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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 011130: Optical Observations of Chandra sources
  2. GRB011130 (XRF011130) Chandra Observations
  3. GRB011130 (=XRF011130): Scheduled Target of Opportunity
  4. GRB 011130: Magellan spectroscopy
  5. Sub-mm and Centimeter Detections of the Host Galaxy of GRB000418
  6. GRB011130, optical observations
  7. GRB 011130, K band observations
  8. GRB011130, optical observations
  9. GRB011130 (=XRF011130): Second Revised Localization by HETE
  10. GRB 011130 I-band Observation
  11. GRB011130 (XRF011130) optical observations
  12. GRB011130 (XRF011130) SDSS PT i-band observations
  13. XRF011130: Infrared Observations
  14. GRB011130, Radio Observations
  15. Detection of the X-ray afterglow of GRB011121 by BeppoSAX
  16. GRB011130 (=XRF011130), Optical Observations
  17. XRF011130: NEAT Optical Observations
  18. GRB011130 (=XRF011130): Revised Localization of an X-ray
  19. GRB001109, Radio Monitoring
  20. GRB 011121: Errata URL
  21. GRB 011121
  22. GRB011130 (=H1864): An X-Ray Rich GRB Detected by HETE
  23. GRB 011121: J-band observations
  24. GRB 011121: NIR observations, host galaxy?
  25. GRB010921 - Milagro GeV/TeV Observations
  26. GRB 011121: HST Scheduled
  27. GRB011121: fainter still
  28. Correction: GCN1157 (GRB 011121)
  29. GRB011121: UBRI Observations
  30. GRB011121
  31. GRB 011121: Radio Observations
  32. GRB 011121 J-Band Astrometry
  33. GRB011121: continued decay
  34. GRB 011121: Detection of Bright IR Counterpart
  35. GRB011121: possible redshift, continued decay
  36. GRB011121: fading behavior
  37. GRB011121: possible optical counterpart
  38. GRB011121: BeppoSAX-WFC refined positions
  39. IPN triangulation of GRB011121
  40. BEPPOSAX GRB011121
  41. GRB 011030: TNG K-band observation
  42. XRF011030: J and K band observations
  43. GRB011030, optical observation
  44. XRF011030: Chandra Observations
  45. GRB 011030: K-band observations
  46. GRB011030: Z-band observations
  47. GRB 011030 R band observations
  48. GRB 011030 I-band Observation
  49. The X-ray Flash 011030 ('GRB 011030')
  50. Non-triggered burst 011030 ("GRB 011030")
  51. The Radio Afterglow from the X-ray Rich GRB 011030
  52. GRB 010921: HST Detection of the Afterglow and Host Galaxy
  53. GRB 970828: HST Observations of the Host Galaxy
  54. GRB 000131: HST Detection of the Host Galaxy
  55. GRB 970828: HST Observations of the Host Galaxy
  56. GRB010921, optical observation
  57. GRB 011019 optical observation
  58. Optical observation of SGR 1806-20 at the 6-m SAO telescope
  59. GRB011019: Subaru Optical Observations
  60. GRB 011030 I-band Observations
  61. GRB 011030 K-band Observations
  62. GRB010921, optical observations
  63. GRB 011030, WSRT radio observations
  64. GRB011030 - further refinement WFC position
  65. GRB 011030, Radio observations
  66. GRB011030: radio search
  67. GRB 011030, R-band observations
  68. X-ray rich GRB011030: BeppoSAX refined positions
  69. BeppoSAX ALERT: Possible X-ray rich GRB011030
  70. GRB 010921: Possible supernova component
  71. GRB011019: NEAT Optical Observations
  72. GRB011019: ROTSE-III optical observations
  73. GRB010921, optical observation at early time
  74. GRB 010921, I-band observations
  75. GRB011019: Optical observations
  76. GRB011019, optical observations -- correction
  77. GRB011019, optical observations
  78. GRB011019: A Faint, X-ray Rich GRB localized by HETE
  79. GRB010921: Spectroscopy of the Host Galaxy
  80. GRB 010921: The afterglow of HETE #1761
  81. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  82. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  83. GRB010923 as seen by BeppoSAX GRBM
  84. GRB010928(=H1770): Localization of a Long GRB by HETE
  85. GRB010923(=H1764): A Short Duration GRB Detected by HETE
  86. GRB010921, negative optical observations
  87. GRB010921 field photometry
  88. GRB010921 Optical Observations
  89. GRB 010921 DPOSS Images Available
  90. IPN triangulation of GRB010921 (=H1761)
  91. H1761: A Bright GRB Detected by HETE
  92. HETE Trigger #1760 (GRB 010920B?): new optical source = asteroid
  93. HETE Trigger #1760 (GRB 010920B?): a new optical source
  94. HETE Trigger #1759 (GRB 010920?) optical observations
  95. GRB001109, Host Galaxy Astrometry
  96. GRB000926, Host Galaxy Observations
  97. GRB001109, Host Galaxy Spectroscopic Observations
  98. Probable SGR or Short Duration GRB Detected by HETE
  99. GRB000926 Host Galaxy Observations
  100. GRB 010222: HST observations -- host galaxy and late-time decay

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