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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"

12030 results found.

  1. Fermi GRB 260516B: Global MASTER-Net observations report
  2. EP260514a: COLIBRÍ optical upper limits
  3. SVOM GRB 260515A: Global MASTER-Net observations report
  4. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection
  5. EP260514a: GROWTH-India Telescope optical upper limit
  6. GRB 260511B: GMG Optical Upper Limit
  7. EP260514a: Global MASTER-Net observations report
  8. EP260512a: LCO optical upper limits
  9. Fermi GRB 260514A: Global MASTER-Net observations report
  10. EP260512a: EP-FXT follow-up observation
  11. EP260512a: Global MASTER-Net observations report
  12. Fermi GRB 260513A: Global MASTER-Net observations report
  13. Fermi GRB 260512A: Global MASTER-Net observations report
  14. Konus-Wind detection of GRB 260511B
  15. EP260512a: COLIBRÍ optical upper limits
  16. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  17. Konus-Wind detection of GRB 260511A
  18. GRB 260511B: GROWTH-India Telescope optical observations
  19. EP260509a: LCO optical upper limits
  20. EP260509a: EP-FXT non-detection and upper limit
  21. Fermi GRB 260511A: Global MASTER-Net observations report
  22. GRB 260510B: SVOM/VT optical upper limits
  23. GRB 260510C: SVOM/VT optical upper limits
  24. GRB 260510C: MAXI/GSC detection
  25. EP260509a: Global MASTER-Net observations report
  26. GRB 260510B: GOTO early upper limit
  27. GRB 260510B: LCO optical upper limits
  28. GRB 260509A: NOT spectroscopic redshift upper limit z < 1.95
  29. SVOM GRB 260509A: MASTER-OAFA optical observation
  30. Fermi GRB 260510A: Global MASTER-Net observations report
  31. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  32. EP260507a: Liverpool Telescope optical upper limits
  33. EP260507a: GOTO optical counterpart detection
  34. EP260507a: Kinder optical counterpart candidate
  35. Fermi GRB 260506A: Global MASTER-Net observations report
  36. IceCube Alert 260505A: Global MASTER-Net observations report
  37. GRB 260504B: SVOM/VT optical upper limits
  38. GRB 260421B: radio observation with the VLA
  39. Konus-Wind detection of GRB 260504B (short/hard)
  40. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  41. GRB 260504B: EP-FXT upper limit
  42. GRB 260504B: AST3-2 i-band upper limit
  43. GRB 260504B: LCO z-band upper limit
  44. SVOM GRB 260504B: MASTER-OAFA optical observations
  45. Fermi GRB 260504A: Global MASTER-Net observations report
  46. EP260502a: BOOTES-7: early optical upper limit
  47. EP260502a: Las Cumbres upper limit
  48. EP260429a: Global MASTER-Net observations report
  49. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  50. EP260429a: LCO optical upper limits
  51. EP260430a: LCO optical upper limits
  52. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  53. Fermi GRB 260429A: Global MASTER-Net observations report
  54. EP260430a: Global MASTER-Net observations report
  55. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  56. Fermi GRB 260428A: Global MASTER-Net observations report
  57. EP260416a: Mondy and Terskol optical upper limits
  58. GRB 260424B: COLIBRÍ optical upper limit
  59. Konus-Wind detection of GRB 260424B
  60. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  61. IceCube Alert 260425A: Global MASTER-Net observations report
  62. Fermi trigger No 798737427: Global MASTER-Net observations report
  63. EP260321a: Upper limits from ATCA radio observations
  64. IceCube-Cascade 260418A: Upper limits from a search for additional neutrino events in IceCube
  65. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  66. GRB 260421B: J-band upper limit with WINTER
  67. GRB 260421B: LCO optical counterpart detection
  68. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  69. EP260416a: 1.3m DFOT optical observation
  70. Fermi GRB 260421C: Global MASTER-Net observations report
  71. Fermi GRB 260421B: Global MASTER-Net observations report
  72. Fermi GRB 260421A: Global MASTER-Net observations report
  73. GRB 260412A: LCOGT Optical Upper Limits
  74. EP260416a: Optical follow-up observations with Kinder
  75. Fermi trigger No 798275385: Global MASTER-Net observations report
  76. EP260417a: GROWTH-India Telescope optical upper limit
  77. Fermi GRB 260417B: Global MASTER-Net observations report
  78. EP260417b: GROWTH-India Telescope optical upper limit
  79. EP260417a: Global MASTER-Net observations report
  80. Fermi GRB 260417A: Global MASTER-Net observations report
  81. EP260416a: KAIT optical upper limit
  82. EP260416a: Global MASTER-Net observations report
  83. Fermi trigger No 797912738: Global MASTER-Net observations report
  84. Fermi GRB 260413A: Global MASTER-Net observations report
  85. Fermi GRB 260412A: Global MASTER-Net observations report
  86. GRB 260410A: COLIBRÍ optical upper limit
  87. EP-WXT01709259790: Optical Upper limits with kinder observations
  88. EP-WXT01709259790: Xinglong optical upper limit
  89. EP260409a: SVOM/VT optical upper limits
  90. EP260409a: COLIBRÍ optical upper limits
  91. EP260409a: Global MASTER-Net observations report
  92. EP260402a / GRB 260402A: Mephisto optical upper limits
  93. EP-WXT01709259586: Xinglong optical upper limit
  94. EP260403a: Mephisto optical upper limits
  95. EP260402a/GRB 260402A: Xinglong optical upper limit
  96. EP260321a: Upper limits from VLA radio observations
  97. EP260321a: uGMRT observations
  98. EP260405a: GMOS-N optical upper limits
  99. EP260405a: SVOM/VT optical upper limits
  100. EP260405a: Global MASTER-Net observations report

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