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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. GRB051109A optical observations
  2. GRB 051114: Swift-BAT detection of a short burst
  3. GRB 051111: Further spectroscopic analysis
  4. GRB 051111: Radio afterglow
  5. GRB 051113: Swift-BAT refined analysis
  6. GRB 051113: Swift-BAT detection of a burst
  7. GRB 051111: AEOS optical observations
  8. GRB051103: Radio Observations
  9. GRB 051109A Milagro GeV/TeV Observations
  10. GRB/SGR 050925: XMM-Newton ToO observation
  11. GRB051111: Swift/UVOT Observations
  12. GRB 051111A : R-band temporal decay index based on Lulin
  13. GRB051111: XRT preliminary analysis
  14. GRB 051111: Swift-BAT refined analysis
  15. GRB 051109A Optical Observations
  16. GRB 051111A : Lulin BVRI multi band afterglow observation
  17. GRB051111a: SARA Observations
  18. GRB 051111a: IR photometry
  19. GRB 051111: Keck HIRES redshift
  20. GRB 051111A: KAIT optical observations
  21. GRB 051111a: Afterglow fading in Ic
  22. GRB051111: Super-LOTIS Early Detection
  23. GRB 051111: ROTSE-III Analysis of Prompt Counterpart
  24. Faulkes Telescope R-band detection of GRB051111
  25. GRB 051103 Milagro GeV/TeV Observations
  26. GRB051111: Swift-BAT detection of a bright burst
  27. GRB 051111A: ROTSE-III Detection of Possible Counterpart
  28. GRB 051008 Tautenburg Supernova Search
  29. GRB 051109B. Radio Observations
  30. GRB 051109A
  31. GRB051109A - radio observations
  32. GRB 051105a: GETS optical limit
  33. GRB 051109b: GETS observation
  34. GRB 051109A: KAIT optical observations
  35. Early RAPTOR measurements of GRB 051109a - the movie.
  36. Konus-Wind observation of GRB 051109A
  37. GRB 051109B: Swift-BAT refined analysis
  38. GRB 051109B: ROTSE-III Optical Limits
  39. GRB 051109A: Swift-UVOT Observations
  40. IPN triangulation and Konus spectrum of the short/soft GRB051107 (large
  41. GRB051109B: no UVOT source detected
  42. GRB051109B: XRT refined analysis
  43. GRB 051109B : Lulin Optical Observations
  44. GRB 051109A : Lulin BVRI Optical afterglow observation
  45. GRB051109A: further steepening in the X-ray light curve
  46. GRB051109A: XRT refined analysis
  47. GRB 051109a: BOOTES R & I-band detection of the early afterglow
  48. GRB051109B: XRT position
  49. GRB 051109B: Super-LOTIS Observations
  50. GRB 051109B Kiso optical follow-up observation
  51. GRB051105B: REM Optical observation
  52. GRB 051109B: Swift detection of a burst
  53. GRB 051109: HET Optical Spectrum and Absorption Redshift
  54. GRB 051109: PROMPT Detections
  55. GRB 051109: Rc and Ic observations
  56. GRB051109: Early Super-LOTIS Detection
  57. GRB 051109: Swift-BAT refined analysis
  58. GRB 051109a: IR Photometry and Astrometry
  59. GRB 051109a: MDM Observations
  60. GRB 051109A: ROTSE-III Decline rate for Optical Counterpart
  61. GRB051109: Swift detection of a burst
  62. GRB 051109a: IR Detections
  63. GRB 051109: ROTSE-III Detection of Possible Counterpart
  64. GRB051105B: Swift/XRT upper limit
  65. GRB051105B: Swift/UVOT upper limit
  66. GRB051103: optical observations
  67. GRB 051103, optical observations
  68. GRB051103: MASTER: OT limit and host galaxy candidates
  69. GRB051028: Swift-XRT refined analysis
  70. GRB 051105a, observation from Naini Tal and OSN
  71. GRB 051105A, 2nd epoch optical observations
  72. GRB 051105a: MDM Observations
  73. GRB 051105A: TNG optical observations
  74. GRB051105A: Swift/UVOT Observations
  75. GRB 051105A, radio observations
  76. GRB051103:_MASTER_optical_observations
  77. IPN triangulation and Konus spectrum of the bright short/hard GRB051103
  78. GRB 051105A, optical observations
  79. XRT observations of GRB 051105A
  80. GRB 051105: Swift-BAT improved refined analysis
  81. GRB 051105b: ART optical limits
  82. GRB051105B - A long GRB detected by INTEGRAL
  83. GRB 051105B (INTEGRAL 2701): Optical observation
  84. GRB 051105: Swift-BAT refined analysis
  85. GRB 051105: Optical limit
  86. GRB 051105: Swift detection of a short burst
  87. IBAS Alert 2700: Not a GRB
  88. GRB 051016B host spectroscopy and redshift
  89. GRB051016B: optical observation
  90. Recent GRB UBVRcIc field photometry
  91. Konus-Wind observation of GRB 051028
  92. GRB051028:MASTER correction and final results
  93. GRB 051022: RTT150 optical observations
  94. GRB 051021A: RTT150 optical observations
  95. GRB051028 SARA Observation
  96. GRB051028: optical observations
  97. GRB051028: Swift/UVOT upper limits
  98. GRB051028: confirmation of the afterglow
  99. GRB051028: WHT optical candidate
  100. GRB051028: Swift XRT Position

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