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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"

19586 results found.

  1. GRB 260127A: Prompt enhanced Swift-XRT position
  2. Swift GRB 260127A: Global MASTER-Net observations report
  3. GRB 260127A: Swift detection of a burst
  4. GRB 260125A: Swift-XRT observations
  5. Konus-Wind detection of GRB 260120B
  6. GRB 260125A: Swift ToO observations
  7. GRB 260114A: SVOM/VT optical upper limits
  8. GRB 260122B: Swift-BAT refined analysis
  9. GRB 260120B: SVOM/GRM observation
  10. GRB 260120B: AstroSat CZTI detection
  11. GRB 260114A: Insight-HXMT/HE detection
  12. GRB 260122B: Swift detection of a burst
  13. Swift GRB260122.97: Global MASTER-Net observations report
  14. GRB 260120B: Swift-BAT refined analysis
  15. GRB 260120B: Swift-XRT refined Analysis
  16. GRB 260120B: Fermi GBM Observation
  17. GRB 260120B: Swift/UVOT Detection
  18. GRB 260120B: COLIBRÍ optical upper limits
  19. GRB 260120B: Enhanced Swift-XRT position
  20. GRB 260120B: SVOM/C-GFT optical counterpart detection
  21. GRB 260101A: 239Alferov CubeSat detection
  22. GRB 260120B: Swift detection of a burst
  23. Swift GRB260120B: Global MASTER-Net observations report
  24. GRB 260114A: Swift/UVOT Upper Limits
  25. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  26. GRB 260117A: Swift-XRT afterglow detection
  27. GRB 260117A: ZTSh optical upper limit
  28. Swift GRB260118.48: Global MASTER-Net observations report
  29. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  30. Swift trigger on the HMXB 1A 1118-61
  31. GRB 260117A: SVOM/VT optical candidate
  32. GRB 260117A: SVOM/C-GFT upper limit
  33. GRB 260117A: Swift-XRT observations
  34. GRB 260117A: Swift ToO observations
  35. Swift triggered on the HMXB 1A 1118-61
  36. GRB 260114A: VLT/MUSE spectroscopic observations
  37. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  38. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  39. GRB260114A: STEP/T80S optical limits
  40. GRB 251222A: radio detection with the VLA
  41. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  42. Konus-Wind detection of GRB 260114A
  43. GRB 260114A: Swift-XRT refined Analysis
  44. GRB 260114A: 6 GHz VLA observations
  45. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  46. GRB 260114A : MITSuME Akeno optical upper limits
  47. GRB 260114A: COLIBRÍ optical upper limits
  48. GRB 260114A: TNG NIR upper limit
  49. GRB 260114A: NOT optical observations
  50. Konus-Wind detection of GRB 251230A / EP251230a
  51. GRB 260114A: SVOM/GRM observation of a short burst
  52. Swift GRB 260114A: Global MASTER-Net observations report
  53. GRB 260114A: GECAM-B observation of a short burst
  54. GRB 260114A: Mondy optical observations
  55. GRB 260114A: Fermi GBM observation
  56. GRB 260114A: GMG Optical Observation
  57. GRB 260114A: Swift detection of a short burst
  58. Swift GRB260113.43: Global MASTER-Net observations report
  59. Konus-Wind detection of GRB 260101A
  60. GRB 260111A: Swift-XRT observations
  61. Swift Trigger 1439093: is probably not GRB 260113A
  62. GRB 260111A: COLIBRÍ optical afterglow candidate
  63. GRB 260111A: Fermi GBM Observation
  64. Swift Trigger 1434591 is not a GRB
  65. GRB 260111A: Swift ToO observations
  66. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  67. Swift trigger 1436759 is not an astrophysical event
  68. GRB 260109C: LCO optical upper limits
  69. GRB 260109C: Kilonova-Catcher optical upper limit
  70. Swift Trigger 1434591: possible GRB 260109C
  71. GRB 260102A: Swift-XRT afterglow detection
  72. GRB 260104A: Swift-BAT refined analysis
  73. GRB 260101A: Swift-BAT refined analysis
  74. Swift GRB 251230A: Global MASTER-Net OT detection
  75. Swift GRB 260104A: Global MASTER-Net observations report
  76. GRB 260104A: Swift-XRT refined Analysis
  77. GRB 260104A: Enhanced Swift-XRT position
  78. GRB 260101A: Swift/UVOT Detection
  79. GRB 260104A: Swift detection of a burst
  80. GRB 260102A: LCO optical upper limits
  81. GRB 260102A: Swift-XRT observations
  82. GRB 251230A / EP251230a: GECAM-B detection
  83. GRB 260102A: SVOM/VT optical counterpart
  84. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  85. GRB 260102A: Swift ToO observations
  86. GRB 260101A: Fermi GBM Observation
  87. GRB 260101A: GECAM-B detection
  88. GRB 260101A: NOT spectroscopic observations
  89. GRB 260101A: SVOM/GRM observation
  90. GRB 260101A: Swift-XRT refined Analysis
  91. Swift GRB 260101A: Global MASTER-Net observations report
  92. GRB 260101A: Enhanced Swift-XRT position
  93. GRB 260101A: LCO detection of the optical counterpart
  94. GRB 260101A: Swift detection of a burst with an optical counterpart
  95. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  96. GRB 251230A: GRANDMA/TAROT Early Detection
  97. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  98. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  99. GRB 251230A: 1.3m DFOT optical upper limit
  100. GRB 251230A: Swift-XRT refined Analysis

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