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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"

12312 results found.

  1. EP260221a: Xinglong optical upper limit
  2. Fermi GRB 260221A: Global MASTER-Net observations report
  3. EP260221a: GOTO optical upper limit
  4. EP260221a: COLIBRÍ optical upper limit
  5. SVOM alert sb26021801: LCO optical upper limit
  6. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  7. Fermi GRB 260219A: Global MASTER-Net observations report
  8. SVOM alert sb26021801: LAST optical upper limit
  9. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  10. IceCube Alert 260217A: Global MASTER-Net observations report
  11. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  12. EP-WXT 01709258455: NOT optical upper limits
  13. EP260214b: 1.3m DFOT optical upper limit
  14. EP260210a: Mondy optical upper limits
  15. Konus-Wind detection of GRB 260212A
  16. GRB 260208A: AbAO and Terskol optical upper limits
  17. EP260214b: Optical upper limit with Kinder observations
  18. EP260214a: Optical upper limits with Kinder observations
  19. EP260214b: GROWTH-India Telescope optical upper limit
  20. EP260214a: NOT optical upper limits
  21. EP260214a: COLIBRÍ optical upper limits
  22. EP260214a: SVOM/VT optical upper limits
  23. EP260214a: Global MASTER-Net observations report
  24. EP260213a: Liverpool Telescope optical upper limits
  25. EP260213a: Global MASTER-Net observations report
  26. EP260213a: COLIBRÍ optical upper limits
  27. EP260213a: Optical upper limits with Kinder observations
  28. EP260213a: SVOM/VT optical upper limit
  29. EP260213a: Mondy R-band optical upper limit
  30. EP260213a: NUTTelA-TAO Early Optical Limits
  31. EP260213a: SVOM/C-GFT upper limit
  32. EP/WXT 01709258378: NOT optical upper limits
  33. GRB 260211A: GOTO optical upper limit
  34. Fermi GRB 260212A: Global MASTER-Net observations report
  35. GRB 260211A: LAST optical upper limit
  36. Konus-Wind detection of GRB 260207B
  37. GRB 260211A: LCO optical upper limits
  38. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  39. Fermi trigger No 792537871: Global MASTER-Net observations report
  40. Konus-Wind detection of GRB 260209B
  41. GRB 260208A: Swift UVOT detection
  42. EP260209a: COLIBRÍ optical upper limit
  43. Fermi GRB 260210C: Global MASTER-Net observations report
  44. EP260209a: LCO optical upper limits
  45. EP260210a: Global MASTER-Net observations report
  46. EP260209a: Global MASTER-Net observations report
  47. EP260210a: Optical upper limits with Kinder observations
  48. EP260210a: SVOM/VT optical upper limit
  49. EP260210a: COLIBRÍ optical upper limit
  50. EP260210a: SVOM/C-GFT upper limit
  51. GRB 260204A: Swift-XRT afterglow detection
  52. Fermi GRB 260209A: Global MASTER-Net observations report
  53. GRB 260208B: Swift-XRT observations
  54. GRB 260204A: Swift/UVOT Upper Limits
  55. Fermi GRB 260208C: Global MASTER-Net observations report
  56. Fermi GRB 260208D: Global MASTER-Net observations report
  57. GRB 260208A: Swift-XRT observations
  58. LAT GRB 260208B: Global MASTER-Net observations report
  59. Fermi GRB 260208A: Global MASTER-Net observations report
  60. Fermi GRB 260207B: Global MASTER-Net observations report
  61. GRB 260206A: Swift-XRT observations
  62. Fermi trigger No 792135758: Global MASTER-Net observations report
  63. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  64. GRB 260204A: Swift-XRT observations
  65. GRB 260204A: LCO optical afterglow detection
  66. GRB 260204A : MASTER Global robotic net optical observations
  67. GRB 260204A: GOTO optical upper limit
  68. GRB 260204A: LCO optical upper limits
  69. EP260110a: Late GTC/EMIR near-infrared observations
  70. GRB 260131A/AT2026bwg: Observations by the Zwicky Transient Facility
  71. GRB 260131A/B: EP/FXT X-ray afterglow detection
  72. GRB 260131A: NOT spectroscopic redshift z = 1.434
  73. EP260131a: Liverpool Telescope optical upper limits
  74. EP260131a: Xinglong optical upper limit
  75. EP260131a: VLT/X-shooter spectroscopic redshift z = 0.937
  76. GRB 260131B: MAXI/GSC detection
  77. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  78. Fermi GRB 260130A: Global MASTER-Net observations report
  79. EP260128a / GRB 260128A: NOT and TNG optical and NIR upper limits
  80. Fermi GRB 260129A: Global MASTER-Net observations report
  81. GRB 260128B: LCO optical upper limits
  82. GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  83. EP260128a: J band upper limit by SYSU 80cm infrared telescope
  84. GRB 260127B: Swift-XRT observations
  85. EP260128a: Liverpool Telescope optical observations and possible counterpart
  86. EP260128a: LCO optical upper limits
  87. EP260128a: Global MASTER-Net observations report
  88. Fermi GRB 260127A: Global MASTER-Net observations report
  89. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  90. GRB 260127A: COLIBRÍ optical observations
  91. EP260126a: Seimei/TriCCS optical upper limit
  92. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  93. GRB 260127A: SVOM/C-GFT optical observations
  94. Fermi GRB 260127B: Global MASTER-Net observations report
  95. Swift GRB 260127A: Global MASTER-Net observations report
  96. GRB 260125A: Swift-XRT observations
  97. EP260126a: Optical upper limit with Kinder observations
  98. EP260126a: Liverpool Telescope optical upper limits
  99. EP260126a: Further NOT optical upper limits
  100. EP260126a: COLIBRÍ optical upper limits

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