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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"

26206 results found.

  1. EP260110a: SVOM/C-GFT upper limit
  2. EP260110a: Einstein Probe detection of an X-ray transient
  3. GRB 260109C: LCO optical upper limits
  4. GRB 260109C: Kilonova-Catcher optical upper limit
  5. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  6. Swift Trigger 1434591: possible GRB 260109C
  7. GRB 260109B: Fermi GBM Final Real-time Localization
  8. GRB 260109A: Fermi GBM Final Real-time Localization
  9. GRB 260104A: Swift-BAT refined analysis
  10. GRB 260101A: Swift-BAT refined analysis
  11. Swift GRB 251230A: Global MASTER-Net OT detection
  12. Fermi GRB 260107A: Global MASTER-Net observations report
  13. GRB 260102A: AbAO optical observations
  14. GRB 260107A: Fermi GBM Final Real-time Localization
  15. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  16. The EP-WXT trigger 01709251112 is likely a flaring star
  17. Fermi GRB 260105A: Global MASTER-Net observations report
  18. GRB 260105B: Fermi GBM Detection
  19. EP260105a: FTW optical observations
  20. EP260104a: FTW optical observations
  21. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  22. GRB 260105A: SVOM/GRM observation
  23. GRB 260105B: SVOM/GRM observation
  24. The EP-WXT trigger 01709251028 is likely a flaring star
  25. Fermi GRB 260105B: Global MASTER-Net observations report
  26. EP260105a: SVOM/VT optical upperlimit
  27. GRB 260105B: Fermi GBM Final Real-time Localization
  28. GRB 260105A: Fermi GBM Final Real-time Localization
  29. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  30. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  31. EP260105a: LCO Optical Upper limit
  32. EP260104a: Global MASTER-Net observations report
  33. EP260104a: Einstein Probe detection of a fast X-ray transient
  34. GRB 260101A: COLIBRÍ optical upper limits
  35. EP260105a: Global MASTER-Net observations report
  36. EP260105a: Einstein Probe detection of an X-ray transient
  37. GRB 260104A: COLIBRÍ optical upper limits
  38. GRB 260104C: Fermi GBM Final Real-time Localization
  39. Fermi GRB 260104B: Global MASTER-Net observations report
  40. Swift GRB 260104A: Global MASTER-Net observations report
  41. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  42. GRB 260104A: Swift-XRT refined Analysis
  43. GRB 260101A: Swift/UVOT Detection
  44. GRB 260103A: GECAM-B observation of a burst
  45. GRB 260104B: Fermi GBM Final Localization
  46. GRB 260104A: Swift detection of a burst
  47. GRB 260103A: SVOM/GRM observation of a possible GRB
  48. GRB 260101A: COLIBRÍ optical observations
  49. SVOM GRB260103.08: Global MASTER-Net observations report
  50. GRB 260102B: Fermi GBM Final Real-time Localization
  51. SVOM GRB260102A: Global MASTER-Net observations report
  52. Fermi GBM Sub-Threshold Detection of GRB 260102A
  53. GRB 260102A: EP-FXT follow-up observation
  54. EP260101a: Global MASTER-Net observations report
  55. GRB 260102A: LCO optical upper limits
  56. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  57. Fermi Gamma-ray Burst Monitor trigger 789047602/260102495 is not a GRB
  58. GRB 251230A / EP251230a: GECAM-B detection
  59. GRB 260102A: SVOM/VT optical counterpart
  60. GRB 260101A: Fermi GBM Observation
  61. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  62. GRB 260102A: SVOM detection of a burst
  63. GRB 260101A: GECAM-B detection
  64. GRB 260101A: NOT spectroscopic observations
  65. GRB 260101A: SVOM/GRM observation
  66. GRB 260101A: Swift-XRT refined Analysis
  67. Swift GRB 260101A: Global MASTER-Net observations report
  68. EP260101a: Einstein Probe detection of an X-ray transient
  69. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  70. GRB 260101A: Swift detection of a burst with an optical counterpart
  71. GRB 260101A: Fermi GBM Final Real-time Localization
  72. SVOM GRB251231.57: Global MASTER-Net observations report
  73. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  74. GRB 251230A: GRANDMA/TAROT Early Detection
  75. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  76. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  77. EP251229a: Optical upper limit with Kinder observations
  78. GRB 251230A: 1.3m DFOT optical upper limit
  79. Fermi Gamma-ray Burst Monitor trigger 788833547/251231018 is not a GRB
  80. GRB 251230A: Swift-XRT refined Analysis
  81. GRB 251231A: Fermi GBM Final Real-time Localization
  82. GRB 251222A: Mondy Optical Observations
  83. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  84. GRB 251230A: Swift/UVOT detection
  85. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  86. GRB 251230A: GOTO optical upper limit
  87. EP251229a: NOT optical upper limits
  88. GRB 251230A / EP251230a: SVOM/VT optical observation
  89. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  90. GRB 251230A: Early optical counterpart detection by LCO.
  91. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  92. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  93. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  94. Swift GRB 251230A: Global MASTER-Net observations report
  95. The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
  96. EP251229a: Global MASTER-Net observations report
  97. EP251229a: Einstein Probe detection of an X-ray transient
  98. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  99. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  100. Fermi GRB 251228A: Global MASTER-Net observations report

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