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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. GRB 041218 - A long GRB detected by integral
  2. GRB041217: Optical Observations
  3. GRB041217: NIR and optical observations with REM
  4. GRB041217: P60 Optical Observations
  5. GRB041217: Infrared Observations
  6. GRB041217: The First GRB Located On-Board Swift
  7. GRB041211: Faulkes Telescope continued optical monitoring
  8. Optical Transient in Lynx not a GRB
  9. Optical transient (GRB?) in Lynx
  10. Optical transient (GRB?) in Lynx, UT Dec 11.4436
  11. GRB041211: Continued P60 Observations
  12. GRB041211: RAPTOR observations
  13. GRB041211: Ashra Prototype optical observation
  14. GRB041211, Faulkes Telescope optical observation
  15. GRB041211, BVRcIc field calibration
  16. GRB041211,optical observation
  17. GRB 041211: Infrared Observations
  18. GRB 041211: KAIT observations
  19. GRB 041211: Optical follow-up in East Asian region
  20. GRB 041211(=H3622): A Long GRB Localized by the HETE WXM and SXC
  21. GRB041211: P60 optical imaging
  22. GRB970815: Discovery of Optical Afterglow
  23. Distribution of IBAS Alerts for NON-GRB sources
  24. Triangulation of short GRB 041116 (large error box)
  25. GRB041015: Near-Infrared observations
  26. GRB 040924: Afterglow Color
  27. GRB 041006: GETS Optical Afterglow Observation
  28. Summary of the recent bursts from SGR 1806-20
  29. GRB 041006: Optical Observations
  30. GRB041006, late-time optical photometry
  31. GRB041015, optical observation in CrAO
  32. IBAS GRB Alert # 2034
  33. GRB041006: RTT150 Optical Observations
  34. GRB041015 : Multi epoch optical observations
  35. HST Observations: XRF 040701 and 040812
  36. Bright bursts from SGR1806-20
  37. GRB 041016: BOOTES-2 simultaneous observation
  38. GRB041006: RTT150 Optical Observations
  39. GRB041016,optical observation
  40. GRB 041016: Optical limits
  41. GRB 041016: Optical limits in V, R, I
  42. GRB 041016:Optical limit during first minute
  43. GRB041016: MASTER: Optical observations
  44. GRB 041015: Optical Observations at Rikubetsu
  45. GRB041006: Near Infrared observations
  46. GRB 041016: Optical limit
  47. GRB 041015 R band observations
  48. GRB040924, BVRcIc field calibration
  49. GRB041015: MASTER: Optical observations
  50. GRB041015,optical observation
  51. GRB041006: Fading X-ray Afterglow Observed with Chandra
  52. GRB 041015: Optical limit at Osaka University
  53. GRB041015 : Optical follow-up at Kiso
  54. GRB 041015 - A long GRB detected by INTEGRAL
  55. GRB 041006 R observations in Loiano
  56. GRB041006: VLT observations of the afterglow and host galaxy
  57. GRB041006: Optical observations and Potential host galaxy
  58. GRB041006, BVRcIc field calibration
  59. GRB 040924: VLT spectroscopy
  60. GRB 041006: SARA afterglow observations
  61. GRB041006, optical observation in CrAO
  62. Search for SN light in XRF 040912 with MEGACAM
  63. GRB 040916: Afterglow Color at Early Times
  64. GRB 041006 Optical afterglow observations
  65. IBAS GRB Alert # 2010
  66. GRB 041006: BR observations with VATT
  67. GRB 041006: Redshift confirmed
  68. GRB041006: Liverpool Telescope optical observations
  69. GRB 041006: Colour measurement
  70. GRB041006: break in the light curve
  71. GRB 041006: Radio Observations
  72. GRB041006, further submilllimetre observations
  73. GRB 041006 : optical follow-up observation at Lulin Observatory
  74. SUBJECT: GRB 041006 : Optical follow-up observation at TAROT
  75. GRB041006: Optical photometry and spectroscopy at TNG
  76. GRB 041006: presice astrometry
  77. GRB041006 (= H3570): Chandra Observations In Progress
  78. GRB 041006 : optical observation at Bisei
  79. GRB041006, optical I observation
  80. GRB041006 (=HETE3570): optical observations
  81. ROTSE-IIIa Observations of GRB 041006
  82. GRB041006, optical observation
  83. GRB041006, submillimetre observations
  84. GRB041006: MASTER optical observations
  85. GRB041006,optical observation
  86. GRB 041006: Optical decay
  87. GRB 041006 (=H3570): An X-Ray Rich GRB Localized in Real Time by HETE
  88. Konus-Wind observation of a series SGR 1806-20 bursts on 041005
  89. GRB041006: Fading of optical afterglow candidate
  90. GRB 041006 : Optical follow-up observation at KISO
  91. GRB 041006: Finding chart
  92. GRB 041006: Optical afterglow candidate
  93. Bursts from SGR 1806-20: Preliminary INTEGRAL results
  94. Very strong outburst from SGR 1806-20 detected with INTEGRAL
  95. XRF 020903: Observations of the Host Galaxy (authors)
  96. XRF 020903: Observations of the Host Galaxy
  97. SGR 1806-20 still active
  98. GRB 040924: Second Epoch WSRT Radio Observations
  99. radio observations, GRB 040924
  100. IBAS Alert 1991. Not a real GRB

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