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

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