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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"
  1. Fermi GRB 260907B: Global MASTER-Net observations report
  2. GRB 260903A: SAO RAS optical upper limit
  3. The EP-WXT trigger 01709305715 is likely a flaring star
  4. GRB 260907B: Fermi GBM Final Real-time Localization
  5. Fermi GRB 260907A: Global MASTER-Net observations report
  6. GRB 260907A: Fermi GBM Final Real-time Localization
  7. EP260903a: EP-FXT follow-up observation
  8. EP Alert 260905.11: Global MASTER-Net observations report
  9. The EP-WXT trigger 01709302592 is likely a flaring star
  10. GRB 260903A: J-band upper limit with WINTER
  11. EP Alert 260903.47: Global MASTER-Net observations report
  12. GRB 260903A: SVOM/ECLAIRs refined analysis
  13. GRB260903A: Liverpool Telescope optical observations
  14. GRB 260903A: SAO RAS optical observations
  15. GRB 260830A: GECAM-B detection of a burst
  16. EP260903a: EP-WXT detection of a fast X-ray transient
  17. EP Alert 260903.62: Global MASTER-Net observations report
  18. GRB 260830A: Insight-HXMT/HE detection
  19. GRB 260903A: EP-FXT follow-up observation
  20. GRB 260903A: OHP/T193 optical afterglow detection
  21. GRB 260903A: NOT optical observations and afterglow fading
  22. NuSTAR Transient 260828: SOAR Optical Upper Limits
  23. SVOM GRB260903A: Global MASTER-Net observations report
  24. GRB 260903A: LCO optical observations
  25. GRB 260903A: SVOM/VT optical candidate
  26. GRB 260903A: Retraction of optical counterpart of GCN 45501
  27. GRB 260831A: GECAM-B observation
  28. GRB 260903A: LCO optical counterpart detection
  29. GRB 260827A: Insight-HXMT/HE detection
  30. GRB 260903A: SVOM detection of a soft faint burst
  31. EP260901a: SVOM/VT optical upper limits
  32. EP260901a: EP-FXT follow-up observation
  33. Konus-Wind detection of GRB 260829A
  34. GRB 260829A: SVOM/GRM observation
  35. GRB 260818A: ATCA detection of a candidate radio counterpart
  36. EP260830a: EP-FXT follow-up observation
  37. EP260901a: Global MASTER-Net observations report
  38. IceCube-260827A: No transient candidates from the Zwicky Transient Facility
  39. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  40. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  41. NuSTAR Transient 260828: LCO Optical Upper Limits
  42. EP260901a: EP-WXT detection of a fast X-ray transient
  43. SVOM trigger sb26083106 is not a GRB
  44. GRB 260829A: AstroSat CZTI detection
  45. GRB 260831B: EP-FXT follow-up observation
  46. GRB 260830A: NuSTAR detection of prompt emission
  47. GRB 260831B: LCO optical upper limits
  48. EP260830a: Global MASTER-Net observations report
  49. EP260830a: EP-WXT detection of a fast X-ray transient
  50. GRB 260827A: SVOM/GRM observation
  51. NuSTAR 260828: a 1100s hard X-ray transient
  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. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  67. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  68. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  69. Fermi GBM trigger 809666623/260829141 is not a GRB
  70. GRB 260818B: Further EP-FXT observation
  71. GRB 260818B: VLT optical and nIR observations
  72. GRB 260818B: TNG NIR observations
  73. MAXI GRB260827.40: Global MASTER-Net observations report
  74. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  75. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  76. GRB 260827A: Fermi GBM Final Real-time Localization
  77. GRB 260818B: 6 GHz VLA observations
  78. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  79. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  80. GRB 260808B: SAO RAS observations of the optical rebrightening
  81. EP260822a: Global MASTER-Net observations report
  82. EP Alert 260820.31: Global MASTER-Net observations report
  83. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  84. GRB 260807A: EP-FXT follow-up observations
  85. GRB 260822A: SVOM/ECLAIRs refined analysis
  86. GRB 260809A: SVOM/ECLAIRs refined analysis
  87. GRB 260822A: SVOM/VT optical upper limits
  88. IceCube Alert 260825A: Global MASTER-Net observations report
  89. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  90. GRB 260825A: Fermi GBM Final Real-time Localization
  91. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  92. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  93. GRB 260822A: EP/FXT follow-up observations
  94. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  95. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  96. EP260822a: EP-FXT non-detection and upper limit
  97. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  98. GRB 260822A: GOTO optical counterpart detection
  99. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  100. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate

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