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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. GRB990705: Intriguing Positional Coincidences
  2. GRB990704
  3. Refined BeppoSAX-WFC position of GRB990704: Errata Corrige
  4. GRB990704, optical observations
  5. GRB990704: possible X-ray afterglow
  6. Identification of a possible optical counterpart for GRB990704
  7. GRB990704
  8. Refined BeppoSAX-WFC position of GRB990704
  9. GRB990704: BeppoSAX detection
  10. BeppoSAX NFI Observation of GRB990627 X-ray afterglow
  11. Optical Observations of GRB990627
  12. GRB 990627, radio observations
  13. GRB990627: BeppoSAX-WFC final location
  14. BeppoSAX: GRB990625
  15. Late-time HST/STIS Observation of GRB 990123
  16. GRB 990506 - clarification to GCN 352
  17. GRB 990506 - Optical Observations
  18. Optical Observations of GRB 990506
  19. GRB 990506 Radio Transient
  20. GRB990527 Optical Observations
  21. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  22. IPN error box for GRB990527
  23. Late Afterglows of GRBs 990510, 990123
  24. X-ray/GRB 1SAX J0835.9+5118, TNG V and R observations
  25. X-ray/GRB 1SAX J0835.9+5118, BATSE Observation
  26. X-ray/GRB 1SAX J0835.9+5118, Optical Observations
  27. GRB 990506 optical observation
  28. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  29. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  30. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  31. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  32. radio observations of X-ray/GRB transient field
  33. optical observation of the X-ray/GRB transient SAX J0835.9+5118
  34. Optical report on X-ray/GRB transient
  35. radio detection of X-ray/GRB transient
  36. BeppoSAX: A new fast X-ray transient
  37. GRB 990510: optical observations
  38. GRB990510: photometric and spectroscopic observations with the VLT
  39. GRB 990510: optical linear polarization
  40. GRB 990510: optical observations
  41. GRB990510, VI observations
  42. GRB 990506 R band observations
  43. GRB990510: X-ray afterglow
  44. GRB 990510: optical observation
  45. VLT spectrum of GRB990510
  46. GRB 990510: Broad Band Break
  47. GRB 990510: BATSE Observations
  48. GRB990510: optical observation
  49. GRB 990510 Optical Observations
  50. GRB 990510, BVI photometry
  51. GRB 990510 optical observations
  52. GRB 990510: BeppoSAX/GRBM observations
  53. GRB990510 optical observations
  54. GRB990510
  55. GRB 990510 optical observations
  56. GRB 990510 optical observations
  57. Galactic extinction towards GRB 990510
  58. GRB990510: NFI X-ray source
  59. GRB 990510 optical observations
  60. IPN localization of GRB990510
  61. GRB 990506 Radio Observations
  62. GRB 990123, optical monitoring
  63. GRB 990506: BATSE Observations
  64. GRB 990506, optical observations
  65. GRB 990510: Final BeppoSAX-WFC Coordinates
  66. GRB 990506, Optical Observations
  67. GRB 990506 optical observations
  68. GRB 990506 optical observations
  69. GRB 990506, optical observations
  70. GRB990506 observation plan
  71. Refined IPN error box for GRB990506
  72. GRB 990506: Limits on the possible optical transient
  73. GRB 990506, armchair astronomy
  74. GRB 990506, optical observations from +1 to +3 hours
  75. GRB 990506, optical observations
  76. GRB990506 Optical observations
  77. GRB990506 observation plan
  78. New IPN/RXTE error box for GRB990506
  79. IPN localization for GRB990506
  80. GRB 970228: Redshift and properties of the host galaxy
  81. IPN localization of GRB990427
  82. GRB981220 VLBA observations
  83. GRB980425 Optical observations of exponential decline at late time
  84. GRB990321 REFINED IPN ANNULUS
  85. GRB990323 PRECISE IPN POSITION
  86. GRB990321 IPN TRIANGULATION
  87. GRB 990316 Optical Observations
  88. GRB 990316, Radio observations
  89. GRB 990316, Optical observations
  90. GRB990316, Optical observations
  91. GRB 990316 optical observations
  92. GRB990316: simultaneous optical observation
  93. GRB990316 - Optical null results
  94. ASM/IPN error box for GRB 990308 (BATSE #7457)
  95. GRB990308 not a new SGR
  96. GRB 990308a and GRB 990308b
  97. GRB990308 (Trig. 7457), optical observations
  98. GRB990308, Possible new SGR~0209+70
  99. GRB981220, IPN localization
  100. GRB 981220, radio observations

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