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

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