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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"
  1. GRB 970828: HST Observations of the Host Galaxy
  2. GRB 000131: HST Detection of the Host Galaxy
  3. GRB 970828: HST Observations of the Host Galaxy
  4. GRB010921, optical observation
  5. GRB 011019 optical observation
  6. Optical observation of SGR 1806-20 at the 6-m SAO telescope
  7. GRB011019: Subaru Optical Observations
  8. GRB 011030 I-band Observations
  9. GRB 011030 K-band Observations
  10. GRB010921, optical observations
  11. GRB 011030, WSRT radio observations
  12. GRB011030 - further refinement WFC position
  13. GRB 011030, Radio observations
  14. GRB011030: radio search
  15. GRB 011030, R-band observations
  16. X-ray rich GRB011030: BeppoSAX refined positions
  17. BeppoSAX ALERT: Possible X-ray rich GRB011030
  18. GRB 010921: Possible supernova component
  19. GRB011019: NEAT Optical Observations
  20. GRB011019: ROTSE-III optical observations
  21. GRB010921, optical observation at early time
  22. GRB 010921, I-band observations
  23. GRB011019: Optical observations
  24. GRB011019, optical observations -- correction
  25. GRB011019, optical observations
  26. GRB011019: A Faint, X-ray Rich GRB localized by HETE
  27. GRB010921: Spectroscopy of the Host Galaxy
  28. GRB 010921: The afterglow of HETE #1761
  29. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  30. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  31. GRB010923 as seen by BeppoSAX GRBM
  32. GRB010928(=H1770): Localization of a Long GRB by HETE
  33. GRB010923(=H1764): A Short Duration GRB Detected by HETE
  34. GRB010921, negative optical observations
  35. GRB010921 field photometry
  36. GRB010921 Optical Observations
  37. GRB 010921 DPOSS Images Available
  38. IPN triangulation of GRB010921 (=H1761)
  39. H1761: A Bright GRB Detected by HETE
  40. HETE Trigger #1760 (GRB 010920B?): new optical source = asteroid
  41. HETE Trigger #1760 (GRB 010920B?): a new optical source
  42. HETE Trigger #1759 (GRB 010920?) optical observations
  43. GRB001109, Host Galaxy Astrometry
  44. GRB000926, Host Galaxy Observations
  45. GRB001109, Host Galaxy Spectroscopic Observations
  46. Probable SGR or Short Duration GRB Detected by HETE
  47. GRB000926 Host Galaxy Observations
  48. GRB 010222: HST observations -- host galaxy and late-time decay
  49. BeppoSAX/GRBM detection of GRB 010801
  50. GCN and HETE status
  51. Dramatic Increase in the Rate of X-ray Bursts Reported by HETE
  52. BeppoSAX/GRBM detection of GRB010728
  53. GRB 010222 - WHT BVRI images
  54. SGR1900+14 burst seen by HETE: BeppoSAX data
  55. GRB 010629 Optical Observations
  56. GRB010629: Optical Observations
  57. SGR1900+14: High Fluence Burst Localized by HETE
  58. GRB010629, optical observations
  59. IPN triangulation of GRB010629
  60. GRB010629: A Burst Localized by HETE
  61. SGR1900+14: Second Burst Localized by HETE
  62. SGR1900+14: A Burst Localized by HETE
  63. Possible burst from SGR1806-20
  64. IPN detection of SGR1900+14
  65. SGR1806-20: A Second, Intense Burst Localized by HETE
  66. GRB 00630: Host Galaxy
  67. SGR1806-20: Localization by HETE
  68. IPN triangulation of GRB010613
  69. IPN triangulation of GRB010612
  70. IPN triangulation of GRB010612
  71. HETE Fully-Automated GCN Notices
  72. GRB000301C: Late-time HST/STIS observation
  73. GRB010518: a faint BeppoSAX detection
  74. GRB000418: HST/STIS Second-epoch Observations
  75. X-ray precursors to the large flare from SGR 1900+14
  76. GRB010214, optical observations
  77. GRB010427, Gamma Ray Observations
  78. SGR 1900+14: No evidence of extended X-ray emission
  79. SGR 1900+14 : RXTE observations
  80. BeppoSAX/NFI Follow-up Observation of SGR 1900+14
  81. SGR1900+14 - correction
  82. SGR1900+14
  83. SGR 1900+14: Correction to GCN 1049
  84. GRB 010222 /corrections to VBT data
  85. Millimeter observation of SGR 1900+14
  86. SGR 1900+14: Detection of extended X-ray emission
  87. Chandra Observations of SGR 1900+14
  88. SGR 1900+14, Chandra observations
  89. Chandra Observations of SGR 1900+14
  90. Possible precursor to the SGR1900+14 giant burst
  91. SGR1900+14, I-band observations
  92. IPN Triangulation of the Giant Flare from SGR1900+14
  93. GRB010412, field photometry
  94. Giant flare from SGR1900+14
  95. GRB 010326b Optical Observations
  96. GRB010412: Optical observations
  97. GRB010412: Optical observations
  98. GRB010412: BeppoSAX GRBM and WFC observations
  99. IPN Triangulation of GRB010412
  100. GRB010412: refined positions from BeppoSAX

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