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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. BeppoSAX refined position for GRB991106
  2. BeppoSAX GRB Alert: GRB991106
  3. Revised BeppoSAX WFC position of GRB991105
  4. GRB991105: SAX-GRBM/-WFC detection
  5. BeppoSAX MAIL n. 99/30: GRB991105 refined position (fwd)
  6. GRB ALERT: GRB991105
  7. GRB 991014 - X-ray afterglow identification by BeppoSAX-NFI
  8. GRB 991014, Optical Observations
  9. GRB 991014 - BeppoSAX NFI observations
  10. GRB 991014, Optical Observations
  11. GRB 991014, radio observations
  12. GRB991014 BATSE Observations
  13. GRB 991014, Optical Observations
  14. GRB 991014, optical observations
  15. Super-LOTIS optical observation of GRB991014
  16. IPN/NFI error box for GRB991014
  17. IPN localization of GRB991014 - CORRECTION
  18. IPN localization of GRB991014
  19. BeppoSAX ALERT: GRB991014
  20. GRB 990915 optical observations
  21. GRB 990907 optical observations
  22. BATSE GRB trigger criteria
  23. Optical Observations of GRB990907
  24. IPN error box for GRB990915 (=BATSE 7766)
  25. IPN localization of BATSE #7766 (GRB990915)
  26. GRB990907: BeppoSAX follow up and X-ray afterglow
  27. GRB990907 and 990908
  28. IPN localization of GRB990907
  29. GRB990908, another BeppoSAX-GRBM/WFC burst detection
  30. GRB990907: refined WFC position
  31. BeppoSAX MAIL n. 99/24: GRB ALERT: GRB990907
  32. GRB 990712 Late Optical Decay and Host Galaxy
  33. GRB 990712, Optical Observation
  34. GRB990806 BeppoSAX follow up
  35. GRB990806: BATSE Observations
  36. GRB 990806 Optical observations
  37. Optical Observations of GRB990806
  38. GRB 990806, Optical Observations
  39. GRB 990806, optical observations
  40. GRB 990806, Optical Observations
  41. GRB990806 UBVRIJHK observations
  42. GRB990806: possible X-ray afterglow, BeppoSAX
  43. BeppoSAX ALERT GRB990806: Summer GRB
  44. GRB 990712 Optical Observations
  45. GRB990705: No Evidence for Neutrino Signal
  46. GRB 990712 Optical Decay: Indication of Bright Host Galaxy
  47. VLT spectrum of GRB990712
  48. GRB 990712
  49. Late-time HST/STIS Observations of GRB 990510
  50. Refined BeppoSAX-WFC position of GRB990712
  51. BeppoSAX NFI Observation of GRB990705
  52. BeppoSAX NFI Observation of GRB990705
  53. Updated Astrometry for the IR Counterpart of GRB990705
  54. GRB 990705, R-band observations
  55. Updated IPN localization of GRB990705
  56. IPN localization of GRB990704
  57. IPN localization of GRB990705
  58. Infrared and Optical Observations of GRB990705
  59. GRB 990705, radio observations
  60. GRB990704: SAX-NFI results summary
  61. GRB990704 radio and optical observations
  62. BeppoSAX GRB990705: possible X-ray afterglow
  63. GRB 990704 X-ray Observations
  64. GRB 990704 Optical Observations
  65. GRB 990704, optical observations
  66. GRB990704
  67. GRB990705: Intriguing Positional Coincidences
  68. GRB990704
  69. Refined BeppoSAX-WFC position of GRB990704: Errata Corrige
  70. GRB990704, optical observations
  71. GRB990704: possible X-ray afterglow
  72. Identification of a possible optical counterpart for GRB990704
  73. GRB990704
  74. Refined BeppoSAX-WFC position of GRB990704
  75. GRB990704: BeppoSAX detection
  76. BeppoSAX NFI Observation of GRB990627 X-ray afterglow
  77. Optical Observations of GRB990627
  78. GRB 990627, radio observations
  79. GRB990627: BeppoSAX-WFC final location
  80. BeppoSAX: GRB990625
  81. Late-time HST/STIS Observation of GRB 990123
  82. GRB 990506 - clarification to GCN 352
  83. GRB 990506 - Optical Observations
  84. Optical Observations of GRB 990506
  85. GRB 990506 Radio Transient
  86. GRB990527 Optical Observations
  87. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  88. IPN error box for GRB990527
  89. Late Afterglows of GRBs 990510, 990123
  90. X-ray/GRB 1SAX J0835.9+5118, TNG V and R observations
  91. X-ray/GRB 1SAX J0835.9+5118, BATSE Observation
  92. X-ray/GRB 1SAX J0835.9+5118, Optical Observations
  93. GRB 990506 optical observation
  94. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  95. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  96. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  97. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  98. radio observations of X-ray/GRB transient field
  99. optical observation of the X-ray/GRB transient SAX J0835.9+5118
  100. Optical report on X-ray/GRB transient

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