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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"

23442 results found.

  1. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  2. GRB 260511A: Glowbug gamma-ray detection
  3. GRB 260511B: SAO RAS optical observations
  4. GRB 260510D: Glowbug gamma-ray detection of a likely short burst
  5. GRB 260511B: FRAM-ORM optical detection
  6. GRB 260511B: LCO optical counterpart detection
  7. GRB260511B: MAO/AZT-22 optical observations
  8. GRB 260511B: LCO optical observations
  9. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  10. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  11. GRB 260511B: OSIRIS+/GTC redshift z=2.006
  12. GRB 260509A: SAO RAS optical observations
  13. GRB 260511A: REM near-infrared detection
  14. GRB 260511B: GROWTH-India Telescope optical observations
  15. GRB 260511B: AstroSat CZTI detection
  16. GRB 260506B: Glowbug gamma-ray detection
  17. GRB 260506A: Glowbug gamma-ray detection of a short burst
  18. GRB 260511B: J-band observations by the SYSU 80 cm infrared telescope
  19. GRB 260511B: SVOM/VT optical observation with VHF data
  20. GRB 260511B: TRT optical observation
  21. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  22. GRB 260511B SVOM/C-GFT optical counterpart detection
  23. EP260509a: LCO optical upper limits
  24. GRB 260511A: UTGO H50 optical afterglow observation
  25. GRB 260510C: AstroSat CZTI detection
  26. GRB 260511B: SVOM detection of a burst
  27. GRB 260510C: SVOM/VT optical counterpart confirmation
  28. EP260509a: EP-FXT non-detection and upper limit
  29. GRB 260511A: SVOM/VT optical observation with VHF data
  30. GRB 260511A: KAIT optical afterglow observations
  31. GRB 260511A: LCO optical afterglow detection
  32. GRB 260511A: SVOM/COLIBRÍ (FM-GFT) optical counterpart
  33. GRB 260511A: TRT optical counterpart detection
  34. GRB 260511A: SVOM detection of a bright burst
  35. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  36. GRB 260510B: SVOM/VT optical upper limits
  37. GRB 260510C: SVOM/VT optical upper limits
  38. Fermi GBM Sub-Threshold Detection of GRB 260510B
  39. GRB 260510C: SVOM detection of a burst
  40. GRB 260510B: LCO optical upper limits
  41. EP260509a: Einstein Probe detection of an X-ray transient
  42. GRB 260509A: Liverpool Telescope optical observations
  43. GRB 260510B: SVOM detection of a burst
  44. GRB 260509A: LCO optical observations
  45. SVOM GRB 260509A: MASTER-OAFA optical observation
  46. GRB 260509A: KAIT optical observations
  47. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  48. GRB 260509A: SVOM/VT optical candidate with VHF data
  49. GRB 260509A: LCO optical counterpart detection
  50. GRB 260509A: SVOM detection of a burst
  51. GRB 260506B: AstroSat CZTI detection
  52. EP260507a: REM optical/NIR observations
  53. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  54. EP260507a: COLIBRÍ optical observations
  55. EP260507a: NOT optical observations
  56. EP260507a: further Liverpool Telescope observations
  57. EP260507a: Liverpool Telescope optical upper limits
  58. EP260507a: GOTO optical counterpart detection
  59. EP260507a: TRT optical counterpart detection
  60. EP260507a: Kinder optical counterpart candidate
  61. EP260507a: LCO optical counterpart
  62. EP260507a: Einstein Probe detection of an X-ray transient
  63. GRB 260503A: GECAM-B observation of a burst
  64. GRB 260430B: Glowbug gamma-ray detection
  65. GRB 260421B: radio observation with the VLA
  66. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  67. GRB 260502A: SVOM/GRM observation of a short GRB
  68. GRB 260503A: SVOM/GRM observation of a GRB
  69. GRB 260504B: REM optical/NIR observations
  70. IPN triangulation of GRB 260429A
  71. IPN triangulation of GRB 260428A
  72. GRB 260504B: LCO z-band upper limit
  73. SVOM GRB 260504B: MASTER-OAFA optical observations
  74. GRB 260504B: SVOM detection of a short burst
  75. GRB 260503A: Fermi GBM Final Real-time Localization
  76. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  77. IPN triangulation of a bright burst from SGR 1E1841-045
  78. GRB 260429B / EP260429a: AstroSat CZTI detection
  79. EP260502a: BOOTES-7: early optical upper limit
  80. EP260502a: Las Cumbres upper limit
  81. EP260502a: Einstein Probe detection of an X-ray transient
  82. GRB 260429A: SVOM/GRM observation of a short burst
  83. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  84. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  85. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  86. EP260429a: LCO optical upper limits
  87. EP260430a: LCO optical upper limits
  88. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  89. EP260430a: Einstein Probe detection of an X-ray transient
  90. EP260429a: EP-WXT detection of a fast X-ray transient
  91. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  92. GRB 260428A: AstroSat CZTI detection
  93. EP260416a: Mondy and Terskol optical upper limits
  94. GRB 260424B: Glowbug gamma-ray detection of a short burst
  95. GRB 260424B: COLIBRÍ optical upper limit
  96. Konus-Wind detection of GRB 260424B
  97. IPN triangulation of GRB 260424B (short)
  98. GRB 260401A: cubesat Avion detection
  99. GRB 260424A: AstroSat CZTI detection of a long burst
  100. EP260321a: Upper limits from ATCA radio observations

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