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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. GRB051105B: Swift/XRT upper limit
  2. GRB051105B: Swift/UVOT upper limit
  3. GRB051103: optical observations
  4. GRB 051103, optical observations
  5. GRB051103: MASTER: OT limit and host galaxy candidates
  6. GRB051028: Swift-XRT refined analysis
  7. GRB 051105a, observation from Naini Tal and OSN
  8. GRB 051105A, 2nd epoch optical observations
  9. GRB 051105a: MDM Observations
  10. GRB 051105A: TNG optical observations
  11. GRB051105A: Swift/UVOT Observations
  12. GRB 051105A, radio observations
  13. GRB051103:_MASTER_optical_observations
  14. IPN triangulation and Konus spectrum of the bright short/hard GRB051103
  15. GRB 051105A, optical observations
  16. XRT observations of GRB 051105A
  17. GRB 051105: Swift-BAT improved refined analysis
  18. GRB 051105b: ART optical limits
  19. GRB051105B - A long GRB detected by INTEGRAL
  20. GRB 051105B (INTEGRAL 2701): Optical observation
  21. GRB 051105: Swift-BAT refined analysis
  22. GRB 051105: Optical limit
  23. GRB 051105: Swift detection of a short burst
  24. IBAS Alert 2700: Not a GRB
  25. GRB 051016B host spectroscopy and redshift
  26. GRB051016B: optical observation
  27. Recent GRB UBVRcIc field photometry
  28. Konus-Wind observation of GRB 051028
  29. GRB051028:MASTER correction and final results
  30. GRB 051022: RTT150 optical observations
  31. GRB 051021A: RTT150 optical observations
  32. GRB051028 SARA Observation
  33. GRB051028: optical observations
  34. GRB051028: Swift/UVOT upper limits
  35. GRB051028: confirmation of the afterglow
  36. GRB051028: WHT optical candidate
  37. GRB051028: Swift XRT Position
  38. GRB051028:MASTER observations
  39. GRB 051028 (=H3951): A GRB localized by HETE
  40. GRB051028:MASTER optical observations
  41. GRB 051022: XRT Refined Spectral and Temporal Analysis--Correction
  42. GRB051022: Swift XRT measurement of jet break
  43. SGR 1806-20: continued moderate activity seen with INTEGRAL
  44. GRB051021B: Swift/UVOT Upper limits
  45. GRB 051021, Optical Observations
  46. GRB 051022: XRT Refined Spectral and Temporal Analysis
  47. GRB 051022, refined optical astrometry
  48. Chandra Observations of GRB 051022
  49. GRB051012: Swift-XRT analysis
  50. GRB 051022 Chandra Observations scheduled
  51. GRB051021B: Swift XRT refined analysis
  52. GRB051021a: optical observations
  53. GRB 051022: WSRT Radio Detection
  54. GRB 051022, mm counterpart
  55. GRB051022: host galaxy redshift
  56. GRB 051022: Swift/UVOT Upper Limits
  57. GRB051022: Radio Counterpart
  58. GRB051022: IR observations
  59. GRB 051022: SOAR JKs Observations
  60. GRB051021A: Swift XRT refined analysis
  61. Konus-Wind observation of GRB 051022
  62. GRB051022: Optical Observations
  63. GRB 051022: Magellan NIR imaging
  64. GRB 051021: PROMPT RcIc Observations
  65. GRB051021b: Magellan IR Imaging
  66. GRB 051022: Spectral Analysis Indicates That The Spectrum Is Absorbed
  67. GRB 051021: Correction
  68. GRB 051022, J & K-band observation
  69. GRB 051021, SMARTS optical/IR observations
  70. GRB051022: Swift XRT Position
  71. GRB 051021: P200 Ks Observations
  72. IPN triangulation of GRB051022 (=H3950)
  73. GRB 051021: MDM Upper Limit
  74. GRB 051022 (=H3950): SXC Flight Localization is Valid
  75. GRB051021: Swift/UVOT Upper Limits
  76. GRB 051021B: Refined analysis of the Swift-BAT burst
  77. GRB 051022: SSO40 Optical Observations
  78. GRB051022,optical observation
  79. GRB 051022A: ROTSE-III Optical Limits
  80. GRB051022 (=H3590), A GRB Detected By HETE
  81. GRB 051022: Optical observations
  82. GRB 051021,optical observation
  83. GRB051021B: Swift XRT Position
  84. GRB 051021: SOAR NIR Observations
  85. GRB 051021B: Swift detection of a burst
  86. GRB051021: Swift XRT analysis
  87. GRB051021 (=H3947): Refined Analysis
  88. GRB 051021 : optical afterglow observation at Lulin
  89. GRB 051021: Optical observations
  90. GRB 051021: ROTSE-III Confirmation of Optical Counterpart
  91. GRB 051021: Optical observations and candidate afterglow
  92. GRB051021.63
  93. GRB051021.6: MASTER optical observation
  94. Swift-BAT trigger 160640 is not a real GRB
  95. GRB051021: A GRB Localized by HETE
  96. Swift-BAT trigger 160619 is not a GRB
  97. Swift-BAT triggered on a posible CR Shower or possible GRB
  98. GRB 050502b: Optical limit
  99. GRB 051016b: Optical limit
  100. Afterglow candidate of GRB 051016B observed at Lulin

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