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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"

36132 results found.

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

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