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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"

11756 results found.

  1. EP260119a: Global MASTER-Net observations report
  2. GRB 260117A: ZTSh optical upper limit
  3. EP260119a: COLIBRÍ optical counterpart candidate
  4. EP260119a: preliminary result from the EP-FXT observation
  5. GRB 260110A: SVOM detection of a burst through offline search
  6. EP260119a: EP-WXT detection of a fast X-ray transient
  7. Swift GRB260118.48: Global MASTER-Net observations report
  8. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  9. GRB 260117A: SVOM detection of a long faint burst
  10. EP260116a: Einstein Probe detection of an X-ray transient
  11. IceCube Alert 260115.73: Global MASTER-Net observations report
  12. Fermi GRB 260115A: Global MASTER-Net observations report
  13. Konus-Wind detection of GRB 260114A
  14. GRB 260114A: Swift-XRT refined Analysis
  15. Konus-Wind detection of GRB 251230A / EP251230a
  16. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  17. GRB 260114A: Swift detection of a short burst
  18. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  19. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  20. Konus-Wind detection of GRB 260101A
  21. GRB 260112B: Fermi GBM Final Real-time Localization
  22. IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
  23. IceCube Alert 260111A: Global MASTER-Net observations report
  24. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  25. EP260110a: SVOM/C-GFT upper limit
  26. EP260110a: BOOTES-5/JGU optical upper limit
  27. EP260110a: Einstein Probe detection of an X-ray transient
  28. Fermi GRB 260107A: Global MASTER-Net observations report
  29. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  30. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  31. EP260104a: Einstein Probe detection of a fast X-ray transient
  32. EP260105a: Einstein Probe detection of an X-ray transient
  33. Fermi GRB 260104B: Global MASTER-Net observations report
  34. GRB 260104A: Swift-XRT refined Analysis
  35. GRB 260104A: Swift detection of a burst
  36. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  37. SVOM GRB260103.08: Global MASTER-Net observations report
  38. EP260101a: Einstein Probe detection of an X-ray transient
  39. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  40. EP251229a: Optical upper limit with Kinder observations
  41. GRB 251230A: Swift-XRT refined Analysis
  42. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  43. GRB 251230A: Swift/UVOT detection
  44. GRB251230A: 7DT optical upper limits
  45. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  46. EP251229a: BOOTES-2 early optical upper limit
  47. GRB 251230A / EP251230a: SVOM/VT optical observation
  48. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  49. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  50. EP251229a: Global MASTER-Net observations report
  51. EP251229a: Einstein Probe detection of an X-ray transient
  52. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  53. Fermi GRB 251228A: Global MASTER-Net observations report
  54. SVOM GRB251227.07: Global MASTER-Net observations report
  55. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  56. IceCube-251225A - IceCube observation of a high-energy neutrino candidate track-like event
  57. GRB 251222A/EP251222b: Optical detection with Kinder observations
  58. EP251222a: Optical upper limit with Kinder observations
  59. GRB 251205A: Kilonova-Catcher optical afterglow detection
  60. EP251220a: CrAO ZTSh optical observations
  61. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  62. Konus-Wind detection of GRB 251222A / EP251222b
  63. GRB 251222A: Swift-XRT afterglow detection
  64. GRB 251222A: 1.3m DFOT optical detection
  65. GRB251221A: 7DT optical upper limits
  66. EP251222b/GRB 251222A: SVOM/GRM observation
  67. EP251222a: Einstein Probe detection of an X-ray transient
  68. EP251221a: Einstein Probe detection of a fast X-ray transient
  69. EP251220a: EP-FXT follow-up observation
  70. EP 251220a: GOTO optical counterpart detection
  71. Swift GRB251221A: Global MASTER-Net observations report
  72. EP251220a: Global MASTER-Net observations report
  73. EP251220a: EP detection of a fast X-ray transient
  74. SVOM GRB251220.98: Global MASTER-Net observations report
  75. GRB 251220B: Fermi GBM Final Real-time Localization
  76. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  77. GRB 251220A: MAXI/GSC detection
  78. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  79. SVOM GRB251219.11: Global MASTER-Net observations report
  80. IceCube-251218A - IceCube observation of a high-energy neutrino candidate track-like event
  81. IceCube Alert 251218.85: Global MASTER-Net observations report
  82. Fermi GRB 251217A: Global MASTER-Net observations report
  83. Fermi GRB 251215A: Global MASTER-Net observations report
  84. EP251214a: Optical upper limit with Kinder observations
  85. EP251214b : Einstein Probe detection of a fast X-ray transient
  86. EP251214b : Einstein Probe detection of a fast X-ray transient
  87. EP251214b (EP trigger 01709250023): LCO optical limits
  88. GRB 251203B: AbAO optical observations
  89. GRB 251214B: Swift-XRT refined Analysis
  90. GRB 251214D: AstroSat CZTI detection of a long burst
  91. GRB 251213A: AstroSat CZTI detection
  92. GRB 251214A: AstroSat CZTI detection
  93. GRB 251214B : MASTER optical afterglow detection
  94. Swift GRB 251214B: Global MASTER-Net observations report
  95. GRB 251214B: Swift detection of a burst with an optical counterpart
  96. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  97. EP251212a: Global MASTER-Net observations report
  98. EP251212a / GRB 251212A: AstroSat CZTI detection
  99. GRB 251211B: AstroSat CZTI detection
  100. Fermi-LAT Gamma-ray Observations of IceCube-251210A

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