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

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