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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"

27012 results found.

  1. EP260110a: Global MASTER-Net observations report
  2. Fermi GRB 260111A: Global MASTER-Net observations report
  3. GRB 260111A: Fermi GBM Final Real-time Localization
  4. Swift trigger 1436759 is not an astrophysical event
  5. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  6. EP 260110a: COLIBRÍ optical observations
  7. EP260110a: SVOM/C-GFT upper limit
  8. EP260110a: Einstein Probe detection of an X-ray transient
  9. GRB 260109C: LCO optical upper limits
  10. GRB 260109C: Kilonova-Catcher optical upper limit
  11. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  12. Swift Trigger 1434591: possible GRB 260109C
  13. GRB 260109B: Fermi GBM Final Real-time Localization
  14. GRB 260109A: Fermi GBM Final Real-time Localization
  15. GRB 260104A: Swift-BAT refined analysis
  16. GRB 260101A: Swift-BAT refined analysis
  17. Swift GRB 251230A: Global MASTER-Net OT detection
  18. Fermi GRB 260107A: Global MASTER-Net observations report
  19. GRB 260102A: AbAO optical observations
  20. GRB 260107A: Fermi GBM Final Real-time Localization
  21. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  22. The EP-WXT trigger 01709251112 is likely a flaring star
  23. Fermi GRB 260105A: Global MASTER-Net observations report
  24. GRB 260105B: Fermi GBM Detection
  25. EP260105a: FTW optical observations
  26. EP260104a: FTW optical observations
  27. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  28. GRB 260105A: SVOM/GRM observation
  29. GRB 260105B: SVOM/GRM observation
  30. The EP-WXT trigger 01709251028 is likely a flaring star
  31. Fermi GRB 260105B: Global MASTER-Net observations report
  32. EP260105a: SVOM/VT optical upperlimit
  33. GRB 260105B: Fermi GBM Final Real-time Localization
  34. GRB 260105A: Fermi GBM Final Real-time Localization
  35. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  36. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  37. EP260105a: LCO Optical Upper limit
  38. EP260104a: Global MASTER-Net observations report
  39. EP260104a: Einstein Probe detection of a fast X-ray transient
  40. GRB 260101A: COLIBRÍ optical upper limits
  41. EP260105a: Global MASTER-Net observations report
  42. EP260105a: Einstein Probe detection of an X-ray transient
  43. GRB 260104A: COLIBRÍ optical upper limits
  44. GRB 260104C: Fermi GBM Final Real-time Localization
  45. Fermi GRB 260104B: Global MASTER-Net observations report
  46. Swift GRB 260104A: Global MASTER-Net observations report
  47. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  48. GRB 260104A: Swift-XRT refined Analysis
  49. GRB 260101A: Swift/UVOT Detection
  50. GRB 260103A: GECAM-B observation of a burst
  51. GRB 260104B: Fermi GBM Final Localization
  52. GRB 260104A: Swift detection of a burst
  53. GRB 260103A: SVOM/GRM observation of a possible GRB
  54. GRB 260101A: COLIBRÍ optical observations
  55. SVOM GRB260103.08: Global MASTER-Net observations report
  56. GRB 260102B: Fermi GBM Final Real-time Localization
  57. SVOM GRB260102A: Global MASTER-Net observations report
  58. Fermi GBM Sub-Threshold Detection of GRB 260102A
  59. GRB 260102A: EP-FXT follow-up observation
  60. EP260101a: Global MASTER-Net observations report
  61. GRB 260102A: LCO optical upper limits
  62. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  63. Fermi Gamma-ray Burst Monitor trigger 789047602/260102495 is not a GRB
  64. GRB 251230A / EP251230a: GECAM-B detection
  65. GRB 260102A: SVOM/VT optical counterpart
  66. GRB 260101A: Fermi GBM Observation
  67. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  68. GRB 260102A: SVOM detection of a burst
  69. GRB 260101A: GECAM-B detection
  70. GRB 260101A: NOT spectroscopic observations
  71. GRB 260101A: SVOM/GRM observation
  72. GRB 260101A: Swift-XRT refined Analysis
  73. Swift GRB 260101A: Global MASTER-Net observations report
  74. EP260101a: Einstein Probe detection of an X-ray transient
  75. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  76. GRB 260101A: Swift detection of a burst with an optical counterpart
  77. GRB 260101A: Fermi GBM Final Real-time Localization
  78. SVOM GRB251231.57: Global MASTER-Net observations report
  79. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  80. GRB 251230A: GRANDMA/TAROT Early Detection
  81. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  82. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  83. EP251229a: Optical upper limit with Kinder observations
  84. GRB 251230A: 1.3m DFOT optical upper limit
  85. Fermi Gamma-ray Burst Monitor trigger 788833547/251231018 is not a GRB
  86. GRB 251230A: Swift-XRT refined Analysis
  87. GRB 251231A: Fermi GBM Final Real-time Localization
  88. GRB 251222A: Mondy Optical Observations
  89. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  90. GRB 251230A: Swift/UVOT detection
  91. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  92. GRB 251230A: GOTO optical upper limit
  93. EP251229a: NOT optical upper limits
  94. GRB 251230A / EP251230a: SVOM/VT optical observation
  95. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  96. GRB 251230A: Early optical counterpart detection by LCO.
  97. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  98. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  99. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  100. Swift GRB 251230A: Global MASTER-Net observations report

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