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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').
  1. Bright bursts from SGR1806-20
  2. GRB 041016: BOOTES-2 simultaneous observation
  3. GRB041006: RTT150 Optical Observations
  4. GRB041016,optical observation
  5. GRB 041016: Optical limits
  6. GRB 041016: Optical limits in V, R, I
  7. GRB 041016:Optical limit during first minute
  8. GRB041016: MASTER: Optical observations
  9. GRB 041015: Optical Observations at Rikubetsu
  10. GRB041006: Near Infrared observations
  11. GRB 041016: Optical limit
  12. GRB 041015 R band observations
  13. GRB040924, BVRcIc field calibration
  14. GRB041015: MASTER: Optical observations
  15. GRB041015,optical observation
  16. GRB041006: Fading X-ray Afterglow Observed with Chandra
  17. GRB 041015: Optical limit at Osaka University
  18. GRB041015 : Optical follow-up at Kiso
  19. GRB 041015 - A long GRB detected by INTEGRAL
  20. GRB 041006 R observations in Loiano
  21. GRB041006: VLT observations of the afterglow and host galaxy
  22. GRB041006: Optical observations and Potential host galaxy
  23. GRB041006, BVRcIc field calibration
  24. GRB 040924: VLT spectroscopy
  25. GRB 041006: SARA afterglow observations
  26. GRB041006, optical observation in CrAO
  27. Search for SN light in XRF 040912 with MEGACAM
  28. GRB 040916: Afterglow Color at Early Times
  29. GRB 041006 Optical afterglow observations
  30. IBAS GRB Alert # 2010
  31. GRB 041006: BR observations with VATT
  32. GRB 041006: Redshift confirmed
  33. GRB041006: Liverpool Telescope optical observations
  34. GRB 041006: Colour measurement
  35. GRB041006: break in the light curve
  36. GRB 041006: Radio Observations
  37. GRB041006, further submilllimetre observations
  38. GRB 041006 : optical follow-up observation at Lulin Observatory
  39. SUBJECT: GRB 041006 : Optical follow-up observation at TAROT
  40. GRB041006: Optical photometry and spectroscopy at TNG
  41. GRB 041006: presice astrometry
  42. GRB041006 (= H3570): Chandra Observations In Progress
  43. GRB 041006 : optical observation at Bisei
  44. GRB041006, optical I observation
  45. GRB041006 (=HETE3570): optical observations
  46. ROTSE-IIIa Observations of GRB 041006
  47. GRB041006, optical observation
  48. GRB041006, submillimetre observations
  49. GRB041006: MASTER optical observations
  50. GRB041006,optical observation
  51. GRB 041006: Optical decay
  52. GRB 041006 (=H3570): An X-Ray Rich GRB Localized in Real Time by HETE
  53. Konus-Wind observation of a series SGR 1806-20 bursts on 041005
  54. GRB041006: Fading of optical afterglow candidate
  55. GRB 041006 : Optical follow-up observation at KISO
  56. GRB 041006: Finding chart
  57. GRB 041006: Optical afterglow candidate
  58. Bursts from SGR 1806-20: Preliminary INTEGRAL results
  59. Very strong outburst from SGR 1806-20 detected with INTEGRAL
  60. XRF 020903: Observations of the Host Galaxy (authors)
  61. XRF 020903: Observations of the Host Galaxy
  62. SGR 1806-20 still active
  63. GRB 040924: Second Epoch WSRT Radio Observations
  64. radio observations, GRB 040924
  65. IBAS Alert 1991. Not a real GRB
  66. GRB040929,optical observation
  67. GRB040929: MASTER optical observations
  68. Konus-Wind and Helicon-Coronas-F observations of GRB040924
  69. GRB040924,optical observation
  70. GRB040924, RTT150 optical observation
  71. GRB040924,optical observation
  72. GRB 040924: detection of possible host galaxy by Subaru
  73. GRB040924, RTT150 optical observation
  74. GRB040924: KAIT observations
  75. GRB040924: Afterglow magnitude at t=17.5hr
  76. GRB 040924: WSRT Radio Observations
  77. GRB 040924: NIR finding chart
  78. GRB040924 : Optical candidate observations at Lulin observatory
  79. GRB040924 : Optical candidate observations at Lulin observatory
  80. GRB 040924: Subaru NIR observation
  81. GRB040924: Optical afterglow properties
  82. GRB 040924: RTT150 optical observations
  83. GRB 040924, optical follow-up
  84. GRB040924: MASTER: OT decay
  85. GRB040924: MASTER Optical observations
  86. IPN triangulation of GRB040924 (H3564)
  87. GRB 040924(=H3564): A Short, Bright GRB Localized in Real Time by HETE
  88. GRB040924 (H3564): Optical afterglow candidate
  89. XRF 040912: Radio Observations
  90. XRF 040916: Radio Observations
  91. GRB040912(=H3557): Chandra Candidate X-ray Afterglow
  92. XRF040916: continuing decay of OT
  93. TAROT Observations of GRB 040916 (HETE #3558)
  94. GRB040912(=H3557): Candidate Optical Afterglow
  95. XRF040916, optical observations
  96. XRF040916: Optical Transient Candidate by Subaru
  97. GRB040916 optical limits 17 min after GRB
  98. XRF 040912, identification of CXO sources
  99. XRF 040912 (=H3557): Spectral and Temporal Properties
  100. XRF040916, Ic observations

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