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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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').
Advanced Search

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"

26517 results found.

  1. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  2. GRB 260403A: GECAM-B observation of a long burst
  3. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  4. GRB 260330B: SVOM/VT further optical observation
  5. GRB 260330B: SVOM/ECLAIRs refined analysis
  6. EP260403a: LCO optical observations of the counterpart
  7. GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
  8. EP260403a: LCO optical counterpart detection
  9. EP260403a: COLIBRÍ optical counterpart candidate
  10. GRB 260330B: SVOM/VT optical candidate
  11. EP260403a: Einstein Probe detection of an X-ray transient
  12. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  13. GRB 260403A: AstroSat CZTI detection
  14. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  15. GRB 260402B: GECAM-B observation
  16. EP260402a/GRB 260402A: Jinshan near-infrared upper limit
  17. GRB 260402C: NuSTAR detection of prompt emission
  18. GRB 260402C: AstroSat CZTI detection of a long burst
  19. EP260324A / AT 2026hir: COLIBRÍ optical observations
  20. EP260324A / AT 2026hir: Spectroscopic Observations with the Next Generation Palomar Spectrograph
  21. GRB 260402A: WINTER J-band upper limit
  22. GRB260402A: GROWTH-India Telescope optical upper limit
  23. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  24. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  25. GRB 260401A: SVOM/GRM observation
  26. GRB 260401A: GECAM-B observation
  27. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  28. GRB 260402A: Kilonova-Catcher optical upper limit
  29. GRB 260402A: MASTER optical observations
  30. GRB 260402A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  31. GRB 260402A: SVOM/MXT candidate X-ray afterglow
  32. GRB 260402A: SVOM detection of a burst
  33. GRB 260401A: Fermi GBM Observation
  34. GRB 260401A: NuSTAR detection of prompt emission
  35. GRB 260401A: CALET Gamma-Ray Burst Monitor detection
  36. GRB 260401A: MAXI/GSC detection
  37. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  38. EP260327a: Xinglong optical upper limit
  39. EP260329b: GOTO detection of optical counterpart
  40. GRB 260330B: SVOM/VT optical upper limits
  41. Konus-Wind detection of GRB 260320A
  42. Konus-Wind detection of GRB 260316B
  43. GRB 260321A: SVOM/ECLAIRs refined analysis
  44. EP260329b: J-band upper limits with WINTER
  45. EP260329a: J-band upper limit with WINTER
  46. GRB 260330A: Glowbug gamma-ray detection
  47. Fermi GBM Sub-Threshold Detection of GRB 260330B
  48. GRB 260330B: LCO optical upper limits
  49. GRB 260330B: SVOM detection of a burst
  50. EP260324a / AT2026hir: g- and r-band optical follow-up with the PKU 60cm Telescope
  51. EP260329b: refined analysis of the EP-WXT and EP-FXT observations
  52. EP260329a: COLIBRÍ optical upper limit
  53. EP260329a: EP-FXT follow up observation
  54. EP260329a: NOT optical counterpart candidate
  55. GRB 260327A: Insight-HXMT/HE detection
  56. EP260329b: Optical follow-up with Kinder observations
  57. EP 260329b: COLIBRÍ optical observations
  58. EP260329b: LCO optical observations of the counterpart
  59. GRB 260326A: Insight-HXMT/HE detection
  60. EP260329b: Einstein Probe detection of an X-ray transient
  61. EP260329a: Einstein Probe detection of an X-ray transient
  62. EP-WXT trigger 01709259209: TRT optical counterpart detection
  63. GRID detection of GRB 260326A
  64. EP260327a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  65. EP260327a: SVOM/VT optical upper limits
  66. GRB 260307B: ATCA Radio Upper Limits
  67. EP260327a: WINTER J-band upper limit
  68. EP260327a: COLIBRÍ optical upper limits
  69. GRB 260327A: AstroSat CZTI detection of a long burst
  70. EP260324a: GROWTH-India Telescope optical observation
  71. EP260327a: Einstein Probe detection of an X-ray transient
  72. GRB 260310A / AT 2026fgk: COLIBRÍ photometric evidence of the emerging supernova
  73. GRB 260310A / AT2026fgk: Late-time infrared detection with MIRAGE on the MDM 1.3m telescope
  74. IPN triangulation of GRB 260320A
  75. EP260324a: ZTF discovery of the optical counterpart ZTF26aapviim/AT2026hir
  76. GRB 260310A / AT2026fgk: R- and I-band observations with the PKU 60 cm optical telescope
  77. GRB 260326A: Fermi GBM Detection
  78. EP260321a: Upper limits from a neutrino search with IceCube
  79. GRB 260310A/AT2026fgk: Kilonova-Catcher late optical afterglow detection at about 15 days post trigger time
  80. IPN triangulation of GRB 260316B
  81. EP260321a: J-band observations by the SYSU 80 cm infrared telescope
  82. GRID detection of GRB 260320A
  83. EP260321a: Gemini-South confirmation of a supernova
  84. EP260321a: VLT/FORS2 spectroscopy confirmation of an associated type Ic-BL supernova SN 2026gzf
  85. GRB 260310A: LBT optical observations
  86. EP260321A: Mondy optical observations
  87. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limits at the FXT positions
  88. EP-WXT trigger 01709259112: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  89. GRB 260316B: CALET Gamma-Ray Burst Monitor detection
  90. GRB260310A: Palomar 60-inch photometry of an extremely bright late-time afterglow with a temporal break at 8 days
  91. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  92. GRB 260320A: Glowbug gamma-ray detection
  93. EP260321a: COLIBRÍ further optical observations and brightening
  94. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  95. EP260214b: ATCA 6 GHz detection
  96. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  97. GRB 260321A: EP-FXT follow-up observation
  98. EP260321a: ZTF and Rubin detections of the candidate optical counterpart to EP260321a
  99. EP260321a: GOTO detection of blue variable source
  100. EP260321a: VLT imaging and spectroscopy show the variable source to be at z = 0.0343

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