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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').
  1. Late-time HST/STIS Observation of GRB 990123
  2. GRB 990506 - clarification to GCN 352
  3. GRB 990506 - Optical Observations
  4. Optical Observations of GRB 990506
  5. GRB 990506 Radio Transient
  6. GRB990527 Optical Observations
  7. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  8. IPN error box for GRB990527
  9. Late Afterglows of GRBs 990510, 990123
  10. X-ray/GRB 1SAX J0835.9+5118, TNG V and R observations
  11. X-ray/GRB 1SAX J0835.9+5118, BATSE Observation
  12. X-ray/GRB 1SAX J0835.9+5118, Optical Observations
  13. GRB 990506 optical observation
  14. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  15. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  16. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  17. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  18. radio observations of X-ray/GRB transient field
  19. optical observation of the X-ray/GRB transient SAX J0835.9+5118
  20. Optical report on X-ray/GRB transient
  21. radio detection of X-ray/GRB transient
  22. BeppoSAX: A new fast X-ray transient
  23. GRB 990510: optical observations
  24. GRB990510: photometric and spectroscopic observations with the VLT
  25. GRB 990510: optical linear polarization
  26. GRB 990510: optical observations
  27. GRB990510, VI observations
  28. GRB 990506 R band observations
  29. GRB990510: X-ray afterglow
  30. GRB 990510: optical observation
  31. VLT spectrum of GRB990510
  32. GRB 990510: Broad Band Break
  33. GRB 990510: BATSE Observations
  34. GRB990510: optical observation
  35. GRB 990510 Optical Observations
  36. GRB 990510, BVI photometry
  37. GRB 990510 optical observations
  38. GRB 990510: BeppoSAX/GRBM observations
  39. GRB990510 optical observations
  40. GRB990510
  41. GRB 990510 optical observations
  42. GRB 990510 optical observations
  43. Galactic extinction towards GRB 990510
  44. GRB990510: NFI X-ray source
  45. GRB 990510 optical observations
  46. IPN localization of GRB990510
  47. GRB 990506 Radio Observations
  48. GRB 990123, optical monitoring
  49. GRB 990506: BATSE Observations
  50. GRB 990506, optical observations
  51. GRB 990510: Final BeppoSAX-WFC Coordinates
  52. GRB 990506, Optical Observations
  53. GRB 990506 optical observations
  54. GRB 990506 optical observations
  55. GRB 990506, optical observations
  56. GRB990506 observation plan
  57. Refined IPN error box for GRB990506
  58. GRB 990506: Limits on the possible optical transient
  59. GRB 990506, armchair astronomy
  60. GRB 990506, optical observations from +1 to +3 hours
  61. GRB 990506, optical observations
  62. GRB990506 Optical observations
  63. GRB990506 observation plan
  64. New IPN/RXTE error box for GRB990506
  65. IPN localization for GRB990506
  66. GRB 970228: Redshift and properties of the host galaxy
  67. IPN localization of GRB990427
  68. GRB981220 VLBA observations
  69. GRB980425 Optical observations of exponential decline at late time
  70. GRB990321 REFINED IPN ANNULUS
  71. GRB990323 PRECISE IPN POSITION
  72. GRB990321 IPN TRIANGULATION
  73. GRB 990316 Optical Observations
  74. GRB 990316, Radio observations
  75. GRB 990316, Optical observations
  76. GRB990316, Optical observations
  77. GRB 990316 optical observations
  78. GRB990316: simultaneous optical observation
  79. GRB990316 - Optical null results
  80. ASM/IPN error box for GRB 990308 (BATSE #7457)
  81. GRB990308 not a new SGR
  82. GRB 990308a and GRB 990308b
  83. GRB990308 (Trig. 7457), optical observations
  84. GRB990308, Possible new SGR~0209+70
  85. GRB981220, IPN localization
  86. GRB 981220, radio observations
  87. GRB 990123, Field Photometry
  88. GRB 990217 Optical Observations
  89. GRB 990217, radio observations
  90. BATSE Resumes Normal Operations
  91. BATSE Flight Anomaly
  92. GRB990217: BeppoSAX/GRBM data
  93. Optical Observations of GRB990217
  94. GRB990123: Caltech STIS Photometry and Images
  95. GRB990123 observations
  96. GRB990217 Optical observation
  97. GRB990217, WFC position
  98. GRB990123, Optical Observation
  99. GRB 990123: Discovery of the Probable Host Galaxy
  100. GRB 990123: Reduced HST Images

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