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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. GRB 050223: Swift XRT Position
  2. HETE-2 Observations of GRB 050215b (=U11570): A Likely X-Ray Flash
  3. GRB050219b: CORRECTION to time of UVOT observations
  4. GRB050215b: Faulkes North and SDSS limits on UKIRT candidate
  5. GRB050219b: No Swift UVOT Detection of Afterglow Emission
  6. GRB 050219b: CORRECTION to refined XRT position
  7. GRB 050219a: Optical observations from LCO
  8. GRB 050219b: Optical and near-IR observations from LCO
  9. GRB050219b: No Swift UVOT Detection of Afterglow Emission
  10. GRB 050219b: Refined XRT position
  11. GRB 050219b: Swift-BAT detection of a burst
  12. GRB 050219b: CORRECTION: Swift XRT Position
  13. GRB 050219b: Swift XRT Position
  14. GRB 050219a, optical observations
  15. GRB 050219a: Refined XRT position
  16. GRB050219a: No Swift UVOT Detection of Afterglow Emission
  17. GRB 050219: Swift-BAT detection of a burst
  18. GRB050215b: Swift UVOT Detection of Afterglow Emission
  19. GRB 050219: Prompt X-ray position
  20. GRB 050215B: Radio Observations
  21. GRB 050215b: XRT confirmation of IR afterglow candidate
  22. GRB050215b: P60 Optical Observations
  23. GRB 050215b: Swift XRT Source Variability
  24. GRB 050215B: candidate afterglow
  25. GRB 050215b : Lulin follow-up observation
  26. GRB 050215b, BOOTES-2 simultaneous optical observations
  27. GRB 050215B: UKIRT K-band imaging
  28. GRB 050215b: Swift XRT Observations
  29. GRB050215b: No Swift UVOT Detection of Afterglow Emission
  30. GRB050215a: No Swift UVOT Detection of Afterglow Emission
  31. Swift-BAT detects two bursts: GRB050215a and GRB050215b
  32. GRB 050215b, BOOTES-1B optical limit
  33. GRB050215B: ROTSE-III optical observations
  34. GRB050215A: ROTSE-III Optical Observations
  35. GRB050209: TAROT optical observations
  36. GRB 050209(=U11568): Duration and spectrum
  37. short/hard GRB 050202, optical observations
  38. GRB050209: REM optical observations
  39. GRB 050209 I-band observation
  40. GRB 050209 Optical observations
  41. GRB050209: P60 Optical Observations
  42. GRB050209 (=U11568): A Long GRB Detected by HETE
  43. GRB 050209: Optical observation
  44. GRB 050128: Radio observations
  45. Further analysis of the short Swift-BAT GRB 050202
  46. GRB 050202: Second epoch radio observations
  47. GRB 050129: Optical observations
  48. GRB050202: Radio Observations
  49. GRB 050202: Optical observations with LCO40
  50. GRB 050202: Short burst detected by Swift-BAT
  51. GRB 050128 Optical observation with REM
  52. GRB 050129: a weak long GRB detected with INTEGRAL
  53. SGR1806-20: Swift-BAT detection of a large normal burst
  54. GRB050128: Faulkes Telescope South observations
  55. GRB 050124: Radio Observations
  56. GRB 050128: near-infrared observations with REM
  57. GRB050128,optical observations
  58. GRB 050126: A NIR afterglow candidate in the revised XRT error circle
  59. GRB050126: Updated Swift XRT Position
  60. SGR 1806-20: GMRT results at 240 MHz band.
  61. SGR 1806-20: low frequency GMRT results of 2005 Jan 16.
  62. GRB 050126: Radio Observations
  63. GRB050128 Swift-BAT observations
  64. GRB 050128: Swift XRT prompt afterglow position
  65. HETE #3667: P60 Observations
  66. GRB 050124: K-band afterglow observations
  67. GRB050126: MASTER optical limit for KECK OT
  68. GRB050126: Burst Parameters Measured by BAT
  69. GRB050126: MASTER optical observations
  70. GRB 050126: Detection of NIR afterglow with Keck/NIRC
  71. GRB 050126: Prompt XRT detection and localization
  72. GRB 050124: NIR afterglow confirmed with Keck/NIRC
  73. GRB050124: No Swift UVOT Detection of Afterglow Emission
  74. GRB 050124, SMARTS optical/IR observations
  75. GRB 050117a: Radio Observations
  76. GRB 050124 I-band observation
  77. GRB 050124: NIR Candidates from Keck/NIRC
  78. GRB050124,optical observation
  79. GRB 050124 : Lulin R-band follow-up 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. GRB 050123 : I-band follow-up observation
  85. GRB050123: optical limit 1.8h before GRB
  86. GRB050123,optical observation
  87. GRB 050123: KAIT observations
  88. GRB050123: P60 Observations
  89. GRB 050123(=H3666): A GRB Localized in Real Time by HETE
  90. CFHTLS optical transient unlikely to be a GRB
  91. Unusual optical transient (GRB ???)
  92. GRB050117a: Radio Observations
  93. GRB050117a: Refined analysis
  94. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
  95. GRB050117: Palomar WIRC Ks-band observations
  96. GRB050117b: Swift-BAT detection of a weak burst
  97. GRB050117: optical observation
  98. GRB 050117, I-band observations
  99. GRB 050117: Optical observation
  100. GRB050117: Refined XRT position

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