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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"

38663 results found.

  1. GRB 260104C: Fermi GBM Final Real-time Localization
  2. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  3. GRB 260104A: Swift-XRT refined Analysis
  4. GRB 260104A: Enhanced Swift-XRT position
  5. GRB 260101A: Swift/UVOT Detection
  6. GRB 260103A: GECAM-B observation of a burst
  7. GRB 260104B: Fermi GBM Final Localization
  8. GRB 260104A: Swift detection of a burst
  9. GRB 260103A: SVOM/GRM observation of a possible GRB
  10. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  11. GRB 260101A: COLIBRÍ optical observations
  12. SVOM GRB260103.08: Global MASTER-Net observations report
  13. GRB 260102B: Fermi GBM Final Real-time Localization
  14. SVOM GRB260102A: Global MASTER-Net observations report
  15. Fermi GBM Sub-Threshold Detection of GRB 260102A
  16. GRB 260102A: EP-FXT follow-up observation
  17. GRB 260102A: LCO optical upper limits
  18. GRB 260102A: Swift-XRT observations
  19. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  20. Fermi Gamma-ray Burst Monitor trigger 789047602/260102495 is not a GRB
  21. GRB 251230A / EP251230a: GECAM-B detection
  22. GRB 260102A: SVOM/VT optical counterpart
  23. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  24. GRB 260102A: Swift ToO observations
  25. GRB 260101A: Fermi GBM Observation
  26. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  27. GRB 260102A: SVOM detection of a burst
  28. GRB 260101A: GECAM-B detection
  29. GRB 260101A: NOT spectroscopic observations
  30. GRB 260101A: SVOM/GRM observation
  31. GRB 260101A: Swift-XRT refined Analysis
  32. GRB 260101A: Enhanced Swift-XRT position
  33. EP260101a: Einstein Probe detection of an X-ray transient
  34. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  35. GRB 260101A: LCO detection of the optical counterpart
  36. GRB 260101A: Swift detection of a burst with an optical counterpart
  37. GRB 260101A: Fermi GBM Final Real-time Localization
  38. SVOM GRB251231.57: Global MASTER-Net observations report
  39. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  40. GRB 251230A: GRANDMA/TAROT Early Detection
  41. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  42. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  43. EP251229a: Optical upper limit with Kinder observations
  44. GRB 251230A: 1.3m DFOT optical upper limit
  45. Fermi Gamma-ray Burst Monitor trigger 788833547/251231018 is not a GRB
  46. GRB 251230A: Swift-XRT refined Analysis
  47. GRB 251231A: Fermi GBM Final Real-time Localization
  48. GRB 251222A: Mondy Optical Observations
  49. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  50. GRB 251230A: Swift/UVOT detection
  51. GRB251230A: 7DT optical upper limits
  52. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  53. EP251229a: BOOTES-2 early optical upper limit
  54. GRB 251230A: GOTO optical upper limit
  55. EP251229a: NOT optical upper limits
  56. GRB 251230A / EP251230a: SVOM/VT optical observation
  57. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  58. GRB 251230A: Enhanced Swift-XRT position
  59. GRB 251230A: Early optical counterpart detection by LCO.
  60. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  61. GRB 251230A: Optical Observations via Virtual Telescope Project, Italy
  62. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  63. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  64. EP251229a: Einstein Probe detection of an X-ray transient
  65. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  66. GRB 251226A: Glowbug gamma-ray detection
  67. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  68. GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
  69. The EP-WXT trigger 01709250662 is likely a flaring star
  70. GRB 251228A: Fermi GBM Final Real-time Localization
  71. GRB 251226A: SVOM/GRM observation
  72. GRB 251226A: GECAM-B detection
  73. SVOM GRB251227.07: Global MASTER-Net observations report
  74. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  75. The EP-WXT trigger 01709250617 is likely a flaring star
  76. IceCube-251225A - IceCube observation of a high-energy neutrino candidate track-like event
  77. Fermi Gamma-ray Burst Monitor trigger 788368008/251225630 is not a GRB
  78. GRB 251222A: NUTTelA-TAO Early Measurements
  79. GRB 251222A/EP251222b: Optical detection with Kinder observations
  80. EP251222a: Optical upper limit with Kinder observations
  81. GRB 251205A: Kilonova-Catcher optical afterglow detection
  82. GRB 251222A: AbAO optical observations
  83. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  84. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  85. EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
  86. GRB 251222A: ZTSH BVRI optical observations
  87. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  88. GRB 251222A: Continued 1.3m DFOT optical observation
  89. EP251220a: 3.6m DOT optical afterglow detection
  90. GRB 251222A: Fermi GBM Observation
  91. EP251220a: CrAO ZTSh optical observations
  92. EP251221a: PRIME upper limit
  93. GRB 251222A / EP251222b: GECAM-B observation
  94. EP251221a: Liverpool Telescope upper limits
  95. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  96. EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
  97. Konus-Wind detection of GRB 251222A / EP251222b
  98. GRB 251222A: Swift-XRT afterglow detection
  99. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  100. EP251222a: NTT/ULTRACAM optical observations

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