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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 011212: optical observation at Oslo (relayed)
  2. GRB 011211: Optical Spectroscopy
  3. GRB 011211, Optical Observations
  4. GRB011212, BVRI field photometry
  5. GRB011211, BVRI field photometry
  6. GRB011212: Optical observations
  7. GRB 011211: BVRi-band photometry
  8. GRB011212 (=H10001): An X-Ray Rich GRB Detected by HETE
  9. Fading of the optical source associated of XRF 011211
  10. XMM-Newton observation of GRB011211
  11. GRB 011211 Optical Observations: Likely Afterglow
  12. GRB011130 (=XRF011130): Further analysis of Chandra Target of
  13. GRB011211(=XRF011211): BeppoSAX refined positions
  14. BeppoSAX Alert: GRB011211(=XRF011211)
  15. GRB 011130: Optical Observations of Chandra Sources
  16. GRB 011130: Optical Observations of Chandra sources
  17. GRB011130 (XRF011130) Chandra Observations
  18. GRB011130 (=XRF011130): Scheduled Target of Opportunity
  19. GRB 011130: Magellan spectroscopy
  20. Sub-mm and Centimeter Detections of the Host Galaxy of GRB000418
  21. GRB011130, optical observations
  22. GRB 011130, K band observations
  23. GRB011130, optical observations
  24. GRB011130 (=XRF011130): Second Revised Localization by HETE
  25. GRB 011130 I-band Observation
  26. GRB011130 (XRF011130) optical observations
  27. GRB011130 (XRF011130) SDSS PT i-band observations
  28. XRF011130: Infrared Observations
  29. GRB011130, Radio Observations
  30. Detection of the X-ray afterglow of GRB011121 by BeppoSAX
  31. GRB011130 (=XRF011130), Optical Observations
  32. XRF011130: NEAT Optical Observations
  33. GRB011130 (=XRF011130): Revised Localization of an X-ray
  34. GRB001109, Radio Monitoring
  35. GRB 011121: Errata URL
  36. GRB 011121
  37. GRB011130 (=H1864): An X-Ray Rich GRB Detected by HETE
  38. GRB 011121: J-band observations
  39. GRB 011121: NIR observations, host galaxy?
  40. GRB010921 - Milagro GeV/TeV Observations
  41. GRB 011121: HST Scheduled
  42. GRB011121: fainter still
  43. Correction: GCN1157 (GRB 011121)
  44. GRB011121: UBRI Observations
  45. GRB011121
  46. GRB 011121: Radio Observations
  47. GRB 011121 J-Band Astrometry
  48. GRB011121: continued decay
  49. GRB 011121: Detection of Bright IR Counterpart
  50. GRB011121: possible redshift, continued decay
  51. GRB011121: fading behavior
  52. GRB011121: possible optical counterpart
  53. GRB011121: BeppoSAX-WFC refined positions
  54. IPN triangulation of GRB011121
  55. BEPPOSAX GRB011121
  56. GRB 011030: TNG K-band observation
  57. XRF011030: J and K band observations
  58. GRB011030, optical observation
  59. XRF011030: Chandra Observations
  60. GRB 011030: K-band observations
  61. GRB011030: Z-band observations
  62. GRB 011030 R band observations
  63. GRB 011030 I-band Observation
  64. The X-ray Flash 011030 ('GRB 011030')
  65. Non-triggered burst 011030 ("GRB 011030")
  66. The Radio Afterglow from the X-ray Rich GRB 011030
  67. GRB 010921: HST Detection of the Afterglow and Host Galaxy
  68. GRB 970828: HST Observations of the Host Galaxy
  69. GRB 000131: HST Detection of the Host Galaxy
  70. GRB 970828: HST Observations of the Host Galaxy
  71. GRB010921, optical observation
  72. GRB 011019 optical observation
  73. Optical observation of SGR 1806-20 at the 6-m SAO telescope
  74. GRB011019: Subaru Optical Observations
  75. GRB 011030 I-band Observations
  76. GRB 011030 K-band Observations
  77. GRB010921, optical observations
  78. GRB 011030, WSRT radio observations
  79. GRB011030 - further refinement WFC position
  80. GRB 011030, Radio observations
  81. GRB011030: radio search
  82. GRB 011030, R-band observations
  83. X-ray rich GRB011030: BeppoSAX refined positions
  84. BeppoSAX ALERT: Possible X-ray rich GRB011030
  85. GRB 010921: Possible supernova component
  86. GRB011019: NEAT Optical Observations
  87. GRB011019: ROTSE-III optical observations
  88. GRB010921, optical observation at early time
  89. GRB 010921, I-band observations
  90. GRB011019: Optical observations
  91. GRB011019, optical observations -- correction
  92. GRB011019, optical observations
  93. GRB011019: A Faint, X-ray Rich GRB localized by HETE
  94. GRB010921: Spectroscopy of the Host Galaxy
  95. GRB 010921: The afterglow of HETE #1761
  96. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  97. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  98. GRB010923 as seen by BeppoSAX GRBM
  99. GRB010928(=H1770): Localization of a Long GRB by HETE
  100. GRB010923(=H1764): A Short Duration GRB Detected by HETE

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