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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"

12094 results found.

  1. GRB 260120B: Fermi GBM Final Real-time Localization
  2. Fermi trigger No 790601190: Global MASTER-Net observations report
  3. Fermi trigger No 790570272: Global MASTER-Net observations report
  4. GRB 260120A: Fermi GBM Final Real-time Localization
  5. EP260119a: update of EP-FXT follow-up observation
  6. SVOM GRB260119.90: Global MASTER-Net observations report
  7. EP260116a: COLIBRÍ detection of a fading optical source
  8. EP260119a: Global MASTER-Net observations report
  9. GRB 260117A: ZTSh optical upper limit
  10. EP260119a: COLIBRÍ optical counterpart candidate
  11. EP260119a: preliminary result from the EP-FXT observation
  12. GRB 260110A: SVOM detection of a burst through offline search
  13. EP260119a: EP-WXT detection of a fast X-ray transient
  14. Swift GRB260118.48: Global MASTER-Net observations report
  15. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  16. GRB 260117A: SVOM detection of a long faint burst
  17. EP260116a: Einstein Probe detection of an X-ray transient
  18. IceCube Alert 260115.73: Global MASTER-Net observations report
  19. Fermi GRB 260115A: Global MASTER-Net observations report
  20. Konus-Wind detection of GRB 260114A
  21. GRB 260114A: Swift-XRT refined Analysis
  22. Konus-Wind detection of GRB 251230A / EP251230a
  23. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  24. GRB 260114A: Swift detection of a short burst
  25. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  26. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  27. Konus-Wind detection of GRB 260101A
  28. GRB 260112B: Fermi GBM Final Real-time Localization
  29. IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
  30. IceCube Alert 260111A: Global MASTER-Net observations report
  31. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  32. EP260110a: SVOM/C-GFT upper limit
  33. EP260110a: BOOTES-5/JGU optical upper limit
  34. EP260110a: Einstein Probe detection of an X-ray transient
  35. Fermi GRB 260107A: Global MASTER-Net observations report
  36. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  37. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  38. EP260104a: Einstein Probe detection of a fast X-ray transient
  39. EP260105a: Einstein Probe detection of an X-ray transient
  40. Fermi GRB 260104B: Global MASTER-Net observations report
  41. GRB 260104A: Swift-XRT refined Analysis
  42. GRB 260104A: Swift detection of a burst
  43. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  44. SVOM GRB260103.08: Global MASTER-Net observations report
  45. EP260101a: Einstein Probe detection of an X-ray transient
  46. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  47. EP251229a: Optical upper limit with Kinder observations
  48. GRB 251230A: Swift-XRT refined Analysis
  49. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  50. GRB 251230A: Swift/UVOT detection
  51. GRB251230A: 7DT optical upper limits
  52. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  53. EP251229a: BOOTES-2 early optical upper limit
  54. GRB 251230A / EP251230a: SVOM/VT optical observation
  55. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  56. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  57. EP251229a: Global MASTER-Net observations report
  58. EP251229a: Einstein Probe detection of an X-ray transient
  59. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  60. Fermi GRB 251228A: Global MASTER-Net observations report
  61. SVOM GRB251227.07: Global MASTER-Net observations report
  62. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  63. IceCube-251225A - IceCube observation of a high-energy neutrino candidate track-like event
  64. GRB 251222A/EP251222b: Optical detection with Kinder observations
  65. EP251222a: Optical upper limit with Kinder observations
  66. GRB 251205A: Kilonova-Catcher optical afterglow detection
  67. EP251220a: CrAO ZTSh optical observations
  68. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  69. Konus-Wind detection of GRB 251222A / EP251222b
  70. GRB 251222A: Swift-XRT afterglow detection
  71. GRB 251222A: 1.3m DFOT optical detection
  72. GRB251221A: 7DT optical upper limits
  73. EP251222b/GRB 251222A: SVOM/GRM observation
  74. EP251222a: Einstein Probe detection of an X-ray transient
  75. EP251221a: Einstein Probe detection of a fast X-ray transient
  76. EP251220a: EP-FXT follow-up observation
  77. EP 251220a: GOTO optical counterpart detection
  78. Swift GRB251221A: Global MASTER-Net observations report
  79. EP251220a: Global MASTER-Net observations report
  80. EP251220a: EP detection of a fast X-ray transient
  81. SVOM GRB251220.98: Global MASTER-Net observations report
  82. GRB 251220B: Fermi GBM Final Real-time Localization
  83. GRB 251219A: GECAM-B detection of a possible magnetar X-ray burst from SGR 1830-0645
  84. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  85. GRB 251220A: MAXI/GSC detection
  86. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  87. SVOM GRB251219.11: Global MASTER-Net observations report
  88. IceCube-251218A - IceCube observation of a high-energy neutrino candidate track-like event
  89. IceCube Alert 251218.85: Global MASTER-Net observations report
  90. Fermi GRB 251217A: Global MASTER-Net observations report
  91. Fermi GRB 251215A: Global MASTER-Net observations report
  92. EP251214a: Optical upper limit with Kinder observations
  93. EP251214b : Einstein Probe detection of a fast X-ray transient
  94. EP251214b : Einstein Probe detection of a fast X-ray transient
  95. EP251214b (EP trigger 01709250023): LCO optical limits
  96. GRB 251203B: AbAO optical observations
  97. GRB 251214B: Swift-XRT refined Analysis
  98. GRB 251214D: AstroSat CZTI detection of a long burst
  99. GRB 251213A: AstroSat CZTI detection
  100. GRB 251214A: AstroSat CZTI detection

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