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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"

35946 results found.

  1. Swift-BAT trigger 107873 (GRB050309): possible X-ray counterparts
  2. GRB 050309 : Lulin R-band observation
  3. Swift 107873: P60 Optical Observations
  4. GRB 050306: CORRECTION to date of observation
  5. GRB 050306: R-band observations
  6. GRB 050306: No Swift UVOT Optical Counterpart Detected
  7. GRB 050306: REM optical-infrared observations
  8. GRB 050306: Possible X-ray Afterglow Position from the Swift
  9. Swift trigger 107518: optical observation
  10. GRB 050306: TAROT optical observations
  11. GRB 050306,optical observation
  12. GRB 050306: Swift-BAT detection of a long burst
  13. GRB 050126: Confirmation of the NIR afterglow candidate
  14. PROMPT VRcIc Observations of GRB 050223
  15. XRF/GRB 050215B: Radio Observations
  16. XMM-Newton Images of GRB 050223
  17. GRB 050219b: candidate NIR afterglow
  18. IBAS GRB Alert #2321
  19. GRB 050223: optical observations
  20. INTEGRAL detection of GRB 050223
  21. GRB 050223 : Planned XMM-Newton observation
  22. GRB050223: ROTSE-III Optical Observations
  23. GRB 050223 Swift/BAT detection of a burst
  24. GRB 050223: Swift XRT Position
  25. HETE-2 Observations of GRB 050215b (=U11570): A Likely X-Ray Flash
  26. GRB 050219b: CORRECTION to refined XRT position
  27. GRB 050219a: Optical observations from LCO
  28. GRB 050219b: Optical and near-IR observations from LCO
  29. GRB 050219b: Refined XRT position
  30. GRB 050219b: Swift-BAT detection of a burst
  31. GRB 050219b: CORRECTION: Swift XRT Position
  32. GRB 050219b: Swift XRT Position
  33. GRB 050219a, optical observations
  34. GRB 050219a: Refined XRT position
  35. GRB 050219: Swift-BAT detection of a burst
  36. GRB050215b: Swift UVOT Detection of Afterglow Emission
  37. GRB 050219: Prompt X-ray position
  38. GRB 050215B: Radio Observations
  39. GRB 050215b: XRT confirmation of IR afterglow candidate
  40. GRB050215b: P60 Optical Observations
  41. GRB 050215b: Swift XRT Source Variability
  42. GRB 050215B: candidate afterglow
  43. GRB 050215b : Lulin follow-up observation
  44. GRB 050215b, BOOTES-2 simultaneous optical observations
  45. GRB 050215B: UKIRT K-band imaging
  46. GRB 050215b: Swift XRT Observations
  47. GRB 050215b, BOOTES-1B optical limit
  48. GRB050215A: ROTSE-III Optical Observations
  49. GRB050209: TAROT optical observations
  50. GRB 050209(=U11568): Duration and spectrum
  51. short/hard GRB 050202, optical observations
  52. GRB050209: REM optical observations
  53. GRB 050209 I-band observation
  54. GRB 050209 Optical observations
  55. GRB050209: P60 Optical Observations
  56. GRB050209 (=U11568): A Long GRB Detected by HETE
  57. GRB 050209: Optical observation
  58. GRB 050128: Radio observations
  59. Further analysis of the short Swift-BAT GRB 050202
  60. GRB 050202: Second epoch radio observations
  61. GRB 050129: Optical observations
  62. GRB050202: Radio Observations
  63. GRB 050202: Optical observations with LCO40
  64. GRB 050202: Short burst detected by Swift-BAT
  65. GRB 050128 Optical observation with REM
  66. GRB 050129: a weak long GRB detected with INTEGRAL
  67. GRB050128: Faulkes Telescope South observations
  68. GRB 050124: Radio Observations
  69. GRB 050128: near-infrared observations with REM
  70. GRB050128,optical observations
  71. GRB 050126: A NIR afterglow candidate in the revised XRT error circle
  72. GRB 050126: Radio Observations
  73. GRB050128 Swift-BAT observations
  74. GRB 050128: Swift XRT prompt afterglow position
  75. GRB 050124: K-band afterglow observations
  76. GRB050126: MASTER optical limit for KECK OT
  77. GRB050126: MASTER optical observations
  78. GRB 050126: Detection of NIR afterglow with Keck/NIRC
  79. GRB 050126: Prompt XRT detection and localization
  80. GRB 050124: NIR afterglow confirmed with Keck/NIRC
  81. GRB 050124, SMARTS optical/IR observations
  82. GRB 050117a: Radio Observations
  83. GRB 050124 I-band observation
  84. GRB 050124: NIR Candidates from Keck/NIRC
  85. GRB050124,optical observation
  86. GRB 050124 : Lulin R-band follow-up observation
  87. GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
  88. GRB 050123 : I-band follow-up observation
  89. GRB050123: optical limit 1.8h before GRB
  90. GRB050123,optical observation
  91. GRB 050123: KAIT observations
  92. GRB050123: P60 Observations
  93. GRB 050123(=H3666): A GRB Localized in Real Time by HETE
  94. CFHTLS optical transient unlikely to be a GRB
  95. Unusual optical transient (GRB ???)
  96. GRB050117a: Radio Observations
  97. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
  98. GRB 050117, I-band observations
  99. GRB 050117: Optical observation
  100. GRB050117: Refined XRT position

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