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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. GRB010921, optical observation at early time
  2. GRB 010921, I-band observations
  3. GRB011019: Optical observations
  4. GRB011019, optical observations -- correction
  5. GRB011019, optical observations
  6. GRB011019: A Faint, X-ray Rich GRB localized by HETE
  7. GRB010921: Spectroscopy of the Host Galaxy
  8. GRB 010921: The afterglow of HETE #1761
  9. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  10. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  11. GRB010923 as seen by BeppoSAX GRBM
  12. GRB010928(=H1770): Localization of a Long GRB by HETE
  13. GRB010923(=H1764): A Short Duration GRB Detected by HETE
  14. GRB010921, negative optical observations
  15. GRB010921 field photometry
  16. GRB010921 Optical Observations
  17. GRB 010921 DPOSS Images Available
  18. IPN triangulation of GRB010921 (=H1761)
  19. H1761: A Bright GRB Detected by HETE
  20. HETE Trigger #1760 (GRB 010920B?): new optical source = asteroid
  21. HETE Trigger #1760 (GRB 010920B?): a new optical source
  22. HETE Trigger #1759 (GRB 010920?) optical observations
  23. GRB001109, Host Galaxy Astrometry
  24. GRB000926, Host Galaxy Observations
  25. GRB001109, Host Galaxy Spectroscopic Observations
  26. Probable SGR or Short Duration GRB Detected by HETE
  27. GRB000926 Host Galaxy Observations
  28. GRB 010222: HST observations -- host galaxy and late-time decay
  29. BeppoSAX/GRBM detection of GRB 010801
  30. GCN and HETE status
  31. Dramatic Increase in the Rate of X-ray Bursts Reported by HETE
  32. BeppoSAX/GRBM detection of GRB010728
  33. GRB 010222 - WHT BVRI images
  34. SGR1900+14 burst seen by HETE: BeppoSAX data
  35. GRB 010629 Optical Observations
  36. GRB010629: Optical Observations
  37. SGR1900+14: High Fluence Burst Localized by HETE
  38. GRB010629, optical observations
  39. IPN triangulation of GRB010629
  40. GRB010629: A Burst Localized by HETE
  41. SGR1900+14: Second Burst Localized by HETE
  42. SGR1900+14: A Burst Localized by HETE
  43. Possible burst from SGR1806-20
  44. IPN detection of SGR1900+14
  45. SGR1806-20: A Second, Intense Burst Localized by HETE
  46. GRB 00630: Host Galaxy
  47. SGR1806-20: Localization by HETE
  48. IPN triangulation of GRB010613
  49. IPN triangulation of GRB010612
  50. IPN triangulation of GRB010612
  51. HETE Fully-Automated GCN Notices
  52. GRB000301C: Late-time HST/STIS observation
  53. GRB010518: a faint BeppoSAX detection
  54. GRB000418: HST/STIS Second-epoch Observations
  55. X-ray precursors to the large flare from SGR 1900+14
  56. GRB010214, optical observations
  57. GRB010427, Gamma Ray Observations
  58. SGR 1900+14: No evidence of extended X-ray emission
  59. SGR 1900+14 : RXTE observations
  60. BeppoSAX/NFI Follow-up Observation of SGR 1900+14
  61. SGR1900+14 - correction
  62. SGR1900+14
  63. SGR 1900+14: Correction to GCN 1049
  64. GRB 010222 /corrections to VBT data
  65. Millimeter observation of SGR 1900+14
  66. SGR 1900+14: Detection of extended X-ray emission
  67. Chandra Observations of SGR 1900+14
  68. SGR 1900+14, Chandra observations
  69. Chandra Observations of SGR 1900+14
  70. Possible precursor to the SGR1900+14 giant burst
  71. SGR1900+14, I-band observations
  72. IPN Triangulation of the Giant Flare from SGR1900+14
  73. GRB010412, field photometry
  74. Giant flare from SGR1900+14
  75. GRB 010326b Optical Observations
  76. GRB010412: Optical observations
  77. GRB010412: Optical observations
  78. GRB010412: BeppoSAX GRBM and WFC observations
  79. IPN Triangulation of GRB010412
  80. GRB010412: refined positions from BeppoSAX
  81. BeppoSAX GRB: extension of BSAX operations upto April 30, 2002
  82. BeppoSAX GRB ALERT: GRB010412
  83. GRB Observation Report
  84. GRB010324, revised field photometry
  85. REVISED LOCATION OF GRB010326A
  86. GRB 980326: Late-time HST/STIS observations
  87. GRB010324, field photometry
  88. GRB010326B, field photometry
  89. GRB010326, field photometry
  90. GRB010220, field photometry
  91. Further Optical Observations of GRB 010324
  92. GRB010222, CXO X-ray observations
  93. GRB 010326A: Further optical observations
  94. GRB010324: BeppoSAX/GRBM data
  95. GRB 010326B: Optical observations
  96. GRB010324, optical observations
  97. GRB010326B: Localization by HETE (2nd GRB for this date)
  98. GRB 010326: Optical observations
  99. GRB 010326 optical observations
  100. GRB010326: Refined Localization by HETE

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