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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. Optical Observations of GRB990806
  2. GRB 990806, Optical Observations
  3. GRB 990806, optical observations
  4. GRB 990806, Optical Observations
  5. GRB990806 UBVRIJHK observations
  6. GRB990806: possible X-ray afterglow, BeppoSAX
  7. BeppoSAX ALERT GRB990806: Summer GRB
  8. GRB 990712 Optical Observations
  9. GRB990705: No Evidence for Neutrino Signal
  10. GRB 990712 Optical Decay: Indication of Bright Host Galaxy
  11. VLT spectrum of GRB990712
  12. GRB 990712
  13. Late-time HST/STIS Observations of GRB 990510
  14. Refined BeppoSAX-WFC position of GRB990712
  15. BeppoSAX NFI Observation of GRB990705
  16. BeppoSAX NFI Observation of GRB990705
  17. Updated Astrometry for the IR Counterpart of GRB990705
  18. GRB 990705, R-band observations
  19. Updated IPN localization of GRB990705
  20. IPN localization of GRB990704
  21. IPN localization of GRB990705
  22. Infrared and Optical Observations of GRB990705
  23. GRB 990705, radio observations
  24. GRB990704: SAX-NFI results summary
  25. GRB990704 radio and optical observations
  26. BeppoSAX GRB990705: possible X-ray afterglow
  27. GRB 990704 X-ray Observations
  28. GRB 990704 Optical Observations
  29. GRB 990704, optical observations
  30. GRB990704
  31. GRB990705: Intriguing Positional Coincidences
  32. GRB990704
  33. Refined BeppoSAX-WFC position of GRB990704: Errata Corrige
  34. GRB990704, optical observations
  35. GRB990704: possible X-ray afterglow
  36. Identification of a possible optical counterpart for GRB990704
  37. GRB990704
  38. Refined BeppoSAX-WFC position of GRB990704
  39. GRB990704: BeppoSAX detection
  40. BeppoSAX NFI Observation of GRB990627 X-ray afterglow
  41. Optical Observations of GRB990627
  42. GRB 990627, radio observations
  43. GRB990627: BeppoSAX-WFC final location
  44. BeppoSAX: GRB990625
  45. Late-time HST/STIS Observation of GRB 990123
  46. GRB 990506 - clarification to GCN 352
  47. GRB 990506 - Optical Observations
  48. Optical Observations of GRB 990506
  49. GRB 990506 Radio Transient
  50. GRB990527 Optical Observations
  51. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  52. IPN error box for GRB990527
  53. Late Afterglows of GRBs 990510, 990123
  54. X-ray/GRB 1SAX J0835.9+5118, TNG V and R observations
  55. X-ray/GRB 1SAX J0835.9+5118, BATSE Observation
  56. X-ray/GRB 1SAX J0835.9+5118, Optical Observations
  57. GRB 990506 optical observation
  58. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  59. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  60. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  61. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  62. radio observations of X-ray/GRB transient field
  63. optical observation of the X-ray/GRB transient SAX J0835.9+5118
  64. Optical report on X-ray/GRB transient
  65. radio detection of X-ray/GRB transient
  66. BeppoSAX: A new fast X-ray transient
  67. GRB 990510: optical observations
  68. GRB990510: photometric and spectroscopic observations with the VLT
  69. GRB 990510: optical linear polarization
  70. GRB 990510: optical observations
  71. GRB990510, VI observations
  72. GRB 990506 R band observations
  73. GRB990510: X-ray afterglow
  74. GRB 990510: optical observation
  75. VLT spectrum of GRB990510
  76. GRB 990510: Broad Band Break
  77. GRB 990510: BATSE Observations
  78. GRB990510: optical observation
  79. GRB 990510 Optical Observations
  80. GRB 990510, BVI photometry
  81. GRB 990510 optical observations
  82. GRB 990510: BeppoSAX/GRBM observations
  83. GRB990510 optical observations
  84. GRB990510
  85. GRB 990510 optical observations
  86. GRB 990510 optical observations
  87. Galactic extinction towards GRB 990510
  88. GRB990510: NFI X-ray source
  89. GRB 990510 optical observations
  90. IPN localization of GRB990510
  91. GRB 990506 Radio Observations
  92. GRB 990123, optical monitoring
  93. GRB 990506: BATSE Observations
  94. GRB 990506, optical observations
  95. GRB 990510: Final BeppoSAX-WFC Coordinates
  96. GRB 990506, Optical Observations
  97. GRB 990506 optical observations
  98. GRB 990506 optical observations
  99. GRB 990506, optical observations
  100. GRB990506 observation plan

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