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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"

17798 results found.

  1. EP260512a: LCO optical upper limits
  2. GRB 260511B: Mephisto multi-band optical followup
  3. The EP-WXT trigger 01709262077 is likely a flaring star
  4. EP260512a: EP-FXT follow-up observation
  5. EP260507a: Xinglong Schmidt optical counterpart detection
  6. GRB 260511B: further SAO RAS optical observations
  7. The EP-WXT trigger 01709262036 is likely a flaring star
  8. EP260512a: COLIBRÍ optical upper limits
  9. EP260512a: Einstein Probe detection of an X-ray transient
  10. GRB 260511B: further J-band observations by the SYSU 80 cm infrared telescope
  11. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  12. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  13. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  14. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  15. GRB 260511B: SAO RAS optical observations
  16. GRB 260511B: FRAM-ORM optical detection
  17. GRB 260511A: EP-FXT follow-up observation
  18. GRB 260511B: EP-FXT follow-up observation
  19. GRB 260511B: LCO optical counterpart detection
  20. GRB260511B: MAO/AZT-22 optical observations
  21. GRB 260511B: LCO optical observations
  22. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  23. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  24. GRB 260510B: EP-FXT follow-up observation
  25. GRB 260509A: SAO RAS optical observations
  26. GRB 260511A: REM near-infrared detection
  27. GRB 260511B: GROWTH-India Telescope optical observations
  28. GRB 260511B: J-band observations by the SYSU 80 cm infrared telescope
  29. GRB 260511B: SVOM/VT optical observation with VHF data
  30. GRB 260511B: TRT optical observation
  31. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  32. GRB 260511A: Fermi GBM Detection
  33. GRB 260511B SVOM/C-GFT optical counterpart detection
  34. EP260509a: LCO optical upper limits
  35. GRB 260511A: UTGO H50 optical afterglow observation
  36. GRB 260511B: SVOM detection of a burst
  37. GRB 260510C: EP-FXT follow-up observation
  38. GRB 260510C: SVOM/VT optical counterpart confirmation
  39. EP260509a: EP-FXT non-detection and upper limit
  40. GRB 260511A: SVOM/VT optical observation with VHF data
  41. GRB 260511A: KAIT optical afterglow observations
  42. GRB 260511A: LCO optical afterglow detection
  43. GRB 260511A: SVOM/COLIBRÍ (FM-GFT) optical counterpart
  44. GRB 260511A: TRT optical counterpart detection
  45. GRB 260511A: SVOM detection of a bright burst
  46. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  47. GRB 260510C: SVOM detection of a burst
  48. GRB 260510B: LCO optical upper limits
  49. EP260509a: Einstein Probe detection of an X-ray transient
  50. GRB 260509A: Liverpool Telescope optical observations
  51. GRB 260510B: SVOM detection of a burst
  52. GRB 260509A: LCO optical observations
  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: SVOM detection of a burst
  58. EP260507a: REM optical/NIR observations
  59. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  60. EP260507a: COLIBRÍ optical observations
  61. EP260507a: NOT optical observations
  62. EP260507a: further Liverpool Telescope observations
  63. EP260507a: Liverpool Telescope optical upper limits
  64. EP260507a: TRT optical counterpart detection
  65. EP260507a: Kinder optical counterpart candidate
  66. EP260507a: LCO optical counterpart
  67. EP260507a: Einstein Probe detection of an X-ray transient
  68. GRB 260504B: AstroSat CZTI detection
  69. EP260502a is likely a flaring star
  70. GRB 260421B: radio observation with the VLA
  71. GRB 260504B: EP-FXT upper limit
  72. GRB 260502A: SVOM/GRM observation of a short GRB
  73. GRB 260503A: SVOM/GRM observation of a GRB
  74. GRB 260504B: REM optical/NIR observations
  75. GRB 260504B: LCO z-band upper limit
  76. GRB 260504B: SVOM detection of a short burst
  77. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  78. The EP-WXT trigger 01709261576 is likely a flaring star
  79. GRB 260429B / EP260429a: EP-FXT follow-up observation
  80. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  81. GRB 260429B / EP260429a: AstroSat CZTI detection
  82. EP260502a: Einstein Probe detection of an X-ray transient
  83. GRB 260429A: SVOM/GRM observation of a short burst
  84. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  85. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  86. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  87. EP260429a: LCO optical upper limits
  88. EP260430a: LCO optical upper limits
  89. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  90. EP260430a: Einstein Probe detection of an X-ray transient
  91. EP260429a: EP-WXT detection of a fast X-ray transient
  92. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  93. EP260416a: Mondy and Terskol optical upper limits
  94. GRB 260424B: COLIBRÍ optical upper limit
  95. EP260321a: Upper limits from ATCA radio observations
  96. GRB 260421B: Kilonova-Catcher optical afterglow detection
  97. EP260416a: Mondy optical observations
  98. GRB 260421B: 3.6m DOT optical observation
  99. EP260416a: ZTSh R band observations
  100. EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9

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