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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').
  1. GRB050223 XMM-Newton observation
  2. INTEGRAL detection of GRB 050223
  3. GRB 050223 : Planned XMM-Newton observation
  4. GRB050223: No Swift UVOT Detection of Afterglow Emission
  5. GRB050223: ROTSE-III Optical Observations
  6. GRB 050223 Swift/BAT detection of a burst
  7. GRB 050223: Swift XRT Position
  8. HETE-2 Observations of GRB 050215b (=U11570): A Likely X-Ray Flash
  9. GRB050219b: CORRECTION to time of UVOT observations
  10. GRB050215b: Faulkes North and SDSS limits on UKIRT candidate
  11. GRB050219b: No Swift UVOT Detection of Afterglow Emission
  12. GRB 050219b: CORRECTION to refined XRT position
  13. GRB 050219a: Optical observations from LCO
  14. GRB 050219b: Optical and near-IR observations from LCO
  15. GRB050219b: No Swift UVOT Detection of Afterglow Emission
  16. GRB 050219b: Refined XRT position
  17. GRB 050219b: Swift-BAT detection of a burst
  18. GRB 050219b: CORRECTION: Swift XRT Position
  19. GRB 050219b: Swift XRT Position
  20. GRB 050219a, optical observations
  21. GRB 050219a: Refined XRT position
  22. GRB050219a: No Swift UVOT Detection of Afterglow Emission
  23. GRB 050219: Swift-BAT detection of a burst
  24. GRB050215b: Swift UVOT Detection of Afterglow Emission
  25. GRB 050219: Prompt X-ray position
  26. GRB 050215B: Radio Observations
  27. GRB 050215b: XRT confirmation of IR afterglow candidate
  28. GRB050215b: P60 Optical Observations
  29. GRB 050215b: Swift XRT Source Variability
  30. GRB 050215B: candidate afterglow
  31. GRB 050215b : Lulin follow-up observation
  32. GRB 050215b, BOOTES-2 simultaneous optical observations
  33. GRB 050215B: UKIRT K-band imaging
  34. GRB 050215b: Swift XRT Observations
  35. GRB050215b: No Swift UVOT Detection of Afterglow Emission
  36. GRB050215a: No Swift UVOT Detection of Afterglow Emission
  37. Swift-BAT detects two bursts: GRB050215a and GRB050215b
  38. GRB 050215b, BOOTES-1B optical limit
  39. GRB050215B: ROTSE-III optical observations
  40. GRB050215A: ROTSE-III Optical Observations
  41. GRB050209: TAROT optical observations
  42. GRB 050209(=U11568): Duration and spectrum
  43. short/hard GRB 050202, optical observations
  44. GRB050209: REM optical observations
  45. GRB 050209 I-band observation
  46. GRB 050209 Optical observations
  47. GRB050209: P60 Optical Observations
  48. GRB050209 (=U11568): A Long GRB Detected by HETE
  49. GRB 050209: Optical observation
  50. GRB 050128: Radio observations
  51. Further analysis of the short Swift-BAT GRB 050202
  52. GRB 050202: Second epoch radio observations
  53. GRB 050129: Optical observations
  54. GRB050202: Radio Observations
  55. GRB 050202: Optical observations with LCO40
  56. GRB 050202: Short burst detected by Swift-BAT
  57. GRB 050128 Optical observation with REM
  58. GRB 050129: a weak long GRB detected with INTEGRAL
  59. SGR1806-20: Swift-BAT detection of a large normal burst
  60. GRB050128: Faulkes Telescope South observations
  61. GRB 050124: Radio Observations
  62. GRB 050128: near-infrared observations with REM
  63. GRB050128,optical observations
  64. GRB 050126: A NIR afterglow candidate in the revised XRT error circle
  65. GRB050126: Updated Swift XRT Position
  66. SGR 1806-20: GMRT results at 240 MHz band.
  67. SGR 1806-20: low frequency GMRT results of 2005 Jan 16.
  68. GRB 050126: Radio Observations
  69. GRB050128 Swift-BAT observations
  70. GRB 050128: Swift XRT prompt afterglow position
  71. HETE #3667: P60 Observations
  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: Detection of NIR afterglow with Keck/NIRC
  77. GRB 050126: Prompt XRT detection and localization
  78. GRB 050124: NIR afterglow confirmed with Keck/NIRC
  79. GRB050124: No Swift UVOT Detection of Afterglow Emission
  80. GRB 050124, SMARTS optical/IR observations
  81. GRB 050117a: Radio Observations
  82. GRB 050124 I-band observation
  83. GRB 050124: NIR Candidates from Keck/NIRC
  84. GRB050124,optical observation
  85. GRB 050124 : Lulin R-band follow-up observation
  86. GRB050124: Updated Swift XRT Position and Fluxes
  87. GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
  88. GRB050124: Refined BAT position, spectral and fluence information
  89. GRB050124: Swift-BAT position of a double-peaked burst
  90. GRB 050123 : I-band follow-up observation
  91. GRB050123: optical limit 1.8h before GRB
  92. GRB050123,optical observation
  93. GRB 050123: KAIT observations
  94. GRB050123: P60 Observations
  95. GRB 050123(=H3666): A GRB Localized in Real Time by HETE
  96. CFHTLS optical transient unlikely to be a GRB
  97. Unusual optical transient (GRB ???)
  98. GRB050117a: Radio Observations
  99. GRB050117a: Refined analysis
  100. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations

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