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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').

17101 results found.

  1. GRB 050223: Swift XRT Position
  2. GRB050219b: CORRECTION to time of UVOT observations
  3. GRB050219b: No Swift UVOT Detection of Afterglow Emission
  4. GRB 050219b: CORRECTION to refined XRT position
  5. GRB050219b: No Swift UVOT Detection of Afterglow Emission
  6. GRB 050219b: Refined XRT position
  7. GRB 050219b: Swift-BAT detection of a burst
  8. GRB 050219b: CORRECTION: Swift XRT Position
  9. GRB 050219b: Swift XRT Position
  10. GRB 050219a, optical observations
  11. GRB 050219a: Refined XRT position
  12. GRB050219a: No Swift UVOT Detection of Afterglow Emission
  13. GRB 050219: Swift-BAT detection of a burst
  14. GRB050215b: Swift UVOT Detection of Afterglow Emission
  15. GRB 050219: Prompt X-ray position
  16. GRB 050215b: XRT confirmation of IR afterglow candidate
  17. GRB050215b: P60 Optical Observations
  18. GRB 050215b: Swift XRT Source Variability
  19. GRB 050215B: candidate afterglow
  20. GRB 050215b : Lulin follow-up observation
  21. GRB 050215b, BOOTES-2 simultaneous optical observations
  22. GRB 050215B: UKIRT K-band imaging
  23. GRB 050215b: Swift XRT Observations
  24. GRB050215b: No Swift UVOT Detection of Afterglow Emission
  25. GRB050215a: No Swift UVOT Detection of Afterglow Emission
  26. Swift-BAT detects two bursts: GRB050215a and GRB050215b
  27. GRB050215B: ROTSE-III optical observations
  28. GRB050215A: ROTSE-III Optical Observations
  29. short/hard GRB 050202, optical observations
  30. GRB 050128: Radio observations
  31. Further analysis of the short Swift-BAT GRB 050202
  32. GRB 050202: Second epoch radio observations
  33. GRB050202: Radio Observations
  34. GRB 050202: Short burst detected by Swift-BAT
  35. SGR1806-20: Swift-BAT detection of a large normal burst
  36. GRB050128: Faulkes Telescope South observations
  37. GRB050128,optical observations
  38. GRB050126: Updated Swift XRT Position
  39. GRB 050126: Radio Observations
  40. GRB050128 Swift-BAT observations
  41. GRB 050128: Swift XRT prompt afterglow position
  42. GRB 050124: K-band afterglow observations
  43. GRB050126: MASTER optical limit for KECK OT
  44. GRB050126: Burst Parameters Measured by BAT
  45. GRB050126: MASTER optical observations
  46. GRB 050126: Prompt XRT detection and localization
  47. GRB050124: No Swift UVOT Detection of Afterglow Emission
  48. GRB 050117a: Radio Observations
  49. GRB050124,optical observation
  50. GRB050124: Updated Swift XRT Position and Fluxes
  51. GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
  52. GRB050124: Refined BAT position, spectral and fluence information
  53. GRB050124: Swift-BAT position of a double-peaked burst
  54. GRB050117a: Radio Observations
  55. GRB050117a: Refined analysis
  56. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
  57. GRB050117b: Swift-BAT detection of a weak burst
  58. GRB050117: optical observation
  59. GRB 050117, I-band observations
  60. GRB 050117: Optical observation
  61. GRB050117: Refined XRT position
  62. GRB050117: MASTER optical observations
  63. MASTER:GRB050117 SWIFT
  64. GRB050117: Swift-BAT detection of a long multi-peaked burst
  65. GRB050117: Swift XRT Position
  66. SGR1806-20: Swift-BAT observations of two additional bursts
  67. SGR 1806-20, RHESSI observations of the 041227 giant flare
  68. SGR1806-20: RXTE-PCA observation of the 041227 super-flare
  69. GRB 041217: Optical observations
  70. SGR1806-20: Swift-BAT observation of the 041227 super-flare
  71. GRB041228: ROTSE-III Optical Observations
  72. GRB041228: Swift-BAT detection of a burst
  73. GRB041219; RXTE ASM Observations
  74. NIR Observations of GRB 041219
  75. GRB041226: ROTSE-III Optical Observations
  76. GRB041226: Swift-BAT detection of a burst
  77. GRB041223: decay of the afterglow
  78. GRB041224: ROTSE-III Optical Observations
  79. GRB 041223: XRT afterglow spectrum and light curve
  80. GRB 041223 Fluence measured by Swift-BAT
  81. GRB041224: Swift-BAT detection of a soft burst
  82. GRB041223: optical and NIR observations with REM
  83. Swift-BAT Time History of GRB041219
  84. GRB041223: Swift XRT Detection of X-ray Afterglow Emission
  85. GRB041223: ROTSE-III Optical Observations
  86. GRB041223: Swift-BAT detection of a bright long burst
  87. GRB041220: Swift-BAT burst
  88. GRB 041219 Optical Observations
  89. GRB041219c: Third Burst in One Day from Swift-BAT
  90. GRB041219b: A Swift-BAT burst
  91. Swift-BAT detection of the bright long burst GRB041219
  92. GRB041217: optical limit 30 min after GRB
  93. GRB041217: Optical Observations
  94. GRB041217: NIR and optical observations with REM
  95. GRB041217: P60 Optical Observations
  96. GRB041217: Infrared Observations
  97. GRB041217: The First GRB Located On-Board Swift
  98. GRB040916: Optical observations
  99. GRB040422: optical and NIR observations at the VLT
  100. GRB040223, improved XMM position

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