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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. GRB011211(=XRF011211): BeppoSAX refined positions
  2. BeppoSAX Alert: GRB011211(=XRF011211)
  3. GRB 011130: Optical Observations of Chandra Sources
  4. GRB 011130: Optical Observations of Chandra sources
  5. GRB011130 (XRF011130) Chandra Observations
  6. GRB011130 (=XRF011130): Scheduled Target of Opportunity
  7. GRB 011130: Magellan spectroscopy
  8. Sub-mm and Centimeter Detections of the Host Galaxy of GRB000418
  9. GRB011130, optical observations
  10. GRB 011130, K band observations
  11. GRB011130, optical observations
  12. GRB011130 (=XRF011130): Second Revised Localization by HETE
  13. GRB 011130 I-band Observation
  14. GRB011130 (XRF011130) optical observations
  15. GRB011130 (XRF011130) SDSS PT i-band observations
  16. XRF011130: Infrared Observations
  17. GRB011130, Radio Observations
  18. Detection of the X-ray afterglow of GRB011121 by BeppoSAX
  19. GRB011130 (=XRF011130), Optical Observations
  20. XRF011130: NEAT Optical Observations
  21. GRB011130 (=XRF011130): Revised Localization of an X-ray
  22. GRB001109, Radio Monitoring
  23. GRB 011121: Errata URL
  24. GRB 011121
  25. GRB011130 (=H1864): An X-Ray Rich GRB Detected by HETE
  26. GRB 011121: J-band observations
  27. GRB 011121: NIR observations, host galaxy?
  28. GRB010921 - Milagro GeV/TeV Observations
  29. GRB 011121: HST Scheduled
  30. GRB011121: fainter still
  31. Correction: GCN1157 (GRB 011121)
  32. GRB011121: UBRI Observations
  33. GRB011121
  34. GRB 011121: Radio Observations
  35. GRB 011121 J-Band Astrometry
  36. GRB011121: continued decay
  37. GRB 011121: Detection of Bright IR Counterpart
  38. GRB011121: possible redshift, continued decay
  39. GRB011121: fading behavior
  40. GRB011121: possible optical counterpart
  41. GRB011121: BeppoSAX-WFC refined positions
  42. IPN triangulation of GRB011121
  43. BEPPOSAX GRB011121
  44. GRB 011030: TNG K-band observation
  45. XRF011030: J and K band observations
  46. GRB011030, optical observation
  47. XRF011030: Chandra Observations
  48. GRB 011030: K-band observations
  49. GRB011030: Z-band observations
  50. GRB 011030 R band observations
  51. GRB 011030 I-band Observation
  52. The X-ray Flash 011030 ('GRB 011030')
  53. Non-triggered burst 011030 ("GRB 011030")
  54. The Radio Afterglow from the X-ray Rich GRB 011030
  55. GRB 010921: HST Detection of the Afterglow and Host Galaxy
  56. GRB 970828: HST Observations of the Host Galaxy
  57. GRB 000131: HST Detection of the Host Galaxy
  58. GRB 970828: HST Observations of the Host Galaxy
  59. GRB010921, optical observation
  60. GRB 011019 optical observation
  61. Optical observation of SGR 1806-20 at the 6-m SAO telescope
  62. GRB011019: Subaru Optical Observations
  63. GRB 011030 I-band Observations
  64. GRB 011030 K-band Observations
  65. GRB010921, optical observations
  66. GRB 011030, WSRT radio observations
  67. GRB011030 - further refinement WFC position
  68. GRB 011030, Radio observations
  69. GRB011030: radio search
  70. GRB 011030, R-band observations
  71. X-ray rich GRB011030: BeppoSAX refined positions
  72. BeppoSAX ALERT: Possible X-ray rich GRB011030
  73. GRB 010921: Possible supernova component
  74. GRB011019: NEAT Optical Observations
  75. GRB011019: ROTSE-III optical observations
  76. GRB010921, optical observation at early time
  77. GRB 010921, I-band observations
  78. GRB011019: Optical observations
  79. GRB011019, optical observations -- correction
  80. GRB011019, optical observations
  81. GRB011019: A Faint, X-ray Rich GRB localized by HETE
  82. GRB010921: Spectroscopy of the Host Galaxy
  83. GRB 010921: The afterglow of HETE #1761
  84. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  85. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  86. GRB010923 as seen by BeppoSAX GRBM
  87. GRB010928(=H1770): Localization of a Long GRB by HETE
  88. GRB010923(=H1764): A Short Duration GRB Detected by HETE
  89. GRB010921, negative optical observations
  90. GRB010921 field photometry
  91. GRB010921 Optical Observations
  92. GRB 010921 DPOSS Images Available
  93. IPN triangulation of GRB010921 (=H1761)
  94. H1761: A Bright GRB Detected by HETE
  95. HETE Trigger #1760 (GRB 010920B?): new optical source = asteroid
  96. HETE Trigger #1760 (GRB 010920B?): a new optical source
  97. HETE Trigger #1759 (GRB 010920?) optical observations
  98. GRB001109, Host Galaxy Astrometry
  99. GRB000926, Host Galaxy Observations
  100. GRB001109, Host Galaxy Spectroscopic Observations

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