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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"

45293 results found.

  1. GRB260903A: Liverpool Telescope optical observations
  2. GRB 260903A: SAO RAS optical observations
  3. GRB 260830A: GECAM-B detection of a burst
  4. EP260903a: EP-WXT detection of a fast X-ray transient
  5. EP Alert 260903.62: Global MASTER-Net observations report
  6. GRB 260830A: Insight-HXMT/HE detection
  7. GRB 260903A: EP-FXT follow-up observation
  8. GRB 260903A: OHP/T193 optical afterglow detection
  9. GRB 260903A: NOT optical observations and afterglow fading
  10. NuSTAR Transient 260828: SOAR Optical Upper Limits
  11. SVOM GRB260903A: Global MASTER-Net observations report
  12. GRB 260903A: LCO optical observations
  13. GRB 260903A: SVOM/VT optical candidate
  14. GRB 260903A: Retraction of optical counterpart of GCN 45501
  15. GRB 260831A: GECAM-B observation
  16. GRB 260903A: LCO optical counterpart detection
  17. GRB 260827A: Insight-HXMT/HE detection
  18. GRB 260903A: SVOM detection of a soft faint burst
  19. EP260901a: SVOM/VT optical upper limits
  20. EP260901a: EP-FXT follow-up observation
  21. Konus-Wind detection of GRB 260829A
  22. GRB 260829A: SVOM/GRM observation
  23. GRB 260818A: ATCA detection of a candidate radio counterpart
  24. EP260830a: EP-FXT follow-up observation
  25. EP260901a: Global MASTER-Net observations report
  26. IceCube-260827A: No transient candidates from the Zwicky Transient Facility
  27. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  28. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  29. NuSTAR Transient 260828: LCO Optical Upper Limits
  30. EP260901a: EP-WXT detection of a fast X-ray transient
  31. SVOM trigger sb26083106 is not a GRB
  32. GRB 260829A: AstroSat CZTI detection
  33. GRB 260831B: EP-FXT follow-up observation
  34. GRB 260830A: NuSTAR detection of prompt emission
  35. GRB 260831B: LCO optical upper limits
  36. EP260830a: Global MASTER-Net observations report
  37. EP260830a: EP-WXT detection of a fast X-ray transient
  38. GRB 260827A: SVOM/GRM observation
  39. NuSTAR 260828: a 1100s hard X-ray transient
  40. GRB 260831B: SVOM detection of a possible burst
  41. IPN triangulation of GRB 260829A
  42. GRB 260827A: Glowbug gamma-ray detection
  43. EP260727a: ATCA 10 GHz detection
  44. GRB 260831A: Fermi GBM Final Real-time Localization
  45. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  46. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  47. GRB 260829A: GECAM-B observation of a long burst
  48. GRB 260825A: SVOM/GRM observation of a long burst
  49. GRB 260825A: GECAM-B observation
  50. GRB 260829A: Fermi GBM Detection
  51. GRB 260825A: AstroSat CZTI detection
  52. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  53. GRB 260829A: Fermi GBM Final Real-time Localization
  54. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  55. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  56. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  57. Fermi GBM trigger 809666623/260829141 is not a GRB
  58. GRB 260818B: Further EP-FXT observation
  59. GRB 260818B: VLT optical and nIR observations
  60. GRB 260818B: TNG NIR observations
  61. MAXI GRB260827.40: Global MASTER-Net observations report
  62. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  63. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  64. GRB 260827A: Fermi GBM Final Real-time Localization
  65. GRB 260818B: 6 GHz VLA observations
  66. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  67. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  68. GRB 260808B: SAO RAS observations of the optical rebrightening
  69. EP260822a: Global MASTER-Net observations report
  70. EP Alert 260820.31: Global MASTER-Net observations report
  71. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  72. GRB 260807A: EP-FXT follow-up observations
  73. GRB 260822A: SVOM/ECLAIRs refined analysis
  74. GRB 260809A: SVOM/ECLAIRs refined analysis
  75. GRB 260822A: SVOM/VT optical upper limits
  76. IceCube Alert 260825A: Global MASTER-Net observations report
  77. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  78. GRB 260825A: Fermi GBM Final Real-time Localization
  79. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  80. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  81. GRB 260822A: EP/FXT follow-up observations
  82. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  83. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  84. EP260822a: EP-FXT non-detection and upper limit
  85. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  86. GRB 260822A: GOTO optical counterpart detection
  87. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  88. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  89. EP260822a: Einstein Probe detection of a fast X-ray transient
  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. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  99. GRB 260818B: VLA radio observations
  100. GRB 260818B: SVOM/C-GFT optical upper limit

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