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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"

35952 results found.

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

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