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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. GRB041006, optical observation
  2. GRB041006, submillimetre observations
  3. GRB041006: MASTER optical observations
  4. GRB041006,optical observation
  5. GRB 041006: Optical decay
  6. GRB 041006 (=H3570): An X-Ray Rich GRB Localized in Real Time by HETE
  7. Konus-Wind observation of a series SGR 1806-20 bursts on 041005
  8. GRB041006: Fading of optical afterglow candidate
  9. GRB 041006 : Optical follow-up observation at KISO
  10. GRB 041006: Finding chart
  11. GRB 041006: Optical afterglow candidate
  12. Bursts from SGR 1806-20: Preliminary INTEGRAL results
  13. Very strong outburst from SGR 1806-20 detected with INTEGRAL
  14. XRF 020903: Observations of the Host Galaxy (authors)
  15. XRF 020903: Observations of the Host Galaxy
  16. SGR 1806-20 still active
  17. GRB 040924: Second Epoch WSRT Radio Observations
  18. radio observations, GRB 040924
  19. IBAS Alert 1991. Not a real GRB
  20. GRB040929,optical observation
  21. GRB040929: MASTER optical observations
  22. Konus-Wind and Helicon-Coronas-F observations of GRB040924
  23. GRB040924,optical observation
  24. GRB040924, RTT150 optical observation
  25. GRB040924,optical observation
  26. GRB 040924: detection of possible host galaxy by Subaru
  27. GRB040924, RTT150 optical observation
  28. GRB040924: KAIT observations
  29. GRB040924: Afterglow magnitude at t=17.5hr
  30. GRB 040924: WSRT Radio Observations
  31. GRB 040924: NIR finding chart
  32. GRB040924 : Optical candidate observations at Lulin observatory
  33. GRB040924 : Optical candidate observations at Lulin observatory
  34. GRB 040924: Subaru NIR observation
  35. GRB040924: Optical afterglow properties
  36. GRB 040924: RTT150 optical observations
  37. GRB 040924, optical follow-up
  38. GRB040924: MASTER: OT decay
  39. GRB040924: MASTER Optical observations
  40. IPN triangulation of GRB040924 (H3564)
  41. GRB 040924(=H3564): A Short, Bright GRB Localized in Real Time by HETE
  42. GRB040924 (H3564): Optical afterglow candidate
  43. XRF 040912: Radio Observations
  44. XRF 040916: Radio Observations
  45. GRB040912(=H3557): Chandra Candidate X-ray Afterglow
  46. XRF040916: continuing decay of OT
  47. TAROT Observations of GRB 040916 (HETE #3558)
  48. GRB040912(=H3557): Candidate Optical Afterglow
  49. XRF040916, optical observations
  50. XRF040916: Optical Transient Candidate by Subaru
  51. GRB040916 optical limits 17 min after GRB
  52. XRF 040912, identification of CXO sources
  53. XRF 040912 (=H3557): Spectral and Temporal Properties
  54. XRF040916, Ic observations
  55. XRF040916: optical follow-up observations
  56. XRF040912, BVRcIc field calibration
  57. XRF040916, BVRcIc field calibration
  58. GRB040916: Archival optical observations
  59. XRF 040916, optical follow-up
  60. GRB040912(=H3557): Observations with the Chandra X-ray Observatory
  61. GRB040916: Optical observations
  62. ROTSE-IIIb Observations of GRB 040916 (HETE #3558)
  63. GRB040916 (= H3558): Improved Localization from HETE WXM
  64. GRB040916 (= H3558): A Long XRF Localized by HETE
  65. GRB040912 (= H3557): Chandra Observations Scheduled
  66. GRB 040912: Optical Observations
  67. GRB/XRF040912,optical observations
  68. GRB 040912, BVRI observations
  69. Optical observations of GRB/XRF 040912 = HETE 3557
  70. An intense burst from SGR1806-20
  71. GRB040912 : Kiso Optical follow-up observation
  72. IBAS GRB Alerts 1978-1980
  73. Optical observations of field of GRB040912
  74. HETE 3557: Optical observations
  75. GRB040912 (= H3557): A Long GRB or XRF Localized by HETE
  76. GRB 040827: XMM-Newton data
  77. GRB040903 - A XRF?
  78. GRB040827: analysis of the XMM-Newton observation
  79. GRB040903, REM near-IR observation
  80. GRB 040903 - INTEGRAL data analysis
  81. IBAS Alert 1974. Not a real GRB
  82. Very bright burst detected from SGR 1806-20
  83. ROTSE-III Rapid Response to possible GRB 040903 (INTEGRAL #1972)
  84. Possible GRB 040903 - further analysis
  85. Possible GRB 040903 detected with INTEGRAL
  86. GRB 040827 - Radio Observations
  87. XMM-Newton Images of GRB 040827
  88. GRB040825A: Optical observations
  89. GRB040825A: Optical observations
  90. GRB 040827: optical and NIR observations at the VLT
  91. GRB 040827: UKIRT - 2nd epoch K-band imaging
  92. GRB 040827: 2nd epoch of Magellan K-band imaging
  93. GRB 040827: K imaging - no evidence of variability
  94. GRB 040827: Detection of NIR afterglow
  95. GRB 040827: Possible detection of optical afterglow
  96. GRB 040827: RTT150 optical observations
  97. GRB040827 XMM-Newton observation
  98. GRB040825A: optical limit before GRB
  99. MASTER: GRB040827 possible OT
  100. GRB 040825B: Optical observations

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