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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"
  1. GRB 051021: ROTSE-III Confirmation of Optical Counterpart
  2. GRB 051021: Optical observations and candidate afterglow
  3. GRB051021.63
  4. GRB051021.6: MASTER optical observation
  5. Swift-BAT trigger 160640 is not a real GRB
  6. GRB051021: A GRB Localized by HETE
  7. Swift-BAT trigger 160619 is not a GRB
  8. Swift-BAT triggered on a posible CR Shower or possible GRB
  9. GRB 050502b: Optical limit
  10. GRB 051016b: Optical limit
  11. Afterglow candidate of GRB 051016B observed at Lulin
  12. GRB 051016b: Gemini Near IR Observations
  13. GRB 051016A: Swift/UVOT upper limits
  14. GRB 051016B: refined analysis of the Swift/XRT data
  15. GRB 051016B: Swift/UVOT detection
  16. GRB 051016B,optical observation
  17. GRB 051016B : Optical follow-up at Lulin
  18. GRB 051016B: Refined analysis of the Swift-BAT burst
  19. GRB 051016B: Swift detection of a soft burst
  20. GRB 051016: Swift-BAT refined analysis
  21. GRB051016 XMM-Newton observation
  22. GRB051016: Swift XRT refined analysis.
  23. GRB051016: Planned XMM-Newton observation
  24. GRB 051016: LCO optical and near-IR imaging
  25. GRB 051016: PROMPT Observations
  26. GRB051016: Swift detection of a burst
  27. Photometric calibration of Swift/UVOT and Re-analysis of Swift/UVOT GRB 050922C data
  28. GRB051006: optical observations
  29. GRB 051012: Swift-BAT detection of burst yesterday
  30. Swift trigger 159578 is not a burst
  31. Swift-BAT Trigger 159578 is a possible burst
  32. GRB050805A: Rc optical observations
  33. GRB 051006: Swift/UVOT Upper Limits
  34. IBAS Alert 2675 : not a GRB
  35. GRB051008: optical candidate
  36. GRB 051008: - a high redshift high-luminosity burst?
  37. GRB 051008 - a low redshift low-luminosity burst?
  38. IBAS Alert 2673: not a real GRB
  39. GRB051011: bright nebulae near error box
  40. GRB051011: MASTER optical observation
  41. GRB051008: optical observation
  42. GRB051008: Swift XRT refined analysis
  43. GRB051008 - Swift UVOT upper limits
  44. Konus-Wind observation of GRB 051008
  45. GRB051008: Final refined analysis of the Swift-BAT burst
  46. GRB 051008: R-band upper limit
  47. GRB051008: Refined analysis of the Swift-BAT burst
  48. GRB051008: Radio Observation
  49. GRB 051008: Swift XRT position
  50. GRB 051008, optical observations
  51. GRB 051008: early Swift XRT analysis
  52. GRB 051008: Swift UVOT Candidate
  53. GRB051008: Swift-BAT detection of a bright burst
  54. GRB 051006: P60 Observations
  55. grb test
  56. GRB 051006: XRT refined analysis
  57. Swift-BAT trigger 158700 is a probable Cosmic Ray Shower Event
  58. GRB 051006: optical observations at Sierra Nevada
  59. GRB051006: Refined analysis of the Swift-BAT burst
  60. GRB 051006: XRT position
  61. GRB051006: Swift detection of a burst
  62. GRB 050906, summary of radio observations
  63. Swift-BAT triggers 158261 and 158262 Retraction
  64. GRB051001: Swift UVOT Upper Limits
  65. GRB 050925: Second Epoch WSRT Radio Observations
  66. GRB 051001: Swift XRT refined analysis
  67. GRB 051001, optical observations at Mt. John
  68. GRB 051001: I-band limit
  69. GRB 051001: AAT infra-red observations
  70. GRB 051001: Swift-BAT refined analysis
  71. GRB 051001: Swift Detection of a Burst
  72. GRB 051001: ROTSE-III Optical Limits
  73. GRB050908: optical observations
  74. GRB050922C: optical observation
  75. GRB050922B: optical limit
  76. GRB 050922C: further VLT observations
  77. GRB 050820A: NIR photometry at the TNG
  78. GRB050922C: UVES/VLT high resolution spectroscopy
  79. GRB050925: Swift/XRT limits
  80. GRB/SGR 050925: IR Observations
  81. GRB050922C - Swift UVOT preliminary analysis
  82. GRB 050922C: break in the lightcurve
  83. GRB 050925: WSRT Radio Observations
  84. GRB050925: Swift UVOT upper limits
  85. Refined analysis of the Swift-BAT soft short burst
  86. GRB 050925 : I-band observation at Xinglong observatory
  87. GRB050925: Faulkes Telescope North R-band limit
  88. GRB050925: Swift-BAT detection of a short burst
  89. GRB 050922B: Correction to BAT refined analysis, longer burst
  90. GRB050922C: TNG spectroscopic observations
  91. GRB050922B: refined XRT analysis
  92. Konus-Wind observation of GRB 050922C
  93. GRB 050922C: Refined redshift
  94. GRB050922B: Swift UVOT early upper limits.
  95. GRB OT observation
  96. GRB050922C: observation at MonteBoo
  97. INT 2.5m limit for GRB050922B
  98. GRB 050922B: optical limit
  99. GRB050922C: Optical Observations
  100. GRB 050922C: Swift XRT refined analysis

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