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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. GRB990704 radio and optical observations
  2. BeppoSAX GRB990705: possible X-ray afterglow
  3. GRB 990704 X-ray Observations
  4. GRB 990704 Optical Observations
  5. GRB 990704, optical observations
  6. GRB990704
  7. GRB990705: Intriguing Positional Coincidences
  8. GRB990704
  9. Refined BeppoSAX-WFC position of GRB990704: Errata Corrige
  10. GRB990704, optical observations
  11. GRB990704: possible X-ray afterglow
  12. Identification of a possible optical counterpart for GRB990704
  13. GRB990704
  14. Refined BeppoSAX-WFC position of GRB990704
  15. GRB990704: BeppoSAX detection
  16. BeppoSAX NFI Observation of GRB990627 X-ray afterglow
  17. Optical Observations of GRB990627
  18. GRB 990627, radio observations
  19. GRB990627: BeppoSAX-WFC final location
  20. BeppoSAX: GRB990625
  21. Late-time HST/STIS Observation of GRB 990123
  22. GRB 990506 - clarification to GCN 352
  23. GRB 990506 - Optical Observations
  24. Optical Observations of GRB 990506
  25. GRB 990506 Radio Transient
  26. GRB990527 Optical Observations
  27. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  28. IPN error box for GRB990527
  29. Late Afterglows of GRBs 990510, 990123
  30. X-ray/GRB 1SAX J0835.9+5118, TNG V and R observations
  31. X-ray/GRB 1SAX J0835.9+5118, BATSE Observation
  32. X-ray/GRB 1SAX J0835.9+5118, Optical Observations
  33. GRB 990506 optical observation
  34. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  35. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  36. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  37. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  38. radio observations of X-ray/GRB transient field
  39. optical observation of the X-ray/GRB transient SAX J0835.9+5118
  40. Optical report on X-ray/GRB transient
  41. radio detection of X-ray/GRB transient
  42. BeppoSAX: A new fast X-ray transient
  43. GRB 990510: optical observations
  44. GRB990510: photometric and spectroscopic observations with the VLT
  45. GRB 990510: optical linear polarization
  46. GRB 990510: optical observations
  47. GRB990510, VI observations
  48. GRB 990506 R band observations
  49. GRB990510: X-ray afterglow
  50. GRB 990510: optical observation
  51. VLT spectrum of GRB990510
  52. GRB 990510: Broad Band Break
  53. GRB 990510: BATSE Observations
  54. GRB990510: optical observation
  55. GRB 990510 Optical Observations
  56. GRB 990510, BVI photometry
  57. GRB 990510 optical observations
  58. GRB 990510: BeppoSAX/GRBM observations
  59. GRB990510 optical observations
  60. GRB990510
  61. GRB 990510 optical observations
  62. GRB 990510 optical observations
  63. Galactic extinction towards GRB 990510
  64. GRB990510: NFI X-ray source
  65. GRB 990510 optical observations
  66. IPN localization of GRB990510
  67. GRB 990506 Radio Observations
  68. GRB 990123, optical monitoring
  69. GRB 990506: BATSE Observations
  70. GRB 990506, optical observations
  71. GRB 990510: Final BeppoSAX-WFC Coordinates
  72. GRB 990506, Optical Observations
  73. GRB 990506 optical observations
  74. GRB 990506 optical observations
  75. GRB 990506, optical observations
  76. GRB990506 observation plan
  77. Refined IPN error box for GRB990506
  78. GRB 990506: Limits on the possible optical transient
  79. GRB 990506, armchair astronomy
  80. GRB 990506, optical observations from +1 to +3 hours
  81. GRB 990506, optical observations
  82. GRB990506 Optical observations
  83. GRB990506 observation plan
  84. New IPN/RXTE error box for GRB990506
  85. IPN localization for GRB990506
  86. GRB 970228: Redshift and properties of the host galaxy
  87. IPN localization of GRB990427
  88. GRB981220 VLBA observations
  89. GRB980425 Optical observations of exponential decline at late time
  90. GRB990321 REFINED IPN ANNULUS
  91. GRB990323 PRECISE IPN POSITION
  92. GRB990321 IPN TRIANGULATION
  93. GRB 990316 Optical Observations
  94. GRB 990316, Radio observations
  95. GRB 990316, Optical observations
  96. GRB990316, Optical observations
  97. GRB 990316 optical observations
  98. GRB990316: simultaneous optical observation
  99. GRB990316 - Optical null results
  100. ASM/IPN error box for GRB 990308 (BATSE #7457)

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