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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 990704 Optical Observations
  2. GRB 990704, optical observations
  3. GRB990704
  4. GRB990705: Intriguing Positional Coincidences
  5. GRB990704
  6. Refined BeppoSAX-WFC position of GRB990704: Errata Corrige
  7. GRB990704, optical observations
  8. GRB990704: possible X-ray afterglow
  9. Identification of a possible optical counterpart for GRB990704
  10. GRB990704
  11. Refined BeppoSAX-WFC position of GRB990704
  12. GRB990704: BeppoSAX detection
  13. BeppoSAX NFI Observation of GRB990627 X-ray afterglow
  14. Optical Observations of GRB990627
  15. GRB 990627, radio observations
  16. GRB990627: BeppoSAX-WFC final location
  17. BeppoSAX: GRB990625
  18. Late-time HST/STIS Observation of GRB 990123
  19. GRB 990506 - clarification to GCN 352
  20. GRB 990506 - Optical Observations
  21. Optical Observations of GRB 990506
  22. GRB 990506 Radio Transient
  23. GRB990527 Optical Observations
  24. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  25. IPN error box for GRB990527
  26. Late Afterglows of GRBs 990510, 990123
  27. X-ray/GRB 1SAX J0835.9+5118, TNG V and R observations
  28. X-ray/GRB 1SAX J0835.9+5118, BATSE Observation
  29. X-ray/GRB 1SAX J0835.9+5118, Optical Observations
  30. GRB 990506 optical observation
  31. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  32. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  33. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  34. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  35. radio observations of X-ray/GRB transient field
  36. optical observation of the X-ray/GRB transient SAX J0835.9+5118
  37. Optical report on X-ray/GRB transient
  38. radio detection of X-ray/GRB transient
  39. BeppoSAX: A new fast X-ray transient
  40. GRB 990510: optical observations
  41. GRB990510: photometric and spectroscopic observations with the VLT
  42. GRB 990510: optical linear polarization
  43. GRB 990510: optical observations
  44. GRB990510, VI observations
  45. GRB 990506 R band observations
  46. GRB990510: X-ray afterglow
  47. GRB 990510: optical observation
  48. VLT spectrum of GRB990510
  49. GRB 990510: Broad Band Break
  50. GRB 990510: BATSE Observations
  51. GRB990510: optical observation
  52. GRB 990510 Optical Observations
  53. GRB 990510, BVI photometry
  54. GRB 990510 optical observations
  55. GRB 990510: BeppoSAX/GRBM observations
  56. GRB990510 optical observations
  57. GRB990510
  58. GRB 990510 optical observations
  59. GRB 990510 optical observations
  60. Galactic extinction towards GRB 990510
  61. GRB990510: NFI X-ray source
  62. GRB 990510 optical observations
  63. IPN localization of GRB990510
  64. GRB 990506 Radio Observations
  65. GRB 990123, optical monitoring
  66. GRB 990506: BATSE Observations
  67. GRB 990506, optical observations
  68. GRB 990510: Final BeppoSAX-WFC Coordinates
  69. GRB 990506, Optical Observations
  70. GRB 990506 optical observations
  71. GRB 990506 optical observations
  72. GRB 990506, optical observations
  73. GRB990506 observation plan
  74. Refined IPN error box for GRB990506
  75. GRB 990506: Limits on the possible optical transient
  76. GRB 990506, armchair astronomy
  77. GRB 990506, optical observations from +1 to +3 hours
  78. GRB 990506, optical observations
  79. GRB990506 Optical observations
  80. GRB990506 observation plan
  81. New IPN/RXTE error box for GRB990506
  82. IPN localization for GRB990506
  83. GRB 970228: Redshift and properties of the host galaxy
  84. IPN localization of GRB990427
  85. GRB981220 VLBA observations
  86. GRB980425 Optical observations of exponential decline at late time
  87. GRB990321 REFINED IPN ANNULUS
  88. GRB990323 PRECISE IPN POSITION
  89. GRB990321 IPN TRIANGULATION
  90. GRB 990316 Optical Observations
  91. GRB 990316, Radio observations
  92. GRB 990316, Optical observations
  93. GRB990316, Optical observations
  94. GRB 990316 optical observations
  95. GRB990316: simultaneous optical observation
  96. GRB990316 - Optical null results
  97. ASM/IPN error box for GRB 990308 (BATSE #7457)
  98. GRB990308 not a new SGR
  99. GRB 990308a and GRB 990308b
  100. GRB990308 (Trig. 7457), optical observations

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