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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"

38354 results found.

  1. SAX J2303.2+0015 Optical observations
  2. IR observations of GRB991216
  3. GRB991216 radio observations
  4. GRB991216 Spectroscopy
  5. GRB991216, optical observations
  6. GRB991216 Optical and infrared observations of Beethoven Burst
  7. Refined IPN localization of GRB991216
  8. GRB 991216 Radio Observations
  9. GRB 991208 Keck Spectroscopy
  10. GRB 991208 Infrared Detection
  11. GRB991216
  12. GRB 991216--Summary of RXTE Observations
  13. GRB 991216 Optical Observations
  14. GRB 991216, optical observations
  15. GRB 991208 SAO-RAS Spectroscopy
  16. SAX J2303.2+0015: an x-ray/GRB?
  17. GRB 991216, Optical Transient
  18. GRB 991216, Optical Afterglow
  19. GRB991216 ('Beethoven Burst') B, R, and K Observations
  20. GRB 991216: Comparison with DPOSS images
  21. GRB991216, infrared observations
  22. GRB991216 Optical Observations
  23. GRB 991208 optical observations
  24. Lowell/Perkins observation of GRB 991216
  25. GRB 991216 Optical Observation
  26. GRB 991208 Keck Spectroscopy
  27. GRB 991216: Extremely bright BATSE burst
  28. R-band Observations of GRB991208 at TNG
  29. GRB991208, optical observations
  30. GRB 991208 Keck Spectroscopy
  31. GRB991208 - millimeter detection
  32. GRB 991208, Optical Observation
  33. GRB991208, optical observations
  34. GRB 991208 - OVRO detection
  35. GRB 991208 Optical Decay
  36. GRB 991208 optical observations
  37. GRB 991208 optical observations
  38. GRB 991208: Radio Observations
  39. IPN localization of GRB991208
  40. Optical Observations of GRB991105
  41. GRB991106: BeppoSAX/BATSE results
  42. GRB 991106, optical observations
  43. GRB991106, near-infrared observations
  44. BeppoSAX NFI Observation of GRB991106
  45. GRB 991106, radio observations
  46. GRB991106: the first BeppoSAX short GRB detection?
  47. GRB 991105: BATSE Observations
  48. IPN localization of GRB991105
  49. GRB 991106 Optical Observations
  50. GRB 991105, optical observations
  51. GRB991106, optical observation at SAO-RAS
  52. GRB 991106, LOTIS Optical Observations
  53. GRB 991106, optical observations
  54. BeppoSAX refined position for GRB991106
  55. BeppoSAX GRB Alert: GRB991106
  56. GRB991105: SAX-GRBM/-WFC detection
  57. BeppoSAX MAIL n. 99/30: GRB991105 refined position (fwd)
  58. GRB ALERT: GRB991105
  59. GRB 991014 - X-ray afterglow identification by BeppoSAX-NFI
  60. GRB 991014, Optical Observations
  61. GRB 991014 - BeppoSAX NFI observations
  62. GRB 991014, Optical Observations
  63. GRB 991014, radio observations
  64. GRB991014 BATSE Observations
  65. GRB 991014, Optical Observations
  66. Super-LOTIS optical observation of GRB991014
  67. IPN/NFI error box for GRB991014
  68. IPN localization of GRB991014 - CORRECTION
  69. IPN localization of GRB991014
  70. BeppoSAX ALERT: GRB991014
  71. GRB 990915 optical observations
  72. GRB 990907 optical observations
  73. BATSE GRB trigger criteria
  74. Optical Observations of GRB990907
  75. IPN error box for GRB990915 (=BATSE 7766)
  76. IPN localization of BATSE #7766 (GRB990915)
  77. GRB990907: BeppoSAX follow up and X-ray afterglow
  78. GRB990907 and 990908
  79. IPN localization of GRB990907
  80. GRB990908, another BeppoSAX-GRBM/WFC burst detection
  81. GRB990907: refined WFC position
  82. BeppoSAX MAIL n. 99/24: GRB ALERT: GRB990907
  83. GRB 990712 Late Optical Decay and Host Galaxy
  84. GRB 990712, Optical Observation
  85. GRB990806 BeppoSAX follow up
  86. GRB990806: BATSE Observations
  87. GRB 990806 Optical observations
  88. Optical Observations of GRB990806
  89. GRB 990806, Optical Observations
  90. GRB 990806, Optical Observations
  91. GRB990806 UBVRIJHK observations
  92. GRB990806: possible X-ray afterglow, BeppoSAX
  93. BeppoSAX ALERT GRB990806: Summer GRB
  94. GRB 990712 Optical Observations
  95. GRB990705: No Evidence for Neutrino Signal
  96. GRB 990712 Optical Decay: Indication of Bright Host Galaxy
  97. VLT spectrum of GRB990712
  98. GRB 990712
  99. Late-time HST/STIS Observations of GRB 990510
  100. Refined BeppoSAX-WFC position of GRB990712

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