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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"

28059 results found.

  1. GRB 210323A: Enhanced Swift-XRT position
  2. GRB 210323A: NOT optical afterglow candidate
  3. GRB 210323B: Swift/BAT-GUANO detection and possible arcminute localization
  4. GRB 210323A: Nanshan/NEXT optical upper limit
  5. GRB 210323A: Swift detection of a short burst
  6. GRB 210321A: Swift/UVOT Detection
  7. Konus-Wind detection of GRB 210321A
  8. GRB 210318B: Swift/UVOT Upper Limits
  9. GRB 210321A: CrAO optical upper limit
  10. GRB 210321A: Swift-BAT refined analysis
  11. IceCube 135113_19489408.amon: Swift-XRT observations
  12. GRB 210321A: Mondy optical observations
  13. GRB 210321A: Swift-XRT refined Analysis
  14. GRB 210321A: Redshift from OSIRIS/GTC
  15. GRB 210321A: NOT optical afterglow detection and redshift limit
  16. MAXI GRB210320.89: Global MASTER-Net observations report
  17. GRB 210321A: Enhanced Swift-XRT position
  18. GRB 210321A: DDOTI Afterglow Confirmation
  19. GRB 210321A: Swift/UVOT Detection
  20. GRB 210321A: Swift-XRT observations
  21. GRB 210321A: Swift detection of a burst
  22. GRB 210318B: MITSuME Okayama optical upper limits
  23. GRB 201216C: VIRT optical observations
  24. GRB 200524A: Redshift from Gemini-North
  25. GRB 210318A: Swift-BAT refined analysis
  26. GRB 210318A: Swift-XRT refined Analysis
  27. GRB 210318A: Enhanced Swift-XRT position
  28. GRB 210318B: Fermi GBM detection
  29. GRB 210318B: Swift-BAT refined analysis
  30. GRB210318B: Swift detection of a burst
  31. GRB 210318A: Swift detection of a burst
  32. GRB 210317A: GECAM detection
  33. GRB 210306A: GIT optical follow-up
  34. GRB 210226A: GIT optical upper limit
  35. GRB 210312B: A long GRB detected by INTEGRAL
  36. GRB 210306A: LBT observations
  37. GRB 210306A: Tautenburg observations
  38. Konus-Wind detection of GRB 210308A
  39. Konus-Wind detection of GRB 210306A
  40. Konus-Wind detection of GRB 210305A
  41. GRB 210306B: Fermi GBM detection
  42. GRB 210306A: Swift/UVOT Detection
  43. GRB 210306A: continued Mondy optical observations
  44. GRB 210308A: Mondy and AbAO optical observations
  45. GRB 210308A: Swift-BAT refined analysis
  46. GRB 210307A: Swift-BAT refined analysis
  47. GRB 210308A: Swift/UVOT Detection
  48. GRB 210307A: Swift/UVOT Upper Limits
  49. GRB 210305A: Fermi GBM observation
  50. GRB 210308A: Fermi GBM detection
  51. GRB 210305A: Swift-XRT refined Analysis
  52. GRB 210307A: Swift-XRT refined Analysis
  53. GRB 210308A: Nanshan/NEXT optical upper limits
  54. GRB 210306A: Swift-XRT refined Analysis
  55. GRB 210308A: MITSuME Okayama optical upper limits
  56. GRB 210306A: continued Mondy optical observations
  57. GRB 210308A: Swift detection of a burst with an optical counterpart
  58. GRB 210306A: Swift-BAT refined analysis
  59. GRB 210306A: Mondy optical observations
  60. GRB 210305A: Swift/UVOT Upper Limits
  61. GRB 210307B: GECAM detection
  62. GRB 210307A: LCO Optical Upper Limits
  63. GRB 210306B: Swift-BAT refined analysis
  64. GRB 210305A: Swift-BAT refined analysis
  65. GRB 210307A: Swift detection of a burst
  66. GRB 210306A: MITSuME Akeno optical observation
  67. GRB 210306A: NEXT optical observations
  68. GRB 210306A: Fermi GBM observation
  69. GRB 210306A: Tautenburg observations
  70. GRB 210306A: LCO Optical Afterglow Detection
  71. GRB 210306A: iTelescope optical afterglow observations
  72. GRB 210306A: DDOTI Afterglow Confirmation
  73. GRB 210306A: Swift detection of a burst with a bright optical counterpart
  74. GRB 210305A: Swift detection of a burst
  75. GRB 210228B: Insight-HXMT/HE detection
  76. Trigger 1035744: Swift detection of Sco X-1 due to Star Tracker loss of lock
  77. GRB 210217A: 3.6m DOT optical observations
  78. GRB 210226A: Swift/UVOT Upper Limits
  79. Fermi trigger No 636187116: Global MASTER-Net observations report
  80. GRB 210228A: GECAM detection
  81. GRB 210225A: Insight-HXMT/HE detection
  82. Integral GRB210227.19: Global MASTER-Net OT detection
  83. GRB 210226A: Swift-BAT refined analysis
  84. GRB 210226A: Fermi GBM detection
  85. GRB 210217A: Mondy optical observations
  86. GRB 210226A: Swift-XRT refined Analysis
  87. GRB 210218A: Swift-XRT confirmation of afterglow
  88. GRB 210226A: Burke-Gaffney Observatory optical upper limit
  89. GRB 210226A: Enhanced Swift-XRT position
  90. GRB 210222B: 1.3m DFOT Optical upper limit
  91. GRB 210226A: Swift detection of a burst
  92. GRB 210222B: REM observations of the optical/NIR afterglow
  93. GRB 210222B: MITSuME Akeno optical upper limits
  94. GRB 210222B: Zeiss-1000 of Koshka observatory, optical observations
  95. GRB 210222B: VIRT optical detection
  96. GRB 210222B: Swift-BAT refined analysis
  97. GRB 210222B: Swift-XRT refined Analysis
  98. GRB 210222B: Swift/UVOT Detection
  99. GRB 210218A: Swift/UVOT observations
  100. GRB 210217A: Swift/UVOT Detection

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Download all Circulars as a .tar.gz archive (updated once a day):
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