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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').
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"

21214 results found.

  1. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection
  2. GRB 260515A: SVOM/VT optical candidate from VHF data
  3. GRB 260515A: JinShan optical counterpart candidate
  4. GRB 260515A: SVOM detection of a burst
  5. EP260514a: GROWTH-India Telescope optical upper limit
  6. Konus-Wind detection of GRB 260512A
  7. GRB 260511B: GMG Optical Upper Limit
  8. EP260514a: Einstein Probe detection of a fast X-ray transient
  9. EP260512a: LCO optical upper limits
  10. GRB 260511B: Mephisto multi-band optical followup
  11. GRB 260512A: AstroSat CZTI detection
  12. EP260512a: EP-FXT follow-up observation
  13. EP260507a: Xinglong Schmidt optical counterpart detection
  14. GRB 260511B: further SAO RAS optical observations
  15. Konus-Wind detection of GRB 260511B
  16. EP260512a: COLIBRÍ optical upper limits
  17. EP260512a: Einstein Probe detection of an X-ray transient
  18. GRB 260511B: further J-band observations by the SYSU 80 cm infrared telescope
  19. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  20. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  21. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  22. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  23. Konus-Wind detection of GRB 260511A
  24. GRB 260511B: SAO RAS optical observations
  25. GRB 260511B: FRAM-ORM optical detection
  26. GRB 260511B: LCO optical counterpart detection
  27. GRB260511B: MAO/AZT-22 optical observations
  28. GRB 260511B: LCO optical observations
  29. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  30. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  31. GRB 260509A: SAO RAS optical observations
  32. GRB 260511A: REM near-infrared detection
  33. GRB 260511B: GROWTH-India Telescope optical observations
  34. GRB 260511B: AstroSat CZTI detection
  35. GRB 260511B: J-band observations by the SYSU 80 cm infrared telescope
  36. GRB 260511B: SVOM/VT optical observation with VHF data
  37. GRB 260511B: TRT optical observation
  38. GRB 260510B: SVOM/ECLAIRs refined analysis
  39. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  40. GRB 260511B SVOM/C-GFT optical counterpart detection
  41. EP260509a: LCO optical upper limits
  42. GRB 260511A: UTGO H50 optical afterglow observation
  43. GRB 260510C: AstroSat CZTI detection
  44. GRB 260511B: SVOM detection of a burst
  45. EP260509a: EP-FXT non-detection and upper limit
  46. GRB 260511A: SVOM/VT optical observation with VHF data
  47. GRB 260511A: KAIT optical afterglow observations
  48. GRB 260511A: LCO optical afterglow detection
  49. GRB 260511A: SVOM/COLIBRÍ (FM-GFT) optical counterpart
  50. GRB 260511A: TRT optical counterpart detection
  51. GRB 260511A: SVOM detection of a bright burst
  52. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  53. GRB 260510B: GOTO early upper limit
  54. GRB 260510C: SVOM detection of a burst
  55. GRB 260510A: GECAM-B observation
  56. GRB 260510B: LCO optical upper limits
  57. EP260509a: Einstein Probe detection of an X-ray transient
  58. GRB 260509A: Liverpool Telescope optical observations
  59. GRB 260510B: SVOM detection of a burst
  60. GRB 260509A: LCO optical observations
  61. SVOM GRB 260509A: MASTER-OAFA optical observation
  62. GRB 260509A: KAIT optical observations
  63. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  64. GRB 260509A: SVOM/VT optical candidate with VHF data
  65. GRB 260509A: LCO optical counterpart detection
  66. GRB 260509A: GOTO optical counterpart candidate
  67. GRB 260509A: SVOM detection of a burst
  68. EP260507a: REM optical/NIR observations
  69. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  70. EP260507a: COLIBRÍ optical observations
  71. EP260507a: NOT optical observations
  72. EP260507a: further Liverpool Telescope observations
  73. EP260507a: Liverpool Telescope optical upper limits
  74. EP260507a: TRT optical counterpart detection
  75. EP260507a: Kinder optical counterpart candidate
  76. EP260507a: LCO optical counterpart
  77. EP260507a: Einstein Probe detection of an X-ray transient
  78. GRB 260504B: SVOM/ECLAIRs refined analysis
  79. EP260502a is likely a flaring star
  80. GRB 260504B: SVOM/VT optical upper limits
  81. GRB 260421B: radio observation with the VLA
  82. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  83. Konus-Wind detection of GRB 260504B (short/hard)
  84. GRB 260504B: SVOM/MXT refined analysis and potential detection
  85. GRB 260504B: EP-FXT upper limit
  86. GRB 260502A: SVOM/GRM observation of a short GRB
  87. GRB 260503A: SVOM/GRM observation of a GRB
  88. Konus-Wind detection of GRB 260411C
  89. GRB 260504B: REM optical/NIR observations
  90. GRB 260504B: LCO z-band upper limit
  91. SVOM GRB 260504B: MASTER-OAFA optical observations
  92. GRB 260504B: SVOM detection of a short burst
  93. Fermi GRB 260504A: Global MASTER-Net observations report
  94. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  95. EP260502a: Einstein Probe detection of an X-ray transient
  96. GRB 260429A: SVOM/GRM observation of a short burst
  97. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  98. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  99. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  100. EP260429a: LCO optical upper limits

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