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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. GRB011121: continued decay
  2. GRB 011121: Detection of Bright IR Counterpart
  3. GRB011121: possible redshift, continued decay
  4. GRB011121: fading behavior
  5. GRB011121: possible optical counterpart
  6. GRB011121: BeppoSAX-WFC refined positions
  7. IPN triangulation of GRB011121
  8. BEPPOSAX GRB011121
  9. GRB 011030: TNG K-band observation
  10. XRF011030: J and K band observations
  11. GRB011030, optical observation
  12. XRF011030: Chandra Observations
  13. GRB 011030: K-band observations
  14. GRB011030: Z-band observations
  15. GRB 011030 R band observations
  16. GRB 011030 I-band Observation
  17. The X-ray Flash 011030 ('GRB 011030')
  18. Non-triggered burst 011030 ("GRB 011030")
  19. The Radio Afterglow from the X-ray Rich GRB 011030
  20. GRB 010921: HST Detection of the Afterglow and Host Galaxy
  21. GRB 970828: HST Observations of the Host Galaxy
  22. GRB 000131: HST Detection of the Host Galaxy
  23. GRB 970828: HST Observations of the Host Galaxy
  24. GRB010921, optical observation
  25. GRB 011019 optical observation
  26. Optical observation of SGR 1806-20 at the 6-m SAO telescope
  27. GRB011019: Subaru Optical Observations
  28. GRB 011030 I-band Observations
  29. GRB 011030 K-band Observations
  30. GRB010921, optical observations
  31. GRB 011030, WSRT radio observations
  32. GRB011030 - further refinement WFC position
  33. GRB 011030, Radio observations
  34. GRB011030: radio search
  35. GRB 011030, R-band observations
  36. X-ray rich GRB011030: BeppoSAX refined positions
  37. BeppoSAX ALERT: Possible X-ray rich GRB011030
  38. GRB 010921: Possible supernova component
  39. GRB011019: NEAT Optical Observations
  40. GRB011019: ROTSE-III optical observations
  41. GRB010921, optical observation at early time
  42. GRB 010921, I-band observations
  43. GRB011019: Optical observations
  44. GRB011019, optical observations -- correction
  45. GRB011019, optical observations
  46. GRB011019: A Faint, X-ray Rich GRB localized by HETE
  47. GRB010921: Spectroscopy of the Host Galaxy
  48. GRB 010921: The afterglow of HETE #1761
  49. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  50. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  51. GRB010923 as seen by BeppoSAX GRBM
  52. GRB010928(=H1770): Localization of a Long GRB by HETE
  53. GRB010923(=H1764): A Short Duration GRB Detected by HETE
  54. GRB010921, negative optical observations
  55. GRB010921 field photometry
  56. GRB010921 Optical Observations
  57. GRB 010921 DPOSS Images Available
  58. IPN triangulation of GRB010921 (=H1761)
  59. H1761: A Bright GRB Detected by HETE
  60. HETE Trigger #1760 (GRB 010920B?): new optical source = asteroid
  61. HETE Trigger #1760 (GRB 010920B?): a new optical source
  62. HETE Trigger #1759 (GRB 010920?) optical observations
  63. GRB001109, Host Galaxy Astrometry
  64. GRB000926, Host Galaxy Observations
  65. GRB001109, Host Galaxy Spectroscopic Observations
  66. Probable SGR or Short Duration GRB Detected by HETE
  67. GRB000926 Host Galaxy Observations
  68. GRB 010222: HST observations -- host galaxy and late-time decay
  69. BeppoSAX/GRBM detection of GRB 010801
  70. GCN and HETE status
  71. Dramatic Increase in the Rate of X-ray Bursts Reported by HETE
  72. BeppoSAX/GRBM detection of GRB010728
  73. GRB 010222 - WHT BVRI images
  74. SGR1900+14 burst seen by HETE: BeppoSAX data
  75. GRB 010629 Optical Observations
  76. GRB010629: Optical Observations
  77. SGR1900+14: High Fluence Burst Localized by HETE
  78. GRB010629, optical observations
  79. IPN triangulation of GRB010629
  80. GRB010629: A Burst Localized by HETE
  81. SGR1900+14: Second Burst Localized by HETE
  82. SGR1900+14: A Burst Localized by HETE
  83. Possible burst from SGR1806-20
  84. IPN detection of SGR1900+14
  85. SGR1806-20: A Second, Intense Burst Localized by HETE
  86. GRB 00630: Host Galaxy
  87. SGR1806-20: Localization by HETE
  88. IPN triangulation of GRB010613
  89. IPN triangulation of GRB010612
  90. IPN triangulation of GRB010612
  91. HETE Fully-Automated GCN Notices
  92. GRB000301C: Late-time HST/STIS observation
  93. GRB010518: a faint BeppoSAX detection
  94. GRB000418: HST/STIS Second-epoch Observations
  95. X-ray precursors to the large flare from SGR 1900+14
  96. GRB010214, optical observations
  97. GRB010427, Gamma Ray Observations
  98. SGR 1900+14: No evidence of extended X-ray emission
  99. SGR 1900+14 : RXTE observations
  100. BeppoSAX/NFI Follow-up Observation of SGR 1900+14

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