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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"

26037 results found.

  1. GRB 260117A: Swift-XRT afterglow detection
  2. EP260119a: LCO optical observations
  3. GRB 260117A: ZTSh optical upper limit
  4. Swift GRB260118.48: Global MASTER-Net observations report
  5. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  6. Swift trigger on the HMXB 1A 1118-61
  7. GRB 260117A: SVOM/VT optical candidate
  8. GRB 260117A: SVOM/C-GFT upper limit
  9. GRB 260117A: Swift-XRT observations
  10. GRB 260117A: Swift ToO observations
  11. Swift triggered on the HMXB 1A 1118-61
  12. GRB 260114A: VLT/MUSE spectroscopic observations
  13. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  14. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  15. GRB260114A: STEP/T80S optical limits
  16. GRB 251222A: radio detection with the VLA
  17. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  18. Konus-Wind detection of GRB 260114A
  19. GRB 260114A: Swift-XRT refined Analysis
  20. GRB 260114A: 6 GHz VLA observations
  21. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  22. GRB 260114A : MITSuME Akeno optical upper limits
  23. GRB 260114A: COLIBRÍ optical upper limits
  24. GRB 260114A: TNG NIR upper limit
  25. GRB 260114A: NOT optical observations
  26. Konus-Wind detection of GRB 251230A / EP251230a
  27. GRB 260114A: SVOM/GRM observation of a short burst
  28. Swift GRB 260114A: Global MASTER-Net observations report
  29. GRB 260114A: GECAM-B observation of a short burst
  30. GRB 260114A: Mondy optical observations
  31. GRB 260114A: Fermi GBM observation
  32. GRB 260114A: GMG Optical Observation
  33. GRB 260114A: Swift detection of a short burst
  34. Swift GRB260113.43: Global MASTER-Net observations report
  35. Konus-Wind detection of GRB 260101A
  36. GRB 260111A: Swift-XRT observations
  37. Swift Trigger 1439093: is probably not GRB 260113A
  38. GRB 260111A: COLIBRÍ optical afterglow candidate
  39. GRB 260111A: Fermi GBM Observation
  40. Swift Trigger 1434591 is not a GRB
  41. GRB 260111A: Swift ToO observations
  42. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  43. Swift trigger 1436759 is not an astrophysical event
  44. GRB 260109C: LCO optical upper limits
  45. GRB 260109C: Kilonova-Catcher optical upper limit
  46. Swift Trigger 1434591: possible GRB 260109C
  47. GRB 260102A: Swift-XRT afterglow detection
  48. GRB 260104A: Swift-BAT refined analysis
  49. GRB 260101A: Swift-BAT refined analysis
  50. Swift GRB 251230A: Global MASTER-Net OT detection
  51. GRB 260101A: COLIBRÍ optical upper limits
  52. GRB 260104A: COLIBRÍ optical upper limits
  53. Swift GRB 260104A: Global MASTER-Net observations report
  54. GRB 260104A: Swift-XRT refined Analysis
  55. GRB 260104A: Enhanced Swift-XRT position
  56. GRB 260101A: Swift/UVOT Detection
  57. GRB 260104A: Swift detection of a burst
  58. GRB 260101A: COLIBRÍ optical observations
  59. GRB 260102A: LCO optical upper limits
  60. GRB 260102A: Swift-XRT observations
  61. GRB 251230A / EP251230a: GECAM-B detection
  62. GRB 260102A: SVOM/VT optical counterpart
  63. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  64. GRB 260102A: Swift ToO observations
  65. GRB 260101A: Fermi GBM Observation
  66. GRB 260101A: GECAM-B detection
  67. GRB 260101A: NOT spectroscopic observations
  68. GRB 260101A: SVOM/GRM observation
  69. GRB 260101A: Swift-XRT refined Analysis
  70. Swift GRB 260101A: Global MASTER-Net observations report
  71. GRB 260101A: Enhanced Swift-XRT position
  72. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  73. GRB 260101A: LCO detection of the optical counterpart
  74. GRB 260101A: Swift detection of a burst with an optical counterpart
  75. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  76. GRB 251230A: GRANDMA/TAROT Early Detection
  77. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  78. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  79. GRB 251230A: 1.3m DFOT optical upper limit
  80. GRB 251230A: Swift-XRT refined Analysis
  81. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  82. GRB 251230A: Swift/UVOT detection
  83. GRB251230A: 7DT optical upper limits
  84. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  85. GRB 251230A: GOTO optical upper limit
  86. GRB 251230A / EP251230a: SVOM/VT optical observation
  87. GRB 251230A: Enhanced Swift-XRT position
  88. GRB 251230A: Early optical counterpart detection by LCO.
  89. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  90. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  91. Swift GRB 251230A: Global MASTER-Net observations report
  92. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  93. GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
  94. GRB 251222A/EP251222b: Optical detection with Kinder observations
  95. GRB 251221A: Swift-BAT refined analysis
  96. GRB 251205A: Kilonova-Catcher optical afterglow detection
  97. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  98. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  99. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  100. GRB 251222A: Continued 1.3m DFOT optical observation

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