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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"

21393 results found.

  1. GRB050215b: P60 Optical Observations
  2. GRB 050215b: Swift XRT Source Variability
  3. GRB 050215B: candidate afterglow
  4. GRB 050215b : Lulin follow-up observation
  5. GRB 050215b, BOOTES-2 simultaneous optical observations
  6. GRB 050215B: UKIRT K-band imaging
  7. GRB 050215b: Swift XRT Observations
  8. GRB050215b: No Swift UVOT Detection of Afterglow Emission
  9. GRB050215a: No Swift UVOT Detection of Afterglow Emission
  10. Swift-BAT detects two bursts: GRB050215a and GRB050215b
  11. GRB050215B: ROTSE-III optical observations
  12. GRB050215A: ROTSE-III Optical Observations
  13. short/hard GRB 050202, optical observations
  14. GRB 050128: Radio observations
  15. Further analysis of the short Swift-BAT GRB 050202
  16. GRB 050202: Second epoch radio observations
  17. GRB050202: Radio Observations
  18. GRB 050202: Short burst detected by Swift-BAT
  19. GRB 050128 Optical observation with REM
  20. SGR1806-20: Swift-BAT detection of a large normal burst
  21. GRB050128: Faulkes Telescope South observations
  22. GRB 050128: near-infrared observations with REM
  23. GRB050128,optical observations
  24. GRB 050126: A NIR afterglow candidate in the revised XRT error circle
  25. GRB050126: Updated Swift XRT Position
  26. GRB 050126: Radio Observations
  27. GRB050128 Swift-BAT observations
  28. GRB 050128: Swift XRT prompt afterglow position
  29. GRB 050124: K-band afterglow observations
  30. GRB050126: MASTER optical limit for KECK OT
  31. GRB050126: Burst Parameters Measured by BAT
  32. GRB050126: MASTER optical observations
  33. GRB 050126: Detection of NIR afterglow with Keck/NIRC
  34. GRB 050126: Prompt XRT detection and localization
  35. GRB 050124: NIR afterglow confirmed with Keck/NIRC
  36. GRB050124: No Swift UVOT Detection of Afterglow Emission
  37. GRB 050117a: Radio Observations
  38. GRB 050124: NIR Candidates from Keck/NIRC
  39. GRB050124,optical observation
  40. GRB050124: Updated Swift XRT Position and Fluxes
  41. GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
  42. GRB050124: Refined BAT position, spectral and fluence information
  43. GRB050124: Swift-BAT position of a double-peaked burst
  44. GRB050117a: Radio Observations
  45. GRB050117a: Refined analysis
  46. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
  47. GRB050117: Palomar WIRC Ks-band observations
  48. GRB050117b: Swift-BAT detection of a weak burst
  49. GRB050117: optical observation
  50. GRB 050117, I-band observations
  51. GRB 050117: Optical observation
  52. GRB050117: Refined XRT position
  53. GRB050117: MASTER optical observations
  54. MASTER:GRB050117 SWIFT
  55. GRB050117: Swift-BAT detection of a long multi-peaked burst
  56. GRB050117: Swift XRT Position
  57. SGR1806-20: Swift-BAT observations of two additional bursts
  58. SGR 1806-20, RHESSI observations of the 041227 giant flare
  59. SGR1806-20: RXTE-PCA observation of the 041227 super-flare
  60. GRB 041217: Optical observations
  61. SGR1806-20: Swift-BAT observation of the 041227 super-flare
  62. GRB041228: ROTSE-III Optical Observations
  63. GRB041228: Swift-BAT detection of a burst
  64. GRB041219; RXTE ASM Observations
  65. NIR Observations of GRB 041219
  66. GRB041226: ROTSE-III Optical Observations
  67. GRB041226: Swift-BAT detection of a burst
  68. GRB041223: decay of the afterglow
  69. GRB041224: ROTSE-III Optical Observations
  70. GRB 041223: XRT afterglow spectrum and light curve
  71. GRB 041223 Fluence measured by Swift-BAT
  72. GRB041224: Swift-BAT detection of a soft burst
  73. GRB041223: optical and NIR observations with REM
  74. Swift-BAT Time History of GRB041219
  75. GRB 041223: Detection of Optical Transient with LCO40
  76. GRB041223: Swift XRT Detection of X-ray Afterglow Emission
  77. GRB041223: ROTSE-III Optical Observations
  78. GRB041223: Swift-BAT detection of a bright long burst
  79. GRB041220: Swift-BAT burst
  80. GRB 041219 Optical Observations
  81. GRB041219c: Third Burst in One Day from Swift-BAT
  82. GRB041219b: A Swift-BAT burst
  83. Swift-BAT detection of the bright long burst GRB041219
  84. GRB041217: optical limit 30 min after GRB
  85. GRB041217: Optical Observations
  86. GRB041217: NIR and optical observations with REM
  87. GRB041217: P60 Optical Observations
  88. GRB041217: Infrared Observations
  89. GRB041217: The First GRB Located On-Board Swift
  90. GRB040916: Optical observations
  91. GRB040422: optical and NIR observations at the VLT
  92. GRB040223, improved XMM position
  93. SN 2003jd (SN/GRB?) - possible association with GRB 030929

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