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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 041006 Optical afterglow observations
  2. IBAS GRB Alert # 2010
  3. GRB 041006: BR observations with VATT
  4. GRB 041006: Redshift confirmed
  5. GRB041006: Liverpool Telescope optical observations
  6. GRB 041006: Colour measurement
  7. GRB041006: break in the light curve
  8. GRB 041006: Radio Observations
  9. GRB041006, further submilllimetre observations
  10. GRB 041006 : optical follow-up observation at Lulin Observatory
  11. GRB 041006 : Optical follow-up observation at TAROT
  12. GRB041006: Optical photometry and spectroscopy at TNG
  13. GRB 041006: presice astrometry
  14. GRB041006 (= H3570): Chandra Observations In Progress
  15. GRB 041006 : optical observation at Bisei
  16. GRB041006, optical I observation
  17. GRB041006 (=HETE3570): optical observations
  18. ROTSE-IIIa Observations of GRB 041006
  19. GRB041006, optical observation
  20. GRB041006, submillimetre observations
  21. GRB041006: MASTER optical observations
  22. GRB041006,optical observation
  23. GRB 041006: Optical decay
  24. GRB 041006 (=H3570): An X-Ray Rich GRB Localized in Real Time by HETE
  25. Konus-Wind observation of a series SGR 1806-20 bursts on 041005
  26. GRB041006: Fading of optical afterglow candidate
  27. GRB 041006 : Optical follow-up observation at KISO
  28. GRB 041006: Finding chart
  29. GRB 041006: Optical afterglow candidate
  30. Bursts from SGR 1806-20: Preliminary INTEGRAL results
  31. Very strong outburst from SGR 1806-20 detected with INTEGRAL
  32. XRF 020903: Observations of the Host Galaxy (authors)
  33. XRF 020903: Observations of the Host Galaxy
  34. SGR 1806-20 still active
  35. GRB 040924: Second Epoch WSRT Radio Observations
  36. radio observations, GRB 040924
  37. IBAS Alert 1991. Not a real GRB
  38. GRB040929,optical observation
  39. GRB040929: MASTER optical observations
  40. Konus-Wind and Helicon-Coronas-F observations of GRB040924
  41. GRB040924,optical observation
  42. GRB040924, RTT150 optical observation
  43. GRB040924,optical observation
  44. GRB 040924: detection of possible host galaxy by Subaru
  45. GRB040924, RTT150 optical observation
  46. GRB040924: KAIT observations
  47. GRB040924: Afterglow magnitude at t=17.5hr
  48. GRB 040924: WSRT Radio Observations
  49. GRB 040924: NIR finding chart
  50. GRB040924 : Optical candidate observations at Lulin observatory
  51. GRB040924 : Optical candidate observations at Lulin observatory
  52. GRB 040924: Subaru NIR observation
  53. GRB040924: Optical afterglow properties
  54. GRB 040924: RTT150 optical observations
  55. GRB 040924, optical follow-up
  56. GRB040924: MASTER: OT decay
  57. GRB040924: MASTER Optical observations
  58. IPN triangulation of GRB040924 (H3564)
  59. GRB 040924(=H3564): A Short, Bright GRB Localized in Real Time by HETE
  60. GRB040924 (H3564): Optical afterglow candidate
  61. XRF 040912: Radio Observations
  62. XRF 040916: Radio Observations
  63. GRB040912(=H3557): Chandra Candidate X-ray Afterglow
  64. XRF040916: continuing decay of OT
  65. TAROT Observations of GRB 040916 (HETE #3558)
  66. GRB040912(=H3557): Candidate Optical Afterglow
  67. XRF040916, optical observations
  68. XRF040916: Optical Transient Candidate by Subaru
  69. GRB040916 optical limits 17 min after GRB
  70. XRF 040912, identification of CXO sources
  71. XRF 040912 (=H3557): Spectral and Temporal Properties
  72. XRF040916, Ic observations
  73. XRF040916: optical follow-up observations
  74. XRF040912, BVRcIc field calibration
  75. XRF040916, BVRcIc field calibration
  76. GRB040916: Archival optical observations
  77. XRF 040916, optical follow-up
  78. GRB040912(=H3557): Observations with the Chandra X-ray Observatory
  79. GRB040916: Optical observations
  80. ROTSE-IIIb Observations of GRB 040916 (HETE #3558)
  81. GRB040916 (= H3558): Improved Localization from HETE WXM
  82. GRB040916 (= H3558): A Long XRF Localized by HETE
  83. GRB040912 (= H3557): Chandra Observations Scheduled
  84. GRB 040912: Optical Observations
  85. GRB/XRF040912,optical observations
  86. GRB 040912, BVRI observations
  87. Optical observations of GRB/XRF 040912 = HETE 3557
  88. An intense burst from SGR1806-20
  89. GRB040912 : Kiso Optical follow-up observation
  90. IBAS GRB Alerts 1978-1980
  91. Optical observations of field of GRB040912
  92. HETE 3557: Optical observations
  93. GRB040912 (= H3557): A Long GRB or XRF Localized by HETE
  94. GRB 040827: XMM-Newton data
  95. GRB040903 - A XRF?
  96. GRB040827: analysis of the XMM-Newton observation
  97. GRB040903, REM near-IR observation
  98. GRB 040903 - INTEGRAL data analysis
  99. IBAS Alert 1974. Not a real GRB
  100. Very bright burst detected from SGR 1806-20

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