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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. SGR1900+14 - correction
  2. SGR1900+14
  3. SGR 1900+14: Correction to GCN 1049
  4. GRB 010222 /corrections to VBT data
  5. Millimeter observation of SGR 1900+14
  6. SGR 1900+14: Detection of extended X-ray emission
  7. Chandra Observations of SGR 1900+14
  8. SGR 1900+14, Chandra observations
  9. Chandra Observations of SGR 1900+14
  10. Possible precursor to the SGR1900+14 giant burst
  11. SGR1900+14, I-band observations
  12. IPN Triangulation of the Giant Flare from SGR1900+14
  13. GRB010412, field photometry
  14. Giant flare from SGR1900+14
  15. GRB 010326b Optical Observations
  16. GRB010412: Optical observations
  17. GRB010412: Optical observations
  18. GRB010412: BeppoSAX GRBM and WFC observations
  19. IPN Triangulation of GRB010412
  20. GRB010412: refined positions from BeppoSAX
  21. BeppoSAX GRB: extension of BSAX operations upto April 30, 2002
  22. BeppoSAX GRB ALERT: GRB010412
  23. GRB Observation Report
  24. GRB010324, revised field photometry
  25. REVISED LOCATION OF GRB010326A
  26. GRB 980326: Late-time HST/STIS observations
  27. GRB010324, field photometry
  28. GRB010326B, field photometry
  29. GRB010326, field photometry
  30. GRB010220, field photometry
  31. Further Optical Observations of GRB 010324
  32. GRB010222, CXO X-ray observations
  33. GRB 010326A: Further optical observations
  34. GRB010324: BeppoSAX/GRBM data
  35. GRB 010326B: Optical observations
  36. GRB010324, optical observations
  37. GRB010326B: Localization by HETE (2nd GRB for this date)
  38. GRB 010326: Optical observations
  39. GRB 010326 optical observations
  40. GRB010326: Refined Localization by HETE
  41. GRB010326: Localization by HETE
  42. Duration, ECT, peak flux and fluence of GRB010324
  43. Optical Observations of GRB 010324
  44. IPN TRIANGULATION OF GRB010324
  45. GRB990705, VLT-FORS1 observations of the host galaxy
  46. GRB010222, late-time optical observation
  47. Support extension to the BeppoSAX mission
  48. GRB 010222 - HEGRA GeV/TeV Observations
  49. Congratulate Scott on the 1000th GRB Coordinates Network Circular!
  50. GRB010222: Chandra X-ray Observatory Observation
  51. GRB010222: Sub-millimeter vanishing act
  52. GRB010222 - Optical observation
  53. GRB 010222, Optical Observations
  54. GRB010220 optical obsercations
  55. GRB010222 - Optical observation
  56. GRB 010222: High-Resolution Keck Spectroscopy
  57. GRB010222: Optical observation and decay
  58. GRB 010214, I-band data
  59. Sub-millimeter Excess/GRB 010222
  60. GRB 010222
  61. GRB 010222 HST/Chandra TOO
  62. GRB 010222
  63. GRB010222 further R-band photometry
  64. GRB010222: R-band data
  65. GRB010222 Optical observations
  66. GRB 010222: Keck Spectroscopy
  67. GRB010214, field photometry
  68. GRB010222, field photometry
  69. GRB010222 further R-band photometry
  70. GRB010222, possible increase of optical decay slope
  71. GRB 010222 Kyoto optical observation
  72. GRB010222: fading behavior
  73. GRB 010222 BV optical observations
  74. GRB010220, Optical Observations
  75. GRB010222 R-BAND OBSERVATION
  76. GRB 010220: Near-IR Observations
  77. GRB010214 follow-up from Hanle
  78. GRB 010222: Near-IR Observations
  79. GRB 010222: Optical Observations
  80. GRB 010222, Decay Slope Confirmed
  81. GRB010222: Another absorption line system
  82. GRB010222: Optical decay slope
  83. GRB 010214, Optical Observations
  84. GRB010222: Sub-millimeter detection
  85. GRB010222: R-band fading behavior
  86. GRB010222: Optical Observations
  87. GRB010222, radio observations
  88. GRB010222, optical observations
  89. GRB010222: BeppoSAX/NFI Observations
  90. Redshift of the Optical Transient of GRB010222
  91. GRB010214B,Gamma Ray Observations
  92. GRB010222: possible optical counterpart
  93. GRB010222
  94. GRB010222
  95. GRB010222: BeppoSAX refined position
  96. ALERT: GRB010222: the brightest GRB observed by BeppoSAX
  97. GRB010220, Radio and Optical Observations
  98. GRB 010220, simultaneous optical observations
  99. GRB010220: BeppoSAX WFC and GRBM preliminary data
  100. GRB010214, candidate optical afterglow

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