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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. EP260901a: EP-FXT follow-up observation
  2. Konus-Wind detection of GRB 260829A
  3. GRB 260829A: SVOM/GRM observation
  4. GRB 260818A: ATCA detection of a candidate radio counterpart
  5. EP260830a: EP-FXT follow-up observation
  6. EP260901a: Global MASTER-Net observations report
  7. IceCube-260827A: No transient candidates from the Zwicky Transient Facility
  8. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  9. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  10. NuSTAR Transient 260828: LCO Optical Upper Limits
  11. EP260901a: EP-WXT detection of a fast X-ray transient
  12. SVOM trigger sb26083106 is not a GRB
  13. GRB 260829A: AstroSat CZTI detection
  14. GRB 260831B: EP-FXT follow-up observation
  15. GRB 260830A: NuSTAR detection of prompt emission
  16. GRB 260831B: LCO optical upper limits
  17. EP260830a: Global MASTER-Net observations report
  18. EP260830a: EP-WXT detection of a fast X-ray transient
  19. GRB 260827A: SVOM/GRM observation
  20. NuSTAR 260828: a 1100s hard X-ray transient
  21. GRB 260831B: SVOM detection of a possible burst
  22. IPN triangulation of GRB 260829A
  23. GRB 260827A: Glowbug gamma-ray detection
  24. EP260727a: ATCA 10 GHz detection
  25. GRB 260831A: Fermi GBM Final Real-time Localization
  26. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  27. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  28. GRB 260829A: GECAM-B observation of a long burst
  29. GRB 260825A: SVOM/GRM observation of a long burst
  30. GRB 260825A: GECAM-B observation
  31. GRB 260829A: Fermi GBM Detection
  32. GRB 260825A: AstroSat CZTI detection
  33. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  34. GRB 260829A: Fermi GBM Final Real-time Localization
  35. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  36. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  37. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  38. Fermi GBM trigger 809666623/260829141 is not a GRB
  39. GRB 260818B: Further EP-FXT observation
  40. GRB 260818B: VLT optical and nIR observations
  41. GRB 260818B: TNG NIR observations
  42. MAXI GRB260827.40: Global MASTER-Net observations report
  43. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  44. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  45. GRB 260827A: Fermi GBM Final Real-time Localization
  46. GRB 260818B: 6 GHz VLA observations
  47. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  48. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  49. GRB 260808B: SAO RAS observations of the optical rebrightening
  50. EP260822a: Global MASTER-Net observations report
  51. EP Alert 260820.31: Global MASTER-Net observations report
  52. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  53. GRB 260807A: EP-FXT follow-up observations
  54. GRB 260822A: SVOM/ECLAIRs refined analysis
  55. GRB 260809A: SVOM/ECLAIRs refined analysis
  56. GRB 260822A: SVOM/VT optical upper limits
  57. IceCube Alert 260825A: Global MASTER-Net observations report
  58. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  59. GRB 260825A: Fermi GBM Final Real-time Localization
  60. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  61. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  62. GRB 260822A: EP/FXT follow-up observations
  63. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  64. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  65. EP260822a: EP-FXT non-detection and upper limit
  66. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  67. GRB 260822A: GOTO optical counterpart detection
  68. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  69. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  70. EP260822a: Einstein Probe detection of a fast X-ray transient
  71. GRB 260822A: LCO optical upper limits
  72. The EP-WXT trigger 01709287395 is likely a flaring star
  73. GRB260822B: Fermi GBM Final Localization
  74. GRB 260822A: GROWTH-India Telescope Upper Limits
  75. GRB 260822A: GOTO optical upper limit
  76. GRB 260822A: SVOM detection of a short burst
  77. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  78. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  79. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  80. GRB 260818B: VLA radio observations
  81. GRB 260818B: SVOM/C-GFT optical upper limit
  82. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  83. IceCube Alert 260821A: Global MASTER-Net observations report
  84. The EP-WXT trigger 01709286204 is likely a flaring star
  85. GRB 260820A: Insight-HXMT/HE detection
  86. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  87. GRB 260818B: SVOM/GRM observation
  88. EP detected a brightening of LMXB 1ES 1735-26.9
  89. GRB260820A: Fermi GBM Final Real-Time Localization
  90. GRB 260818B: Insight-HXMT detection
  91. GRB 260818B: EP-FXT follow-up observation
  92. GRB 260818A: J-band observations with WINTER
  93. GRB 260818B: SVOM/ECLAIRs refined analysis
  94. GRB 260818A: SVOM/ECLAIRs refined analysis
  95. GRB 260818B: NOT optical upper limits
  96. GRB 260810A: SVOM/GRM observation
  97. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  98. GRB260818A: EP-FXT follow-up observation
  99. GRB 260818B: LCO optical upper limits
  100. GRB 260818B: SVOM detection of a short burst

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