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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 011211: BVRi-band photometry
  2. GRB011212 (=H10001): An X-Ray Rich GRB Detected by HETE
  3. Fading of the optical source associated of XRF 011211
  4. XMM-Newton observation of GRB011211
  5. GRB 011211 Optical Observations: Likely Afterglow
  6. GRB011130 (=XRF011130): Further analysis of Chandra Target of
  7. GRB011211(=XRF011211): BeppoSAX refined positions
  8. BeppoSAX Alert: GRB011211(=XRF011211)
  9. GRB 011130: Optical Observations of Chandra Sources
  10. GRB 011130: Optical Observations of Chandra sources
  11. GRB011130 (XRF011130) Chandra Observations
  12. GRB011130 (=XRF011130): Scheduled Target of Opportunity
  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): Second Revised Localization by HETE
  19. GRB 011130 I-band Observation
  20. GRB011130 (XRF011130) optical observations
  21. GRB011130 (XRF011130) SDSS PT i-band observations
  22. XRF011130: Infrared Observations
  23. GRB011130, Radio Observations
  24. Detection of the X-ray afterglow of GRB011121 by BeppoSAX
  25. GRB011130 (=XRF011130), Optical Observations
  26. XRF011130: NEAT Optical Observations
  27. GRB011130 (=XRF011130): Revised Localization of an X-ray
  28. GRB001109, Radio Monitoring
  29. GRB 011121: Errata URL
  30. GRB 011121
  31. GRB011130 (=H1864): An X-Ray Rich GRB Detected by HETE
  32. GRB 011121: J-band observations
  33. GRB 011121: NIR observations, host galaxy?
  34. GRB010921 - Milagro GeV/TeV Observations
  35. GRB 011121: HST Scheduled
  36. GRB011121: fainter still
  37. Correction: GCN1157 (GRB 011121)
  38. GRB011121: UBRI Observations
  39. GRB011121
  40. GRB 011121: Radio Observations
  41. GRB 011121 J-Band Astrometry
  42. GRB011121: continued decay
  43. GRB 011121: Detection of Bright IR Counterpart
  44. GRB011121: possible redshift, continued decay
  45. GRB011121: fading behavior
  46. GRB011121: possible optical counterpart
  47. GRB011121: BeppoSAX-WFC refined positions
  48. IPN triangulation of GRB011121
  49. BEPPOSAX GRB011121
  50. GRB 011030: TNG K-band observation
  51. XRF011030: J and K band observations
  52. GRB011030, optical observation
  53. XRF011030: Chandra Observations
  54. GRB 011030: K-band observations
  55. GRB011030: Z-band observations
  56. GRB 011030 R band observations
  57. GRB 011030 I-band Observation
  58. The X-ray Flash 011030 ('GRB 011030')
  59. Non-triggered burst 011030 ("GRB 011030")
  60. The Radio Afterglow from the X-ray Rich GRB 011030
  61. GRB 010921: HST Detection of the Afterglow and Host Galaxy
  62. GRB 970828: HST Observations of the Host Galaxy
  63. GRB 000131: HST Detection of the Host Galaxy
  64. GRB 970828: HST Observations of the Host Galaxy
  65. GRB010921, optical observation
  66. GRB 011019 optical observation
  67. Optical observation of SGR 1806-20 at the 6-m SAO telescope
  68. GRB011019: Subaru Optical Observations
  69. GRB 011030 I-band Observations
  70. GRB 011030 K-band Observations
  71. GRB010921, optical observations
  72. GRB 011030, WSRT radio observations
  73. GRB011030 - further refinement WFC position
  74. GRB 011030, Radio observations
  75. GRB011030: radio search
  76. GRB 011030, R-band observations
  77. X-ray rich GRB011030: BeppoSAX refined positions
  78. BeppoSAX ALERT: Possible X-ray rich GRB011030
  79. GRB 010921: Possible supernova component
  80. GRB011019: NEAT Optical Observations
  81. GRB011019: ROTSE-III optical observations
  82. GRB010921, optical observation at early time
  83. GRB 010921, I-band observations
  84. GRB011019: Optical observations
  85. GRB011019, optical observations -- correction
  86. GRB011019, optical observations
  87. GRB011019: A Faint, X-ray Rich GRB localized by HETE
  88. GRB010921: Spectroscopy of the Host Galaxy
  89. GRB 010921: The afterglow of HETE #1761
  90. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  91. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  92. GRB010923 as seen by BeppoSAX GRBM
  93. GRB010928(=H1770): Localization of a Long GRB by HETE
  94. GRB010923(=H1764): A Short Duration GRB Detected by HETE
  95. GRB010921, negative optical observations
  96. GRB010921 field photometry
  97. GRB010921 Optical Observations
  98. GRB 010921 DPOSS Images Available
  99. IPN triangulation of GRB010921 (=H1761)
  100. H1761: A Bright GRB Detected by HETE

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