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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"

28118 results found.

  1. GRB 260109C: Kilonova-Catcher optical upper limit
  2. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  3. Swift Trigger 1434591: possible GRB 260109C
  4. GRB 260102A: Swift-XRT afterglow detection
  5. GRB 260104A: Swift-BAT refined analysis
  6. GRB 260101A: Swift-BAT refined analysis
  7. Swift GRB 251230A: Global MASTER-Net OT detection
  8. Fermi GRB 260107A: Global MASTER-Net observations report
  9. GRB 260102A: AbAO optical observations
  10. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  11. Fermi GRB 260105A: Global MASTER-Net observations report
  12. GRB 260105B: Fermi GBM Detection
  13. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  14. GRB 260105A: SVOM/GRM observation
  15. GRB 260105B: SVOM/GRM observation
  16. FRB 20251229A: COLIBRÍ optical upper limits
  17. Fermi GRB 260105B: Global MASTER-Net observations report
  18. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  19. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  20. EP260105a: LCO Optical Upper limit
  21. EP260104a: Global MASTER-Net observations report
  22. EP260104a: Einstein Probe detection of a fast X-ray transient
  23. GRB 260101A: COLIBRÍ optical upper limits
  24. EP260105a: Global MASTER-Net observations report
  25. EP260105a: Einstein Probe detection of an X-ray transient
  26. GRB 260104A: COLIBRÍ optical upper limits
  27. Fermi GRB 260104B: Global MASTER-Net observations report
  28. Swift GRB 260104A: Global MASTER-Net observations report
  29. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  30. GRB 260104A: Swift-XRT refined Analysis
  31. GRB 260104A: Enhanced Swift-XRT position
  32. GRB 260101A: Swift/UVOT Detection
  33. GRB 260103A: GECAM-B observation of a burst
  34. GRB 260104A: Swift detection of a burst
  35. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  36. GRB 260101A: COLIBRÍ optical observations
  37. SVOM GRB260103.08: Global MASTER-Net observations report
  38. SVOM GRB260102A: Global MASTER-Net observations report
  39. Fermi GBM Sub-Threshold Detection of GRB 260102A
  40. GRB 260102A: EP-FXT follow-up observation
  41. EP260101a: Global MASTER-Net observations report
  42. GRB 260102A: LCO optical upper limits
  43. GRB 260102A: Swift-XRT observations
  44. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  45. GRB 260101A: Fermi GBM Observation
  46. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  47. GRB 260102A: SVOM detection of a burst
  48. GRB 260101A: NOT spectroscopic observations
  49. GRB 260101A: SVOM/GRM observation
  50. GRB 260101A: Swift-XRT refined Analysis
  51. Swift GRB 260101A: Global MASTER-Net observations report
  52. GRB 260101A: Enhanced Swift-XRT position
  53. EP260101a: Einstein Probe detection of an X-ray transient
  54. GRB 260101A: LCO detection of the optical counterpart
  55. GRB 260101A: Swift detection of a burst with an optical counterpart
  56. GRB 260101A: Fermi GBM Final Real-time Localization
  57. SVOM GRB251231.57: Global MASTER-Net observations report
  58. GRB 251230A: GRANDMA/TAROT Early Detection
  59. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  60. EP251229a: Optical upper limit with Kinder observations
  61. GRB 251230A: 1.3m DFOT optical upper limit
  62. GRB 251230A: Swift-XRT refined Analysis
  63. GRB 251222A: Mondy Optical Observations
  64. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  65. GRB 251230A: Swift/UVOT detection
  66. GRB251230A: 7DT optical upper limits
  67. GRB 251230A: GOTO optical upper limit
  68. EP251229a: NOT optical upper limits
  69. GRB 251230A / EP251230a: SVOM/VT optical observation
  70. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  71. GRB 251230A: Enhanced Swift-XRT position
  72. GRB 251230A: Early optical counterpart detection by LCO.
  73. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  74. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  75. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  76. Swift GRB 251230A: Global MASTER-Net observations report
  77. EP251229a: Global MASTER-Net observations report
  78. EP251229a: Einstein Probe detection of an X-ray transient
  79. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  80. GRB 251226A: Glowbug gamma-ray detection
  81. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  82. Fermi GRB 251228A: Global MASTER-Net observations report
  83. GRB 251226A: SVOM/GRM observation
  84. GRB 251226A: GECAM-B detection
  85. SVOM GRB251227.07: Global MASTER-Net observations report
  86. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  87. IceCube Alert 251225.84: Global MASTER-Net observations report
  88. GRB 251222A/EP251222b: Optical detection with Kinder observations
  89. EP251222a: Optical upper limit with Kinder observations
  90. GRB 251221A: Swift-BAT refined analysis
  91. GRB 251205A: Kilonova-Catcher optical afterglow detection
  92. GRB 251222A: AbAO optical observations
  93. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  94. GRB 251222A: ZTSH BVRI optical observations
  95. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  96. GRB 251222A: Continued 1.3m DFOT optical observation
  97. EP251220a: 3.6m DOT optical afterglow detection
  98. GRB 251222A: Fermi GBM Observation
  99. EP251220a: CrAO ZTSh optical observations
  100. EP251221a: PRIME upper limit

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