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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 011130 I-band Observation
  2. GRB011130 (XRF011130) optical observations
  3. GRB011130 (XRF011130) SDSS PT i-band observations
  4. XRF011130: Infrared Observations
  5. GRB011130, Radio Observations
  6. Detection of the X-ray afterglow of GRB011121 by BeppoSAX
  7. GRB011130 (=XRF011130), Optical Observations
  8. XRF011130: NEAT Optical Observations
  9. GRB011130 (=XRF011130): Revised Localization of an X-ray
  10. GRB001109, Radio Monitoring
  11. GRB 011121: Errata URL
  12. GRB 011121
  13. GRB011130 (=H1864): An X-Ray Rich GRB Detected by HETE
  14. GRB 011121: J-band observations
  15. GRB 011121: NIR observations, host galaxy?
  16. GRB010921 - Milagro GeV/TeV Observations
  17. GRB 011121: HST Scheduled
  18. GRB011121: fainter still
  19. Correction: GCN1157 (GRB 011121)
  20. GRB011121: UBRI Observations
  21. GRB011121
  22. GRB 011121: Radio Observations
  23. GRB 011121 J-Band Astrometry
  24. GRB011121: continued decay
  25. GRB 011121: Detection of Bright IR Counterpart
  26. GRB011121: possible redshift, continued decay
  27. GRB011121: fading behavior
  28. GRB011121: possible optical counterpart
  29. GRB011121: BeppoSAX-WFC refined positions
  30. IPN triangulation of GRB011121
  31. BEPPOSAX GRB011121
  32. GRB 011030: TNG K-band observation
  33. XRF011030: J and K band observations
  34. GRB011030, optical observation
  35. XRF011030: Chandra Observations
  36. GRB 011030: K-band observations
  37. GRB011030: Z-band observations
  38. GRB 011030 R band observations
  39. GRB 011030 I-band Observation
  40. The X-ray Flash 011030 ('GRB 011030')
  41. Non-triggered burst 011030 ("GRB 011030")
  42. The Radio Afterglow from the X-ray Rich GRB 011030
  43. GRB 010921: HST Detection of the Afterglow and Host Galaxy
  44. GRB 970828: HST Observations of the Host Galaxy
  45. GRB 000131: HST Detection of the Host Galaxy
  46. GRB 970828: HST Observations of the Host Galaxy
  47. GRB010921, optical observation
  48. GRB 011019 optical observation
  49. Optical observation of SGR 1806-20 at the 6-m SAO telescope
  50. GRB011019: Subaru Optical Observations
  51. GRB 011030 I-band Observations
  52. GRB 011030 K-band Observations
  53. GRB010921, optical observations
  54. GRB 011030, WSRT radio observations
  55. GRB011030 - further refinement WFC position
  56. GRB 011030, Radio observations
  57. GRB011030: radio search
  58. GRB 011030, R-band observations
  59. X-ray rich GRB011030: BeppoSAX refined positions
  60. BeppoSAX ALERT: Possible X-ray rich GRB011030
  61. GRB 010921: Possible supernova component
  62. GRB011019: NEAT Optical Observations
  63. GRB011019: ROTSE-III optical observations
  64. GRB010921, optical observation at early time
  65. GRB 010921, I-band observations
  66. GRB011019: Optical observations
  67. GRB011019, optical observations -- correction
  68. GRB011019, optical observations
  69. GRB011019: A Faint, X-ray Rich GRB localized by HETE
  70. GRB010921: Spectroscopy of the Host Galaxy
  71. GRB 010921: The afterglow of HETE #1761
  72. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  73. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  74. GRB010923 as seen by BeppoSAX GRBM
  75. GRB010928(=H1770): Localization of a Long GRB by HETE
  76. GRB010923(=H1764): A Short Duration GRB Detected by HETE
  77. GRB010921, negative optical observations
  78. GRB010921 field photometry
  79. GRB010921 Optical Observations
  80. GRB 010921 DPOSS Images Available
  81. IPN triangulation of GRB010921 (=H1761)
  82. H1761: A Bright GRB Detected by HETE
  83. HETE Trigger #1760 (GRB 010920B?): new optical source = asteroid
  84. HETE Trigger #1760 (GRB 010920B?): a new optical source
  85. HETE Trigger #1759 (GRB 010920?) optical observations
  86. GRB001109, Host Galaxy Astrometry
  87. GRB000926, Host Galaxy Observations
  88. GRB001109, Host Galaxy Spectroscopic Observations
  89. Probable SGR or Short Duration GRB Detected by HETE
  90. GRB000926 Host Galaxy Observations
  91. GRB 010222: HST observations -- host galaxy and late-time decay
  92. BeppoSAX/GRBM detection of GRB 010801
  93. GCN and HETE status
  94. Dramatic Increase in the Rate of X-ray Bursts Reported by HETE
  95. BeppoSAX/GRBM detection of GRB010728
  96. GRB 010222 - WHT BVRI images
  97. SGR1900+14 burst seen by HETE: BeppoSAX data
  98. GRB 010629 Optical Observations
  99. GRB010629: Optical Observations
  100. SGR1900+14: High Fluence Burst Localized by HETE

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