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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"

12319 results found.

  1. Fermi GRB 260513A: Global MASTER-Net observations report
  2. Fermi GRB 260512A: Global MASTER-Net observations report
  3. Konus-Wind detection of GRB 260511B
  4. EP260512a: COLIBRÍ optical upper limits
  5. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  6. Konus-Wind detection of GRB 260511A
  7. GRB 260511B: GROWTH-India Telescope optical observations
  8. EP260509a: LCO optical upper limits
  9. EP260509a: EP-FXT non-detection and upper limit
  10. Fermi GRB 260511A: Global MASTER-Net observations report
  11. GRB 260510B: SVOM/VT optical upper limits
  12. GRB 260510C: SVOM/VT optical upper limits
  13. GRB 260510C: MAXI/GSC detection
  14. EP260509a: Global MASTER-Net observations report
  15. GRB 260510B: GOTO early upper limit
  16. GRB 260510B: LCO optical upper limits
  17. GRB 260509A: NOT spectroscopic redshift upper limit z < 1.95
  18. SVOM GRB 260509A: MASTER-OAFA optical observation
  19. Fermi GRB 260510A: Global MASTER-Net observations report
  20. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  21. EP260507a: Liverpool Telescope optical upper limits
  22. EP260507a: GOTO optical counterpart detection
  23. EP260507a: Kinder optical counterpart candidate
  24. Fermi GRB 260506A: Global MASTER-Net observations report
  25. IceCube Alert 260505A: Global MASTER-Net observations report
  26. GRB 260504B: SVOM/VT optical upper limits
  27. GRB 260421B: radio observation with the VLA
  28. Konus-Wind detection of GRB 260504B (short/hard)
  29. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  30. GRB 260504B: EP-FXT upper limit
  31. GRB 260504B: AST3-2 i-band upper limit
  32. GRB 260504B: LCO z-band upper limit
  33. SVOM GRB 260504B: MASTER-OAFA optical observations
  34. Fermi GRB 260504A: Global MASTER-Net observations report
  35. EP260502a: BOOTES-7: early optical upper limit
  36. EP260502a: Las Cumbres upper limit
  37. EP260429a: Global MASTER-Net observations report
  38. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  39. EP260429a: LCO optical upper limits
  40. EP260430a: LCO optical upper limits
  41. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  42. Fermi GRB 260429A: Global MASTER-Net observations report
  43. EP260430a: Global MASTER-Net observations report
  44. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  45. Fermi GRB 260428A: Global MASTER-Net observations report
  46. EP260416a: Mondy and Terskol optical upper limits
  47. GRB 260424B: COLIBRÍ optical upper limit
  48. Konus-Wind detection of GRB 260424B
  49. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  50. IceCube Alert 260425A: Global MASTER-Net observations report
  51. Fermi trigger No 798737427: Global MASTER-Net observations report
  52. EP260321a: Upper limits from ATCA radio observations
  53. IceCube-Cascade 260418A: Upper limits from a search for additional neutrino events in IceCube
  54. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  55. GRB 260421B: J-band upper limit with WINTER
  56. GRB 260421B: LCO optical counterpart detection
  57. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  58. EP260416a: 1.3m DFOT optical observation
  59. Fermi GRB 260421C: Global MASTER-Net observations report
  60. Fermi GRB 260421B: Global MASTER-Net observations report
  61. Fermi GRB 260421A: Global MASTER-Net observations report
  62. GRB 260412A: LCOGT Optical Upper Limits
  63. EP260416a: Optical follow-up observations with Kinder
  64. Fermi trigger No 798275385: Global MASTER-Net observations report
  65. EP260417a: GROWTH-India Telescope optical upper limit
  66. Fermi GRB 260417B: Global MASTER-Net observations report
  67. EP260417b: GROWTH-India Telescope optical upper limit
  68. EP260417a: Global MASTER-Net observations report
  69. Fermi GRB 260417A: Global MASTER-Net observations report
  70. EP260416a: KAIT optical upper limit
  71. EP260416a: Global MASTER-Net observations report
  72. Fermi trigger No 797912738: Global MASTER-Net observations report
  73. Fermi GRB 260413A: Global MASTER-Net observations report
  74. Fermi GRB 260412A: Global MASTER-Net observations report
  75. GRB 260410A: COLIBRÍ optical upper limit
  76. EP-WXT01709259790: Optical Upper limits with kinder observations
  77. EP-WXT01709259790: Xinglong optical upper limit
  78. EP260409a: SVOM/VT optical upper limits
  79. EP260409a: COLIBRÍ optical upper limits
  80. EP260409a: Global MASTER-Net observations report
  81. EP260402a / GRB 260402A: Mephisto optical upper limits
  82. EP-WXT01709259586: Xinglong optical upper limit
  83. EP260403a: Mephisto optical upper limits
  84. EP260402a/GRB 260402A: Xinglong optical upper limit
  85. EP260321a: Upper limits from VLA radio observations
  86. EP260321a: uGMRT observations
  87. EP260405a: GMOS-N optical upper limits
  88. EP260405a: SVOM/VT optical upper limits
  89. EP260405a: Global MASTER-Net observations report
  90. EP260405a: Einstein Probe detection of a fast X-ray transient
  91. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  92. Fermi trigger No 797039833: Global MASTER-Net observations report
  93. GRB 260330B: SVOM/VT optical candidate
  94. EP260402a/GRB 260402A: Jinshan near-infrared upper limit
  95. GRB 260402A: WINTER J-band upper limit
  96. GRB260402A: GROWTH-India Telescope optical upper limit
  97. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  98. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  99. GRB 260402A: Kilonova-Catcher optical upper limit
  100. GRB 260402A: SVOM/COLIBRÍ (FM-GFT) optical upper limit

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