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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"

1518 results found.

  1. IceCube-260827A: No transient candidates from the Zwicky Transient Facility
  2. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  3. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  4. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  5. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  6. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  7. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  8. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  9. IceCube Alert 260825A: Global MASTER-Net observations report
  10. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  11. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  12. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  13. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  14. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  15. IceCube Alert 260821A: Global MASTER-Net observations report
  16. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  17. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  18. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  19. IceCube Alert 260807A: Global MASTER-Net observations report
  20. IceCube-260805A: One candidate from the Zwicky Transient Facility
  21. IceCube-260807A - IceCube observation of a high-energy neutrino candidate track-like event
  22. GRB 260708A: cubesat Avion detection
  23. IceCube-260805A - IceCube observation of a high-energy neutrino candidate track-like event
  24. IceCube-Cascade 260801A: Upper limits from a search for additional neutrino events in IceCube
  25. Fermi-LAT Gamma-ray Observations of IceCube-260722A
  26. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  27. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  28. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  29. IceCube Alert 260722A: Global MASTER-Net observations report
  30. IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
  31. IceCube-260708A: Follow-up studies of cosmic-ray origin of high-energy neutrino alert
  32. IceCube-260712A: No candidates with the Zwicky Transient Facility (ZTF)
  33. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  34. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  35. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  36. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  37. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  38. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  39. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  40. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  41. IceCube-260708A: One candidate from the Zwicky Transient Facility
  42. IceCube Alert 260709A: Global MASTER-Net observations report
  43. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
  44. IceCube-260704A: No candidates from the Zwicky Transient Facility
  45. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  46. IceCube260704A: OHP/T193 optical observations
  47. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  48. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  49. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  50. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  51. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  52. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  53. IceCube-260610A: Upper limits from a search for additional neutrino events in IceCube
  54. IceCube-260610A: No candidates from the Zwicky Transient Facility
  55. IceCube-260610A: EP-FXT follow-up observation
  56. IceCube-260610A - IceCube observation of a high-energy neutrino candidate track-like event
  57. IceCube-260504A: No Candidate Transients from the Zwicky Transient Facility
  58. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  59. IceCube Alert 260505A: Global MASTER-Net observations report
  60. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  61. IceCube-260504A - IceCube observation of a high-energy neutrino candidate track-like event
  62. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  63. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  64. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  65. IceCube Alert 260425A: Global MASTER-Net observations report
  66. IceCube-Cascade 260418A: Upper limits from a search for additional neutrino events in IceCube
  67. EP260321a: Upper limits from a neutrino search with IceCube
  68. IceCube-260315A: No Candidate Transients from the Zwicky Transient Facility
  69. IceCube-260315A/AT2026fpm: EP-FXT follow-up observation
  70. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  71. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  72. IceCube-260315A: COLIBRÍ optical observations
  73. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  74. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  75. IceCube Alert 260315A: Global MASTER-Net observations report
  76. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  77. IceCube cascade alert 142200_1517143 retraction
  78. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  79. IceCube Alert 260217A: Global MASTER-Net observations report
  80. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  81. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  82. IceCube-260125A: No Candidate Transients from the Zwicky Transient Facility
  83. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  84. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  85. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  86. IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
  87. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  88. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  89. IceCube Alert 260115.73: Global MASTER-Net observations report
  90. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  91. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  92. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  93. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  94. IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
  95. IceCube Alert 260111A: Global MASTER-Net observations report
  96. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  97. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  98. IceCube Alert 251225.84: Global MASTER-Net observations report
  99. IceCube-251225A - IceCube observation of a high-energy neutrino candidate track-like event
  100. IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility

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