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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 000301C R-band observation
  2. GRB 000301C, Optical Observation
  3. GRB000301C, near-infrared observations (JHK' photometry)
  4. GRB 000301C: OT confirmed
  5. GRB000301c optical observations
  6. GRB 000301A, Radio Observations
  7. GRB000301C, optical observations
  8. GRB000301c, near-infrared observations
  9. GRB000301C
  10. GRB 000301C : Optical Candidate
  11. Radio observations of the error box of GRB000301A
  12. GRB000301C: RXTE/ASM and IPN localizations
  13. GRB000301A [IPN Position]
  14. GRB000226 [IPN Position]
  15. HST Observations of GRB 990712
  16. GRB 000214 near-IR observations
  17. GRB 000115 Optical observations
  18. GRB 000214, Radio Observations
  19. GRB 000214 ``Valentine's Day Burst'': BeppoSAX NFI Observation
  20. GRB000210, Radio Observations
  21. Correction to GCN 557 (GRB000214: BeppoSAX GRBM and WFC Detection)
  22. GRB 000115, BVRI field photometry
  23. GRB000214: BeppoSAX GRBM and WFC Detection
  24. IPN annulus for GRB000214
  25. BATSE GRB trigger criterion changed
  26. Optical observations of GRB000210
  27. GRB000210 X-ray afterglow
  28. GRB000214: X-ray afterglow candidate
  29. GRB000214 refined BeppoSAX-WFC position
  30. BeppoSAX GRB000214 ("S. Valentine's day GRB")
  31. GRB 000210: BATSE Observations
  32. Correction to Chandra Position of GRB000210 afterglow
  33. Optical observations of the Chandra X-ray source for GRB000210
  34. GRB000210, Radio Observations
  35. Optical candidate for GRB000210
  36. Chandra Observations of GRB000210 X-ray Afterglow
  37. IPN triangulation of GRB000210
  38. GRB000210: possible afterglow detection with BeppoSAX NFI
  39. GRB000201, Radio Observations
  40. GRB000210: BeppoSAX GRBM and WFC Detection
  41. SAX_WFC_GRB_NOTICE
  42. SAX_WFC_GRB_NOTICE
  43. Optical observations of GRB000131
  44. GRB000201 Optical Observations
  45. GRB 000201: TAROT optical observations
  46. GRB 000131 Optical Observations
  47. GRB000126 Optical Observations
  48. BATSE GRB trigger criteria changed
  49. GRB 991208, radio observations
  50. BATSE+IPN location of GRB000131
  51. IPN localization of GRB000131
  52. GRB 000126, optical observations
  53. GRB000126, optical observations
  54. BATSE location of GRB000126
  55. IPN localization of GRB000126
  56. GRB 000115 Optical observations
  57. BATSE Observations of GRB000115
  58. Correction to GCN 520 (IPN annulus for GRB000115)
  59. IPN annulus for GRB000115
  60. Second RXTE Observation of GRB 000115
  61. GRB991216, UBVRIJHK field photometry
  62. GRB991216 late optical observation
  63. Single IPN error box for GRB991229
  64. GCN resumes full operations
  65. GRB 991216 VLBA Observations
  66. BEPPOSAX GRBM Localization of GRB991226
  67. IPN error boxes for GRB991229
  68. GRB 991216: J band spectrophotometry
  69. GRB 991216: Detection of the Host and/or Absorber Galaxy
  70. IPN localization of GRB991226
  71. Single IPN error box for GRB991221
  72. IPN error boxes for GRB991221
  73. GRB 991216 RXTE ASM Observations
  74. IPN error box for GRB991216
  75. GRB 991216: Updated BATSE parameters
  76. Lowell/Perkins observation of GRB 991216
  77. GRB 991217 (SAX J2303.2+0015) Optical observations
  78. GRB991217/SAX J2303.2+0015, optical observations
  79. Chandra observation of the X-ray afterglow of GRB991216
  80. GRB 991216, optical observations
  81. GRB 991216 Optical Observations
  82. GRB 991216 Optical spectroscopy/imaging
  83. VLT spectra of GRB991216
  84. GRB991216 Optical and IR observations
  85. K observations of GRB991216
  86. SAX J2303.2+0015 Optical observations
  87. IR observations of GRB991216
  88. GRB991216 radio observations
  89. GRB 991217 (SAX J2303.2+0015) Optical observations
  90. GRB991216 radio observations
  91. GRB991216 Spectroscopy
  92. Lowell/Perkins observation of GRB 991216
  93. GRB991216, optical observations
  94. GRB991216 Optical and infrared observations of Beethoven Burst
  95. Refined IPN localization of GRB991216
  96. GRB 991216 Radio Observations
  97. GRB 991217
  98. GRB 991208 Keck Spectroscopy
  99. GRB 991208 Infrared Detection
  100. GRB991216

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