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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"

18631 results found.

  1. GRB 050306: ROTSE-III early limits
  2. GRB 050315: Swift-BAT further refined analysis
  3. GRB050315: Swift-BAT Refined analysis
  4. Non-detection of GRB050315 in ATCA Radio Observations
  5. GRB 050315: Swift XRT Position
  6. GRB 050315: Early Observations with Swift/UVOT
  7. Swift-BAT detection of GRB 050315
  8. GRB050223: No XMM-Newton OM detection of afterglow emission
  9. GRB050309: CONCAM pre-trigger and trigger coincident optical
  10. GRB 050126: Redshift determination
  11. Swift-BAT trigger 107873: No Swift XRT counterpart
  12. GRB 050306: Confirmation of X-ray afterglow
  13. GRB 050309, Early optical limits from RAPTOR
  14. Swift-BAT trigger 107873 (GRB050309): possible X-ray counterparts
  15. GRB 050309 : Lulin R-band observation
  16. Swift 107873: P60 Optical Observations
  17. GRB 050306: CORRECTION to date of observation
  18. GRB 050306: No Swift UVOT Optical Counterpart Detected
  19. GRB 050306: Possible X-ray Afterglow Position from the Swift
  20. Swift trigger 107518: optical observation
  21. GRB 050306,optical observation
  22. GRB 050306: Swift-BAT detection of a long burst
  23. GRB050215B: Late-Time Swift UVOT Observations
  24. PROMPT VRcIc Observations of GRB 050223
  25. GRB 050223: optical observations
  26. GRB050223 XMM-Newton observation
  27. INTEGRAL detection of GRB 050223
  28. GRB050223: No Swift UVOT Detection of Afterglow Emission
  29. GRB050223: ROTSE-III Optical Observations
  30. GRB 050223 Swift/BAT detection of a burst
  31. GRB 050223: Swift XRT Position
  32. GRB050219b: CORRECTION to time of UVOT observations
  33. GRB050219b: No Swift UVOT Detection of Afterglow Emission
  34. GRB 050219b: CORRECTION to refined XRT position
  35. GRB050219b: No Swift UVOT Detection of Afterglow Emission
  36. GRB 050219b: Refined XRT position
  37. GRB 050219b: Swift-BAT detection of a burst
  38. GRB 050219b: CORRECTION: Swift XRT Position
  39. GRB 050219b: Swift XRT Position
  40. GRB 050219a, optical observations
  41. GRB 050219a: Refined XRT position
  42. GRB050219a: No Swift UVOT Detection of Afterglow Emission
  43. GRB 050219: Swift-BAT detection of a burst
  44. GRB050215b: Swift UVOT Detection of Afterglow Emission
  45. GRB 050219: Prompt X-ray position
  46. GRB 050215b: XRT confirmation of IR afterglow candidate
  47. GRB050215b: P60 Optical Observations
  48. GRB 050215b: Swift XRT Source Variability
  49. GRB 050215B: candidate afterglow
  50. GRB 050215b : Lulin follow-up observation
  51. GRB 050215b, BOOTES-2 simultaneous optical observations
  52. GRB 050215B: UKIRT K-band imaging
  53. GRB 050215b: Swift XRT Observations
  54. GRB050215b: No Swift UVOT Detection of Afterglow Emission
  55. GRB050215a: No Swift UVOT Detection of Afterglow Emission
  56. Swift-BAT detects two bursts: GRB050215a and GRB050215b
  57. GRB050215B: ROTSE-III optical observations
  58. GRB050215A: ROTSE-III Optical Observations
  59. short/hard GRB 050202, optical observations
  60. GRB 050128: Radio observations
  61. Further analysis of the short Swift-BAT GRB 050202
  62. GRB 050202: Second epoch radio observations
  63. GRB050202: Radio Observations
  64. GRB 050202: Short burst detected by Swift-BAT
  65. SGR1806-20: Swift-BAT detection of a large normal burst
  66. GRB050128: Faulkes Telescope South observations
  67. GRB050128,optical observations
  68. GRB050126: Updated Swift XRT Position
  69. GRB 050126: Radio Observations
  70. GRB050128 Swift-BAT observations
  71. GRB 050128: Swift XRT prompt afterglow position
  72. GRB 050124: K-band afterglow observations
  73. GRB050126: MASTER optical limit for KECK OT
  74. GRB050126: Burst Parameters Measured by BAT
  75. GRB050126: MASTER optical observations
  76. GRB 050126: Prompt XRT detection and localization
  77. GRB050124: No Swift UVOT Detection of Afterglow Emission
  78. GRB 050117a: Radio Observations
  79. GRB050124,optical observation
  80. GRB050124: Updated Swift XRT Position and Fluxes
  81. GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
  82. GRB050124: Refined BAT position, spectral and fluence information
  83. GRB050124: Swift-BAT position of a double-peaked burst
  84. GRB050117a: Radio Observations
  85. GRB050117a: Refined analysis
  86. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
  87. GRB050117b: Swift-BAT detection of a weak burst
  88. GRB050117: optical observation
  89. GRB 050117, I-band observations
  90. GRB 050117: Optical observation
  91. GRB050117: Refined XRT position
  92. GRB050117: MASTER optical observations
  93. MASTER:GRB050117 SWIFT
  94. GRB050117: Swift-BAT detection of a long multi-peaked burst
  95. GRB050117: Swift XRT Position
  96. SGR1806-20: Swift-BAT observations of two additional bursts
  97. SGR 1806-20, RHESSI observations of the 041227 giant flare
  98. SGR1806-20: RXTE-PCA observation of the 041227 super-flare
  99. GRB 041217: Optical observations
  100. SGR1806-20: Swift-BAT observation of the 041227 super-flare

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