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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"

36134 results found.

  1. GRB 050223: optical observations
  2. INTEGRAL detection of GRB 050223
  3. GRB 050223 : Planned XMM-Newton observation
  4. GRB050223: ROTSE-III Optical Observations
  5. GRB 050223 Swift/BAT detection of a burst
  6. GRB 050223: Swift XRT Position
  7. HETE-2 Observations of GRB 050215b (=U11570): A Likely X-Ray Flash
  8. GRB 050219b: CORRECTION to refined XRT position
  9. GRB 050219a: Optical observations from LCO
  10. GRB 050219b: Optical and near-IR observations from LCO
  11. GRB 050219b: Refined XRT position
  12. GRB 050219b: Swift-BAT detection of a burst
  13. GRB 050219b: CORRECTION: Swift XRT Position
  14. GRB 050219b: Swift XRT Position
  15. GRB 050219a, optical observations
  16. GRB 050219a: Refined XRT position
  17. GRB 050219: Swift-BAT detection of a burst
  18. GRB050215b: Swift UVOT Detection of Afterglow Emission
  19. GRB 050219: Prompt X-ray position
  20. GRB 050215B: Radio Observations
  21. GRB 050215b: XRT confirmation of IR afterglow candidate
  22. GRB050215b: P60 Optical Observations
  23. GRB 050215b: Swift XRT Source Variability
  24. GRB 050215B: candidate afterglow
  25. GRB 050215b : Lulin follow-up observation
  26. GRB 050215b, BOOTES-2 simultaneous optical observations
  27. GRB 050215B: UKIRT K-band imaging
  28. GRB 050215b: Swift XRT Observations
  29. GRB 050215b, BOOTES-1B optical limit
  30. GRB050215A: ROTSE-III Optical Observations
  31. GRB050209: TAROT optical observations
  32. GRB 050209(=U11568): Duration and spectrum
  33. short/hard GRB 050202, optical observations
  34. GRB050209: REM optical observations
  35. GRB 050209 I-band observation
  36. GRB 050209 Optical observations
  37. GRB050209: P60 Optical Observations
  38. GRB050209 (=U11568): A Long GRB Detected by HETE
  39. GRB 050209: Optical observation
  40. GRB 050128: Radio observations
  41. Further analysis of the short Swift-BAT GRB 050202
  42. GRB 050202: Second epoch radio observations
  43. GRB 050129: Optical observations
  44. GRB050202: Radio Observations
  45. GRB 050202: Optical observations with LCO40
  46. GRB 050202: Short burst detected by Swift-BAT
  47. GRB 050128 Optical observation with REM
  48. GRB 050129: a weak long GRB detected with INTEGRAL
  49. GRB050128: Faulkes Telescope South observations
  50. GRB 050124: Radio Observations
  51. GRB 050128: near-infrared observations with REM
  52. GRB050128,optical observations
  53. GRB 050126: A NIR afterglow candidate in the revised XRT error circle
  54. GRB 050126: Radio Observations
  55. GRB050128 Swift-BAT observations
  56. GRB 050128: Swift XRT prompt afterglow position
  57. GRB 050124: K-band afterglow observations
  58. GRB050126: MASTER optical limit for KECK OT
  59. GRB050126: MASTER optical observations
  60. GRB 050126: Detection of NIR afterglow with Keck/NIRC
  61. GRB 050126: Prompt XRT detection and localization
  62. GRB 050124: NIR afterglow confirmed with Keck/NIRC
  63. GRB 050124, SMARTS optical/IR observations
  64. GRB 050117a: Radio Observations
  65. GRB 050124 I-band observation
  66. GRB 050124: NIR Candidates from Keck/NIRC
  67. GRB050124,optical observation
  68. GRB 050124 : Lulin R-band follow-up observation
  69. GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
  70. GRB 050123 : I-band follow-up observation
  71. GRB050123: optical limit 1.8h before GRB
  72. GRB050123,optical observation
  73. GRB 050123: KAIT observations
  74. GRB050123: P60 Observations
  75. GRB 050123(=H3666): A GRB Localized in Real Time by HETE
  76. CFHTLS optical transient unlikely to be a GRB
  77. Unusual optical transient (GRB ???)
  78. GRB050117a: Radio Observations
  79. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
  80. GRB 050117, I-band observations
  81. GRB 050117: Optical observation
  82. GRB050117: Refined XRT position
  83. GRB050117: MASTER optical observations
  84. MASTER:GRB050117 SWIFT
  85. GRB050117: Swift-BAT detection of a long multi-peaked burst
  86. Triangulation of Short Hard GRB050112 (large error box)
  87. SGR1806: Optical Transient Candidates in SOHO/LASCO Images
  88. SGR 1806-20 and extragalactic short-duration GRBs
  89. SGR 1806-20: Low frequency GMRT results; submission to GCN circulars
  90. SGR 1806-20: Temporal and Spectral behavior of radio transient
  91. SGR 1806-20, RHESSI observations of the 041227 giant flare
  92. SGR1806: Detection of a Sudden Ionospheric Disturbance
  93. GRB 041217: Optical observations
  94. GRB041219, early time observations
  95. IPN localization of giant flare from SGR1806-20
  96. GRB041219; RXTE ASM Observations
  97. NIR Observations of GRB 041219
  98. GRB041223: decay of the afterglow
  99. GRB 041224: near-infrared observations with REM
  100. GRB 041223: XRT afterglow spectrum and light curve

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