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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"

24927 results found.

  1. GRB050319: RTT150 Optical Observations
  2. GRB 050318: Swift-BAT refined analysis
  3. GRB050319: VLA Observations
  4. GRB050319: radio observation
  5. GRB 050319: Swift-UVOT detection of the afterglow
  6. GRB 050315: Variability Analysis of Swift BAT Time History
  7. GRB050319: Radio Observations
  8. GRB 050319: NIR afterglow candidate
  9. GRB 050319:Near IR afterglow
  10. GRB 050318: SWIFT-UVOT refined analysis
  11. GRB 050319: Swift-BAT refined analysis
  12. GRB050319,optical observation
  13. GRB 050318: Swift/UVOT detection of afterglow emission
  14. RXTE Observations of GRB050318
  15. Swift-BAT detection of GRB 050318
  16. GRB050223: analysis of the XMM-Newton observation
  17. GRB050316: MASTER before, simultanious and follow up optical
  18. GRB 050306: ROTSE-III early limits
  19. GRB050316: MASTER optical observations
  20. GRB 050315 I-band observations
  21. GRB050315: Radio afterglow
  22. GRB 050315: Absorption redshift
  23. GRB 050219b: Gemini/GNIRS near-infrared spectroscopy
  24. GRB 050315: Early Observations with Swift/UVOT
  25. Swift-BAT detection of GRB 050315
  26. GRB 050306: Radio Observations
  27. GRB050306: 250 GHz upper limit with MAMBO at the IRAM 30m
  28. GRB 050306: optical afterglow
  29. GRB 050126: Redshift determination
  30. Swift-BAT trigger 107873: No Swift XRT counterpart
  31. GRB 050306: Confirmation of X-ray afterglow
  32. GRB 050306: further TAROT optical data
  33. GRB050309: Early optical limit from P60
  34. Swift-BAT trigger 107873 (GRB050309): possible X-ray counterparts
  35. Swift 107873: P60 Optical Observations
  36. GRB 050306: R-band observations
  37. GRB 050306: REM optical-infrared observations
  38. GRB 050306: Possible X-ray Afterglow Position from the Swift
  39. GRB 050306: TAROT optical observations
  40. GRB 050306,optical observation
  41. GRB 050306: Swift-BAT detection of a long burst
  42. Ongoing activity of SGR 1806-20 after the giant flare
  43. GRB050215B: Late-Time Swift UVOT Observations
  44. PROMPT VRcIc Observations of GRB 050223
  45. XMM-Newton Images of GRB 050223
  46. GRB 050219b: candidate NIR afterglow
  47. Confirmed XRF nature for GRB050215b
  48. GRB 050223: optical observations
  49. GRB050223 XMM-Newton observation
  50. GRB050223: ROTSE-III Optical Observations
  51. GRB 050223 Swift/BAT detection of a burst
  52. GRB 050223: Swift XRT Position
  53. HETE-2 Observations of GRB 050215b (=U11570): A Likely X-Ray Flash
  54. GRB050215b: Faulkes North and SDSS limits on UKIRT candidate
  55. GRB 050219a: Optical observations from LCO
  56. GRB 050219b: Optical and near-IR observations from LCO
  57. GRB 050219b: Swift-BAT detection of a burst
  58. GRB 050219b: CORRECTION: Swift XRT Position
  59. GRB 050219b: Swift XRT Position
  60. GRB 050219a, optical observations
  61. GRB 050219: Swift-BAT detection of a burst
  62. GRB 050215b: XRT confirmation of IR afterglow candidate
  63. GRB050215b: P60 Optical Observations
  64. GRB 050215b: Swift XRT Source Variability
  65. GRB 050215B: candidate afterglow
  66. GRB 050215b, BOOTES-2 simultaneous optical observations
  67. GRB 050215b, BOOTES-1B optical limit
  68. GRB050215A: ROTSE-III Optical Observations
  69. GRB050209: TAROT optical observations
  70. GRB 050209(=U11568): Duration and spectrum
  71. short/hard GRB 050202, optical observations
  72. GRB050209: REM optical observations
  73. GRB 050209 I-band observation
  74. GRB 050209 Optical observations
  75. GRB050209: P60 Optical Observations
  76. GRB 050128: Radio observations
  77. GRB 050202: Short burst detected by Swift-BAT
  78. GRB 050128 Optical observation with REM
  79. GRB050128: Faulkes Telescope South observations
  80. GRB 050124: Radio Observations
  81. GRB 050128: near-infrared observations with REM
  82. GRB050128,optical observations
  83. GRB050128 Swift-BAT observations
  84. GRB 050128: Swift XRT prompt afterglow position
  85. GRB050126: MASTER optical limit for KECK OT
  86. GRB050126: Burst Parameters Measured by BAT
  87. GRB050126: MASTER optical observations
  88. GRB 050117a: Radio Observations
  89. GRB 050124 I-band observation
  90. GRB050124,optical observation
  91. GRB050124: Updated Swift XRT Position and Fluxes
  92. GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
  93. GRB050124: Refined BAT position, spectral and fluence information
  94. GRB050123: optical limit 1.8h before GRB
  95. GRB050123,optical observation
  96. GRB 050123: KAIT observations
  97. CFHTLS optical transient unlikely to be a GRB
  98. Unusual optical transient (GRB ???)
  99. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
  100. GRB050117b: Swift-BAT detection of a weak burst

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