410A: Fermi-LAT detection
  47. GRB 260407A: GECAM-A detection
  48. GRB 260407A: Insight-HXMT/HE detection
  49. GRB 260402A: SVOM/ECLAIRs refined analysis
  50. GRB 260310A / AT2026fgk: X-ray rebrightening
  51. EP260402a / GRB 260402A: Mephisto optical upper limits
  52. EP260403a: Mephisto optical upper limits
  53. GRID detection of GRB 260401A
  54. GRB 260403A: GECAM-B observation of a long burst
  55. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  56. GRB 260330B: SVOM/ECLAIRs refined analysis
  57. EP260403a: LCO optical observations of the counterpart
  58. GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
  59. EP260403a: LCO optical counterpart detection
  60. GRB 260403A: AstroSat CZTI detection
  61. GRB 260402B: GECAM-B observation
  62. EP260402a/GRB 260402A: Jinshan near-infrared upper limit
  63. GRB 260402C: AstroSat CZTI detection of a long burst
  64. EP260324A / AT 2026hir: COLIBRÍ optical observations
  65. GRB 260402A: WINTER J-band upper limit
  66. GRB260402A: GROWTH-India Telescope optical upper limit
  67. GRB 260401A: SVOM/GRM observation
  68. GRB 260401A: GECAM-B observation
  69. GRB 260402A: SVOM/MXT candidate X-ray afterglow
  70. GRB 260402A: SVOM detection of a burst
  71. GRB 260401A: Fermi GBM Observation
  72. EP260329b: Mondy and Assy-Turgen optical upper limits
  73. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  74. EP260329b: GOTO detection of optical counterpart
  75. Konus-Wind detection of GRB 260320A
  76. Konus-Wind detection of GRB 260316B
  77. GRB 260321A: SVOM/ECLAIRs refined analysis
  78. GRB 260310A: VLA Multi-frequency Radio Observations
  79. GRB 260330B: SVOM detection of a burst
  80. EP260324a / AT2026hir: g- and r-band optical follow-up with the PKU 60cm Telescope
  81. EP260329a: COLIBRÍ optical upper limit
  82. EP260329a: EP-FXT follow up observation
  83. GRB 260327A: Insight-HXMT/HE detection
  84. EP260329b: Optical follow-up with Kinder observations
  85. EP 260329b: COLIBRÍ optical observations
  86. EP260329a: Optical upper limit with Kinder observations
  87. EP260329b: LCO optical observations of the counterpart
  88. GRB 260326A: Insight-HXMT/HE detection
  89. EP260329b: Einstein Probe detection of an X-ray transient
  90. EP-WXT trigger 01709259209: TRT optical counterpart detection
  91. GRID detection of GRB 260326A
  92. EP260327a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  93. GRB 260327A: AstroSat CZTI detection of a long burst
  94. EP260324a: GROWTH-India Telescope optical observation
  95. GRB 260310A / AT 2026fgk: COLIBRÍ photometric evidence of the emerging supernova
  96. GRB 260310A: OSIRIS+/GTC spectroscopic detection of the associated BL-Ic, SN 2026fgk
  97. EP260324a: ZTF discovery of the optical counterpart ZTF26aapviim/AT2026hir
  98. GRB 260310A / AT2026fgk: R- and I-band observations with the PKU 60 cm optical telescope
  99. GRB 260326A: Fermi GBM Detection
  100. EP260321a: Upper limits from a neutrino search with IceCube

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