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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.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

12318 results found.

  1. Fermi GRB 260512A: Global MASTER-Net observations report
  2. Konus-Wind detection of GRB 260511B
  3. EP260512a: COLIBRÍ optical upper limits
  4. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  5. Konus-Wind detection of GRB 260511A
  6. GRB 260511B: GROWTH-India Telescope optical observations
  7. EP260509a: LCO optical upper limits
  8. EP260509a: EP-FXT non-detection and upper limit
  9. Fermi GRB 260511A: Global MASTER-Net observations report
  10. GRB 260510B: SVOM/VT optical upper limits
  11. GRB 260510C: SVOM/VT optical upper limits
  12. GRB 260510C: MAXI/GSC detection
  13. EP260509a: Global MASTER-Net observations report
  14. GRB 260510B: GOTO early upper limit
  15. GRB 260510B: LCO optical upper limits
  16. GRB 260509A: NOT spectroscopic redshift upper limit z < 1.95
  17. SVOM GRB 260509A: MASTER-OAFA optical observation
  18. Fermi GRB 260510A: Global MASTER-Net observations report
  19. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  20. EP260507a: Liverpool Telescope optical upper limits
  21. EP260507a: GOTO optical counterpart detection
  22. EP260507a: Kinder optical counterpart candidate
  23. Fermi GRB 260506A: Global MASTER-Net observations report
  24. IceCube Alert 260505A: Global MASTER-Net observations report
  25. GRB 260504B: SVOM/VT optical upper limits
  26. GRB 260421B: radio observation with the VLA
  27. Konus-Wind detection of GRB 260504B (short/hard)
  28. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  29. GRB 260504B: EP-FXT upper limit
  30. GRB 260504B: AST3-2 i-band upper limit
  31. GRB 260504B: LCO z-band upper limit
  32. SVOM GRB 260504B: MASTER-OAFA optical observations
  33. Fermi GRB 260504A: Global MASTER-Net observations report
  34. EP260502a: BOOTES-7: early optical upper limit
  35. EP260502a: Las Cumbres upper limit
  36. EP260429a: Global MASTER-Net observations report
  37. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  38. EP260429a: LCO optical upper limits
  39. EP260430a: LCO optical upper limits
  40. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  41. Fermi GRB 260429A: Global MASTER-Net observations report
  42. EP260430a: Global MASTER-Net observations report
  43. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  44. Fermi GRB 260428A: Global MASTER-Net observations report
  45. EP260416a: Mondy and Terskol optical upper limits
  46. GRB 260424B: COLIBRÍ optical upper limit
  47. Konus-Wind detection of GRB 260424B
  48. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  49. IceCube Alert 260425A: Global MASTER-Net observations report
  50. Fermi trigger No 798737427: Global MASTER-Net observations report
  51. EP260321a: Upper limits from ATCA radio observations
  52. IceCube-Cascade 260418A: Upper limits from a search for additional neutrino events in IceCube
  53. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  54. GRB 260421B: J-band upper limit with WINTER
  55. GRB 260421B: LCO optical counterpart detection
  56. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  57. EP260416a: 1.3m DFOT optical observation
  58. Fermi GRB 260421C: Global MASTER-Net observations report
  59. Fermi GRB 260421B: Global MASTER-Net observations report
  60. Fermi GRB 260421A: Global MASTER-Net observations report
  61. GRB 260412A: LCOGT Optical Upper Limits
  62. EP260416a: Optical follow-up observations with Kinder
  63. Fermi trigger No 798275385: Global MASTER-Net observations report
  64. EP260417a: GROWTH-India Telescope optical upper limit
  65. Fermi GRB 260417B: Global MASTER-Net observations report
  66. EP260417b: GROWTH-India Telescope optical upper limit
  67. EP260417a: Global MASTER-Net observations report
  68. Fermi GRB 260417A: Global MASTER-Net observations report
  69. EP260416a: KAIT optical upper limit
  70. EP260416a: Global MASTER-Net observations report
  71. Fermi trigger No 797912738: Global MASTER-Net observations report
  72. Fermi GRB 260413A: Global MASTER-Net observations report
  73. Fermi GRB 260412A: Global MASTER-Net observations report
  74. GRB 260410A: COLIBRÍ optical upper limit
  75. EP-WXT01709259790: Optical Upper limits with kinder observations
  76. EP-WXT01709259790: Xinglong optical upper limit
  77. EP260409a: SVOM/VT optical upper limits
  78. EP260409a: COLIBRÍ optical upper limits
  79. EP260409a: Global MASTER-Net observations report
  80. EP260402a / GRB 260402A: Mephisto optical upper limits
  81. EP-WXT01709259586: Xinglong optical upper limit
  82. EP260403a: Mephisto optical upper limits
  83. EP260402a/GRB 260402A: Xinglong optical upper limit
  84. EP260321a: Upper limits from VLA radio observations
  85. EP260321a: uGMRT observations
  86. EP260405a: GMOS-N optical upper limits
  87. EP260405a: SVOM/VT optical upper limits
  88. EP260405a: Global MASTER-Net observations report
  89. EP260405a: Einstein Probe detection of a fast X-ray transient
  90. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  91. Fermi trigger No 797039833: Global MASTER-Net observations report
  92. GRB 260330B: SVOM/VT optical candidate
  93. EP260402a/GRB 260402A: Jinshan near-infrared upper limit
  94. GRB 260402A: WINTER J-band upper limit
  95. GRB260402A: GROWTH-India Telescope optical upper limit
  96. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  97. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  98. GRB 260402A: Kilonova-Catcher optical upper limit
  99. GRB 260402A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  100. Fermi GRB 260401A: Global MASTER-Net observations report

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