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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

42442 results found.

  1. Swift GRB 251230A: Global MASTER-Net OT detection
  2. Fermi GRB 260107A: Global MASTER-Net observations report
  3. GRB 260102A: AbAO optical observations
  4. GRB 260107A: Fermi GBM Final Real-time Localization
  5. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  6. The EP-WXT trigger 01709251112 is likely a flaring star
  7. Fermi GRB 260105A: Global MASTER-Net observations report
  8. GRB 260105B: Fermi GBM Detection
  9. EP260105a: FTW optical observations
  10. EP260104a: FTW optical observations
  11. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  12. GRB 260105A: SVOM/GRM observation
  13. GRB 260105B: SVOM/GRM observation
  14. The EP-WXT trigger 01709251028 is likely a flaring star
  15. FRB 20251229A: COLIBRÍ optical upper limits
  16. Fermi GRB 260105B: Global MASTER-Net observations report
  17. EP260105a: SVOM/VT optical upperlimit
  18. GRB 260105B: Fermi GBM Final Real-time Localization
  19. GRB 260105A: Fermi GBM Final Real-time Localization
  20. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  21. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  22. EP260105a: LCO Optical Upper limit
  23. EP260104a: Global MASTER-Net observations report
  24. EP260104a: Einstein Probe detection of a fast X-ray transient
  25. GRB 260101A: COLIBRÍ optical upper limits
  26. EP260105a: Global MASTER-Net observations report
  27. EP260105a: Einstein Probe detection of an X-ray transient
  28. GRB 260103A: Insight-HXMT/HE detection
  29. GRB 260104A: COLIBRÍ optical upper limits
  30. GRB 260104C: Fermi GBM Final Real-time Localization
  31. Fermi GRB 260104B: Global MASTER-Net observations report
  32. Swift GRB 260104A: Global MASTER-Net observations report
  33. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  34. GRB 260104A: Swift-XRT refined Analysis
  35. GRB 260104A: Enhanced Swift-XRT position
  36. GRB 260101A: Swift/UVOT Detection
  37. GRB 260103A: GECAM-B observation of a burst
  38. GRB 260104B: Fermi GBM Final Localization
  39. GRB 260104A: Swift detection of a burst
  40. GRB 260103A: SVOM/GRM observation of a possible GRB
  41. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  42. GRB 260101A: COLIBRÍ optical observations
  43. SVOM GRB260103.08: Global MASTER-Net observations report
  44. GRB 260102B: Fermi GBM Final Real-time Localization
  45. SVOM GRB260102A: Global MASTER-Net observations report
  46. Fermi GBM Sub-Threshold Detection of GRB 260102A
  47. GRB 260102A: EP-FXT follow-up observation
  48. EP260101a: Global MASTER-Net observations report
  49. GRB 260102A: LCO optical upper limits
  50. GRB 260102A: Swift-XRT observations
  51. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  52. GRB 251230A / EP251230a: GECAM-B detection
  53. GRB 260102A: SVOM/VT optical counterpart
  54. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  55. GRB 260102A: Swift ToO observations
  56. GRB 260101A: Fermi GBM Observation
  57. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  58. GRB 260102A: SVOM detection of a burst
  59. GRB 260101A: GECAM-B detection
  60. GRB 260101A: NOT spectroscopic observations
  61. GRB 260101A: SVOM/GRM observation
  62. GRB 260101A: Swift-XRT refined Analysis
  63. Swift GRB 260101A: Global MASTER-Net observations report
  64. GRB 260101A: Enhanced Swift-XRT position
  65. EP260101a: Einstein Probe detection of an X-ray transient
  66. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  67. GRB 260101A: LCO detection of the optical counterpart
  68. GRB 260101A: Swift detection of a burst with an optical counterpart
  69. GRB 260101A: Fermi GBM Final Real-time Localization
  70. SVOM GRB251231.57: Global MASTER-Net observations report
  71. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  72. GRB 251230A: GRANDMA/TAROT Early Detection
  73. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  74. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  75. EP251229a: Optical upper limit with Kinder observations
  76. GRB 251230A: 1.3m DFOT optical upper limit
  77. GRB 251230A: Swift-XRT refined Analysis
  78. GRB 251231A: Fermi GBM Final Real-time Localization
  79. GRB 251222A: Mondy Optical Observations
  80. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  81. GRB 251230A: Swift/UVOT detection
  82. GRB251230A: 7DT optical upper limits
  83. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  84. EP251229a: BOOTES-2 early optical upper limit
  85. GRB 251230A: GOTO optical upper limit
  86. EP251229a: NOT optical upper limits
  87. GRB 251230A / EP251230a: SVOM/VT optical observation
  88. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  89. GRB 251230A: Enhanced Swift-XRT position
  90. GRB 251230A: Early optical counterpart detection by LCO.
  91. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  92. GRB 251230A: Optical Observations via Virtual Telescope Project, Italy
  93. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  94. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  95. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  96. Swift GRB 251230A: Global MASTER-Net observations report
  97. The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
  98. EP251229a: Global MASTER-Net observations report
  99. EP251229a: Einstein Probe detection of an X-ray transient
  100. GRB 251230A: Swift detection of a burst with a bright optical counterpart

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