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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. EP260903a: EP-FXT follow-up observation
  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. GRB 260903A: SAO RAS optical observations
  9. GRB 260830A: GECAM-B detection of a burst
  10. EP260903a: EP-WXT detection of a fast X-ray transient
  11. EP Alert 260903.62: Global MASTER-Net observations report
  12. GRB 260830A: Insight-HXMT/HE detection
  13. GRB 260903A: EP-FXT follow-up observation
  14. GRB 260903A: OHP/T193 optical afterglow detection
  15. GRB 260903A: NOT optical observations and afterglow fading
  16. NuSTAR Transient 260828: SOAR Optical Upper Limits
  17. SVOM GRB260903A: Global MASTER-Net observations report
  18. GRB 260903A: LCO optical observations
  19. GRB 260903A: SVOM/VT optical candidate
  20. GRB 260903A: Retraction of optical counterpart of GCN 45501
  21. GRB 260831A: GECAM-B observation
  22. GRB 260903A: LCO optical counterpart detection
  23. GRB 260827A: Insight-HXMT/HE detection
  24. GRB 260903A: SVOM detection of a soft faint burst
  25. EP260901a: SVOM/VT optical upper limits
  26. EP260901a: EP-FXT follow-up observation
  27. Konus-Wind detection of GRB 260829A
  28. GRB 260829A: SVOM/GRM observation
  29. GRB 260818A: ATCA detection of a candidate radio counterpart
  30. EP260830a: EP-FXT follow-up observation
  31. EP260901a: Global MASTER-Net observations report
  32. IceCube-260827A: No transient candidates from the Zwicky Transient Facility
  33. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  34. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  35. NuSTAR Transient 260828: LCO Optical Upper Limits
  36. EP260901a: EP-WXT detection of a fast X-ray transient
  37. SVOM trigger sb26083106 is not a GRB
  38. GRB 260829A: AstroSat CZTI detection
  39. GRB 260831B: EP-FXT follow-up observation
  40. GRB 260830A: NuSTAR detection of prompt emission
  41. GRB 260831B: LCO optical upper limits
  42. EP260830a: Global MASTER-Net observations report
  43. EP260830a: EP-WXT detection of a fast X-ray transient
  44. GRB 260827A: SVOM/GRM observation
  45. NuSTAR 260828: a 1100s hard X-ray transient
  46. GRB 260831B: SVOM detection of a possible burst
  47. IPN triangulation of GRB 260829A
  48. GRB 260827A: Glowbug gamma-ray detection
  49. EP260727a: ATCA 10 GHz detection
  50. GRB 260831A: Fermi GBM Final Real-time Localization
  51. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  52. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  53. GRB 260829A: GECAM-B observation of a long burst
  54. GRB 260825A: SVOM/GRM observation of a long burst
  55. GRB 260825A: GECAM-B observation
  56. GRB 260829A: Fermi GBM Detection
  57. GRB 260825A: AstroSat CZTI detection
  58. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  59. GRB 260829A: Fermi GBM Final Real-time Localization
  60. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  61. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  62. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  63. Fermi GBM trigger 809666623/260829141 is not a GRB
  64. GRB 260818B: Further EP-FXT observation
  65. GRB 260818B: VLT optical and nIR observations
  66. GRB 260818B: TNG NIR observations
  67. MAXI GRB260827.40: Global MASTER-Net observations report
  68. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  69. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  70. GRB 260827A: Fermi GBM Final Real-time Localization
  71. GRB 260818B: 6 GHz VLA observations
  72. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  73. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  74. GRB 260808B: SAO RAS observations of the optical rebrightening
  75. EP260822a: Global MASTER-Net observations report
  76. EP Alert 260820.31: Global MASTER-Net observations report
  77. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  78. GRB 260807A: EP-FXT follow-up observations
  79. GRB 260822A: SVOM/ECLAIRs refined analysis
  80. GRB 260809A: SVOM/ECLAIRs refined analysis
  81. GRB 260822A: SVOM/VT optical upper limits
  82. IceCube Alert 260825A: Global MASTER-Net observations report
  83. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  84. GRB 260825A: Fermi GBM Final Real-time Localization
  85. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  86. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  87. GRB 260822A: EP/FXT follow-up observations
  88. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  89. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  90. EP260822a: EP-FXT non-detection and upper limit
  91. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  92. GRB 260822A: GOTO optical counterpart detection
  93. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  94. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  95. EP260822a: Einstein Probe detection of a fast X-ray transient
  96. GRB 260822A: LCO optical upper limits
  97. The EP-WXT trigger 01709287395 is likely a flaring star
  98. GRB260822B: Fermi GBM Final Localization
  99. GRB 260822A: GROWTH-India Telescope Upper Limits
  100. GRB 260822A: GOTO optical upper limit

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