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

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