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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. GRB020124(=H1896): Localization of a Long GRB by HETE
  2. HETE 1896: Optical observations
  3. GRB optical counterpart candidate in GCN 1217 is M dwarf
  4. Possible optical counterpart to a GRB
  5. GRB011212, Optical Observations
  6. GRB011211: BeppoSAX/GRBM data
  7. Optical polarization observations for GRB011211
  8. GRB 011211: Detection of the Probable Host Galaxy
  9. GRB 011130 and GRB 011212 - Milagro GeV/TeV Observations
  10. Color indices of the afterglow of GRB011211
  11. GRB011212: Optical observations at Gunma
  12. GRB 011211, spectrum and optical photometry
  13. GRB 011130: Optical Observations of X-ray and Radio Sources
  14. GRB 011130, Radio/X-ray Comparison
  15. GRB011212: Optical observations
  16. GRB 011212: optical observation at Asiago
  17. GRB 011211: Evidence for an Optical Break
  18. GRB 011211: TNG Spectroscopic Observations
  19. optical follow-up of GRB(XRF) 011211
  20. GRB 011212: optical observation at Oslo (relayed)
  21. GRB 011211: Optical Spectroscopy
  22. GRB 011211, Optical Observations
  23. GRB011212, BVRI field photometry
  24. GRB011211, BVRI field photometry
  25. GRB011212: Optical observations
  26. GRB 011211: BVRi-band photometry
  27. GRB011212 (=H10001): An X-Ray Rich GRB Detected by HETE
  28. Fading of the optical source associated of XRF 011211
  29. XMM-Newton observation of GRB011211
  30. GRB 011211 Optical Observations: Likely Afterglow
  31. GRB011130 (=XRF011130): Further analysis of Chandra Target of
  32. GRB011211(=XRF011211): BeppoSAX refined positions
  33. BeppoSAX Alert: GRB011211(=XRF011211)
  34. GRB 011130: Optical Observations of Chandra Sources
  35. GRB 011130: Optical Observations of Chandra sources
  36. GRB011130 (XRF011130) Chandra Observations
  37. GRB011130 (=XRF011130): Scheduled Target of Opportunity
  38. GRB 011130: Magellan spectroscopy
  39. Sub-mm and Centimeter Detections of the Host Galaxy of GRB000418
  40. GRB011130, optical observations
  41. GRB 011130, K band observations
  42. GRB011130, optical observations
  43. GRB011130 (=XRF011130): Second Revised Localization by HETE
  44. GRB 011130 I-band Observation
  45. GRB011130 (XRF011130) optical observations
  46. GRB011130 (XRF011130) SDSS PT i-band observations
  47. XRF011130: Infrared Observations
  48. GRB011130, Radio Observations
  49. Detection of the X-ray afterglow of GRB011121 by BeppoSAX
  50. GRB011130 (=XRF011130), Optical Observations
  51. XRF011130: NEAT Optical Observations
  52. GRB011130 (=XRF011130): Revised Localization of an X-ray
  53. GRB001109, Radio Monitoring
  54. GRB 011121: Errata URL
  55. GRB 011121
  56. GRB011130 (=H1864): An X-Ray Rich GRB Detected by HETE
  57. GRB 011121: J-band observations
  58. GRB 011121: NIR observations, host galaxy?
  59. GRB010921 - Milagro GeV/TeV Observations
  60. GRB 011121: HST Scheduled
  61. GRB011121: fainter still
  62. Correction: GCN1157 (GRB 011121)
  63. GRB011121: UBRI Observations
  64. GRB011121
  65. GRB 011121: Radio Observations
  66. GRB 011121 J-Band Astrometry
  67. GRB011121: continued decay
  68. GRB 011121: Detection of Bright IR Counterpart
  69. GRB011121: possible redshift, continued decay
  70. GRB011121: fading behavior
  71. GRB011121: possible optical counterpart
  72. GRB011121: BeppoSAX-WFC refined positions
  73. IPN triangulation of GRB011121
  74. BEPPOSAX GRB011121
  75. GRB 011030: TNG K-band observation
  76. XRF011030: J and K band observations
  77. GRB011030, optical observation
  78. XRF011030: Chandra Observations
  79. GRB 011030: K-band observations
  80. GRB011030: Z-band observations
  81. GRB 011030 R band observations
  82. GRB 011030 I-band Observation
  83. The X-ray Flash 011030 ('GRB 011030')
  84. Non-triggered burst 011030 ("GRB 011030")
  85. The Radio Afterglow from the X-ray Rich GRB 011030
  86. GRB 010921: HST Detection of the Afterglow and Host Galaxy
  87. GRB 970828: HST Observations of the Host Galaxy
  88. GRB 000131: HST Detection of the Host Galaxy
  89. GRB 970828: HST Observations of the Host Galaxy
  90. GRB010921, optical observation
  91. GRB 011019 optical observation
  92. Optical observation of SGR 1806-20 at the 6-m SAO telescope
  93. GRB011019: Subaru Optical Observations
  94. GRB 011030 I-band Observations
  95. GRB 011030 K-band Observations
  96. GRB010921, optical observations
  97. GRB 011030, WSRT radio observations
  98. GRB011030 - further refinement WFC position
  99. GRB 011030, Radio observations
  100. GRB011030: radio search

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