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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"

45893 results found.

  1. GRB 260104A: Swift detection of a burst
  2. GRB 260103A: SVOM/GRM observation of a possible GRB
  3. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  4. GRB 260101A: COLIBRÍ optical observations
  5. SVOM GRB260103.08: Global MASTER-Net observations report
  6. GRB 260102B: Fermi GBM Final Real-time Localization
  7. SVOM GRB260102A: Global MASTER-Net observations report
  8. Fermi GBM Sub-Threshold Detection of GRB 260102A
  9. GRB 260102A: EP-FXT follow-up observation
  10. EP260101a: Global MASTER-Net observations report
  11. GRB 260102A: LCO optical upper limits
  12. GRB 260102A: Swift-XRT observations
  13. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  14. Fermi Gamma-ray Burst Monitor trigger 789047602/260102495 is not a GRB
  15. GRB 251230A / EP251230a: GECAM-B detection
  16. GRB 260102A: SVOM/VT optical counterpart
  17. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  18. GRB 260102A: Swift ToO observations
  19. GRB 260101A: Fermi GBM Observation
  20. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  21. GRB 260102A: SVOM detection of a burst
  22. GRB 260101A: GECAM-B detection
  23. GRB 260101A: NOT spectroscopic observations
  24. GRB 260101A: SVOM/GRM observation
  25. GRB 260101A: Swift-XRT refined Analysis
  26. Swift GRB 260101A: Global MASTER-Net observations report
  27. GRB 260101A: Enhanced Swift-XRT position
  28. EP260101a: Einstein Probe detection of an X-ray transient
  29. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  30. GRB 260101A: LCO detection of the optical counterpart
  31. GRB 260101A: Swift detection of a burst with an optical counterpart
  32. GRB 260101A: Fermi GBM Final Real-time Localization
  33. SVOM GRB251231.57: Global MASTER-Net observations report
  34. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  35. GRB 251230A: GRANDMA/TAROT Early Detection
  36. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  37. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  38. EP251229a: Optical upper limit with Kinder observations
  39. GRB 251230A: 1.3m DFOT optical upper limit
  40. Fermi Gamma-ray Burst Monitor trigger 788833547/251231018 is not a GRB
  41. GRB 251230A: Swift-XRT refined Analysis
  42. GRB 251231A: Fermi GBM Final Real-time Localization
  43. GRB 251222A: Mondy Optical Observations
  44. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  45. GRB 251230A: Swift/UVOT detection
  46. GRB251230A: 7DT optical upper limits
  47. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  48. EP251229a: BOOTES-2 early optical upper limit
  49. GRB 251230A: GOTO optical upper limit
  50. EP251229a: NOT optical upper limits
  51. GRB 251230A / EP251230a: SVOM/VT optical observation
  52. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  53. GRB 251230A: Enhanced Swift-XRT position
  54. GRB 251230A: Early optical counterpart detection by LCO.
  55. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  56. GRB 251230A: Optical Observations via Virtual Telescope Project, Italy
  57. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  58. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  59. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  60. Swift GRB 251230A: Global MASTER-Net observations report
  61. The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
  62. EP251229a: Global MASTER-Net observations report
  63. EP251229a: Einstein Probe detection of an X-ray transient
  64. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  65. GRB 251226A: Glowbug gamma-ray detection
  66. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  67. GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
  68. Fermi GRB 251228A: Global MASTER-Net observations report
  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 Alert 251225.84: Global MASTER-Net observations report
  77. IceCube-251225A - IceCube observation of a high-energy neutrino candidate track-like event
  78. Fermi Gamma-ray Burst Monitor trigger 788368008/251225630 is not a GRB
  79. GRB 251222A: NUTTelA-TAO Early Measurements
  80. GRB 251222A/EP251222b: Optical detection with Kinder observations
  81. EP251222a: Optical upper limit with Kinder observations
  82. GRB 251221A: Swift-BAT refined analysis
  83. GRB 251222A/EP251222b: FTW optical and NIR observations
  84. EP251222a: FTW optical and NIR observations
  85. GRB 251205A: Kilonova-Catcher optical afterglow detection
  86. GRB 251222A: AbAO optical observations
  87. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  88. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  89. EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
  90. GRB 251222A: ZTSH BVRI optical observations
  91. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  92. GRB 251222A: Continued 1.3m DFOT optical observation
  93. EP251220a: 3.6m DOT optical afterglow detection
  94. GRB 251222A: Fermi GBM Observation
  95. EP251220a: CrAO ZTSh optical observations
  96. EP251221a: PRIME upper limit
  97. EP251222a: Global MASTER-Net observations report
  98. GRB 251222A / EP251222b: GECAM-B observation
  99. EP251221a: Liverpool Telescope upper limits
  100. EP251222a: refined analysis of the EP-WXT and EP-FXT observations

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