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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. XRF011130: NEAT Optical Observations
  3. GRB011130 (=XRF011130): Revised Localization of an X-ray
  4. GRB001109, Radio Monitoring
  5. GRB 011121: Errata URL
  6. GRB 011121
  7. GRB011130 (=H1864): An X-Ray Rich GRB Detected by HETE
  8. GRB 011121: J-band observations
  9. GRB 011121: NIR observations, host galaxy?
  10. GRB010921 - Milagro GeV/TeV Observations
  11. GRB 011121: HST Scheduled
  12. GRB011121: fainter still
  13. Correction: GCN1157 (GRB 011121)
  14. GRB011121: UBRI Observations
  15. GRB011121
  16. GRB 011121: Radio Observations
  17. GRB 011121 J-Band Astrometry
  18. GRB011121: continued decay
  19. GRB 011121: Detection of Bright IR Counterpart
  20. GRB011121: possible redshift, continued decay
  21. GRB011121: fading behavior
  22. GRB011121: possible optical counterpart
  23. GRB011121: BeppoSAX-WFC refined positions
  24. IPN triangulation of GRB011121
  25. BEPPOSAX GRB011121
  26. GRB 011030: TNG K-band observation
  27. XRF011030: J and K band observations
  28. GRB011030, optical observation
  29. XRF011030: Chandra Observations
  30. GRB 011030: K-band observations
  31. GRB011030: Z-band observations
  32. GRB 011030 R band observations
  33. GRB 011030 I-band Observation
  34. The X-ray Flash 011030 ('GRB 011030')
  35. Non-triggered burst 011030 ("GRB 011030")
  36. The Radio Afterglow from the X-ray Rich GRB 011030
  37. GRB 010921: HST Detection of the Afterglow and Host Galaxy
  38. GRB 970828: HST Observations of the Host Galaxy
  39. GRB 000131: HST Detection of the Host Galaxy
  40. GRB 970828: HST Observations of the Host Galaxy
  41. GRB010921, optical observation
  42. GRB 011019 optical observation
  43. Optical observation of SGR 1806-20 at the 6-m SAO telescope
  44. GRB011019: Subaru Optical Observations
  45. GRB 011030 I-band Observations
  46. GRB 011030 K-band Observations
  47. GRB010921, optical observations
  48. GRB 011030, WSRT radio observations
  49. GRB011030 - further refinement WFC position
  50. GRB 011030, Radio observations
  51. GRB011030: radio search
  52. GRB 011030, R-band observations
  53. X-ray rich GRB011030: BeppoSAX refined positions
  54. BeppoSAX ALERT: Possible X-ray rich GRB011030
  55. GRB 010921: Possible supernova component
  56. GRB011019: NEAT Optical Observations
  57. GRB011019: ROTSE-III optical observations
  58. GRB010921, optical observation at early time
  59. GRB 010921, I-band observations
  60. GRB011019: Optical observations
  61. GRB011019, optical observations -- correction
  62. GRB011019, optical observations
  63. GRB011019: A Faint, X-ray Rich GRB localized by HETE
  64. GRB010921: Spectroscopy of the Host Galaxy
  65. GRB 010921: The afterglow of HETE #1761
  66. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  67. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  68. GRB010923 as seen by BeppoSAX GRBM
  69. GRB010928(=H1770): Localization of a Long GRB by HETE
  70. GRB010923(=H1764): A Short Duration GRB Detected by HETE
  71. GRB010921, negative optical observations
  72. GRB010921 field photometry
  73. GRB010921 Optical Observations
  74. GRB 010921 DPOSS Images Available
  75. IPN triangulation of GRB010921 (=H1761)
  76. H1761: A Bright GRB Detected by HETE
  77. HETE Trigger #1760 (GRB 010920B?): new optical source = asteroid
  78. HETE Trigger #1760 (GRB 010920B?): a new optical source
  79. HETE Trigger #1759 (GRB 010920?) optical observations
  80. GRB001109, Host Galaxy Astrometry
  81. GRB000926, Host Galaxy Observations
  82. GRB001109, Host Galaxy Spectroscopic Observations
  83. Probable SGR or Short Duration GRB Detected by HETE
  84. GRB000926 Host Galaxy Observations
  85. GRB 010222: HST observations -- host galaxy and late-time decay
  86. BeppoSAX/GRBM detection of GRB 010801
  87. GCN and HETE status
  88. Dramatic Increase in the Rate of X-ray Bursts Reported by HETE
  89. BeppoSAX/GRBM detection of GRB010728
  90. GRB 010222 - WHT BVRI images
  91. SGR1900+14 burst seen by HETE: BeppoSAX data
  92. GRB 010629 Optical Observations
  93. GRB010629: Optical Observations
  94. SGR1900+14: High Fluence Burst Localized by HETE
  95. GRB010629, optical observations
  96. IPN triangulation of GRB010629
  97. GRB010629: A Burst Localized by HETE
  98. SGR1900+14: Second Burst Localized by HETE
  99. SGR1900+14: A Burst Localized by HETE
  100. Possible burst from SGR1806-20

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