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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 041006: presice astrometry
  2. GRB041006 (= H3570): Chandra Observations In Progress
  3. GRB 041006 : optical observation at Bisei
  4. GRB041006, optical I observation
  5. GRB041006 (=HETE3570): optical observations
  6. ROTSE-IIIa Observations of GRB 041006
  7. GRB041006, optical observation
  8. GRB041006, submillimetre observations
  9. GRB041006: MASTER optical observations
  10. GRB041006,optical observation
  11. GRB 041006: Optical decay
  12. GRB 041006 (=H3570): An X-Ray Rich GRB Localized in Real Time by HETE
  13. Konus-Wind observation of a series SGR 1806-20 bursts on 041005
  14. GRB041006: Fading of optical afterglow candidate
  15. GRB 041006 : Optical follow-up observation at KISO
  16. GRB 041006: Finding chart
  17. GRB 041006: Optical afterglow candidate
  18. Bursts from SGR 1806-20: Preliminary INTEGRAL results
  19. Very strong outburst from SGR 1806-20 detected with INTEGRAL
  20. XRF 020903: Observations of the Host Galaxy (authors)
  21. XRF 020903: Observations of the Host Galaxy
  22. SGR 1806-20 still active
  23. GRB 040924: Second Epoch WSRT Radio Observations
  24. radio observations, GRB 040924
  25. IBAS Alert 1991. Not a real GRB
  26. GRB040929,optical observation
  27. GRB040929: MASTER optical observations
  28. Konus-Wind and Helicon-Coronas-F observations of GRB040924
  29. GRB040924,optical observation
  30. GRB040924, RTT150 optical observation
  31. GRB040924,optical observation
  32. GRB 040924: detection of possible host galaxy by Subaru
  33. GRB040924, RTT150 optical observation
  34. GRB040924: KAIT observations
  35. GRB040924: Afterglow magnitude at t=17.5hr
  36. GRB 040924: WSRT Radio Observations
  37. GRB 040924: NIR finding chart
  38. GRB040924 : Optical candidate observations at Lulin observatory
  39. GRB040924 : Optical candidate observations at Lulin observatory
  40. GRB 040924: Subaru NIR observation
  41. GRB040924: Optical afterglow properties
  42. GRB 040924: RTT150 optical observations
  43. GRB 040924, optical follow-up
  44. GRB040924: MASTER: OT decay
  45. GRB040924: MASTER Optical observations
  46. IPN triangulation of GRB040924 (H3564)
  47. GRB 040924(=H3564): A Short, Bright GRB Localized in Real Time by HETE
  48. GRB040924 (H3564): Optical afterglow candidate
  49. XRF 040912: Radio Observations
  50. XRF 040916: Radio Observations
  51. GRB040912(=H3557): Chandra Candidate X-ray Afterglow
  52. XRF040916: continuing decay of OT
  53. TAROT Observations of GRB 040916 (HETE #3558)
  54. GRB040912(=H3557): Candidate Optical Afterglow
  55. XRF040916, optical observations
  56. XRF040916: Optical Transient Candidate by Subaru
  57. GRB040916 optical limits 17 min after GRB
  58. XRF 040912, identification of CXO sources
  59. XRF 040912 (=H3557): Spectral and Temporal Properties
  60. XRF040916, Ic observations
  61. XRF040916: optical follow-up observations
  62. XRF040912, BVRcIc field calibration
  63. XRF040916, BVRcIc field calibration
  64. GRB040916: Archival optical observations
  65. XRF 040916, optical follow-up
  66. GRB040912(=H3557): Observations with the Chandra X-ray Observatory
  67. GRB040916: Optical observations
  68. ROTSE-IIIb Observations of GRB 040916 (HETE #3558)
  69. GRB040916 (= H3558): Improved Localization from HETE WXM
  70. GRB040916 (= H3558): A Long XRF Localized by HETE
  71. GRB040912 (= H3557): Chandra Observations Scheduled
  72. GRB 040912: Optical Observations
  73. GRB/XRF040912,optical observations
  74. GRB 040912, BVRI observations
  75. Optical observations of GRB/XRF 040912 = HETE 3557
  76. An intense burst from SGR1806-20
  77. GRB040912 : Kiso Optical follow-up observation
  78. IBAS GRB Alerts 1978-1980
  79. Optical observations of field of GRB040912
  80. HETE 3557: Optical observations
  81. GRB040912 (= H3557): A Long GRB or XRF Localized by HETE
  82. GRB 040827: XMM-Newton data
  83. GRB040903 - A XRF?
  84. GRB040827: analysis of the XMM-Newton observation
  85. GRB040903, REM near-IR observation
  86. GRB 040903 - INTEGRAL data analysis
  87. IBAS Alert 1974. Not a real GRB
  88. Very bright burst detected from SGR 1806-20
  89. ROTSE-III Rapid Response to possible GRB 040903 (INTEGRAL #1972)
  90. Possible GRB 040903 - further analysis
  91. Possible GRB 040903 detected with INTEGRAL
  92. GRB 040827 - Radio Observations
  93. XMM-Newton Images of GRB 040827
  94. GRB040825A: Optical observations
  95. GRB040825A: Optical observations
  96. GRB 040827: optical and NIR observations at the VLT
  97. GRB 040827: UKIRT - 2nd epoch K-band imaging
  98. GRB 040827: 2nd epoch of Magellan K-band imaging
  99. GRB 040827: K imaging - no evidence of variability
  100. GRB 040827: Detection of NIR afterglow

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