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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"

19596 results found.

  1. GRB 050219b: Refined XRT position
  2. GRB 050219b: Swift-BAT detection of a burst
  3. GRB 050219b: CORRECTION: Swift XRT Position
  4. GRB 050219b: Swift XRT Position
  5. GRB 050219a, optical observations
  6. GRB 050219a: Refined XRT position
  7. GRB050219a: No Swift UVOT Detection of Afterglow Emission
  8. GRB 050219: Swift-BAT detection of a burst
  9. GRB050215b: Swift UVOT Detection of Afterglow Emission
  10. GRB 050219: Prompt X-ray position
  11. GRB 050215b: XRT confirmation of IR afterglow candidate
  12. GRB050215b: P60 Optical Observations
  13. GRB 050215b: Swift XRT Source Variability
  14. GRB 050215B: candidate afterglow
  15. GRB 050215b : Lulin follow-up observation
  16. GRB 050215b, BOOTES-2 simultaneous optical observations
  17. GRB 050215B: UKIRT K-band imaging
  18. GRB 050215b: Swift XRT Observations
  19. GRB050215b: No Swift UVOT Detection of Afterglow Emission
  20. GRB050215a: No Swift UVOT Detection of Afterglow Emission
  21. Swift-BAT detects two bursts: GRB050215a and GRB050215b
  22. GRB050215B: ROTSE-III optical observations
  23. GRB050215A: ROTSE-III Optical Observations
  24. short/hard GRB 050202, optical observations
  25. GRB 050128: Radio observations
  26. Further analysis of the short Swift-BAT GRB 050202
  27. GRB 050202: Second epoch radio observations
  28. GRB050202: Radio Observations
  29. GRB 050202: Short burst detected by Swift-BAT
  30. SGR1806-20: Swift-BAT detection of a large normal burst
  31. GRB050128: Faulkes Telescope South observations
  32. GRB050128,optical observations
  33. GRB050126: Updated Swift XRT Position
  34. GRB 050126: Radio Observations
  35. GRB050128 Swift-BAT observations
  36. GRB 050128: Swift XRT prompt afterglow position
  37. GRB 050124: K-band afterglow observations
  38. GRB050126: MASTER optical limit for KECK OT
  39. GRB050126: Burst Parameters Measured by BAT
  40. GRB050126: MASTER optical observations
  41. GRB 050126: Prompt XRT detection and localization
  42. GRB050124: No Swift UVOT Detection of Afterglow Emission
  43. GRB 050117a: Radio Observations
  44. GRB050124,optical observation
  45. GRB050124: Updated Swift XRT Position and Fluxes
  46. GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
  47. GRB050124: Refined BAT position, spectral and fluence information
  48. GRB050124: Swift-BAT position of a double-peaked burst
  49. GRB050117a: Radio Observations
  50. GRB050117a: Refined analysis
  51. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
  52. GRB050117b: Swift-BAT detection of a weak burst
  53. GRB050117: optical observation
  54. GRB 050117, I-band observations
  55. GRB 050117: Optical observation
  56. GRB050117: Refined XRT position
  57. GRB050117: MASTER optical observations
  58. MASTER:GRB050117 SWIFT
  59. GRB050117: Swift-BAT detection of a long multi-peaked burst
  60. GRB050117: Swift XRT Position
  61. SGR1806-20: Swift-BAT observations of two additional bursts
  62. SGR 1806-20, RHESSI observations of the 041227 giant flare
  63. SGR1806-20: RXTE-PCA observation of the 041227 super-flare
  64. GRB 041217: Optical observations
  65. SGR1806-20: Swift-BAT observation of the 041227 super-flare
  66. GRB041228: ROTSE-III Optical Observations
  67. GRB041228: Swift-BAT detection of a burst
  68. GRB041219; RXTE ASM Observations
  69. NIR Observations of GRB 041219
  70. GRB041226: ROTSE-III Optical Observations
  71. GRB041226: Swift-BAT detection of a burst
  72. GRB041223: decay of the afterglow
  73. GRB041224: ROTSE-III Optical Observations
  74. GRB 041223: XRT afterglow spectrum and light curve
  75. GRB 041223 Fluence measured by Swift-BAT
  76. GRB041224: Swift-BAT detection of a soft burst
  77. GRB041223: optical and NIR observations with REM
  78. Swift-BAT Time History of GRB041219
  79. GRB041223: Swift XRT Detection of X-ray Afterglow Emission
  80. GRB041223: ROTSE-III Optical Observations
  81. GRB041223: Swift-BAT detection of a bright long burst
  82. GRB041220: Swift-BAT burst
  83. GRB 041219 Optical Observations
  84. GRB041219c: Third Burst in One Day from Swift-BAT
  85. GRB041219b: A Swift-BAT burst
  86. Swift-BAT detection of the bright long burst GRB041219
  87. GRB041217: optical limit 30 min after GRB
  88. GRB041217: Optical Observations
  89. GRB041217: NIR and optical observations with REM
  90. GRB041217: P60 Optical Observations
  91. GRB041217: Infrared Observations
  92. GRB041217: The First GRB Located On-Board Swift
  93. GRB040916: Optical observations
  94. GRB040422: optical and NIR observations at the VLT
  95. GRB040223, improved XMM position
  96. SN 2003jd (SN/GRB?) - possible association with GRB 030929

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