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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"

28049 results found.

  1. Type Ib/c SN2002ap (SN/GRB?) Radio Observations
  2. GRB020124, optical observations
  3. GRB 020127, I-band observations starting 3.14-hr after the event
  4. GRB010921 Optical Observations
  5. GRB020127(=H1902): Localization of a Double-Peaked GRB by HETE
  6. GRB020124: Optical observations
  7. GRB 020124: Optical observations
  8. GRB 020124: Optical afterglow
  9. GRB020124(=H1896): Localization of a Long GRB by HETE
  10. Possible optical counterpart to a GRB
  11. GRB011212, Optical Observations
  12. Optical polarization observations for GRB011211
  13. GRB 011211: Detection of the Probable Host Galaxy
  14. GRB 011130 and GRB 011212 - Milagro GeV/TeV Observations
  15. GRB 011130: Optical Observations of X-ray and Radio Sources
  16. GRB 011212: optical observation at Asiago
  17. GRB 011211: Evidence for an Optical Break
  18. GRB 011211: TNG Spectroscopic Observations
  19. optical follow-up of GRB(XRF) 011211
  20. GRB 011212: optical observation at Oslo (relayed)
  21. GRB 011211, Optical Observations
  22. GRB011212, BVRI field photometry
  23. GRB011211, BVRI field photometry
  24. GRB011212 (=H10001): An X-Ray Rich GRB Detected by HETE
  25. Fading of the optical source associated of XRF 011211
  26. GRB 011211 Optical Observations: Likely Afterglow
  27. GRB011130 (=XRF011130): Further analysis of Chandra Target of
  28. GRB011130 (XRF011130) Chandra Observations
  29. GRB011130 (=XRF011130): Scheduled Target of Opportunity
  30. GRB 011130, K band observations
  31. GRB011130, optical observations
  32. GRB011130 (=XRF011130): Second Revised Localization by HETE
  33. GRB011130 (XRF011130) SDSS PT i-band observations
  34. XRF011130: Infrared Observations
  35. GRB 011121
  36. GRB011130 (=H1864): An X-Ray Rich GRB Detected by HETE
  37. GRB 011121: J-band observations
  38. GRB 011121: NIR observations, host galaxy?
  39. GRB011121: UBRI Observations
  40. GRB 011121 J-Band Astrometry
  41. GRB 011121: Detection of Bright IR Counterpart
  42. GRB011121: possible redshift, continued decay
  43. GRB 011030: TNG K-band observation
  44. XRF011030: J and K band observations
  45. XRF011030: Chandra 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. Optical observation of SGR 1806-20 at the 6-m SAO telescope
  57. GRB011019: Subaru Optical Observations
  58. GRB 011030 I-band Observations
  59. GRB 011030 K-band Observations
  60. GRB010921, optical observations
  61. GRB011030 - further refinement WFC position
  62. GRB 011030, Radio observations
  63. GRB011030: radio search
  64. GRB 010921: Possible supernova component
  65. GRB010921, optical observation at early time
  66. GRB 010921, I-band observations
  67. GRB011019, optical observations
  68. GRB011019: A Faint, X-ray Rich GRB localized by HETE
  69. GRB 010921: The afterglow of HETE #1761
  70. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  71. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  72. GRB010923 as seen by BeppoSAX GRBM
  73. GRB010928(=H1770): Localization of a Long GRB by HETE
  74. GRB010923(=H1764): A Short Duration GRB Detected by HETE
  75. GRB010921, negative optical observations
  76. GRB010921 field photometry
  77. H1761: A Bright GRB Detected by HETE
  78. GRB000926, Host Galaxy Observations
  79. GRB001109, Host Galaxy Spectroscopic Observations
  80. Probable SGR or Short Duration GRB Detected by HETE
  81. GCN and HETE status
  82. Dramatic Increase in the Rate of X-ray Bursts Reported by HETE
  83. GRB 010222 - WHT BVRI images
  84. SGR1900+14 burst seen by HETE: BeppoSAX data
  85. GRB 010629 Optical Observations
  86. SGR1900+14: High Fluence Burst Localized by HETE
  87. GRB010629, optical observations
  88. GRB010629: A Burst Localized by HETE
  89. SGR1900+14: Second Burst Localized by HETE
  90. SGR1900+14: A Burst Localized by HETE
  91. SGR1806-20: A Second, Intense Burst Localized by HETE
  92. SGR1806-20: Localization by HETE
  93. HETE Fully-Automated GCN Notices
  94. GRB000301C: Late-time HST/STIS observation
  95. GRB010518: a faint BeppoSAX detection
  96. GRB000418: HST/STIS Second-epoch Observations
  97. X-ray precursors to the large flare from SGR 1900+14
  98. GRB010427, Gamma Ray Observations
  99. SGR 1900+14: No evidence of extended X-ray emission
  100. SGR 1900+14 : RXTE observations

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