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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"

28700 results found.

  1. GRB 260907A: SVOM/GRM observation
  2. GRB 260909A: CrAO and AbAO optical upper limits
  3. GRB 260909A: SVOM/ECLAIRs refined analysis
  4. GRB 260910B: GOTO tentative optical counterpart candidates
  5. GRB 260910B: Fermi GBM Final Real-time Localization
  6. EP Alert 260909.53: Global MASTER-Net observations report
  7. GRB 260909A: EP-FXT follow-up observation
  8. GRB 260910A: Fermi GBM Final Real-time Localization
  9. GRB 260909A: SVOM/GRM observation
  10. GRB 260909A: Mondy optical observations and afterglow candidate
  11. GRB 260909A: Xinglong 2.16m optical upper limit
  12. GRB 260909A: SVOM/C-GFT optical upper limit
  13. GRB 260909A: SVOM detection of a burst
  14. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  15. Fermi trigger No 810554827: Global MASTER-Net observations report
  16. EP Alert 260908.60: Global MASTER-Net observations report
  17. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  18. Fermi GRB 260907B: Global MASTER-Net observations report
  19. The EP-WXT trigger 01709305715 is likely a flaring star
  20. GRB 260907B: Fermi GBM Final Real-time Localization
  21. Fermi GRB 260907A: Global MASTER-Net observations report
  22. GRB 260907A: Fermi GBM Final Real-time Localization
  23. EP Alert 260905.11: Global MASTER-Net observations report
  24. The EP-WXT trigger 01709302592 is likely a flaring star
  25. GRB 260903A: J-band upper limit with WINTER
  26. EP Alert 260903.47: Global MASTER-Net observations report
  27. GRB 260903A: SVOM/ECLAIRs refined analysis
  28. GRB260903A: Liverpool Telescope optical observations
  29. EP Alert 260903.62: Global MASTER-Net observations report
  30. GRB 260903A: EP-FXT follow-up observation
  31. GRB 260903A: NOT optical observations and afterglow fading
  32. SVOM GRB260903A: Global MASTER-Net observations report
  33. GRB 260903A: LCO optical observations
  34. GRB 260903A: SVOM/VT optical candidate
  35. GRB 260831A: GECAM-B observation
  36. GRB 260903A: LCO optical counterpart detection
  37. GRB 260827A: Insight-HXMT/HE detection
  38. GRB 260903A: SVOM detection of a soft faint burst
  39. EP260901a: SVOM/VT optical upper limits
  40. Konus-Wind detection of GRB 260829A
  41. GRB 260829A: SVOM/GRM observation
  42. GRB 260818A: ATCA detection of a candidate radio counterpart
  43. EP260901a: Global MASTER-Net observations report
  44. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  45. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  46. SVOM trigger sb26083106 is not a GRB
  47. GRB 260829A: AstroSat CZTI detection
  48. GRB 260831B: EP-FXT follow-up observation
  49. GRB 260831B: LCO optical upper limits
  50. EP260830a: Global MASTER-Net observations report
  51. GRB 260827A: SVOM/GRM observation
  52. GRB 260831B: SVOM detection of a possible burst
  53. IPN triangulation of GRB 260829A
  54. GRB 260827A: Glowbug gamma-ray detection
  55. EP260727a: ATCA 10 GHz detection
  56. GRB 260831A: Fermi GBM Final Real-time Localization
  57. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  58. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  59. GRB 260829A: GECAM-B observation of a long burst
  60. GRB 260825A: SVOM/GRM observation of a long burst
  61. GRB 260825A: GECAM-B observation
  62. GRB 260829A: Fermi GBM Detection
  63. GRB 260825A: AstroSat CZTI detection
  64. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  65. GRB 260829A: Fermi GBM Final Real-time Localization
  66. Fermi GBM trigger 809666623/260829141 is not a GRB
  67. GRB 260818B: Further EP-FXT observation
  68. GRB 260818B: VLT optical and nIR observations
  69. GRB 260818B: TNG NIR observations
  70. MAXI GRB260827.40: Global MASTER-Net observations report
  71. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  72. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  73. GRB 260827A: Fermi GBM Final Real-time Localization
  74. GRB 260818B: 6 GHz VLA observations
  75. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  76. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  77. EP260822a: Global MASTER-Net observations report
  78. EP Alert 260820.31: Global MASTER-Net observations report
  79. GRB 260807A: EP-FXT follow-up observations
  80. GRB 260822A: SVOM/ECLAIRs refined analysis
  81. GRB 260809A: SVOM/ECLAIRs refined analysis
  82. IceCube Alert 260825A: Global MASTER-Net observations report
  83. GRB 260825A: Fermi GBM Final Real-time Localization
  84. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  85. GRB 260822A: EP/FXT follow-up observations
  86. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  87. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  88. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  89. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  90. GRB 260822A: LCO optical upper limits
  91. The EP-WXT trigger 01709287395 is likely a flaring star
  92. GRB260822B: Fermi GBM Final Localization
  93. GRB 260822A: GROWTH-India Telescope Upper Limits
  94. GRB 260822A: GOTO optical upper limit
  95. GRB 260822A: SVOM detection of a short burst
  96. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  97. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  98. GRB 260818B: SVOM/C-GFT optical upper limit
  99. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  100. IceCube Alert 260821A: Global MASTER-Net observations report

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