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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. Swift-BAT trigger 165579 is not a GRB
  2. GRB 051127: Swift-BAT detection of a possible burst
  3. GRB051117B: Swift XRT refined analysis
  4. GRB051117b: No Swift/UVOT Detection
  5. GRB051111: Rc optical observations: correction
  6. GRB 051117A: Swift/UVOT Detection of an Afterglow: Correction
  7. GRB 051117A: Swift/UVOT Detection of an Afterglow
  8. GRB051111: Suzaku WAM observation of the prompt emission
  9. GRB051111: Rc optical observations
  10. GRB051008: Suzaku WAM observation of the prompt emission
  11. GRB 051109B: GAO 150cm telescope Optical limit
  12. GRB 051109A : GAO 150cm telescope Rc-band detection
  13. GRB 051021 Optical Observations
  14. GRB 051117B: MARGE Optical Limits
  15. GRB 051117A and B: Radio Observations
  16. GRB 051117B: R and I observations of possible host galaxy
  17. GRB 051117b: NIR observations
  18. GRB 051117A: Refined analysis of the Swift-BAT burst
  19. GRB 051117B: Refined analysis of the Swift-BAT burst
  20. GRB051117A : XRT refined analysis
  21. GRB 051117B,optical observation
  22. GRB 051117B: Lulin R and I band observation
  23. GRB 051117B: Optical observations
  24. GRB 051117B: ROTSE-III Optical Limits
  25. GRB051117B: Swift XRT position
  26. GRB 051117B: Swift detection of a burst
  27. GRB 051117: Swift detection of a bright burst
  28. GRB051114: results of the Swift-XRT observation
  29. GRB 051028 Optical Observations
  30. GRB 051109B : Nainital upper limits
  31. GRB 051114: Radio Observations
  32. GRB 051114: Swift-BAT refined analysis
  33. GRB050925: analysis of the XMM-Newton observation
  34. GRB051109A optical observations
  35. GRB 051114: Swift-BAT detection of a short burst
  36. GRB 051111: Further spectroscopic analysis
  37. GRB 051111: Radio afterglow
  38. GRB 051113: Swift-BAT refined analysis
  39. GRB 051113: Swift-BAT detection of a burst
  40. GRB 051111: AEOS optical observations
  41. GRB051103: Radio Observations
  42. GRB 051109A Milagro GeV/TeV Observations
  43. GRB/SGR 050925: XMM-Newton ToO observation
  44. GRB051111: Swift/UVOT Observations
  45. GRB 051111A : R-band temporal decay index based on Lulin
  46. GRB051111: XRT preliminary analysis
  47. GRB 051111: Swift-BAT refined analysis
  48. GRB 051109A Optical Observations
  49. GRB 051111A : Lulin BVRI multi band afterglow observation
  50. GRB051111a: SARA Observations
  51. GRB 051111a: IR photometry
  52. GRB 051111: Keck HIRES redshift
  53. GRB 051111A: KAIT optical observations
  54. GRB 051111a: Afterglow fading in Ic
  55. GRB051111: Super-LOTIS Early Detection
  56. GRB 051111: ROTSE-III Analysis of Prompt Counterpart
  57. Faulkes Telescope R-band detection of GRB051111
  58. GRB 051103 Milagro GeV/TeV Observations
  59. GRB051111: Swift-BAT detection of a bright burst
  60. GRB 051111A: ROTSE-III Detection of Possible Counterpart
  61. GRB 051008 Tautenburg Supernova Search
  62. GRB 051109B. Radio Observations
  63. GRB 051109A
  64. GRB051109A - radio observations
  65. GRB 051105a: GETS optical limit
  66. GRB 051109b: GETS observation
  67. GRB 051109A: KAIT optical observations
  68. Early RAPTOR measurements of GRB 051109a - the movie.
  69. Konus-Wind observation of GRB 051109A
  70. GRB 051109B: Swift-BAT refined analysis
  71. GRB 051109B: ROTSE-III Optical Limits
  72. GRB 051109A: Swift-UVOT Observations
  73. IPN triangulation and Konus spectrum of the short/soft GRB051107 (large
  74. GRB051109B: no UVOT source detected
  75. GRB051109B: XRT refined analysis
  76. GRB 051109B : Lulin Optical Observations
  77. GRB 051109A : Lulin BVRI Optical afterglow observation
  78. GRB051109A: further steepening in the X-ray light curve
  79. GRB051109A: XRT refined analysis
  80. GRB 051109a: BOOTES R & I-band detection of the early afterglow
  81. GRB051109B: XRT position
  82. GRB 051109B: Super-LOTIS Observations
  83. GRB 051109B Kiso optical follow-up observation
  84. GRB051105B: REM Optical observation
  85. GRB 051109B: Swift detection of a burst
  86. GRB 051109: HET Optical Spectrum and Absorption Redshift
  87. GRB 051109: PROMPT Detections
  88. GRB 051109: Rc and Ic observations
  89. GRB051109: Early Super-LOTIS Detection
  90. GRB 051109: Swift-BAT refined analysis
  91. GRB 051109a: IR Photometry and Astrometry
  92. GRB 051109a: MDM Observations
  93. GRB 051109A: ROTSE-III Decline rate for Optical Counterpart
  94. GRB051109: Swift detection of a burst
  95. GRB 051109a: IR Detections
  96. GRB 051109: ROTSE-III Detection of Possible Counterpart
  97. GRB051105B: Swift/XRT upper limit
  98. GRB051105B: Swift/UVOT upper limit
  99. GRB051103: optical observations
  100. GRB 051103, optical observations

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