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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. GRB041006: Fading X-ray Afterglow Observed with Chandra
  2. GRB 041015: Optical limit at Osaka University
  3. GRB041015 : Optical follow-up at Kiso
  4. GRB 041015 - A long GRB detected by INTEGRAL
  5. GRB 041006 R observations in Loiano
  6. GRB041006: VLT observations of the afterglow and host galaxy
  7. GRB041006: Optical observations and Potential host galaxy
  8. GRB041006, BVRcIc field calibration
  9. GRB 040924: VLT spectroscopy
  10. GRB 041006: SARA afterglow observations
  11. GRB041006, optical observation in CrAO
  12. Search for SN light in XRF 040912 with MEGACAM
  13. GRB 040916: Afterglow Color at Early Times
  14. GRB 041006 Optical afterglow observations
  15. IBAS GRB Alert # 2010
  16. GRB 041006: BR observations with VATT
  17. GRB 041006: Redshift confirmed
  18. GRB041006: Liverpool Telescope optical observations
  19. GRB 041006: Colour measurement
  20. GRB041006: break in the light curve
  21. GRB 041006: Radio Observations
  22. GRB041006, further submilllimetre observations
  23. GRB 041006 : optical follow-up observation at Lulin Observatory
  24. SUBJECT: GRB 041006 : Optical follow-up observation at TAROT
  25. GRB041006: Optical photometry and spectroscopy at TNG
  26. GRB 041006: presice astrometry
  27. GRB041006 (= H3570): Chandra Observations In Progress
  28. GRB 041006 : optical observation at Bisei
  29. GRB041006, optical I observation
  30. GRB041006 (=HETE3570): optical observations
  31. ROTSE-IIIa Observations of GRB 041006
  32. GRB041006, optical observation
  33. GRB041006, submillimetre observations
  34. GRB041006: MASTER optical observations
  35. GRB041006,optical observation
  36. GRB 041006: Optical decay
  37. GRB 041006 (=H3570): An X-Ray Rich GRB Localized in Real Time by HETE
  38. Konus-Wind observation of a series SGR 1806-20 bursts on 041005
  39. GRB041006: Fading of optical afterglow candidate
  40. GRB 041006 : Optical follow-up observation at KISO
  41. GRB 041006: Finding chart
  42. GRB 041006: Optical afterglow candidate
  43. Bursts from SGR 1806-20: Preliminary INTEGRAL results
  44. Very strong outburst from SGR 1806-20 detected with INTEGRAL
  45. XRF 020903: Observations of the Host Galaxy (authors)
  46. XRF 020903: Observations of the Host Galaxy
  47. SGR 1806-20 still active
  48. GRB 040924: Second Epoch WSRT Radio Observations
  49. radio observations, GRB 040924
  50. IBAS Alert 1991. Not a real GRB
  51. GRB040929,optical observation
  52. GRB040929: MASTER optical observations
  53. Konus-Wind and Helicon-Coronas-F observations of GRB040924
  54. GRB040924,optical observation
  55. GRB040924, RTT150 optical observation
  56. GRB040924,optical observation
  57. GRB 040924: detection of possible host galaxy by Subaru
  58. GRB040924, RTT150 optical observation
  59. GRB040924: KAIT observations
  60. GRB040924: Afterglow magnitude at t=17.5hr
  61. GRB 040924: WSRT Radio Observations
  62. GRB 040924: NIR finding chart
  63. GRB040924 : Optical candidate observations at Lulin observatory
  64. GRB040924 : Optical candidate observations at Lulin observatory
  65. GRB 040924: Subaru NIR observation
  66. GRB040924: Optical afterglow properties
  67. GRB 040924: RTT150 optical observations
  68. GRB 040924, optical follow-up
  69. GRB040924: MASTER: OT decay
  70. GRB040924: MASTER Optical observations
  71. IPN triangulation of GRB040924 (H3564)
  72. GRB 040924(=H3564): A Short, Bright GRB Localized in Real Time by HETE
  73. GRB040924 (H3564): Optical afterglow candidate
  74. XRF 040912: Radio Observations
  75. XRF 040916: Radio Observations
  76. GRB040912(=H3557): Chandra Candidate X-ray Afterglow
  77. XRF040916: continuing decay of OT
  78. TAROT Observations of GRB 040916 (HETE #3558)
  79. GRB040912(=H3557): Candidate Optical Afterglow
  80. XRF040916, optical observations
  81. XRF040916: Optical Transient Candidate by Subaru
  82. GRB040916 optical limits 17 min after GRB
  83. XRF 040912, identification of CXO sources
  84. XRF 040912 (=H3557): Spectral and Temporal Properties
  85. XRF040916, Ic observations
  86. XRF040916: optical follow-up observations
  87. XRF040912, BVRcIc field calibration
  88. XRF040916, BVRcIc field calibration
  89. GRB040916: Archival optical observations
  90. XRF 040916, optical follow-up
  91. GRB040912(=H3557): Observations with the Chandra X-ray Observatory
  92. GRB040916: Optical observations
  93. ROTSE-IIIb Observations of GRB 040916 (HETE #3558)
  94. GRB040916 (= H3558): Improved Localization from HETE WXM
  95. GRB040916 (= H3558): A Long XRF Localized by HETE
  96. GRB040912 (= H3557): Chandra Observations Scheduled
  97. GRB 040912: Optical Observations
  98. GRB/XRF040912,optical observations
  99. GRB 040912, BVRI observations
  100. Optical observations of GRB/XRF 040912 = HETE 3557

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