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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"

1360 results found.

  1. LIGO/Virgo/KAGRA S250206dm: Two counterpart neutrino candidates from IceCube neutrino searches
  2. IceCube-250203A - IceCube observation of a high-energy neutrino candidate track-like event
  3. EP250108A / SN 2025kg: Upper limits from a neutrino search with IceCube
  4. Fermi-LAT Gamma-ray Observations of IceCube-250102A
  5. Fermi-LAT Gamma-ray Observations of IceCube-250101A
  6. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  7. LIGO/Virgo/KAGRA S250105bn: 1 counterpart neutrino candidate event from an IceCube neutrino search
  8. IceCube-250102A: Upper limits from a search for additional neutrino events in IceCube
  9. IceCube-250101A: Upper limits from a search for additional neutrino events in IceCube
  10. IceCube Alert 250102.58: Global MASTER-Net observations report
  11. IceCube-250102A - IceCube observation of a high-energy neutrino candidate track-like event
  12. IceCube-250101A - IceCube observation of a high-energy neutrino candidate track-like event
  13. IceCube-Cascade 241228A: Upper limits from a search for additional neutrino events in IceCube
  14. IceCube-241224A: No transient candidates from the Zwicky Transient Facility
  15. IceCube-241224A: Upper limits from a search for additional neutrino events in IceCube
  16. LIGO/Virgo/KAGRA S241225c: Two counterpart neutrino candidates from IceCube neutrino searches
  17. IceCube-241224A - IceCube observation of a high-energy neutrino candidate track-like event
  18. IceCube Alert 241224.30: Global MASTER-Net observations report
  19. IceCube-241127A: No transient candidates from the Zwicky Transient Facility
  20. IceCube-241127A: Upper limits from a search for additional neutrino events in IceCube
  21. Swift-XRT observations of IceCube -241127A
  22. Fermi-LAT gamma-ray observations of IceCube-241127A
  23. IceCube Alert 241127.59: Global MASTER-Net observations report
  24. IceCube-241127A: IceCube observation of a high-energy neutrino candidate track-like event
  25. LIGO/Virgo/KAGRA S241109bn: Upper limits from a two-week IceCube neutrino search
  26. Updates to IceCube realtime alert system for muon tracks
  27. IceCube-Cascade 241116A: Upper limits from a search for additional neutrino events in IceCube
  28. IceCube-241113A: Upper limits from a search for additional neutrino events in IceCube
  29. Fermi-LAT gamma-ray observations of IceCube-241113A
  30. IceCube-241113A - IceCube observation of a high-energy neutrino candidate track-like event
  31. IceCube Alert 241113.02: Global MASTER-Net observations report
  32. LIGO/Virgo/KAGRA S241110bk: 1 counterpart neutrino candidate event from an IceCube neutrino search
  33. LIGO/Virgo/KAGRA S241106ba: 1 counterpart neutrino candidate event from an IceCube neutrino search
  34. LIGO/Virgo/KAGRA S241102o: 1 counterpart neutrino candidate event from an IceCube neutrino search
  35. IceCube-Cascade 241019A: Upper limits from a search for additional neutrino events in IceCube
  36. IceCube alert 139977_2910365 retraction
  37. IceCube Alert 241016.04: Global MASTER-Net observations report
  38. IceCube-241006A: Upper limits from a search for additional neutrino events in IceCube
  39. Fermi-LAT Gamma-ray Observations of IceCube-241006A
  40. IceCube-241006A: No candidates from the Zwicky Transient Facility
  41. Fermi-LAT Gamma-ray Observations of NuEm-240926A
  42. IceCube Alert 241006.94: Global MASTER-Net observations report
  43. IceCube-241006A - IceCube observation of a high-energy neutrino candidate track-like event
  44. NuEm-240926A: Upper limits from a search for coincident neutrino events in IceCube
  45. Fermi-LAT Gamma-ray Observations of IceCube-240929A
  46. IceCube-240929A: Upper limits from a search for additional neutrino events in IceCube
  47. LIGO/Virgo/KAGRA S240930df: 1 counterpart neutrino candidate event from an IceCube neutrino search
  48. AMON NuEM 240926A: Swift XRT Follow-up
  49. IceCube-240929A - IceCube observation of a high-energy neutrino candidate track-like event
  50. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-240926A
  51. GRB 240825A: Upper limits from a neutrino search with IceCube
  52. IceCube-240721A: AT2023qqp and AT2024pge likely unrelated
  53. IceCube-240808A: Upper limits from a search for additional neutrino events in IceCube
  54. Fermi-LAT gamma-ray observations of IceCube-240808A
  55. IceCube Alert 240808.27: Global MASTER-Net observations report
  56. IceCube-240808A - IceCube observation of a high-energy neutrino candidate track-like event
  57. IceCube-240725A: Upper limits from a search for additional neutrino events in IceCube
  58. Fermi-LAT gamma-ray observations of IceCube-240725A
  59. IceCube Alert 240725.22: Global MASTER-Net observations report
  60. IceCube-240725A - IceCube observation of a high-energy neutrino candidate track-like event
  61. IceCube-240721A: Two candidates from the Zwicky Transient Facility
  62. IceCube-240721A: Upper limits from a search for additional neutrino events in IceCube
  63. Fermi-LAT gamma-ray observations of IceCube-240721A
  64. IceCube-240721A - IceCube observation of a high-energy neutrino candidate track-like event
  65. IceCube Alert 240721.68: Global MASTER-Net observations report
  66. IceCube-Cascade 240714A: TRT optical observations on the EP/FXT positions
  67. IceCube-Cascade 240714A: X-ray follow-up observation with EP-FXT
  68. Fermi-LAT gamma-ray observations of IceCube-cascade-240714A
  69. IceCube-Cascade 240626A: Upper limits from a search for additional neutrino events in IceCube
  70. IceCube-Cascade 240518A: Upper limits from a search for additional neutrino events in IceCube
  71. LIGO/Virgo/KAGRA S240422ed: Upper limits from a two-week IceCube neutrino search
  72. IceCube-240424A: GRANDMA Optical Upper Limit of Fermi J2151.3+0220
  73. Fermi-LAT gamma-ray observations of IceCube-240424A
  74. IceCube-240424A: Upper limits from a search for additional neutrino events in IceCube
  75. IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event
  76. IceCube Alert 240424.08: Global MASTER-Net observations report
  77. IceCube-240419A: Upper limits from a search for additional neutrino events in IceCube
  78. Fermi-LAT gamma-ray observations of IceCube-240419A
  79. IceCube Alert 240419.98: Global MASTER-Net observations report
  80. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  81. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  82. IceCube-Cascade 240416A: Upper limits from a search for additional neutrino events in IceCube
  83. IceCube-240412A: Upper limits from a search for additional neutrino events in IceCube
  84. Fermi-LAT gamma-ray observations of IceCube-240412A
  85. IceCube Alert 240412.23: Global MASTER-Net observations report
  86. IceCube-240412A - IceCube observation of a high-energy neutrino candidate track-like event
  87. IceCube-240327B: GRANDMA/Kilonova-Catcher observations of 4FGL J0555.9+0030 and optical upper limits
  88. Fermi-LAT gamma-ray observations of IceCube-240327B
  89. Fermi-LAT gamma-ray observations of IceCube-240327A
  90. IceCube-240327B: GRANDMA observations of 4FGL J0555.9+0030
  91. IceCube-240327B: Upper limits from a search for additional neutrino events in IceCube
  92. IceCube-240327A: Upper limits from a search for additional neutrino events in IceCube
  93. IceCube-240327B: No candidates from the Zwicky Transient Facility
  94. IceCube Alert 240327.68: Global MASTER-Net observations report
  95. IceCube-240327B - IceCube observation of a high-energy neutrino candidate track-like event
  96. IceCube-240327A - IceCube observation of a high-energy neutrino candidate track-like event
  97. Fermi-LAT gamma-ray observations of IceCube-240307A
  98. IceCube-240307A: Upper limits from a search for additional neutrino events in IceCube
  99. IceCube-240307A - IceCube observation of a high-energy neutrino candidate track-like event
  100. IceCube Alert 240307.32: Global MASTER-Net observations report

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