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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 991216, optical observations
  2. GRB 991216 Optical Observations
  3. GRB 991216 Optical spectroscopy/imaging
  4. VLT spectra of GRB991216
  5. GRB991216 Optical and IR observations
  6. K observations of GRB991216
  7. SAX J2303.2+0015 Optical observations
  8. IR observations of GRB991216
  9. GRB991216 radio observations
  10. GRB 991217 (SAX J2303.2+0015) Optical observations
  11. GRB991216 radio observations
  12. GRB991216 Spectroscopy
  13. Lowell/Perkins observation of GRB 991216
  14. GRB991216, optical observations
  15. GRB991216 Optical and infrared observations of Beethoven Burst
  16. Refined IPN localization of GRB991216
  17. GRB 991216 Radio Observations
  18. GRB 991217
  19. GRB 991208 Keck Spectroscopy
  20. GRB 991208 Infrared Detection
  21. GRB991216
  22. GRB 991216--Summary of RXTE Observations
  23. GRB 991216 Optical Observations
  24. GRB 991216, optical observations
  25. GRB 991208 SAO-RAS Spectroscopy
  26. SAX J2303.2+0015: an x-ray/GRB?
  27. GRB 991216, Optical Transient
  28. GRB 991216, Optical Afterglow
  29. GRB991216 ('Beethoven Burst') B, R, and K Observations
  30. GRB 991216: Comparison with DPOSS images
  31. GRB991216, infrared observations
  32. GRB991216 Optical Observations
  33. GRB 991208 optical observations
  34. Lowell/Perkins observation of GRB 991216
  35. GRB 991216 Optical Observation
  36. GRB 991208 Keck Spectroscopy
  37. GRB 991216: Extremely bright BATSE burst
  38. R-band Observations of GRB991208 at TNG
  39. GRB991208, optical observations
  40. GRB 991208 Keck Spectroscopy
  41. GRB991208 - millimeter detection
  42. GRB 991208, Optical Observation
  43. GRB991208 15-GHz observations
  44. GRB991208, optical observations
  45. GRB 991208 - OVRO detection
  46. GRB 991208 Optical Decay
  47. GRB 991208 optical observations
  48. GRB 991208 optical observations
  49. GRB 991208: Radio Observations
  50. IPN localization of GRB991208
  51. Optical Observations of GRB991105
  52. GRB991106: BeppoSAX/BATSE results
  53. GRB 991106, optical observations
  54. GRB991106, near-infrared observations
  55. BeppoSAX NFI Observation of GRB991106
  56. GRB 991106, radio observations
  57. GRB991106: the first BeppoSAX short GRB detection?
  58. GRB 991105: BATSE Observations
  59. IPN localization of GRB991105
  60. GRB 991106 Optical Observations
  61. GRB 991105, optical observations
  62. GRB991106, optical observation at SAO-RAS
  63. GRB 991106, LOTIS Optical Observations
  64. GRB 991106, optical observations
  65. BeppoSAX refined position for GRB991106
  66. BeppoSAX GRB Alert: GRB991106
  67. Revised BeppoSAX WFC position of GRB991105
  68. GRB991105: SAX-GRBM/-WFC detection
  69. BeppoSAX MAIL n. 99/30: GRB991105 refined position (fwd)
  70. GRB ALERT: GRB991105
  71. GRB 991014 - X-ray afterglow identification by BeppoSAX-NFI
  72. GRB 991014, Optical Observations
  73. GRB 991014 - BeppoSAX NFI observations
  74. GRB 991014, Optical Observations
  75. GRB 991014, radio observations
  76. GRB991014 BATSE Observations
  77. GRB 991014, Optical Observations
  78. GRB 991014, optical observations
  79. Super-LOTIS optical observation of GRB991014
  80. IPN/NFI error box for GRB991014
  81. IPN localization of GRB991014 - CORRECTION
  82. IPN localization of GRB991014
  83. BeppoSAX ALERT: GRB991014
  84. GRB 990915 optical observations
  85. GRB 990907 optical observations
  86. BATSE GRB trigger criteria
  87. Optical Observations of GRB990907
  88. IPN error box for GRB990915 (=BATSE 7766)
  89. IPN localization of BATSE #7766 (GRB990915)
  90. GRB990907: BeppoSAX follow up and X-ray afterglow
  91. GRB990907 and 990908
  92. IPN localization of GRB990907
  93. GRB990908, another BeppoSAX-GRBM/WFC burst detection
  94. GRB990907: refined WFC position
  95. BeppoSAX MAIL n. 99/24: GRB ALERT: GRB990907
  96. GRB 990712 Late Optical Decay and Host Galaxy
  97. GRB 990712, Optical Observation
  98. GRB990806 BeppoSAX follow up
  99. GRB990806: BATSE Observations
  100. GRB 990806 Optical observations

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