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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"
  1. GRB 260104C: Fermi GBM Final Real-time Localization
  2. Fermi GRB 260104B: Global MASTER-Net observations report
  3. Swift GRB 260104A: Global MASTER-Net observations report
  4. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  5. GRB 260104A: Swift-XRT refined Analysis
  6. GRB 260104A: Enhanced Swift-XRT position
  7. GRB 260101A: Swift/UVOT Detection
  8. GRB 260103A: GECAM-B observation of a burst
  9. GRB 260104B: Fermi GBM Final Localization
  10. GRB 260104A: Swift detection of a burst
  11. GRB 260103A: SVOM/GRM observation of a possible GRB
  12. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  13. GRB 260101A: COLIBRÍ optical observations
  14. SVOM GRB260103.08: Global MASTER-Net observations report
  15. GRB 260102B: Fermi GBM Final Real-time Localization
  16. SVOM GRB260102A: Global MASTER-Net observations report
  17. Fermi GBM Sub-Threshold Detection of GRB 260102A
  18. GRB 260102A: EP-FXT follow-up observation
  19. EP260101a: Global MASTER-Net observations report
  20. GRB 260102A: LCO optical upper limits
  21. GRB 260102A: Swift-XRT observations
  22. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  23. Fermi Gamma-ray Burst Monitor trigger 789047602/260102495 is not a GRB
  24. GRB 251230A / EP251230a: GECAM-B detection
  25. GRB 260102A: SVOM/VT optical counterpart
  26. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  27. GRB 260102A: Swift ToO observations
  28. GRB 260101A: Fermi GBM Observation
  29. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  30. GRB 260102A: SVOM detection of a burst
  31. GRB 260101A: GECAM-B detection
  32. GRB 260101A: NOT spectroscopic observations
  33. GRB 260101A: SVOM/GRM observation
  34. GRB 260101A: Swift-XRT refined Analysis
  35. Swift GRB 260101A: Global MASTER-Net observations report
  36. GRB 260101A: Enhanced Swift-XRT position
  37. EP260101a: Einstein Probe detection of an X-ray transient
  38. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  39. GRB 260101A: LCO detection of the optical counterpart
  40. GRB 260101A: Swift detection of a burst with an optical counterpart
  41. GRB 260101A: Fermi GBM Final Real-time Localization
  42. SVOM GRB251231.57: Global MASTER-Net observations report
  43. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  44. GRB 251230A: GRANDMA/TAROT Early Detection
  45. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  46. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  47. EP251229a: Optical upper limit with Kinder observations
  48. GRB 251230A: 1.3m DFOT optical upper limit
  49. Fermi Gamma-ray Burst Monitor trigger 788833547/251231018 is not a GRB
  50. GRB 251230A: Swift-XRT refined Analysis
  51. GRB 251231A: Fermi GBM Final Real-time Localization
  52. GRB 251222A: Mondy Optical Observations
  53. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  54. GRB 251230A: Swift/UVOT detection
  55. GRB251230A: 7DT optical upper limits
  56. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  57. EP251229a: BOOTES-2 early optical upper limit
  58. GRB 251230A: GOTO optical upper limit
  59. EP251229a: NOT optical upper limits
  60. GRB 251230A / EP251230a: SVOM/VT optical observation
  61. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  62. GRB 251230A: Enhanced Swift-XRT position
  63. GRB 251230A: Early optical counterpart detection by LCO.
  64. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  65. GRB 251230A: Optical Observations via Virtual Telescope Project, Italy
  66. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  67. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  68. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  69. Swift GRB 251230A: Global MASTER-Net observations report
  70. The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
  71. EP251229a: Global MASTER-Net observations report
  72. EP251229a: Einstein Probe detection of an X-ray transient
  73. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  74. GRB 251226A: Glowbug gamma-ray detection
  75. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  76. GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
  77. Fermi GRB 251228A: Global MASTER-Net observations report
  78. The EP-WXT trigger 01709250662 is likely a flaring star
  79. GRB 251228A: Fermi GBM Final Real-time Localization
  80. GRB 251226A: SVOM/GRM observation
  81. GRB 251226A: GECAM-B detection
  82. SVOM GRB251227.07: Global MASTER-Net observations report
  83. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  84. The EP-WXT trigger 01709250617 is likely a flaring star
  85. IceCube Alert 251225.84: Global MASTER-Net observations report
  86. IceCube-251225A - IceCube observation of a high-energy neutrino candidate track-like event
  87. Fermi Gamma-ray Burst Monitor trigger 788368008/251225630 is not a GRB
  88. GRB 251222A: NUTTelA-TAO Early Measurements
  89. GRB 251222A/EP251222b: Optical detection with Kinder observations
  90. EP251222a: Optical upper limit with Kinder observations
  91. GRB 251221A: Swift-BAT refined analysis
  92. GRB 251222A/EP251222b: FTW optical and NIR observations
  93. EP251222a: FTW optical and NIR observations
  94. GRB 251205A: Kilonova-Catcher optical afterglow detection
  95. GRB 251222A: AbAO optical observations
  96. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  97. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  98. EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
  99. GRB 251222A: ZTSH BVRI optical observations
  100. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations

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