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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"

19585 results found.

  1. GRB 260125A: Swift ToO observations
  2. GRB 260114A: SVOM/VT optical upper limits
  3. GRB 260122B: Swift-BAT refined analysis
  4. GRB 260120B: SVOM/GRM observation
  5. GRB 260120B: AstroSat CZTI detection
  6. GRB 260114A: Insight-HXMT/HE detection
  7. GRB 260122B: Swift detection of a burst
  8. Swift GRB260122.97: Global MASTER-Net observations report
  9. GRB 260120B: Swift-BAT refined analysis
  10. GRB 260120B: Swift-XRT refined Analysis
  11. GRB 260120B: Fermi GBM Observation
  12. GRB 260120B: Swift/UVOT Detection
  13. GRB 260120B: COLIBRÍ optical upper limits
  14. GRB 260120B: Enhanced Swift-XRT position
  15. GRB 260120B: SVOM/C-GFT optical counterpart detection
  16. GRB 260101A: 239Alferov CubeSat detection
  17. GRB 260120B: Swift detection of a burst
  18. Swift GRB260120B: Global MASTER-Net observations report
  19. GRB 260114A: Swift/UVOT Upper Limits
  20. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  21. GRB 260117A: Swift-XRT afterglow detection
  22. GRB 260117A: ZTSh optical upper limit
  23. Swift GRB260118.48: Global MASTER-Net observations report
  24. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  25. Swift trigger on the HMXB 1A 1118-61
  26. GRB 260117A: SVOM/VT optical candidate
  27. GRB 260117A: SVOM/C-GFT upper limit
  28. GRB 260117A: Swift-XRT observations
  29. GRB 260117A: Swift ToO observations
  30. Swift triggered on the HMXB 1A 1118-61
  31. GRB 260114A: VLT/MUSE spectroscopic observations
  32. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  33. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  34. GRB260114A: STEP/T80S optical limits
  35. GRB 251222A: radio detection with the VLA
  36. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  37. Konus-Wind detection of GRB 260114A
  38. GRB 260114A: Swift-XRT refined Analysis
  39. GRB 260114A: 6 GHz VLA observations
  40. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  41. GRB 260114A : MITSuME Akeno optical upper limits
  42. GRB 260114A: COLIBRÍ optical upper limits
  43. GRB 260114A: TNG NIR upper limit
  44. GRB 260114A: NOT optical observations
  45. Konus-Wind detection of GRB 251230A / EP251230a
  46. GRB 260114A: SVOM/GRM observation of a short burst
  47. Swift GRB 260114A: Global MASTER-Net observations report
  48. GRB 260114A: GECAM-B observation of a short burst
  49. GRB 260114A: Mondy optical observations
  50. GRB 260114A: Fermi GBM observation
  51. GRB 260114A: GMG Optical Observation
  52. GRB 260114A: Swift detection of a short burst
  53. Swift GRB260113.43: Global MASTER-Net observations report
  54. Konus-Wind detection of GRB 260101A
  55. GRB 260111A: Swift-XRT observations
  56. Swift Trigger 1439093: is probably not GRB 260113A
  57. GRB 260111A: COLIBRÍ optical afterglow candidate
  58. GRB 260111A: Fermi GBM Observation
  59. Swift Trigger 1434591 is not a GRB
  60. GRB 260111A: Swift ToO observations
  61. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  62. Swift trigger 1436759 is not an astrophysical event
  63. GRB 260109C: LCO optical upper limits
  64. GRB 260109C: Kilonova-Catcher optical upper limit
  65. Swift Trigger 1434591: possible GRB 260109C
  66. GRB 260102A: Swift-XRT afterglow detection
  67. GRB 260104A: Swift-BAT refined analysis
  68. GRB 260101A: Swift-BAT refined analysis
  69. Swift GRB 251230A: Global MASTER-Net OT detection
  70. Swift GRB 260104A: Global MASTER-Net observations report
  71. GRB 260104A: Swift-XRT refined Analysis
  72. GRB 260104A: Enhanced Swift-XRT position
  73. GRB 260101A: Swift/UVOT Detection
  74. GRB 260104A: Swift detection of a burst
  75. GRB 260102A: LCO optical upper limits
  76. GRB 260102A: Swift-XRT observations
  77. GRB 251230A / EP251230a: GECAM-B detection
  78. GRB 260102A: SVOM/VT optical counterpart
  79. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  80. GRB 260102A: Swift ToO observations
  81. GRB 260101A: Fermi GBM Observation
  82. GRB 260101A: GECAM-B detection
  83. GRB 260101A: NOT spectroscopic observations
  84. GRB 260101A: SVOM/GRM observation
  85. GRB 260101A: Swift-XRT refined Analysis
  86. Swift GRB 260101A: Global MASTER-Net observations report
  87. GRB 260101A: Enhanced Swift-XRT position
  88. GRB 260101A: LCO detection of the optical counterpart
  89. GRB 260101A: Swift detection of a burst with an optical counterpart
  90. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  91. GRB 251230A: GRANDMA/TAROT Early Detection
  92. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  93. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  94. GRB 251230A: 1.3m DFOT optical upper limit
  95. GRB 251230A: Swift-XRT refined Analysis
  96. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  97. GRB 251230A: Swift/UVOT detection
  98. GRB251230A: 7DT optical upper limits
  99. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  100. GRB 251230A: GOTO optical upper limit

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