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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. GRB041218: optical observations
  2. GRB041217: optical limit 30 min after GRB
  3. GRB 041218; optical candidate
  4. GRB 041218: Optical observations
  5. GRB 041217: LCO40 Optical Observations and Possible Candidates
  6. GRB 041218 - A long GRB detected by integral
  7. GRB041217: Optical Observations
  8. GRB041217: NIR and optical observations with REM
  9. GRB041217: P60 Optical Observations
  10. GRB041217: Infrared Observations
  11. GRB041217: The First GRB Located On-Board Swift
  12. GRB041211: Faulkes Telescope continued optical monitoring
  13. Optical Transient in Lynx not a GRB
  14. Optical transient (GRB?) in Lynx
  15. Optical transient (GRB?) in Lynx, UT Dec 11.4436
  16. GRB041211: Continued P60 Observations
  17. GRB041211: RAPTOR observations
  18. GRB041211: Ashra Prototype optical observation
  19. GRB041211, Faulkes Telescope optical observation
  20. GRB041211, BVRcIc field calibration
  21. GRB041211,optical observation
  22. GRB 041211: Infrared Observations
  23. GRB 041211: KAIT observations
  24. GRB 041211: Optical follow-up in East Asian region
  25. GRB 041211(=H3622): A Long GRB Localized by the HETE WXM and SXC
  26. GRB041211: P60 optical imaging
  27. GRB970815: Discovery of Optical Afterglow
  28. Distribution of IBAS Alerts for NON-GRB sources
  29. Triangulation of short GRB 041116 (large error box)
  30. GRB041015: Near-Infrared observations
  31. GRB 040924: Afterglow Color
  32. GRB 041006: GETS Optical Afterglow Observation
  33. Summary of the recent bursts from SGR 1806-20
  34. GRB 041006: Optical Observations
  35. GRB041006, late-time optical photometry
  36. GRB041015, optical observation in CrAO
  37. IBAS GRB Alert # 2034
  38. GRB041006: RTT150 Optical Observations
  39. GRB041015 : Multi epoch optical observations
  40. HST Observations: XRF 040701 and 040812
  41. Bright bursts from SGR1806-20
  42. GRB 041016: BOOTES-2 simultaneous observation
  43. GRB041006: RTT150 Optical Observations
  44. GRB041016,optical observation
  45. GRB 041016: Optical limits
  46. GRB 041016: Optical limits in V, R, I
  47. GRB 041016:Optical limit during first minute
  48. GRB041016: MASTER: Optical observations
  49. GRB 041015: Optical Observations at Rikubetsu
  50. GRB041006: Near Infrared observations
  51. GRB 041016: Optical limit
  52. GRB 041015 R band observations
  53. GRB040924, BVRcIc field calibration
  54. GRB041015: MASTER: Optical observations
  55. GRB041015,optical observation
  56. GRB041006: Fading X-ray Afterglow Observed with Chandra
  57. GRB 041015: Optical limit at Osaka University
  58. GRB041015 : Optical follow-up at Kiso
  59. GRB 041015 - A long GRB detected by INTEGRAL
  60. GRB 041006 R observations in Loiano
  61. GRB041006: VLT observations of the afterglow and host galaxy
  62. GRB041006: Optical observations and Potential host galaxy
  63. GRB041006, BVRcIc field calibration
  64. GRB 040924: VLT spectroscopy
  65. GRB 041006: SARA afterglow observations
  66. GRB041006, optical observation in CrAO
  67. Search for SN light in XRF 040912 with MEGACAM
  68. GRB 040916: Afterglow Color at Early Times
  69. GRB 041006 Optical afterglow observations
  70. IBAS GRB Alert # 2010
  71. GRB 041006: BR observations with VATT
  72. GRB 041006: Redshift confirmed
  73. GRB041006: Liverpool Telescope optical observations
  74. GRB 041006: Colour measurement
  75. GRB041006: break in the light curve
  76. GRB 041006: Radio Observations
  77. GRB041006, further submilllimetre observations
  78. GRB 041006 : optical follow-up observation at Lulin Observatory
  79. SUBJECT: GRB 041006 : Optical follow-up observation at TAROT
  80. GRB041006: Optical photometry and spectroscopy at TNG
  81. GRB 041006: presice astrometry
  82. GRB041006 (= H3570): Chandra Observations In Progress
  83. GRB 041006 : optical observation at Bisei
  84. GRB041006, optical I observation
  85. GRB041006 (=HETE3570): optical observations
  86. ROTSE-IIIa Observations of GRB 041006
  87. GRB041006, optical observation
  88. GRB041006, submillimetre observations
  89. GRB041006: MASTER optical observations
  90. GRB041006,optical observation
  91. GRB 041006: Optical decay
  92. GRB 041006 (=H3570): An X-Ray Rich GRB Localized in Real Time by HETE
  93. Konus-Wind observation of a series SGR 1806-20 bursts on 041005
  94. GRB041006: Fading of optical afterglow candidate
  95. GRB 041006 : Optical follow-up observation at KISO
  96. GRB 041006: Finding chart
  97. GRB 041006: Optical afterglow candidate
  98. Bursts from SGR 1806-20: Preliminary INTEGRAL results
  99. Very strong outburst from SGR 1806-20 detected with INTEGRAL
  100. XRF 020903: Observations of the Host Galaxy (authors)

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