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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

35932 results found.

  1. GRB 260112B: Fermi GBM Final Real-time Localization
  2. GRB 260111A: Swift ToO observations
  3. GRB 251230A: Mondy Optical Observations
  4. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  5. GRB 260112A: Fermi GBM Final Real-time Localization
  6. Fermi GRB 260111A: Global MASTER-Net observations report
  7. GRB 260111A: Fermi GBM Final Real-time Localization
  8. EP260110a: KAIT optical upper limit
  9. GRB 260109C: LCO optical upper limits
  10. GRB 260109C: Kilonova-Catcher optical upper limit
  11. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  12. Swift Trigger 1434591: possible GRB 260109C
  13. GRB 260109B: Fermi GBM Final Real-time Localization
  14. GRB 260102A: Swift-XRT afterglow detection
  15. GRB 260109A: Fermi GBM Final Real-time Localization
  16. GRB 260104A: Swift-BAT refined analysis
  17. GRB 260101A: Swift-BAT refined analysis
  18. Swift GRB 251230A: Global MASTER-Net OT detection
  19. Fermi GRB 260107A: Global MASTER-Net observations report
  20. GRB 260102A: AbAO optical observations
  21. GRB 260107A: Fermi GBM Final Real-time Localization
  22. Fermi GRB 260105A: Global MASTER-Net observations report
  23. GRB 260105B: Fermi GBM Detection
  24. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  25. GRB 260105A: SVOM/GRM observation
  26. GRB 260105B: SVOM/GRM observation
  27. Fermi GRB 260105B: Global MASTER-Net observations report
  28. GRB 260105B: Fermi GBM Final Real-time Localization
  29. GRB 260105A: Fermi GBM Final Real-time Localization
  30. GRB 260101A: COLIBRÍ optical upper limits
  31. GRB 260103A: Insight-HXMT/HE detection
  32. GRB 260104A: COLIBRÍ optical upper limits
  33. GRB 260104C: Fermi GBM Final Real-time Localization
  34. Fermi GRB 260104B: Global MASTER-Net observations report
  35. Swift GRB 260104A: Global MASTER-Net observations report
  36. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  37. GRB 260104A: Swift-XRT refined Analysis
  38. GRB 260104A: Enhanced Swift-XRT position
  39. GRB 260101A: Swift/UVOT Detection
  40. GRB 260103A: GECAM-B observation of a burst
  41. GRB 260104B: Fermi GBM Final Localization
  42. GRB 260104A: Swift detection of a burst
  43. GRB 260103A: SVOM/GRM observation of a possible GRB
  44. GRB 260101A: COLIBRÍ optical observations
  45. GRB 260102B: Fermi GBM Final Real-time Localization
  46. Fermi GBM Sub-Threshold Detection of GRB 260102A
  47. GRB 260102A: EP-FXT follow-up observation
  48. GRB 260102A: LCO optical upper limits
  49. GRB 260102A: Swift-XRT observations
  50. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  51. Fermi Gamma-ray Burst Monitor trigger 789047602/260102495 is not a GRB
  52. GRB 251230A / EP251230a: GECAM-B detection
  53. GRB 260102A: SVOM/VT optical counterpart
  54. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  55. GRB 260102A: Swift ToO observations
  56. GRB 260101A: Fermi GBM Observation
  57. GRB 260102A: SVOM detection of a burst
  58. GRB 260101A: GECAM-B detection
  59. GRB 260101A: NOT spectroscopic observations
  60. GRB 260101A: SVOM/GRM observation
  61. GRB 260101A: Swift-XRT refined Analysis
  62. Swift GRB 260101A: Global MASTER-Net observations report
  63. GRB 260101A: Enhanced Swift-XRT position
  64. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  65. GRB 260101A: LCO detection of the optical counterpart
  66. GRB 260101A: Swift detection of a burst with an optical counterpart
  67. GRB 260101A: Fermi GBM Final Real-time Localization
  68. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  69. GRB 251230A: GRANDMA/TAROT Early Detection
  70. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  71. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  72. GRB 251230A: 1.3m DFOT optical upper limit
  73. Fermi Gamma-ray Burst Monitor trigger 788833547/251231018 is not a GRB
  74. GRB 251230A: Swift-XRT refined Analysis
  75. GRB 251231A: Fermi GBM Final Real-time Localization
  76. GRB 251222A: Mondy Optical Observations
  77. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  78. GRB 251230A: Swift/UVOT detection
  79. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  80. GRB 251230A: GOTO optical upper limit
  81. GRB 251230A / EP251230a: SVOM/VT optical observation
  82. GRB 251230A: Enhanced Swift-XRT position
  83. GRB 251230A: Early optical counterpart detection by LCO.
  84. GRB 251230A: Optical Observations via Virtual Telescope Project, Italy
  85. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  86. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  87. Swift GRB 251230A: Global MASTER-Net observations report
  88. The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
  89. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  90. GRB 251226A: Glowbug gamma-ray detection
  91. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  92. GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
  93. Fermi GRB 251228A: Global MASTER-Net observations report
  94. GRB 251228A: Fermi GBM Final Real-time Localization
  95. GRB 251226A: SVOM/GRM observation
  96. GRB 251226A: GECAM-B detection
  97. Fermi Gamma-ray Burst Monitor trigger 788368008/251225630 is not a GRB
  98. GRB 251222A: NUTTelA-TAO Early Measurements
  99. GRB 251222A/EP251222b: Optical detection with Kinder observations
  100. GRB 251221A: Swift-BAT refined analysis

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