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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"

11749 results found.

  1. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  2. GRB 260117A: SVOM detection of a long faint burst
  3. EP260116a: Einstein Probe detection of an X-ray transient
  4. IceCube Alert 260115.73: Global MASTER-Net observations report
  5. Fermi GRB 260115A: Global MASTER-Net observations report
  6. Konus-Wind detection of GRB 260114A
  7. GRB 260114A: Swift-XRT refined Analysis
  8. Konus-Wind detection of GRB 251230A / EP251230a
  9. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  10. GRB 260114A: Swift detection of a short burst
  11. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  12. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  13. Konus-Wind detection of GRB 260101A
  14. GRB 260112B: Fermi GBM Final Real-time Localization
  15. IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
  16. IceCube Alert 260111A: Global MASTER-Net observations report
  17. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  18. EP260110a: SVOM/C-GFT upper limit
  19. EP260110a: BOOTES-5/JGU optical upper limit
  20. EP260110a: Einstein Probe detection of an X-ray transient
  21. Fermi GRB 260107A: Global MASTER-Net observations report
  22. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  23. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  24. EP260104a: Einstein Probe detection of a fast X-ray transient
  25. EP260105a: Einstein Probe detection of an X-ray transient
  26. Fermi GRB 260104B: Global MASTER-Net observations report
  27. GRB 260104A: Swift-XRT refined Analysis
  28. GRB 260104A: Swift detection of a burst
  29. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  30. SVOM GRB260103.08: Global MASTER-Net observations report
  31. EP260101a: Einstein Probe detection of an X-ray transient
  32. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  33. EP251229a: Optical upper limit with Kinder observations
  34. GRB 251230A: Swift-XRT refined Analysis
  35. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  36. GRB 251230A: Swift/UVOT detection
  37. GRB251230A: 7DT optical upper limits
  38. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  39. EP251229a: BOOTES-2 early optical upper limit
  40. GRB 251230A / EP251230a: SVOM/VT optical observation
  41. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  42. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  43. EP251229a: Global MASTER-Net observations report
  44. EP251229a: Einstein Probe detection of an X-ray transient
  45. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  46. Fermi GRB 251228A: Global MASTER-Net observations report
  47. SVOM GRB251227.07: Global MASTER-Net observations report
  48. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  49. IceCube-251225A - IceCube observation of a high-energy neutrino candidate track-like event
  50. GRB 251222A/EP251222b: Optical detection with Kinder observations
  51. EP251222a: Optical upper limit with Kinder observations
  52. GRB 251205A: Kilonova-Catcher optical afterglow detection
  53. EP251220a: CrAO ZTSh optical observations
  54. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  55. Konus-Wind detection of GRB 251222A / EP251222b
  56. GRB 251222A: Swift-XRT afterglow detection
  57. GRB 251222A: 1.3m DFOT optical detection
  58. GRB251221A: 7DT optical upper limits
  59. EP251222b/GRB 251222A: SVOM/GRM observation
  60. EP251222a: Einstein Probe detection of an X-ray transient
  61. EP251221a: Einstein Probe detection of a fast X-ray transient
  62. EP251220a: EP-FXT follow-up observation
  63. EP 251220a: GOTO optical counterpart detection
  64. Swift GRB251221A: Global MASTER-Net observations report
  65. EP251220a: Global MASTER-Net observations report
  66. EP251220a: EP detection of a fast X-ray transient
  67. SVOM GRB251220.98: Global MASTER-Net observations report
  68. GRB 251220B: Fermi GBM Final Real-time Localization
  69. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  70. GRB 251220A: MAXI/GSC detection
  71. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  72. SVOM GRB251219.11: Global MASTER-Net observations report
  73. IceCube-251218A - IceCube observation of a high-energy neutrino candidate track-like event
  74. IceCube Alert 251218.85: Global MASTER-Net observations report
  75. Fermi GRB 251217A: Global MASTER-Net observations report
  76. Fermi GRB 251215A: Global MASTER-Net observations report
  77. EP251214a: Optical upper limit with Kinder observations
  78. EP251214b : Einstein Probe detection of a fast X-ray transient
  79. EP251214b : Einstein Probe detection of a fast X-ray transient
  80. EP251214b (EP trigger 01709250023): LCO optical limits
  81. GRB 251203B: AbAO optical observations
  82. GRB 251214B: Swift-XRT refined Analysis
  83. GRB 251214D: AstroSat CZTI detection of a long burst
  84. GRB 251213A: AstroSat CZTI detection
  85. GRB 251214A: AstroSat CZTI detection
  86. GRB 251214B : MASTER optical afterglow detection
  87. Swift GRB 251214B: Global MASTER-Net observations report
  88. GRB 251214B: Swift detection of a burst with an optical counterpart
  89. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  90. EP251212a: Global MASTER-Net observations report
  91. EP251212a / GRB 251212A: AstroSat CZTI detection
  92. GRB 251211B: AstroSat CZTI detection
  93. Fermi-LAT Gamma-ray Observations of IceCube-251210A
  94. Fermi GRB 251211B: Global MASTER-Net observations report
  95. GRB 251211B: Fermi GBM Final Real-time Localization
  96. GRB 251209A: AstroSat CZTI detection
  97. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  98. EP251130a: Mondy and AbAO optical observations
  99. GRB 251208A: AstroSat CZTI detection
  100. GRB 251208B: Swift-XRT afterglow detection

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