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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"

35427 results found.

  1. GRB 260117A: Swift-XRT observations
  2. GRB 260117A: Swift ToO observations
  3. GRB 260117A: SVOM detection of a long faint burst
  4. GRB 260115A: GECAM-B observation
  5. GRB 260114A: VLT/MUSE spectroscopic observations
  6. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  7. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  8. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  9. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  10. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  11. Fermi GRB 260115A: Global MASTER-Net observations report
  12. GRB 260115A: Fermi GBM Final Real-time Localization
  13. GRB 251222A: radio detection with the VLA
  14. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  15. Konus-Wind detection of GRB 260114A
  16. GRB 260114A: Swift-XRT refined Analysis
  17. GRB 260114A: 6 GHz VLA observations
  18. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  19. GRB 260114A : MITSuME Akeno optical upper limits
  20. GRB 260114A: COLIBRÍ optical upper limits
  21. GRB 260114A: TNG NIR upper limit
  22. GRB 260114A: NOT optical observations
  23. Konus-Wind detection of GRB 251230A / EP251230a
  24. GRB 260114A: SVOM/GRM observation of a short burst
  25. Swift GRB 260114A: Global MASTER-Net observations report
  26. GRB 260114A: GECAM-B observation of a short burst
  27. GRB 260114A: Mondy optical observations
  28. GRB 260114A: Fermi GBM observation
  29. GRB 260112B: GECAM-B observation
  30. GRB 260114A: GMG Optical Observation
  31. GRB 260114A: Swift detection of a short burst
  32. GRB 260114A: Fermi GBM Final Real-time Localization
  33. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  34. Konus-Wind detection of GRB 260101A
  35. GRB 260111A: Swift-XRT observations
  36. Swift Trigger 1439093: is probably not GRB 260113A
  37. GRB 260111A: COLIBRÍ optical afterglow candidate
  38. GRB 260111A: GECAM-B observation of a burst
  39. GRB 260111A: Fermi GBM Observation
  40. Swift Trigger 1434591 is not a GRB
  41. GRB 260111A: GOTO optical upper limits
  42. GRB 260112B: Fermi GBM Final Real-time Localization
  43. GRB 260111A: Swift ToO observations
  44. GRB 251230A: Mondy Optical Observations
  45. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  46. GRB 260112A: Fermi GBM Final Real-time Localization
  47. Fermi GRB 260111A: Global MASTER-Net observations report
  48. GRB 260111A: Fermi GBM Final Real-time Localization
  49. EP260110a: KAIT optical upper limit
  50. GRB 260109C: LCO optical upper limits
  51. GRB 260109C: Kilonova-Catcher optical upper limit
  52. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  53. Swift Trigger 1434591: possible GRB 260109C
  54. GRB 260109B: Fermi GBM Final Real-time Localization
  55. GRB 260102A: Swift-XRT afterglow detection
  56. GRB 260109A: Fermi GBM Final Real-time Localization
  57. GRB 260104A: Swift-BAT refined analysis
  58. GRB 260101A: Swift-BAT refined analysis
  59. Swift GRB 251230A: Global MASTER-Net OT detection
  60. Fermi GRB 260107A: Global MASTER-Net observations report
  61. GRB 260102A: AbAO optical observations
  62. GRB 260107A: Fermi GBM Final Real-time Localization
  63. Fermi GRB 260105A: Global MASTER-Net observations report
  64. GRB 260105B: Fermi GBM Detection
  65. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  66. GRB 260105A: SVOM/GRM observation
  67. GRB 260105B: SVOM/GRM observation
  68. Fermi GRB 260105B: Global MASTER-Net observations report
  69. GRB 260105B: Fermi GBM Final Real-time Localization
  70. GRB 260105A: Fermi GBM Final Real-time Localization
  71. GRB 260101A: COLIBRÍ optical upper limits
  72. GRB 260103A: Insight-HXMT/HE detection
  73. GRB 260104A: COLIBRÍ optical upper limits
  74. GRB 260104C: Fermi GBM Final Real-time Localization
  75. Fermi GRB 260104B: Global MASTER-Net observations report
  76. Swift GRB 260104A: Global MASTER-Net observations report
  77. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  78. GRB 260104A: Swift-XRT refined Analysis
  79. GRB 260104A: Enhanced Swift-XRT position
  80. GRB 260101A: Swift/UVOT Detection
  81. GRB 260103A: GECAM-B observation of a burst
  82. GRB 260104B: Fermi GBM Final Localization
  83. GRB 260104A: Swift detection of a burst
  84. GRB 260103A: SVOM/GRM observation of a possible GRB
  85. GRB 260101A: COLIBRÍ optical observations
  86. GRB 260102B: Fermi GBM Final Real-time Localization
  87. Fermi GBM Sub-Threshold Detection of GRB 260102A
  88. GRB 260102A: EP-FXT follow-up observation
  89. GRB 260102A: LCO optical upper limits
  90. GRB 260102A: Swift-XRT observations
  91. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  92. Fermi Gamma-ray Burst Monitor trigger 789047602/260102495 is not a GRB
  93. GRB 251230A / EP251230a: GECAM-B detection
  94. GRB 260102A: SVOM/VT optical counterpart
  95. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  96. GRB 260102A: Swift ToO observations
  97. GRB 260101A: Fermi GBM Observation
  98. GRB 260102A: SVOM detection of a burst
  99. GRB 260101A: GECAM-B detection
  100. GRB 260101A: NOT spectroscopic observations

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