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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. GRB041211, BVRcIc field calibration
  2. GRB041211,optical observation
  3. GRB 041211: Infrared Observations
  4. GRB 041211: KAIT observations
  5. GRB 041211: Optical follow-up in East Asian region
  6. GRB 041211(=H3622): A Long GRB Localized by the HETE WXM and SXC
  7. GRB041211: P60 optical imaging
  8. GRB970815: Discovery of Optical Afterglow
  9. Distribution of IBAS Alerts for NON-GRB sources
  10. Triangulation of short GRB 041116 (large error box)
  11. GRB041015: Near-Infrared observations
  12. GRB 040924: Afterglow Color
  13. GRB 041006: GETS Optical Afterglow Observation
  14. Summary of the recent bursts from SGR 1806-20
  15. GRB 041006: Optical Observations
  16. GRB041006, late-time optical photometry
  17. GRB041015, optical observation in CrAO
  18. IBAS GRB Alert # 2034
  19. GRB041006: RTT150 Optical Observations
  20. GRB041015 : Multi epoch optical observations
  21. HST Observations: XRF 040701 and 040812
  22. Bright bursts from SGR1806-20
  23. GRB 041016: BOOTES-2 simultaneous observation
  24. GRB041006: RTT150 Optical Observations
  25. GRB041016,optical observation
  26. GRB 041016: Optical limits
  27. GRB 041016: Optical limits in V, R, I
  28. GRB 041016:Optical limit during first minute
  29. GRB041016: MASTER: Optical observations
  30. GRB 041015: Optical Observations at Rikubetsu
  31. GRB041006: Near Infrared observations
  32. GRB 041016: Optical limit
  33. GRB 041015 R band observations
  34. GRB040924, BVRcIc field calibration
  35. GRB041015: MASTER: Optical observations
  36. GRB041015,optical observation
  37. GRB041006: Fading X-ray Afterglow Observed with Chandra
  38. GRB 041015: Optical limit at Osaka University
  39. GRB041015 : Optical follow-up at Kiso
  40. GRB 041015 - A long GRB detected by INTEGRAL
  41. GRB 041006 R observations in Loiano
  42. GRB041006: VLT observations of the afterglow and host galaxy
  43. GRB041006: Optical observations and Potential host galaxy
  44. GRB041006, BVRcIc field calibration
  45. GRB 040924: VLT spectroscopy
  46. GRB 041006: SARA afterglow observations
  47. GRB041006, optical observation in CrAO
  48. Search for SN light in XRF 040912 with MEGACAM
  49. GRB 040916: Afterglow Color at Early Times
  50. GRB 041006 Optical afterglow observations
  51. IBAS GRB Alert # 2010
  52. GRB 041006: BR observations with VATT
  53. GRB 041006: Redshift confirmed
  54. GRB041006: Liverpool Telescope optical observations
  55. GRB 041006: Colour measurement
  56. GRB041006: break in the light curve
  57. GRB 041006: Radio Observations
  58. GRB041006, further submilllimetre observations
  59. GRB 041006 : optical follow-up observation at Lulin Observatory
  60. GRB 041006 : Optical follow-up observation at TAROT
  61. GRB041006: Optical photometry and spectroscopy at TNG
  62. GRB 041006: presice astrometry
  63. GRB041006 (= H3570): Chandra Observations In Progress
  64. GRB 041006 : optical observation at Bisei
  65. GRB041006, optical I observation
  66. GRB041006 (=HETE3570): optical observations
  67. ROTSE-IIIa Observations of GRB 041006
  68. GRB041006, optical observation
  69. GRB041006, submillimetre observations
  70. GRB041006: MASTER optical observations
  71. GRB041006,optical observation
  72. GRB 041006: Optical decay
  73. GRB 041006 (=H3570): An X-Ray Rich GRB Localized in Real Time by HETE
  74. Konus-Wind observation of a series SGR 1806-20 bursts on 041005
  75. GRB041006: Fading of optical afterglow candidate
  76. GRB 041006 : Optical follow-up observation at KISO
  77. GRB 041006: Finding chart
  78. GRB 041006: Optical afterglow candidate
  79. Bursts from SGR 1806-20: Preliminary INTEGRAL results
  80. Very strong outburst from SGR 1806-20 detected with INTEGRAL
  81. XRF 020903: Observations of the Host Galaxy (authors)
  82. XRF 020903: Observations of the Host Galaxy
  83. SGR 1806-20 still active
  84. GRB 040924: Second Epoch WSRT Radio Observations
  85. radio observations, GRB 040924
  86. IBAS Alert 1991. Not a real GRB
  87. GRB040929,optical observation
  88. GRB040929: MASTER optical observations
  89. Konus-Wind and Helicon-Coronas-F observations of GRB040924
  90. GRB040924,optical observation
  91. GRB040924, RTT150 optical observation
  92. GRB040924,optical observation
  93. GRB 040924: detection of possible host galaxy by Subaru
  94. GRB040924, RTT150 optical observation
  95. GRB040924: KAIT observations
  96. GRB040924: Afterglow magnitude at t=17.5hr
  97. GRB 040924: WSRT Radio Observations
  98. GRB 040924: NIR finding chart
  99. GRB040924 : Optical candidate observations at Lulin observatory
  100. GRB040924 : Optical candidate observations at Lulin observatory

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