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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"

26332 results found.

  1. GRB 210318B: Fermi GBM detection
  2. GRB 210318B: Swift-BAT refined analysis
  3. GRB210318B: Swift detection of a burst
  4. GRB 210318A: Swift detection of a burst
  5. GRB 210317A: GECAM detection
  6. GRB 210306A: GIT optical follow-up
  7. GRB 210226A: GIT optical upper limit
  8. GRB 210312B: A long GRB detected by INTEGRAL
  9. GRB 210306A: LBT observations
  10. GRB 210306A: Tautenburg observations
  11. Konus-Wind detection of GRB 210308A
  12. Konus-Wind detection of GRB 210306A
  13. Konus-Wind detection of GRB 210305A
  14. GRB 210306B: Fermi GBM detection
  15. GRB 210306A: Swift/UVOT Detection
  16. GRB 210306A: continued Mondy optical observations
  17. GRB 210308A: Mondy and AbAO optical observations
  18. GRB 210308A: Swift-BAT refined analysis
  19. GRB 210307A: Swift-BAT refined analysis
  20. GRB 210308A: Swift/UVOT Detection
  21. GRB 210307A: Swift/UVOT Upper Limits
  22. GRB 210305A: Fermi GBM observation
  23. GRB 210308A: Fermi GBM detection
  24. GRB 210305A: Swift-XRT refined Analysis
  25. GRB 210307A: Swift-XRT refined Analysis
  26. GRB 210308A: Nanshan/NEXT optical upper limits
  27. GRB 210306A: Swift-XRT refined Analysis
  28. GRB 210308A: MITSuME Okayama optical upper limits
  29. GRB 210306A: continued Mondy optical observations
  30. GRB 210308A: Swift detection of a burst with an optical counterpart
  31. GRB 210306A: Swift-BAT refined analysis
  32. GRB 210306A: Mondy optical observations
  33. GRB 210305A: Swift/UVOT Upper Limits
  34. GRB 210307B: GECAM detection
  35. GRB 210307A: LCO Optical Upper Limits
  36. GRB 210306B: Swift-BAT refined analysis
  37. GRB 210305A: Swift-BAT refined analysis
  38. GRB 210307A: Swift detection of a burst
  39. GRB 210306A: MITSuME Akeno optical observation
  40. GRB 210306A: NEXT optical observations
  41. GRB 210306A: Fermi GBM observation
  42. GRB 210306A: Tautenburg observations
  43. GRB 210306A: LCO Optical Afterglow Detection
  44. GRB 210306A: iTelescope optical afterglow observations
  45. GRB 210306A: DDOTI Afterglow Confirmation
  46. GRB 210306A: Swift detection of a burst with a bright optical counterpart
  47. GRB 210305A: Swift detection of a burst
  48. GRB 210228B: Insight-HXMT/HE detection
  49. Trigger 1035744: Swift detection of Sco X-1 due to Star Tracker loss of lock
  50. GRB 210217A: 3.6m DOT optical observations
  51. GRB 210226A: Swift/UVOT Upper Limits
  52. Fermi trigger No 636187116: Global MASTER-Net observations report
  53. GRB 210228A: GECAM detection
  54. GRB 210225A: Insight-HXMT/HE detection
  55. Integral GRB210227.19: Global MASTER-Net OT detection
  56. GRB 210226A: Swift-BAT refined analysis
  57. GRB 210226A: Fermi GBM detection
  58. GRB 210217A: Mondy optical observations
  59. GRB 210226A: Swift-XRT refined Analysis
  60. GRB 210218A: Swift-XRT confirmation of afterglow
  61. GRB 210226A: Burke-Gaffney Observatory optical upper limit
  62. GRB 210226A: Enhanced Swift-XRT position
  63. GRB 210222B: 1.3m DFOT Optical upper limit
  64. GRB 210226A: Swift detection of a burst
  65. GRB 210222B: REM observations of the optical/NIR afterglow
  66. GRB 210222B: MITSuME Akeno optical upper limits
  67. GRB 210222B: Zeiss-1000 of Koshka observatory, optical observations
  68. GRB 210222B: VIRT optical detection
  69. GRB 210222B: Swift-BAT refined analysis
  70. GRB 210222B: Swift-XRT refined Analysis
  71. GRB 210222B: Swift/UVOT Detection
  72. GRB 210218A: Swift/UVOT observations
  73. GRB 210217A: Swift/UVOT Detection
  74. GRB 210222B: MASTER OT observation
  75. GRB 210222B: Redshift from FORS2/VLT
  76. GRB 210222B: NEXT early optical afterglow observations
  77. GRB 210222B: GOTO confirmation of afterglow detection (correction to GCN29548)
  78. GRB 210222B: Liverpool Telescope optical detection
  79. GRB 210222B: GOTO confirmation of afterglow detection
  80. GRB210222B: LCO Optical Afterglow Detection
  81. GRB210222B: BOOTES-1 optical afterglow detection
  82. GRB 210222B: Swift detection of a burst with an optical counterpart
  83. GRB 210222A: MAXI/GSC detection
  84. GRB 210218A: Swift-XRT observations
  85. GRB 210212A: Lowell Discovery Telescope observations
  86. GRB 210217A: Swift-XRT refined Analysis
  87. GRB 210218A: Swift-BAT refined analysis
  88. Fermi GBM Sub-Threshold Detection of GRB 210217A
  89. GRB 210217A: Liverpool Telescope First Hour Observations
  90. GRB 210217A: Swift-BAT refined analysis
  91. GRB 210218A: MITSuME Akeno optical upper limits
  92. GRB 210218A: NEXT optical upper limit
  93. ZTF21aakruew/AT2021cwd: GROND observations
  94. GRB 210212A: REM early-time optical/NIR upper limits
  95. GRB 210217A: Enhanced Swift-XRT position
  96. GRB 210217A: NEXT early optical afterglow observations
  97. GRB 210212A: Mondy optical observations
  98. GRB 210217A: Swift detection of a burst with an optical counterpart
  99. IceCube-210210A: Two Additional Optical Candidate Counterparts Found by DECam
  100. GRB 210208A: 1.3m DFOT Optical upper limit

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