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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"

45280 results found.

  1. GRB 260903A: SAO RAS optical observations
  2. GRB 260830A: GECAM-B detection of a burst
  3. EP260903a: EP-WXT detection of a fast X-ray transient
  4. EP Alert 260903.62: Global MASTER-Net observations report
  5. GRB 260830A: Insight-HXMT/HE detection
  6. GRB 260903A: EP-FXT follow-up observation
  7. GRB 260903A: OHP/T193 optical afterglow detection
  8. GRB 260903A: NOT optical observations and afterglow fading
  9. NuSTAR Transient 260828: SOAR Optical Upper Limits
  10. SVOM GRB260903A: Global MASTER-Net observations report
  11. GRB 260903A: LCO optical observations
  12. GRB 260903A: SVOM/VT optical candidate
  13. GRB 260903A: Retraction of optical counterpart of GCN 45501
  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. EP260901a: EP-FXT follow-up observation
  20. Konus-Wind detection of GRB 260829A
  21. GRB 260829A: SVOM/GRM observation
  22. GRB 260818A: ATCA detection of a candidate radio counterpart
  23. EP260830a: EP-FXT follow-up observation
  24. EP260901a: Global MASTER-Net observations report
  25. IceCube-260827A: No transient candidates from the Zwicky Transient Facility
  26. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  27. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  28. NuSTAR Transient 260828: LCO Optical Upper Limits
  29. EP260901a: EP-WXT detection of a fast X-ray transient
  30. SVOM trigger sb26083106 is not a GRB
  31. GRB 260829A: AstroSat CZTI detection
  32. GRB 260831B: EP-FXT follow-up observation
  33. GRB 260830A: NuSTAR detection of prompt emission
  34. GRB 260831B: LCO optical upper limits
  35. EP260830a: Global MASTER-Net observations report
  36. EP260830a: EP-WXT detection of a fast X-ray transient
  37. GRB 260827A: SVOM/GRM observation
  38. NuSTAR 260828: a 1100s hard X-ray transient
  39. GRB 260831B: SVOM detection of a possible burst
  40. IPN triangulation of GRB 260829A
  41. GRB 260827A: Glowbug gamma-ray detection
  42. EP260727a: ATCA 10 GHz detection
  43. GRB 260831A: Fermi GBM Final Real-time Localization
  44. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  45. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  46. GRB 260829A: GECAM-B observation of a long burst
  47. GRB 260825A: SVOM/GRM observation of a long burst
  48. GRB 260825A: GECAM-B observation
  49. GRB 260829A: Fermi GBM Detection
  50. GRB 260825A: AstroSat CZTI detection
  51. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  52. GRB 260829A: Fermi GBM Final Real-time Localization
  53. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  54. IceCube-260825A: 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. Fermi GBM trigger 809666623/260829141 is not a GRB
  57. GRB 260818B: Further EP-FXT observation
  58. GRB 260818B: VLT optical and nIR observations
  59. GRB 260818B: TNG NIR observations
  60. MAXI GRB260827.40: Global MASTER-Net observations report
  61. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  62. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  63. GRB 260827A: Fermi GBM Final Real-time Localization
  64. GRB 260818B: 6 GHz VLA observations
  65. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  66. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  67. GRB 260808B: SAO RAS observations of the optical rebrightening
  68. EP260822a: Global MASTER-Net observations report
  69. EP Alert 260820.31: Global MASTER-Net observations report
  70. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  71. GRB 260807A: EP-FXT follow-up observations
  72. GRB 260822A: SVOM/ECLAIRs refined analysis
  73. GRB 260809A: SVOM/ECLAIRs refined analysis
  74. GRB 260822A: SVOM/VT optical upper limits
  75. IceCube Alert 260825A: Global MASTER-Net observations report
  76. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  77. GRB 260825A: Fermi GBM Final Real-time Localization
  78. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  79. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  80. GRB 260822A: EP/FXT follow-up observations
  81. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  82. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  83. EP260822a: EP-FXT non-detection and upper limit
  84. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  85. GRB 260822A: GOTO optical counterpart detection
  86. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  87. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  88. EP260822a: Einstein Probe detection of a fast X-ray transient
  89. GRB 260822A: LCO optical upper limits
  90. The EP-WXT trigger 01709287395 is likely a flaring star
  91. GRB260822B: Fermi GBM Final Localization
  92. GRB 260822A: GROWTH-India Telescope Upper Limits
  93. GRB 260822A: GOTO optical upper limit
  94. GRB 260822A: SVOM detection of a short burst
  95. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  96. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  97. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  98. GRB 260818B: VLA radio observations
  99. GRB 260818B: SVOM/C-GFT optical upper limit
  100. EP260731a: SVOM/ECLAIRs detection through offline targeted search

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