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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. GRB020127 Optical Observations -- Erratum to GCN 1230
  2. GRB010921 Optical Observations
  3. GRB020127(=H1902): Localization of a Double-Peaked GRB by HETE
  4. GRB020124: Optical observations
  5. VLT observations of GRB 020124: The fading optical/near-infrared afterglow
  6. GRB020124: Optical observations
  7. GRB 020124: Optical observations
  8. GRB 020124 Optical Observations
  9. IPN triangulation of GRB020124 (HETE 1896)
  10. IPN observations of SGR1806-20
  11. GRB 020124: Optical afterglow
  12. GRB020124(=H1896): Localization of a Long GRB by HETE
  13. HETE 1896: Optical observations
  14. GRB optical counterpart candidate in GCN 1217 is M dwarf
  15. Possible optical counterpart to a GRB
  16. GRB011212, Optical Observations
  17. GRB011211: BeppoSAX/GRBM data
  18. Optical polarization observations for GRB011211
  19. GRB 011211: Detection of the Probable Host Galaxy
  20. GRB 011130 and GRB 011212 - Milagro GeV/TeV Observations
  21. Color indices of the afterglow of GRB011211
  22. GRB011212: Optical observations at Gunma
  23. GRB 011211, spectrum and optical photometry
  24. GRB 011130: Optical Observations of X-ray and Radio Sources
  25. GRB 011130, Radio/X-ray Comparison
  26. GRB011212: Optical observations
  27. GRB 011212: optical observation at Asiago
  28. GRB 011211: Evidence for an Optical Break
  29. GRB 011211: TNG Spectroscopic Observations
  30. optical follow-up of GRB(XRF) 011211
  31. GRB 011212: optical observation at Oslo (relayed)
  32. GRB 011211: Optical Spectroscopy
  33. GRB 011211, Optical Observations
  34. GRB011212, BVRI field photometry
  35. GRB011211, BVRI field photometry
  36. GRB011212: Optical observations
  37. GRB 011211: BVRi-band photometry
  38. GRB011212 (=H10001): An X-Ray Rich GRB Detected by HETE
  39. Fading of the optical source associated of XRF 011211
  40. XMM-Newton observation of GRB011211
  41. GRB 011211 Optical Observations: Likely Afterglow
  42. GRB011130 (=XRF011130): Further analysis of Chandra Target of
  43. GRB011211(=XRF011211): BeppoSAX refined positions
  44. BeppoSAX Alert: GRB011211(=XRF011211)
  45. GRB 011130: Optical Observations of Chandra Sources
  46. GRB 011130: Optical Observations of Chandra sources
  47. GRB011130 (XRF011130) Chandra Observations
  48. GRB011130 (=XRF011130): Scheduled Target of Opportunity
  49. GRB 011130: Magellan spectroscopy
  50. Sub-mm and Centimeter Detections of the Host Galaxy of GRB000418
  51. GRB011130, optical observations
  52. GRB 011130, K band observations
  53. GRB011130, optical observations
  54. GRB011130 (=XRF011130): Second Revised Localization by HETE
  55. GRB 011130 I-band Observation
  56. GRB011130 (XRF011130) optical observations
  57. GRB011130 (XRF011130) SDSS PT i-band observations
  58. XRF011130: Infrared Observations
  59. GRB011130, Radio Observations
  60. Detection of the X-ray afterglow of GRB011121 by BeppoSAX
  61. GRB011130 (=XRF011130), Optical Observations
  62. XRF011130: NEAT Optical Observations
  63. GRB011130 (=XRF011130): Revised Localization of an X-ray
  64. GRB001109, Radio Monitoring
  65. GRB 011121: Errata URL
  66. GRB 011121
  67. GRB011130 (=H1864): An X-Ray Rich GRB Detected by HETE
  68. GRB 011121: J-band observations
  69. GRB 011121: NIR observations, host galaxy?
  70. GRB010921 - Milagro GeV/TeV Observations
  71. GRB 011121: HST Scheduled
  72. GRB011121: fainter still
  73. Correction: GCN1157 (GRB 011121)
  74. GRB011121: UBRI Observations
  75. GRB011121
  76. GRB 011121: Radio Observations
  77. GRB 011121 J-Band Astrometry
  78. GRB011121: continued decay
  79. GRB 011121: Detection of Bright IR Counterpart
  80. GRB011121: possible redshift, continued decay
  81. GRB011121: fading behavior
  82. GRB011121: possible optical counterpart
  83. GRB011121: BeppoSAX-WFC refined positions
  84. IPN triangulation of GRB011121
  85. BEPPOSAX GRB011121
  86. GRB 011030: TNG K-band observation
  87. XRF011030: J and K band observations
  88. GRB011030, optical observation
  89. XRF011030: Chandra Observations
  90. GRB 011030: K-band observations
  91. GRB011030: Z-band observations
  92. GRB 011030 R band observations
  93. GRB 011030 I-band Observation
  94. The X-ray Flash 011030 ('GRB 011030')
  95. Non-triggered burst 011030 ("GRB 011030")
  96. The Radio Afterglow from the X-ray Rich GRB 011030
  97. GRB 010921: HST Detection of the Afterglow and Host Galaxy
  98. GRB 970828: HST Observations of the Host Galaxy
  99. GRB 000131: HST Detection of the Host Galaxy
  100. GRB 970828: HST Observations of the Host Galaxy

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