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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"

19540 results found.

  1. GRB 260511B: Mephisto multi-band optical followup
  2. EP260512a: EP-FXT follow-up observation
  3. EP260507a: Xinglong Schmidt optical counterpart detection
  4. Fermi GRB 260513A: Global MASTER-Net observations report
  5. GRB 260511B: further SAO RAS optical observations
  6. EP260512a: COLIBRÍ optical upper limits
  7. EP260512a: Einstein Probe detection of an X-ray transient
  8. GRB 260511B: further J-band observations by the SYSU 80 cm infrared telescope
  9. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  10. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  11. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  12. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  13. Konus-Wind detection of GRB 260511A
  14. GRB 260511B: SAO RAS optical observations
  15. GRB 260511B: FRAM-ORM optical detection
  16. GRB 260511B: LCO optical counterpart detection
  17. GRB260511B: MAO/AZT-22 optical observations
  18. GRB 260511B: LCO optical observations
  19. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  20. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  21. GRB 260509A: SAO RAS optical observations
  22. GRB 260511A: REM near-infrared detection
  23. GRB 260511B: GROWTH-India Telescope optical observations
  24. GRB 260511B: J-band observations by the SYSU 80 cm infrared telescope
  25. GRB 260511B: SVOM/VT optical observation with VHF data
  26. GRB 260511B: TRT optical observation
  27. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  28. GRB 260511B SVOM/C-GFT optical counterpart detection
  29. EP260509a: LCO optical upper limits
  30. GRB 260511A: UTGO H50 optical afterglow observation
  31. GRB 260511B: SVOM detection of a burst
  32. EP260509a: EP-FXT non-detection and upper limit
  33. GRB 260511A: SVOM/VT optical observation with VHF data
  34. GRB 260511A: KAIT optical afterglow observations
  35. GRB 260511A: LCO optical afterglow detection
  36. GRB 260511A: SVOM/COLIBRÍ (FM-GFT) optical counterpart
  37. GRB 260511A: TRT optical counterpart detection
  38. GRB 260511A: SVOM detection of a bright burst
  39. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  40. Fermi GBM Sub-Threshold Detection of GRB 260510B
  41. GRB 260510C: SVOM detection of a burst
  42. GRB 260510B: LCO optical upper limits
  43. EP260509a: Einstein Probe detection of an X-ray transient
  44. GRB 260509A: Liverpool Telescope optical observations
  45. GRB 260510B: SVOM detection of a burst
  46. GRB 260509A: LCO optical observations
  47. SVOM GRB 260509A: MASTER-OAFA optical observation
  48. GRB 260509A: KAIT optical observations
  49. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  50. GRB 260509A: SVOM/VT optical candidate with VHF data
  51. GRB 260509A: LCO optical counterpart detection
  52. GRB 260509A: SVOM detection of a burst
  53. EP260507a: REM optical/NIR observations
  54. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  55. EP260507a: COLIBRÍ optical observations
  56. EP260507a: NOT optical observations
  57. EP260507a: further Liverpool Telescope observations
  58. EP260507a: Liverpool Telescope optical upper limits
  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 260504B: SVOM/VT optical upper limits
  64. GRB 260421B: radio observation with the VLA
  65. GRB 260504B: SVOM/MXT refined analysis and potential detection
  66. GRB 260502A: SVOM/GRM observation of a short GRB
  67. GRB 260503A: SVOM/GRM observation of a GRB
  68. Konus-Wind detection of GRB 260411C
  69. GRB 260504B: REM optical/NIR observations
  70. GRB 260504B: LCO z-band upper limit
  71. SVOM GRB 260504B: MASTER-OAFA optical observations
  72. GRB 260504B: SVOM detection of a short burst
  73. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  74. EP260502a: Einstein Probe detection of an X-ray transient
  75. GRB 260429A: SVOM/GRM observation of a short burst
  76. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  77. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  78. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  79. EP260429a: LCO optical upper limits
  80. EP260430a: LCO optical upper limits
  81. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  82. EP260430a: Einstein Probe detection of an X-ray transient
  83. EP260429a: EP-WXT detection of a fast X-ray transient
  84. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  85. EP260416a: Mondy and Terskol optical upper limits
  86. GRB 260424B: COLIBRÍ optical upper limit
  87. GRB 260401A: cubesat Avion detection
  88. EP260321a: Upper limits from ATCA radio observations
  89. GRB 260421B: Kilonova-Catcher optical afterglow detection
  90. The EP-WXT trigger 01709258652: Mondy optical observations
  91. EP260416a: Mondy optical observations
  92. GRB 260421B: 3.6m DOT optical observation
  93. EP260416a: ZTSh R band observations
  94. GRB 260421B: SVOM/GRM observation
  95. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  96. GOTO26djh/AT2026jpw: ATCA radio detection
  97. GRB 260421B: J-band upper limit with WINTER
  98. GRB 260421B: LCO optical counterpart detection
  99. GRB 260421A: AstroSat CZTI detection
  100. GRB 260421B: SVOM/VT optical observations

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