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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 010222
  2. GRB010222 further R-band photometry
  3. GRB010222: R-band data
  4. GRB010222 Optical observations
  5. GRB 010222: Keck Spectroscopy
  6. GRB010214, field photometry
  7. GRB010222, field photometry
  8. GRB010222 further R-band photometry
  9. GRB010222, possible increase of optical decay slope
  10. GRB 010222 Kyoto optical observation
  11. GRB010222: fading behavior
  12. GRB 010222 BV optical observations
  13. GRB010220, Optical Observations
  14. GRB010222 R-BAND OBSERVATION
  15. GRB 010220: Near-IR Observations
  16. GRB010214 follow-up from Hanle
  17. GRB 010222: Near-IR Observations
  18. GRB 010222: Optical Observations
  19. GRB 010222, Decay Slope Confirmed
  20. GRB010222: Another absorption line system
  21. GRB010222: Optical decay slope
  22. GRB 010214, Optical Observations
  23. GRB010222: Sub-millimeter detection
  24. GRB010222: R-band fading behavior
  25. GRB010222: Optical Observations
  26. GRB010222, radio observations
  27. GRB010222, optical observations
  28. GRB010222: BeppoSAX/NFI Observations
  29. Redshift of the Optical Transient of GRB010222
  30. GRB010214B,Gamma Ray Observations
  31. GRB010222: possible optical counterpart
  32. GRB010222
  33. GRB010222
  34. GRB010222: BeppoSAX refined position
  35. ALERT: GRB010222: the brightest GRB observed by BeppoSAX
  36. GRB010220, Radio and Optical Observations
  37. GRB 010220, simultaneous optical observations
  38. GRB010220: BeppoSAX WFC and GRBM preliminary data
  39. GRB010214, candidate optical afterglow
  40. GRB010214, optical observations
  41. BeppoSAX GRB010220: refined position
  42. BeppoSAX ALERT: GRB010220
  43. GRB010214: BeppoSAX WFC and GRBM preliminary data
  44. GRB 010214: X-Ray afterglow
  45. GRB 010214, Optical Observations
  46. GRB 010214 optical observation
  47. GRB010213, Radio Observations
  48. GRB010213 Optical Observation
  49. GRB010213, Radio Observations
  50. J-Band Observation of GRB 010214.
  51. GRB010214, Radio Observations
  52. GRB010214, optical observations
  53. GRB010213, optical observations
  54. GRB010213, Near-IR observations
  55. Possible InfraRed Transient of GRB 010214.
  56. GRB010214 Optical Observation
  57. GRB010214: BeppoSAX/NFI Observations
  58. GRB010213 (HETE) TAROT observations
  59. GRB 010214, optical observations
  60. GRB010213 detected by HETE
  61. GRB010214 refined WFC position
  62. BeppoSAX ALERT: GRB010214
  63. IPN Status Report
  64. HETE Status
  65. GRB010126 opt. obs.
  66. IPN/RXTE TRIANGULATION OF GRB010126
  67. GRB010126: CONCAM crude optical limits during GRB
  68. GRB010126, TNG R-band observations
  69. GRB010126 Optical Observations
  70. GRB010126 optical observations
  71. GRB010126: Optical observations
  72. IPN TRIANGULATION OF GRB010126
  73. IPN/RXTE TRIANGULATION OF GRB010126
  74. GRB 010119, optical observations
  75. GRB010119: Optical observations
  76. Optical Observations of GRB 001018 at Keck
  77. GRB010119, Radio observations
  78. IPN TRIANGULATION OF GRB010119 (SHORT/HARD)
  79. Optical observations of GRB 001018 with JCAM
  80. IPN TRIANGULATION OF GRB010115
  81. IPN TRIANGULATION OF GRB010109
  82. IPN TRIANGULATION OF GRB010109
  83. GRB010103, optical observations
  84. IPN triangulation of GRB010104
  85. IPN triangulation of GRB010103
  86. GRB 001204: Ks observations
  87. H band observation of GRB 001212
  88. GRB & BeppoSAX: ground operations restored back to 24 hrs a day
  89. IPN triangulation of GRB001219
  90. GRB 001212 Optical Observation
  91. GRB 001212 Optical Observation
  92. GRB 001212 optical observation
  93. GRB 001212 possible OA in 2MASS
  94. GRB 001212 possible OA
  95. IPN triangulation of GRB001212
  96. GRB001204: Optical observations
  97. Confirmation of IPN position for GRB001204
  98. GRB001204, Radio observations
  99. IPN triangulation of GRB001204 (short/hard)
  100. GRB 001105, further optical observations

Advanced

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