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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"

1462 results found.

  1. IceCube-260504A: No Candidate Transients from the Zwicky Transient Facility
  2. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  3. IceCube Alert 260505A: Global MASTER-Net observations report
  4. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  5. IceCube-260504A - IceCube observation of a high-energy neutrino candidate track-like event
  6. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  7. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  8. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  9. IceCube Alert 260425A: Global MASTER-Net observations report
  10. IceCube-Cascade 260418A: Upper limits from a search for additional neutrino events in IceCube
  11. EP260321a: Upper limits from a neutrino search with IceCube
  12. IceCube-260315A: No Candidate Transients from the Zwicky Transient Facility
  13. IceCube-260315A/AT2026fpm: EP-FXT follow-up observation
  14. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  15. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  16. IceCube-260315A: COLIBRÍ optical observations
  17. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  18. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  19. IceCube Alert 260315A: Global MASTER-Net observations report
  20. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  21. IceCube cascade alert 142200_1517143 retraction
  22. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  23. IceCube Alert 260217A: Global MASTER-Net observations report
  24. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  25. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  26. IceCube-260125A: No Candidate Transients from the Zwicky Transient Facility
  27. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  28. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  29. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  30. IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
  31. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  32. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  33. IceCube Alert 260115.73: Global MASTER-Net observations report
  34. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  35. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  36. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  37. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  38. IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
  39. IceCube Alert 260111A: Global MASTER-Net observations report
  40. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  41. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  42. IceCube Alert 251225.84: Global MASTER-Net observations report
  43. IceCube-251225A - IceCube observation of a high-energy neutrino candidate track-like event
  44. IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
  45. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  46. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  47. IceCube-251218A: COLIBRÍ optical upper limits
  48. IceCube-251218A - IceCube observation of a high-energy neutrino candidate track-like event
  49. IceCube Alert 251218.85: Global MASTER-Net observations report
  50. IceCube-251210A: No Candidate Transients from the Zwicky Transient Facility
  51. Fermi-LAT Gamma-ray Observations of IceCube-251210A
  52. IceCube-251210A: Upper limits from a search for additional neutrino events in IceCube
  53. IceCube-251210A: DDOTI Optical Upper Limit
  54. IceCube Alert 251210.46: Global MASTER-Net observations report
  55. IceCube-251210A - IceCube observation of a high-energy neutrino candidate track-like event
  56. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  57. IceCube-251130A: Upper limits from a search for additional neutrino events in IceCube
  58. IceCube Alert 251130.75: Global MASTER-Net observations report
  59. IceCube-251130A - IceCube observation of a high-energy neutrino candidate track-like event
  60. IceCube-Cascade 251112A: Upper limits from a search for additional neutrino events in IceCube
  61. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  62. LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
  63. IceCube-Cascade 251107A: Upper limits from a search for additional neutrino events in IceCube
  64. IceCube-251025A: Two Transient Candidates from the Zwicky Transient Facility
  65. IceCube-251025A: Upper limits from a search for additional neutrino events in IceCube
  66. Fermi-LAT Gamma-ray Observations of IceCube-251025A
  67. IceCube-251025A: DDOTI Optical Upper Limit
  68. IceCube Alert 251025.57: Global MASTER-Net observations report
  69. IceCube-251025A - IceCube observation of a high-energy neutrino candidate track-like event
  70. Fermi-LAT gamma-ray observations of IceCube-251018A
  71. IceCube-251018A: Upper limits from a search for additional neutrino events in IceCube
  72. IceCube-251018A: DDOTI Optical Upper Limit
  73. IceCube-251018A: Global MASTER-Net observations report
  74. IceCube-251018A - IceCube observation of a high-energy neutrino candidate track-like event
  75. IceCube-251018A - IceCube observation of a high-energy neutrino candidate track-like event (duplicate submission)
  76. Upper limits from a search for additional neutrino events in IceCube
  77. IceCube Alert 251014.77: Global MASTER-Net observations report
  78. Fermi-LAT Gamma-ray Observations of IceCube-251014A
  79. IceCube-251014A - IceCube observation of a high-energy neutrino candidate track-like event
  80. IceCube alert 141456_888784 retraction
  81. IceCube Alert 251008A: Global MASTER-Net observations report
  82. Fermi-LAT Gamma-ray Observations of IceCube-250926A
  83. IceCube-250926A: Upper limits from a search for additional neutrino events in IceCube
  84. IceCube Alert 250926.52: Global MASTER-Net observations report
  85. IceCube-250926A - IceCube observation of a high-energy neutrino candidate track-like event
  86. LIGO/Virgo/KAGRA S250918aw: 1 counterpart neutrino candidate event from an IceCube neutrino search
  87. LIGO/Virgo/KAGRA S250917aq: Three counterpart neutrino candidates from IceCube neutrino searches
  88. IceCube-Cascade 250911A: Upper limits from a search for additional neutrino events in IceCube
  89. LIGO/Virgo/KAGRA S250912s: 2 counterpart neutrino candidate events from an IceCube neutrino search
  90. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  91. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  92. IceCube-250905A - IceCube observation of a high-energy neutrino candidate track-like event
  93. IceCube Alert 250905.84: Global MASTER-Net observations report
  94. IceCube-Cascade 250903A: Upper limits from a search for additional neutrino events in IceCube
  95. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  96. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  97. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  98. IceCube-Cascade 250828A: Upper limits from a search for additional neutrino events in IceCube
  99. IceCube Alert 250831.75: Global MASTER-Net observations report
  100. IceCube-250831A - IceCube observation of a high-energy neutrino candidate track-like event

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