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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. Fading of the optical source associated of XRF 011211
  2. XMM-Newton observation of GRB011211
  3. GRB 011211 Optical Observations: Likely Afterglow
  4. GRB011130 (=XRF011130): Further analysis of Chandra Target of
  5. GRB011211(=XRF011211): BeppoSAX refined positions
  6. BeppoSAX Alert: GRB011211(=XRF011211)
  7. GRB 011130: Optical Observations of Chandra Sources
  8. GRB 011130: Optical Observations of Chandra sources
  9. GRB011130 (XRF011130) Chandra Observations
  10. GRB011130 (=XRF011130): Scheduled Target of Opportunity
  11. GRB 011130: Magellan spectroscopy
  12. Sub-mm and Centimeter Detections of the Host Galaxy of GRB000418
  13. GRB011130, optical observations
  14. GRB 011130, K band observations
  15. GRB011130, optical observations
  16. GRB011130 (=XRF011130): Second Revised Localization by HETE
  17. GRB 011130 I-band Observation
  18. GRB011130 (XRF011130) optical observations
  19. GRB011130 (XRF011130) SDSS PT i-band observations
  20. XRF011130: Infrared Observations
  21. GRB011130, Radio Observations
  22. Detection of the X-ray afterglow of GRB011121 by BeppoSAX
  23. GRB011130 (=XRF011130), Optical Observations
  24. XRF011130: NEAT Optical Observations
  25. GRB011130 (=XRF011130): Revised Localization of an X-ray
  26. GRB001109, Radio Monitoring
  27. GRB 011121: Errata URL
  28. GRB 011121
  29. GRB011130 (=H1864): An X-Ray Rich GRB Detected by HETE
  30. GRB 011121: J-band observations
  31. GRB 011121: NIR observations, host galaxy?
  32. GRB010921 - Milagro GeV/TeV Observations
  33. GRB 011121: HST Scheduled
  34. GRB011121: fainter still
  35. Correction: GCN1157 (GRB 011121)
  36. GRB011121: UBRI Observations
  37. GRB011121
  38. GRB 011121: Radio Observations
  39. GRB 011121 J-Band Astrometry
  40. GRB011121: continued decay
  41. GRB 011121: Detection of Bright IR Counterpart
  42. GRB011121: possible redshift, continued decay
  43. GRB011121: fading behavior
  44. GRB011121: possible optical counterpart
  45. GRB011121: BeppoSAX-WFC refined positions
  46. IPN triangulation of GRB011121
  47. BEPPOSAX GRB011121
  48. GRB 011030: TNG K-band observation
  49. XRF011030: J and K band observations
  50. GRB011030, optical observation
  51. XRF011030: Chandra Observations
  52. GRB 011030: K-band observations
  53. GRB011030: Z-band observations
  54. GRB 011030 R band observations
  55. GRB 011030 I-band Observation
  56. The X-ray Flash 011030 ('GRB 011030')
  57. Non-triggered burst 011030 ("GRB 011030")
  58. The Radio Afterglow from the X-ray Rich GRB 011030
  59. GRB 010921: HST Detection of the Afterglow and Host Galaxy
  60. GRB 970828: HST Observations of the Host Galaxy
  61. GRB 000131: HST Detection of the Host Galaxy
  62. GRB 970828: HST Observations of the Host Galaxy
  63. GRB010921, optical observation
  64. GRB 011019 optical observation
  65. Optical observation of SGR 1806-20 at the 6-m SAO telescope
  66. GRB011019: Subaru Optical Observations
  67. GRB 011030 I-band Observations
  68. GRB 011030 K-band Observations
  69. GRB010921, optical observations
  70. GRB 011030, WSRT radio observations
  71. GRB011030 - further refinement WFC position
  72. GRB 011030, Radio observations
  73. GRB011030: radio search
  74. GRB 011030, R-band observations
  75. X-ray rich GRB011030: BeppoSAX refined positions
  76. BeppoSAX ALERT: Possible X-ray rich GRB011030
  77. GRB 010921: Possible supernova component
  78. GRB011019: NEAT Optical Observations
  79. GRB011019: ROTSE-III optical observations
  80. GRB010921, optical observation at early time
  81. GRB 010921, I-band observations
  82. GRB011019: Optical observations
  83. GRB011019, optical observations -- correction
  84. GRB011019, optical observations
  85. GRB011019: A Faint, X-ray Rich GRB localized by HETE
  86. GRB010921: Spectroscopy of the Host Galaxy
  87. GRB 010921: The afterglow of HETE #1761
  88. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  89. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  90. GRB010923 as seen by BeppoSAX GRBM
  91. GRB010928(=H1770): Localization of a Long GRB by HETE
  92. GRB010923(=H1764): A Short Duration GRB Detected by HETE
  93. GRB010921, negative optical observations
  94. GRB010921 field photometry
  95. GRB010921 Optical Observations
  96. GRB 010921 DPOSS Images Available
  97. IPN triangulation of GRB010921 (=H1761)
  98. H1761: A Bright GRB Detected by HETE
  99. HETE Trigger #1760 (GRB 010920B?): new optical source = asteroid
  100. HETE Trigger #1760 (GRB 010920B?): a new optical source

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