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

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