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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"

28879 results found.

  1. GRB 260907A: Fermi GBM Final Real-time Localization
  2. EP Alert 260905.11: Global MASTER-Net observations report
  3. The EP-WXT trigger 01709302592 is likely a flaring star
  4. GRB 260903A: J-band upper limit with WINTER
  5. EP Alert 260903.47: Global MASTER-Net observations report
  6. GRB 260903A: SVOM/ECLAIRs refined analysis
  7. GRB260903A: Liverpool Telescope optical observations
  8. EP Alert 260903.62: Global MASTER-Net observations report
  9. GRB 260903A: EP-FXT follow-up observation
  10. GRB 260903A: NOT optical observations and afterglow fading
  11. SVOM GRB260903A: Global MASTER-Net observations report
  12. GRB 260903A: LCO optical observations
  13. GRB 260903A: SVOM/VT optical candidate
  14. GRB 260831A: GECAM-B observation
  15. GRB 260903A: LCO optical counterpart detection
  16. GRB 260827A: Insight-HXMT/HE detection
  17. GRB 260903A: SVOM detection of a soft faint burst
  18. EP260901a: SVOM/VT optical upper limits
  19. Konus-Wind detection of GRB 260829A
  20. GRB 260829A: SVOM/GRM observation
  21. GRB 260818A: ATCA detection of a candidate radio counterpart
  22. EP260901a: Global MASTER-Net observations report
  23. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  24. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  25. SVOM trigger sb26083106 is not a GRB
  26. GRB 260829A: AstroSat CZTI detection
  27. GRB 260831B: EP-FXT follow-up observation
  28. GRB 260831B: LCO optical upper limits
  29. EP260830a: Global MASTER-Net observations report
  30. GRB 260827A: SVOM/GRM observation
  31. GRB 260831B: SVOM detection of a possible burst
  32. IPN triangulation of GRB 260829A
  33. GRB 260827A: Glowbug gamma-ray detection
  34. EP260727a: ATCA 10 GHz detection
  35. GRB 260831A: Fermi GBM Final Real-time Localization
  36. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  37. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  38. GRB 260829A: GECAM-B observation of a long burst
  39. GRB 260825A: SVOM/GRM observation of a long burst
  40. GRB 260825A: GECAM-B observation
  41. GRB 260829A: Fermi GBM Detection
  42. GRB 260825A: AstroSat CZTI detection
  43. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  44. GRB 260829A: Fermi GBM Final Real-time Localization
  45. Fermi GBM trigger 809666623/260829141 is not a GRB
  46. GRB 260818B: Further EP-FXT observation
  47. GRB 260818B: VLT optical and nIR observations
  48. GRB 260818B: TNG NIR observations
  49. MAXI GRB260827.40: Global MASTER-Net observations report
  50. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  51. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  52. GRB 260827A: Fermi GBM Final Real-time Localization
  53. GRB 260818B: 6 GHz VLA observations
  54. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  55. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  56. EP260822a: Global MASTER-Net observations report
  57. EP Alert 260820.31: Global MASTER-Net observations report
  58. GRB 260807A: EP-FXT follow-up observations
  59. GRB 260822A: SVOM/ECLAIRs refined analysis
  60. GRB 260809A: SVOM/ECLAIRs refined analysis
  61. IceCube Alert 260825A: Global MASTER-Net observations report
  62. GRB 260825A: Fermi GBM Final Real-time Localization
  63. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  64. GRB 260822A: EP/FXT follow-up observations
  65. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  66. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  67. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  68. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  69. GRB 260822A: LCO optical upper limits
  70. The EP-WXT trigger 01709287395 is likely a flaring star
  71. GRB260822B: Fermi GBM Final Localization
  72. GRB 260822A: GROWTH-India Telescope Upper Limits
  73. GRB 260822A: GOTO optical upper limit
  74. GRB 260822A: SVOM detection of a short burst
  75. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  76. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  77. GRB 260818B: SVOM/C-GFT optical upper limit
  78. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  79. IceCube Alert 260821A: Global MASTER-Net observations report
  80. The EP-WXT trigger 01709286204 is likely a flaring star
  81. GRB 260820A: Insight-HXMT/HE detection
  82. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  83. GRB260820A: Fermi GBM Final Real-Time Localization
  84. GRB 260818B: EP-FXT follow-up observation
  85. GRB 260818A: J-band observations with WINTER
  86. GRB 260818B: SVOM/ECLAIRs refined analysis
  87. GRB 260818A: SVOM/ECLAIRs refined analysis
  88. GRB 260818B: NOT optical upper limits
  89. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  90. GRB260818A: EP-FXT follow-up observation
  91. GRB 260818B: LCO optical upper limits
  92. GRB 260818B: SVOM detection of a short burst
  93. SVOM trigger sb26081806 is not a GRB
  94. EP260806a: SAO RAS multicolor optical observations
  95. GRB 260818A: LCO optical upper limits
  96. EP260812a: AbAO optical upper limit
  97. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  98. GRB 260818A: SVOM possible detection of a long and faint GRB
  99. EP260806a: SVOM/ECLAIRs detection through targeted search
  100. The EP-WXT trigger 01709281429 is likely a flaring star

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