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

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