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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"

19044 results found.

  1. EP260514a: GROWTH-India Telescope optical upper limit
  2. GRB 260511B: GMG Optical Upper Limit
  3. EP260514a: Einstein Probe detection of a fast X-ray transient
  4. EP260512a: LCO optical upper limits
  5. GRB 260511B: Mephisto multi-band optical followup
  6. EP260512a: EP-FXT follow-up observation
  7. EP260507a: Xinglong Schmidt optical counterpart detection
  8. Fermi GRB 260513A: Global MASTER-Net observations report
  9. GRB 260511B: further SAO RAS optical observations
  10. EP260512a: COLIBRÍ optical upper limits
  11. EP260512a: Einstein Probe detection of an X-ray transient
  12. GRB 260511B: further J-band observations by the SYSU 80 cm infrared telescope
  13. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  14. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  15. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  16. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  17. Konus-Wind detection of GRB 260511A
  18. GRB 260511B: SAO RAS optical observations
  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 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 260511B SVOM/C-GFT optical counterpart detection
  33. EP260509a: LCO optical upper limits
  34. GRB 260511A: UTGO H50 optical afterglow observation
  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. Fermi GBM Sub-Threshold Detection of GRB 260510B
  45. GRB 260510C: SVOM detection of a burst
  46. GRB 260510B: LCO optical upper limits
  47. EP260509a: Einstein Probe detection of an X-ray transient
  48. GRB 260509A: Liverpool Telescope optical observations
  49. GRB 260510B: SVOM detection of a burst
  50. GRB 260509A: LCO optical observations
  51. SVOM GRB 260509A: MASTER-OAFA optical observation
  52. GRB 260509A: KAIT optical observations
  53. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  54. GRB 260509A: SVOM/VT optical candidate with VHF data
  55. GRB 260509A: LCO optical counterpart detection
  56. GRB 260509A: SVOM detection of a burst
  57. EP260507a: REM optical/NIR observations
  58. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  59. EP260507a: COLIBRÍ optical observations
  60. EP260507a: NOT optical observations
  61. EP260507a: further Liverpool Telescope observations
  62. EP260507a: Liverpool Telescope optical upper limits
  63. EP260507a: TRT optical counterpart detection
  64. EP260507a: Kinder optical counterpart candidate
  65. EP260507a: LCO optical counterpart
  66. EP260507a: Einstein Probe detection of an X-ray transient
  67. GRB 260504B: SVOM/VT optical upper limits
  68. GRB 260421B: radio observation with the VLA
  69. GRB 260504B: SVOM/MXT refined analysis and potential detection
  70. GRB 260502A: SVOM/GRM observation of a short GRB
  71. GRB 260503A: SVOM/GRM observation of a GRB
  72. Konus-Wind detection of GRB 260411C
  73. GRB 260504B: REM optical/NIR observations
  74. GRB 260504B: LCO z-band upper limit
  75. SVOM GRB 260504B: MASTER-OAFA optical observations
  76. GRB 260504B: SVOM detection of a short burst
  77. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  78. EP260502a: Einstein Probe detection of an X-ray transient
  79. GRB 260429A: SVOM/GRM observation of a short burst
  80. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  81. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  82. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  83. EP260429a: LCO optical upper limits
  84. EP260430a: LCO optical upper limits
  85. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  86. EP260430a: Einstein Probe detection of an X-ray transient
  87. EP260429a: EP-WXT detection of a fast X-ray transient
  88. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  89. EP260416a: Mondy and Terskol optical upper limits
  90. GRB 260424B: COLIBRÍ optical upper limit
  91. GRB 260401A: cubesat Avion detection
  92. EP260321a: Upper limits from ATCA radio observations
  93. GRB 260421B: Kilonova-Catcher optical afterglow detection
  94. The EP-WXT trigger 01709258652: Mondy optical observations
  95. EP260416a: Mondy optical observations
  96. GRB 260421B: 3.6m DOT optical observation
  97. EP260416a: ZTSh R band observations
  98. GRB 260421B: SVOM/GRM observation
  99. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  100. GOTO26djh/AT2026jpw: ATCA radio detection

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