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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"

19318 results found.

  1. EP260104a: FTW optical observations
  2. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  3. GRB 260105A: SVOM/GRM observation
  4. GRB 260105B: SVOM/GRM observation
  5. The EP-WXT trigger 01709251028 is likely a flaring star
  6. FRB 20251229A: COLIBRÍ optical upper limits
  7. Fermi GRB 260105B: Global MASTER-Net observations report
  8. EP260105a: SVOM/VT optical upperlimit
  9. GRB 260105B: Fermi GBM Final Real-time Localization
  10. GRB 260105A: Fermi GBM Final Real-time Localization
  11. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  12. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  13. EP260105a: LCO Optical Upper limit
  14. EP260104a: Global MASTER-Net observations report
  15. EP260104a: Einstein Probe detection of a fast X-ray transient
  16. GRB 260101A: COLIBRÍ optical upper limits
  17. EP260105a: Global MASTER-Net observations report
  18. EP260105a: Einstein Probe detection of an X-ray transient
  19. GRB 260103A: Insight-HXMT/HE detection
  20. GRB 260104A: COLIBRÍ optical upper limits
  21. GRB 260104C: Fermi GBM Final Real-time Localization
  22. Fermi GRB 260104B: Global MASTER-Net observations report
  23. Swift GRB 260104A: Global MASTER-Net observations report
  24. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  25. GRB 260104A: Swift-XRT refined Analysis
  26. GRB 260103A: GECAM-B observation of a burst
  27. GRB 260104B: Fermi GBM Final Localization
  28. GRB 260103A: SVOM/GRM observation of a possible GRB
  29. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  30. GRB 260101A: COLIBRÍ optical observations
  31. SVOM GRB260103.08: Global MASTER-Net observations report
  32. GRB 260102B: Fermi GBM Final Real-time Localization
  33. SVOM GRB260102A: Global MASTER-Net observations report
  34. Fermi GBM Sub-Threshold Detection of GRB 260102A
  35. GRB 260102A: EP-FXT follow-up observation
  36. EP260101a: Global MASTER-Net observations report
  37. GRB 260102A: LCO optical upper limits
  38. GRB 260102A: Swift-XRT observations
  39. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  40. Fermi Gamma-ray Burst Monitor trigger 789047602/260102495 is not a GRB
  41. GRB 260102A: SVOM/VT optical counterpart
  42. GRB 260101A: Fermi GBM Observation
  43. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  44. GRB 260102A: SVOM detection of a burst
  45. GRB 260101A: GECAM-B detection
  46. GRB 260101A: NOT spectroscopic observations
  47. GRB 260101A: SVOM/GRM observation
  48. GRB 260101A: Swift-XRT refined Analysis
  49. Swift GRB 260101A: Global MASTER-Net observations report
  50. EP260101a: Einstein Probe detection of an X-ray transient
  51. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  52. GRB 260101A: LCO detection of the optical counterpart
  53. GRB 260101A: Swift detection of a burst with an optical counterpart
  54. GRB 260101A: Fermi GBM Final Real-time Localization
  55. SVOM GRB251231.57: Global MASTER-Net observations report
  56. GRB 251230A: Swift-XRT refined Analysis
  57. GRB251230A: 7DT optical upper limits
  58. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  59. GRB 251230A: Enhanced Swift-XRT position
  60. GRB 251230A: Early optical counterpart detection by LCO.
  61. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  62. Swift GRB 251230A: Global MASTER-Net observations report
  63. EP251229a: Global MASTER-Net observations report
  64. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  65. GRB 251226A: Glowbug gamma-ray detection
  66. Fermi GRB 251228A: Global MASTER-Net observations report
  67. GRB 251226A: GECAM-B detection
  68. SVOM GRB251227.07: Global MASTER-Net observations report
  69. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  70. IceCube Alert 251225.84: Global MASTER-Net observations report
  71. GRB 251222A/EP251222b: Optical detection with Kinder observations
  72. GRB 251221A: Swift-BAT refined analysis
  73. GRB 251222A: AbAO optical observations
  74. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  75. GRB 251222A: Fermi GBM Observation
  76. EP251222a: Global MASTER-Net observations report
  77. EP251221a: Liverpool Telescope upper limits
  78. GRB 251222A: Swift-XRT afterglow detection
  79. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  80. GRB251221A: 7DT optical upper limits
  81. EP251222a: GSP Optical Counterpart Detection
  82. EP251221a: Global MASTER-Net observations report
  83. GRB 251222A: BALROG localization (Fermi Trigger / GRB 251222712)
  84. GRB 251222A: SVOM/VT optical candidate
  85. GRB 251222A: SVOM detection of a long burst
  86. SVOM GRB251222A: Global MASTER-Net observations report
  87. GRB 251221A: Swift-XRT refined Analysis
  88. EP251221a: Einstein Probe detection of a fast X-ray transient
  89. GRB 251221A: Fermi GBM Observation
  90. GRB 251221A: Swift detection of a burst
  91. Swift GRB251221A: Global MASTER-Net observations report
  92. EP251220a: Global MASTER-Net observations report
  93. SVOM GRB251220.98: Global MASTER-Net observations report
  94. GRB 251219A: GECAM-B detection of a possible magnetar X-ray burst from SGR 1830-0645
  95. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  96. GRB 251220A: MAXI/GSC detection
  97. GRB 251215A: Swift-XRT afterglow detection
  98. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  99. IceCube-251218A: COLIBRÍ optical upper limits
  100. SVOM GRB251219.11: Global MASTER-Net observations report

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