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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"

22856 results found.

  1. GRB 260511B: GMG Optical Upper Limit
  2. EP260514a: Einstein Probe detection of a fast X-ray transient
  3. EP260512a: LCO optical upper limits
  4. IPN triangulation of GRB 260512A
  5. GRB 260511B: Mephisto multi-band optical followup
  6. EP260512a: EP-FXT follow-up observation
  7. EP260507a: Xinglong Schmidt optical counterpart detection
  8. GRB 260511B: further SAO RAS optical observations
  9. EP260512a: COLIBRÍ optical upper limits
  10. EP260512a: Einstein Probe detection of an X-ray transient
  11. GRB 260511B: further J-band observations by the SYSU 80 cm infrared telescope
  12. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  13. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  14. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  15. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  16. GRB 260511A: Glowbug gamma-ray detection
  17. GRB 260511B: SAO RAS optical observations
  18. GRB 260510D: Glowbug gamma-ray detection of a likely short burst
  19. GRB 260511B: FRAM-ORM optical detection
  20. GRB 260511B: LCO optical counterpart detection
  21. GRB260511B: MAO/AZT-22 optical observations
  22. GRB 260511B: LCO optical observations
  23. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  24. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  25. GRB 260511B: OSIRIS+/GTC redshift z=2.006
  26. GRB 260509A: SAO RAS optical observations
  27. GRB 260511A: REM near-infrared detection
  28. GRB 260511B: GROWTH-India Telescope optical observations
  29. GRB 260511B: AstroSat CZTI detection
  30. GRB 260506B: Glowbug gamma-ray detection
  31. GRB 260506A: Glowbug gamma-ray detection of a short burst
  32. GRB 260511B: J-band observations by the SYSU 80 cm infrared telescope
  33. GRB 260511B: SVOM/VT optical observation with VHF data
  34. GRB 260511B: TRT optical observation
  35. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  36. GRB 260511B SVOM/C-GFT optical counterpart detection
  37. EP260509a: LCO optical upper limits
  38. GRB 260511A: UTGO H50 optical afterglow observation
  39. GRB 260510C: AstroSat CZTI detection
  40. GRB 260511B: SVOM detection of a burst
  41. GRB 260510C: SVOM/VT optical counterpart confirmation
  42. EP260509a: EP-FXT non-detection and upper limit
  43. GRB 260511A: SVOM/VT optical observation with VHF data
  44. GRB 260511A: KAIT optical afterglow observations
  45. GRB 260511A: LCO optical afterglow detection
  46. GRB 260511A: SVOM/COLIBRÍ (FM-GFT) optical counterpart
  47. GRB 260511A: TRT optical counterpart detection
  48. GRB 260511A: SVOM detection of a bright burst
  49. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  50. GRB 260510B: SVOM/VT optical upper limits
  51. GRB 260510C: SVOM/VT optical upper limits
  52. Fermi GBM Sub-Threshold Detection of GRB 260510B
  53. GRB 260510C: SVOM detection of a burst
  54. GRB 260510B: LCO optical upper limits
  55. EP260509a: Einstein Probe detection of an X-ray transient
  56. GRB 260509A: Liverpool Telescope optical observations
  57. GRB 260510B: SVOM detection of a burst
  58. GRB 260509A: LCO optical observations
  59. SVOM GRB 260509A: MASTER-OAFA optical observation
  60. GRB 260509A: KAIT optical observations
  61. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  62. GRB 260509A: SVOM/VT optical candidate with VHF data
  63. GRB 260509A: LCO optical counterpart detection
  64. GRB 260509A: SVOM detection of a burst
  65. GRB 260506B: AstroSat CZTI detection
  66. EP260507a: REM optical/NIR observations
  67. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  68. EP260507a: COLIBRÍ optical observations
  69. EP260507a: NOT optical observations
  70. EP260507a: further Liverpool Telescope observations
  71. EP260507a: Liverpool Telescope optical upper limits
  72. EP260507a: GOTO optical counterpart detection
  73. EP260507a: TRT optical counterpart detection
  74. EP260507a: Kinder optical counterpart candidate
  75. EP260507a: LCO optical counterpart
  76. EP260507a: Einstein Probe detection of an X-ray transient
  77. GRB 260503A: GECAM-B observation of a burst
  78. GRB 260430B: Glowbug gamma-ray detection
  79. GRB 260421B: radio observation with the VLA
  80. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  81. GRB 260502A: SVOM/GRM observation of a short GRB
  82. GRB 260503A: SVOM/GRM observation of a GRB
  83. GRB 260504B: REM optical/NIR observations
  84. IPN triangulation of GRB 260429A
  85. IPN triangulation of GRB 260428A
  86. GRB 260504B: LCO z-band upper limit
  87. SVOM GRB 260504B: MASTER-OAFA optical observations
  88. GRB 260504B: SVOM detection of a short burst
  89. GRB 260503A: Fermi GBM Final Real-time Localization
  90. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  91. IPN triangulation of a bright burst from SGR 1E1841-045
  92. GRB 260429B / EP260429a: AstroSat CZTI detection
  93. EP260502a: BOOTES-7: early optical upper limit
  94. EP260502a: Las Cumbres upper limit
  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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