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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"

21205 results found.

  1. GRB 260511B: Mephisto multi-band optical followup
  2. GRB 260512A: AstroSat CZTI detection
  3. EP260512a: EP-FXT follow-up observation
  4. EP260507a: Xinglong Schmidt optical counterpart detection
  5. GRB 260511B: further SAO RAS optical observations
  6. Konus-Wind detection of GRB 260511B
  7. EP260512a: COLIBRÍ optical upper limits
  8. EP260512a: Einstein Probe detection of an X-ray transient
  9. GRB 260511B: further J-band observations by the SYSU 80 cm infrared telescope
  10. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  11. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  12. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  13. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  14. Konus-Wind detection of GRB 260511A
  15. GRB 260511B: SAO RAS optical observations
  16. GRB 260511B: FRAM-ORM optical detection
  17. GRB 260511B: LCO optical counterpart detection
  18. GRB260511B: MAO/AZT-22 optical observations
  19. GRB 260511B: LCO optical observations
  20. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  21. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  22. GRB 260509A: SAO RAS optical observations
  23. GRB 260511A: REM near-infrared detection
  24. GRB 260511B: GROWTH-India Telescope optical observations
  25. GRB 260511B: AstroSat CZTI detection
  26. GRB 260511B: J-band observations by the SYSU 80 cm infrared telescope
  27. GRB 260511B: SVOM/VT optical observation with VHF data
  28. GRB 260511B: TRT optical observation
  29. GRB 260510B: SVOM/ECLAIRs refined analysis
  30. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  31. GRB 260511B SVOM/C-GFT optical counterpart detection
  32. EP260509a: LCO optical upper limits
  33. GRB 260511A: UTGO H50 optical afterglow observation
  34. GRB 260510C: AstroSat CZTI detection
  35. GRB 260511B: SVOM detection of a burst
  36. EP260509a: EP-FXT non-detection and upper limit
  37. GRB 260511A: SVOM/VT optical observation with VHF data
  38. GRB 260511A: KAIT optical afterglow observations
  39. GRB 260511A: LCO optical afterglow detection
  40. GRB 260511A: SVOM/COLIBRÍ (FM-GFT) optical counterpart
  41. GRB 260511A: TRT optical counterpart detection
  42. GRB 260511A: SVOM detection of a bright burst
  43. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  44. GRB 260510B: GOTO early upper limit
  45. GRB 260510C: SVOM detection of a burst
  46. GRB 260510A: GECAM-B observation
  47. GRB 260510B: LCO optical upper limits
  48. EP260509a: Einstein Probe detection of an X-ray transient
  49. GRB 260509A: Liverpool Telescope optical observations
  50. GRB 260510B: SVOM detection of a burst
  51. GRB 260509A: LCO optical observations
  52. SVOM GRB 260509A: MASTER-OAFA optical observation
  53. GRB 260509A: KAIT optical observations
  54. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  55. GRB 260509A: SVOM/VT optical candidate with VHF data
  56. GRB 260509A: LCO optical counterpart detection
  57. GRB 260509A: GOTO optical counterpart candidate
  58. GRB 260509A: SVOM detection of a burst
  59. EP260507a: REM optical/NIR observations
  60. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  61. EP260507a: COLIBRÍ optical observations
  62. EP260507a: NOT optical observations
  63. EP260507a: further Liverpool Telescope observations
  64. EP260507a: Liverpool Telescope optical upper limits
  65. EP260507a: TRT optical counterpart detection
  66. EP260507a: Kinder optical counterpart candidate
  67. EP260507a: LCO optical counterpart
  68. EP260507a: Einstein Probe detection of an X-ray transient
  69. GRB 260504B: SVOM/ECLAIRs refined analysis
  70. EP260502a is likely a flaring star
  71. GRB 260504B: SVOM/VT optical upper limits
  72. GRB 260421B: radio observation with the VLA
  73. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  74. Konus-Wind detection of GRB 260504B (short/hard)
  75. GRB 260504B: SVOM/MXT refined analysis and potential detection
  76. GRB 260504B: EP-FXT upper limit
  77. GRB 260502A: SVOM/GRM observation of a short GRB
  78. GRB 260503A: SVOM/GRM observation of a GRB
  79. Konus-Wind detection of GRB 260411C
  80. GRB 260504B: REM optical/NIR observations
  81. GRB 260504B: LCO z-band upper limit
  82. SVOM GRB 260504B: MASTER-OAFA optical observations
  83. GRB 260504B: SVOM detection of a short burst
  84. Fermi GRB 260504A: Global MASTER-Net observations report
  85. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  86. EP260502a: Einstein Probe detection of an X-ray transient
  87. GRB 260429A: SVOM/GRM observation of a short burst
  88. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  89. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  90. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  91. EP260429a: LCO optical upper limits
  92. EP260430a: LCO optical upper limits
  93. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  94. EP260430a: Einstein Probe detection of an X-ray transient
  95. EP260429a: EP-WXT detection of a fast X-ray transient
  96. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  97. EP260416a: Mondy and Terskol optical upper limits
  98. GRB 260424B: COLIBRÍ optical upper limit
  99. Konus-Wind detection of GRB 260424B
  100. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory

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