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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"

2994 results found.

  1. EP260321a: CMO SAI J,K observations
  2. GRB 260414A: Fermi GBM Final Real-time Localization
  3. Fermi GRB 260412A: Global MASTER-Net observations report
  4. GRB 260410B: Fermi GBM Observation
  5. GRB 260411B: Fermi GBM Final Real-time Localization
  6. GRB 260410A: COLIBRÍ optical upper limit
  7. EP260329a: COLIBRÍ optical upper limit
  8. EP260329a: EP-FXT follow up observation
  9. EP-WXT trigger 01709259209: TRT optical counterpart detection
  10. EP260327a: SVOM/VT optical upper limits
  11. EP260327a: Global MASTER-Net observations report
  12. The EP-WXT trigger 01709259045 is likely a flaring star
  13. GRB 260318A: Fermi GBM Final Real-time Localization
  14. IceCube-260315A: No Candidate Transients from the Zwicky Transient Facility
  15. Fermi trigger No 795185313: Global MASTER-Net observations report
  16. Fermi GRB 260313A: Global MASTER-Net observations report
  17. Fermi GRB 260310A: Global MASTER-Net observations report
  18. GRB 260307B: SVOM/C-GFT upper limit
  19. GRB 260303A: SVOM/ECLAIRs refined analysis
  20. Fermi GRB 260305A: Global MASTER-Net observations report
  21. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  22. GRB 260303A: SVOM detection of a burst
  23. GRB 260302A: Fermi GBM Final Real-time Localization
  24. EP260227a: Mephisto optical detection
  25. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  26. Fermi GRB 260226A: Global MASTER-Net observations report
  27. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  28. Fermi GRB 260221B: Global MASTER-Net observations report
  29. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  30. Fermi GRB 260219A: Global MASTER-Net observations report
  31. IPN triangulation of GRB 260212A
  32. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  33. GRB 260204A: SVOM/ECLAIRs refined analysis
  34. Fermi GRB 260209A: Global MASTER-Net observations report
  35. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  36. LAT GRB 260208B: Global MASTER-Net observations report
  37. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  38. GRB 260206A: Swift-XRT observations
  39. Fermi trigger No 792135758: Global MASTER-Net observations report
  40. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  41. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  42. EP260131a: SVOM/VT optical observation
  43. GRB 260130A: Fermi GBM Detection
  44. GRB 260127B: Fermi GBM Detection
  45. Fermi GRB 260129A: Global MASTER-Net observations report
  46. IceCube-260125A: No Candidate Transients from the Zwicky Transient Facility
  47. Fermi GRB 260127B: Global MASTER-Net observations report
  48. Swift GRB 260127A: Global MASTER-Net observations report
  49. GRB 260114A: SVOM/VT optical upper limits
  50. IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
  51. EP260116a: COLIBRÍ further observations
  52. SVOM GRB260121.06: Global MASTER-Net observations report
  53. SVOM GRB260119.90: Global MASTER-Net observations report
  54. EP260119a: Global MASTER-Net observations report
  55. SVOM GRB260117.82: Global MASTER-Net observations report
  56. GRB 260117A: SVOM/C-GFT upper limit
  57. GRB 251222A: radio detection with the VLA
  58. Konus-Wind detection of GRB 251230A / EP251230a
  59. GRB 260112A: Fermi GBM Final Real-time Localization
  60. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  61. Swift Trigger 1434591: possible GRB 260109C
  62. Fermi GRB 260107A: Global MASTER-Net observations report
  63. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  64. The EP-WXT trigger 01709251112 is likely a flaring star
  65. GRB 260105B: Fermi GBM Detection
  66. GRB 260105A: SVOM/GRM observation
  67. The EP-WXT trigger 01709251028 is likely a flaring star
  68. GRB 260105A: Fermi GBM Final Real-time Localization
  69. EP260104a: Global MASTER-Net observations report
  70. EP260105a: Global MASTER-Net observations report
  71. Fermi GRB 260104B: Global MASTER-Net observations report
  72. GRB 260101A: COLIBRÍ optical observations
  73. SVOM GRB260103.08: Global MASTER-Net observations report
  74. GRB 260102B: Fermi GBM Final Real-time Localization
  75. GRB 260102A: EP-FXT follow-up observation
  76. GRB 260101A: NOT spectroscopic observations
  77. Fermi GRB 251228A: Global MASTER-Net observations report
  78. GRB 251228A: Fermi GBM Final Real-time Localization
  79. SVOM GRB251227.07: Global MASTER-Net observations report
  80. GRB 251222A / EP251222b: GOTO optical counterpart detection
  81. IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
  82. GRB 251222A: SVOM/VT optical candidate
  83. SVOM GRB251219.11: Global MASTER-Net observations report
  84. Fermi trigger No 787736968: Global MASTER-Net observations report
  85. Fermi GRB 251216A: Global MASTER-Net observations report
  86. Fermi GRB 251215A: Global MASTER-Net observations report
  87. EP251214a: Global MASTER-Net observations report
  88. Fermi GRB 251214A: Global MASTER-Net observations report
  89. EP251212a: Global MASTER-Net observations report
  90. IceCube-251210A: No Candidate Transients from the Zwicky Transient Facility
  91. Fermi GBM Sub-Threshold Detection of GRB 251205A
  92. Fermi GRB 251208C: Global MASTER-Net observations report
  93. SVOM GRB251208D: Global MASTER-Net observations report
  94. GRB 251205A: COLIBRÍ optical observations
  95. GRB 251205A: Swift detection of a burst with an optical afterglow
  96. GRB 251203C: EP-FXT follow-up observation
  97. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  98. EP251130a: MAO/AZT-22 optical observations
  99. GRB 251201B: Swift detection of a burst with an optical counterpart
  100. EP251130a: SAO RAS optical observations

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