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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 010214, Optical Observations
  2. GRB010222: Sub-millimeter detection
  3. GRB010222: R-band fading behavior
  4. GRB010222: Optical Observations
  5. GRB010222, radio observations
  6. GRB010222, optical observations
  7. GRB010222: BeppoSAX/NFI Observations
  8. Redshift of the Optical Transient of GRB010222
  9. GRB010214B,Gamma Ray Observations
  10. GRB010222: possible optical counterpart
  11. GRB010222
  12. GRB010222
  13. GRB010222: BeppoSAX refined position
  14. ALERT: GRB010222: the brightest GRB observed by BeppoSAX
  15. GRB010220, Radio and Optical Observations
  16. GRB 010220, simultaneous optical observations
  17. GRB010220: BeppoSAX WFC and GRBM preliminary data
  18. GRB010214, candidate optical afterglow
  19. GRB010214, optical observations
  20. BeppoSAX GRB010220: refined position
  21. BeppoSAX ALERT: GRB010220
  22. GRB010214: BeppoSAX WFC and GRBM preliminary data
  23. GRB 010214: X-Ray afterglow
  24. GRB 010214, Optical Observations
  25. GRB 010214 optical observation
  26. GRB010213, Radio Observations
  27. GRB010213 Optical Observation
  28. GRB010213, Radio Observations
  29. J-Band Observation of GRB 010214.
  30. GRB010214, Radio Observations
  31. GRB010214, optical observations
  32. GRB010213, optical observations
  33. GRB010213, Near-IR observations
  34. Possible InfraRed Transient of GRB 010214.
  35. GRB010214 Optical Observation
  36. GRB010214: BeppoSAX/NFI Observations
  37. GRB010213 (HETE) TAROT observations
  38. GRB 010214, optical observations
  39. GRB010213 detected by HETE
  40. GRB010214 refined WFC position
  41. BeppoSAX ALERT: GRB010214
  42. IPN Status Report
  43. HETE Status
  44. GRB010126 opt. obs.
  45. IPN/RXTE TRIANGULATION OF GRB010126
  46. GRB010126: CONCAM crude optical limits during GRB
  47. GRB010126, TNG R-band observations
  48. GRB010126 Optical Observations
  49. GRB010126 optical observations
  50. GRB010126: Optical observations
  51. IPN TRIANGULATION OF GRB010126
  52. IPN/RXTE TRIANGULATION OF GRB010126
  53. GRB 010119, optical observations
  54. GRB010119: Optical observations
  55. Optical Observations of GRB 001018 at Keck
  56. GRB010119, Radio observations
  57. IPN TRIANGULATION OF GRB010119 (SHORT/HARD)
  58. Optical observations of GRB 001018 with JCAM
  59. IPN TRIANGULATION OF GRB010115
  60. IPN TRIANGULATION OF GRB010109
  61. IPN TRIANGULATION OF GRB010109
  62. GRB010103, optical observations
  63. IPN triangulation of GRB010104
  64. IPN triangulation of GRB010103
  65. GRB 001204: Ks observations
  66. H band observation of GRB 001212
  67. GRB & BeppoSAX: ground operations restored back to 24 hrs a day
  68. IPN triangulation of GRB001219
  69. GRB 001212 Optical Observation
  70. GRB 001212 Optical Observation
  71. GRB 001212 optical observation
  72. GRB 001212 possible OA in 2MASS
  73. GRB 001212 possible OA
  74. IPN triangulation of GRB001212
  75. GRB001204: Optical observations
  76. Confirmation of IPN position for GRB001204
  77. GRB001204, Radio observations
  78. IPN triangulation of GRB001204 (short/hard)
  79. GRB 001105, further optical observations
  80. GRB001120: Gunn-i observations
  81. GRB001120: Optical observations
  82. GRB001109, optical observations
  83. GRB001120, optical observations
  84. WSRT 4.8 GHz observations of GRB001109
  85. IPN triangulation of GRB001120
  86. Optical/NIR observations of GRB001109
  87. GRB 001109: deep JHK upper limits
  88. GRB 001109 X-ray afterglow with BeppoSAX
  89. CORRECTION to XMM-Newton observation of GRB001025
  90. GRB001109: Optical observations
  91. GRB001109: BeppoSAX/NFI Observations
  92. GRB001109, R-band optical observations
  93. GRB001109, Radio observations
  94. GRB001109: BeppoSAX refined WFC position
  95. BeppoSAX ALERT: GRB001109
  96. GRB001105 BVRI field photometry correction
  97. GRB001105, BVRI field photometry
  98. GRB 001105, R-band observation
  99. IPN TRIANGULATION OF GRB001105
  100. GRB 001025B, Optical obervations

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