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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"

20510 results found.

  1. GRB 011130: Optical Observations of X-ray and Radio Sources
  2. GRB 011130, Radio/X-ray Comparison
  3. GRB011212: Optical observations
  4. GRB 011212: optical observation at Asiago
  5. GRB 011211: TNG Spectroscopic Observations
  6. GRB 011211, Optical Observations
  7. GRB011212: Optical observations
  8. GRB 011211 Optical Observations: Likely Afterglow
  9. GRB011130 (=XRF011130): Further analysis of Chandra Target of
  10. GRB 011130: Optical Observations of Chandra Sources
  11. GRB 011130: Optical Observations of Chandra sources
  12. GRB011130 (XRF011130) Chandra Observations
  13. GRB 011130: Magellan spectroscopy
  14. Sub-mm and Centimeter Detections of the Host Galaxy of GRB000418
  15. GRB011130, optical observations
  16. GRB 011130, K band observations
  17. GRB011130, optical observations
  18. GRB011130 (XRF011130) optical observations
  19. GRB011130 (XRF011130) SDSS PT i-band observations
  20. XRF011130: Infrared Observations
  21. GRB011130, Radio Observations
  22. GRB011130 (=XRF011130), Optical Observations
  23. XRF011130: NEAT Optical Observations
  24. GRB001109, Radio Monitoring
  25. GRB 011121
  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. GRB011121: UBRI Observations
  32. GRB011121
  33. GRB 011121: Radio Observations
  34. GRB011121: continued decay
  35. GRB 011121: Detection of Bright IR Counterpart
  36. GRB011121: possible redshift, continued decay
  37. GRB011121: fading behavior
  38. GRB011121: possible optical counterpart
  39. XRF011030: J and K band observations
  40. XRF011030: Chandra Observations
  41. GRB 011030: K-band observations
  42. GRB011030: Z-band observations
  43. GRB 011030 R band observations
  44. The X-ray Flash 011030 ('GRB 011030')
  45. Non-triggered burst 011030 ("GRB 011030")
  46. The Radio Afterglow from the X-ray Rich GRB 011030
  47. GRB 010921: HST Detection of the Afterglow and Host Galaxy
  48. GRB 970828: HST Observations of the Host Galaxy
  49. GRB 970828: HST Observations of the Host Galaxy
  50. GRB010921, optical observation
  51. Optical observation of SGR 1806-20 at the 6-m SAO telescope
  52. GRB011019: Subaru Optical Observations
  53. GRB 011030 I-band Observations
  54. GRB 011030 K-band Observations
  55. GRB010921, optical observations
  56. GRB 011030, WSRT radio observations
  57. GRB 011030, Radio observations
  58. GRB 011030, R-band observations
  59. GRB011019: NEAT Optical Observations
  60. GRB011019: ROTSE-III optical observations
  61. GRB 010921, I-band observations
  62. GRB011019: Optical observations
  63. GRB011019, optical observations -- correction
  64. GRB011019, optical observations
  65. GRB 010921: The afterglow of HETE #1761
  66. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  67. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  68. GRB010928(=H1770): Localization of a Long GRB by HETE
  69. GRB010921, negative optical observations
  70. GRB010921 Optical Observations
  71. HETE Trigger #1760 (GRB 010920B?): a new optical source
  72. HETE Trigger #1759 (GRB 010920?) optical observations
  73. GRB000926, Host Galaxy Observations
  74. GRB001109, Host Galaxy Spectroscopic Observations
  75. GRB000926 Host Galaxy Observations
  76. GRB 010222: HST observations -- host galaxy and late-time decay
  77. GRB 010222 - WHT BVRI images
  78. GRB 010629 Optical Observations
  79. GRB010629: Optical Observations
  80. SGR1900+14: High Fluence Burst Localized by HETE
  81. GRB010629, optical observations
  82. GRB010629: A Burst Localized by HETE
  83. SGR1900+14: Second Burst Localized by HETE
  84. SGR1900+14: A Burst Localized by HETE
  85. SGR1806-20: A Second, Intense Burst Localized by HETE
  86. GRB 00630: Host Galaxy
  87. SGR1806-20: Localization by HETE
  88. GRB000301C: Late-time HST/STIS observation
  89. GRB000418: HST/STIS Second-epoch Observations
  90. GRB010214, optical observations
  91. GRB010427, Gamma Ray Observations
  92. SGR 1900+14: No evidence of extended X-ray emission
  93. SGR 1900+14 : RXTE observations
  94. GRB 010222 /corrections to VBT data
  95. Millimeter observation of SGR 1900+14
  96. Chandra Observations of SGR 1900+14
  97. SGR 1900+14, Chandra observations
  98. Chandra Observations of SGR 1900+14
  99. SGR1900+14, I-band observations
  100. GRB 010326b Optical Observations

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