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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"

19593 results found.

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

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