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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"

45596 results found.

  1. GRB 260101A: Swift/UVOT Detection
  2. GRB 260103A: GECAM-B observation of a burst
  3. GRB 260104B: Fermi GBM Final Localization
  4. GRB 260104A: Swift detection of a burst
  5. GRB 260103A: SVOM/GRM observation of a possible GRB
  6. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  7. GRB 260101A: COLIBRÍ optical observations
  8. SVOM GRB260103.08: Global MASTER-Net observations report
  9. GRB 260102B: Fermi GBM Final Real-time Localization
  10. SVOM GRB260102A: Global MASTER-Net observations report
  11. Fermi GBM Sub-Threshold Detection of GRB 260102A
  12. GRB 260102A: EP-FXT follow-up observation
  13. EP260101a: Global MASTER-Net observations report
  14. GRB 260102A: LCO optical upper limits
  15. GRB 260102A: Swift-XRT observations
  16. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  17. Fermi Gamma-ray Burst Monitor trigger 789047602/260102495 is not a GRB
  18. GRB 251230A / EP251230a: GECAM-B detection
  19. GRB 260102A: SVOM/VT optical counterpart
  20. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  21. GRB 260102A: Swift ToO observations
  22. GRB 260101A: Fermi GBM Observation
  23. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  24. GRB 260102A: SVOM detection of a burst
  25. GRB 260101A: GECAM-B detection
  26. GRB 260101A: NOT spectroscopic observations
  27. GRB 260101A: SVOM/GRM observation
  28. GRB 260101A: Swift-XRT refined Analysis
  29. Swift GRB 260101A: Global MASTER-Net observations report
  30. GRB 260101A: Enhanced Swift-XRT position
  31. EP260101a: Einstein Probe detection of an X-ray transient
  32. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  33. GRB 260101A: LCO detection of the optical counterpart
  34. GRB 260101A: Swift detection of a burst with an optical counterpart
  35. GRB 260101A: Fermi GBM Final Real-time Localization
  36. SVOM GRB251231.57: Global MASTER-Net observations report
  37. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  38. GRB 251230A: GRANDMA/TAROT Early Detection
  39. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  40. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  41. EP251229a: Optical upper limit with Kinder observations
  42. GRB 251230A: 1.3m DFOT optical upper limit
  43. Fermi Gamma-ray Burst Monitor trigger 788833547/251231018 is not a GRB
  44. GRB 251230A: Swift-XRT refined Analysis
  45. GRB 251231A: Fermi GBM Final Real-time Localization
  46. GRB 251222A: Mondy Optical Observations
  47. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  48. GRB 251230A: Swift/UVOT detection
  49. GRB251230A: 7DT optical upper limits
  50. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  51. EP251229a: BOOTES-2 early optical upper limit
  52. GRB 251230A: GOTO optical upper limit
  53. EP251229a: NOT optical upper limits
  54. GRB 251230A / EP251230a: SVOM/VT optical observation
  55. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  56. GRB 251230A: Enhanced Swift-XRT position
  57. GRB 251230A: Early optical counterpart detection by LCO.
  58. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  59. GRB 251230A: Optical Observations via Virtual Telescope Project, Italy
  60. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  61. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  62. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  63. Swift GRB 251230A: Global MASTER-Net observations report
  64. The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
  65. EP251229a: Global MASTER-Net observations report
  66. EP251229a: Einstein Probe detection of an X-ray transient
  67. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  68. GRB 251226A: Glowbug gamma-ray detection
  69. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  70. GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
  71. Fermi GRB 251228A: Global MASTER-Net observations report
  72. The EP-WXT trigger 01709250662 is likely a flaring star
  73. GRB 251228A: Fermi GBM Final Real-time Localization
  74. GRB 251226A: SVOM/GRM observation
  75. GRB 251226A: GECAM-B detection
  76. SVOM GRB251227.07: Global MASTER-Net observations report
  77. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  78. The EP-WXT trigger 01709250617 is likely a flaring star
  79. IceCube Alert 251225.84: Global MASTER-Net observations report
  80. IceCube-251225A - IceCube observation of a high-energy neutrino candidate track-like event
  81. Fermi Gamma-ray Burst Monitor trigger 788368008/251225630 is not a GRB
  82. GRB 251222A: NUTTelA-TAO Early Measurements
  83. GRB 251222A/EP251222b: Optical detection with Kinder observations
  84. EP251222a: Optical upper limit with Kinder observations
  85. GRB 251221A: Swift-BAT refined analysis
  86. GRB 251222A/EP251222b: FTW optical and NIR observations
  87. EP251222a: FTW optical and NIR observations
  88. GRB 251205A: Kilonova-Catcher optical afterglow detection
  89. GRB 251222A: AbAO optical observations
  90. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  91. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  92. EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
  93. GRB 251222A: ZTSH BVRI optical observations
  94. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  95. GRB 251222A: Continued 1.3m DFOT optical observation
  96. EP251220a: 3.6m DOT optical afterglow detection
  97. GRB 251222A: Fermi GBM Observation
  98. EP251220a: CrAO ZTSh optical observations
  99. EP251221a: PRIME upper limit
  100. EP251222a: Global MASTER-Net observations report

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