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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. IPN/RXTE TRIANGULATION OF GRB010126
  2. GRB 010119, optical observations
  3. GRB010119: Optical observations
  4. Optical Observations of GRB 001018 at Keck
  5. GRB010119, Radio observations
  6. IPN TRIANGULATION OF GRB010119 (SHORT/HARD)
  7. Optical observations of GRB 001018 with JCAM
  8. IPN TRIANGULATION OF GRB010115
  9. IPN TRIANGULATION OF GRB010109
  10. IPN TRIANGULATION OF GRB010109
  11. GRB010103, optical observations
  12. IPN triangulation of GRB010104
  13. IPN triangulation of GRB010103
  14. GRB 001204: Ks observations
  15. H band observation of GRB 001212
  16. GRB & BeppoSAX: ground operations restored back to 24 hrs a day
  17. IPN triangulation of GRB001219
  18. GRB 001212 Optical Observation
  19. GRB 001212 Optical Observation
  20. GRB 001212 optical observation
  21. GRB 001212 possible OA in 2MASS
  22. GRB 001212 possible OA
  23. IPN triangulation of GRB001212
  24. GRB001204: Optical observations
  25. Confirmation of IPN position for GRB001204
  26. GRB001204, Radio observations
  27. IPN triangulation of GRB001204 (short/hard)
  28. GRB 001105, further optical observations
  29. GRB001120: Gunn-i observations
  30. GRB001120: Optical observations
  31. GRB001109, optical observations
  32. GRB001120, optical observations
  33. WSRT 4.8 GHz observations of GRB001109
  34. IPN triangulation of GRB001120
  35. Optical/NIR observations of GRB001109
  36. GRB 001109: deep JHK upper limits
  37. GRB 001109 X-ray afterglow with BeppoSAX
  38. CORRECTION to XMM-Newton observation of GRB001025
  39. GRB001109: Optical observations
  40. GRB001109: BeppoSAX/NFI Observations
  41. GRB001109, R-band optical observations
  42. GRB001109, Radio observations
  43. GRB001109: BeppoSAX refined WFC position
  44. BeppoSAX ALERT: GRB001109
  45. GRB001105 BVRI field photometry correction
  46. GRB001105, BVRI field photometry
  47. GRB 001105, R-band observation
  48. IPN TRIANGULATION OF GRB001105
  49. GRB 001025B, Optical obervations
  50. GRB 991208: HST Imaging of the Host Galaxy
  51. GRB000926: R-image of the host galaxy
  52. GRB 001025B, I-band observations
  53. XMM-Newton observation of GRB001025
  54. GRB001025B, Radio observations
  55. GRB 001025 Optical Observations
  56. GRB 001025A, optical observation
  57. IPN TRIANGULATION OF GRB001025B (SHORT/HARD)
  58. CORRECTION TO IPN/RXTE ERROR BOX FOR GRB001025
  59. IPN triangulation of GRB001025
  60. GRB001007: Optical observations
  61. ASM Localization of GRB 001025
  62. GRB001007, Radio observations
  63. IPN TRIANGULATION OF GRB001020
  64. GRB001019, Optical Observations
  65. GRB 001018, Possible Radio Afterglow
  66. GRB001018, Gamma Ray Observations
  67. IPN TRIANGULATION OF GRB001019
  68. CORRECTION TO PEAK FLUX OF GRB001018
  69. IPN TRIANGULATION OF GRB001018
  70. IPN TRIANGULATION OF GRB 001017
  71. GRB 000926: Improved Absorber Redshift
  72. V,R,I band observations of GRB000926
  73. The Likely Optical/Infrared Afterglow of GRB 001011
  74. HETE positions added to GCN
  75. GRB001011 BeppoSAX/WFC refined position
  76. BeppoSAX ALERT: GRB001011
  77. GRB 001007, BVR-band observations
  78. GRB000926 - Amateur Optical Observations
  79. GRB001007: Optical observations
  80. CONCAM null result on GRB001005
  81. IPN triangulation of GRB001007
  82. GRB 000926 : the host galaxy
  83. HETE-2 Launches Successfully
  84. IPN triangulation of GRB001005
  85. HETE-2 48 hour Launch Delay
  86. GRB 000926 Chandra Observation
  87. IPN triangulation of GRB 001004
  88. Public availability of BeppoSAX data of GRB000926
  89. GRB000926: X-ray afterglow by BeppoSAX: revised fluxes (fwd)
  90. GRB000926: X-ray afterglow by BeppoSAX. Refined analysis
  91. GRB000926 - Optical observations
  92. GRB000926 - Optical observations
  93. GRB 000926, Optical Decay
  94. GRB000911: VLT infrared observation
  95. GRB000926 - Optical observations
  96. GRB000926 - Optical observations
  97. GRB 000926: optical observations
  98. GRB 000926, Optical Observations
  99. GRB000926 - Optical observations
  100. GRB000911: optical VLT observations

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