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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. Bursts from SGR 1806-20: Preliminary INTEGRAL results
  2. Very strong outburst from SGR 1806-20 detected with INTEGRAL
  3. XRF 020903: Observations of the Host Galaxy (authors)
  4. XRF 020903: Observations of the Host Galaxy
  5. SGR 1806-20 still active
  6. GRB 040924: Second Epoch WSRT Radio Observations
  7. radio observations, GRB 040924
  8. IBAS Alert 1991. Not a real GRB
  9. GRB040929,optical observation
  10. GRB040929: MASTER optical observations
  11. Konus-Wind and Helicon-Coronas-F observations of GRB040924
  12. GRB040924,optical observation
  13. GRB040924, RTT150 optical observation
  14. GRB040924,optical observation
  15. GRB 040924: detection of possible host galaxy by Subaru
  16. GRB040924, RTT150 optical observation
  17. GRB040924: KAIT observations
  18. GRB040924: Afterglow magnitude at t=17.5hr
  19. GRB 040924: WSRT Radio Observations
  20. GRB 040924: NIR finding chart
  21. GRB040924 : Optical candidate observations at Lulin observatory
  22. GRB040924 : Optical candidate observations at Lulin observatory
  23. GRB 040924: Subaru NIR observation
  24. GRB040924: Optical afterglow properties
  25. GRB 040924: RTT150 optical observations
  26. GRB 040924, optical follow-up
  27. GRB040924: MASTER: OT decay
  28. GRB040924: MASTER Optical observations
  29. IPN triangulation of GRB040924 (H3564)
  30. GRB 040924(=H3564): A Short, Bright GRB Localized in Real Time by HETE
  31. GRB040924 (H3564): Optical afterglow candidate
  32. XRF 040912: Radio Observations
  33. XRF 040916: Radio Observations
  34. GRB040912(=H3557): Chandra Candidate X-ray Afterglow
  35. XRF040916: continuing decay of OT
  36. TAROT Observations of GRB 040916 (HETE #3558)
  37. GRB040912(=H3557): Candidate Optical Afterglow
  38. XRF040916, optical observations
  39. XRF040916: Optical Transient Candidate by Subaru
  40. GRB040916 optical limits 17 min after GRB
  41. XRF 040912, identification of CXO sources
  42. XRF 040912 (=H3557): Spectral and Temporal Properties
  43. XRF040916, Ic observations
  44. XRF040916: optical follow-up observations
  45. XRF040912, BVRcIc field calibration
  46. XRF040916, BVRcIc field calibration
  47. GRB040916: Archival optical observations
  48. XRF 040916, optical follow-up
  49. GRB040912(=H3557): Observations with the Chandra X-ray Observatory
  50. GRB040916: Optical observations
  51. ROTSE-IIIb Observations of GRB 040916 (HETE #3558)
  52. GRB040916 (= H3558): Improved Localization from HETE WXM
  53. GRB040916 (= H3558): A Long XRF Localized by HETE
  54. GRB040912 (= H3557): Chandra Observations Scheduled
  55. GRB 040912: Optical Observations
  56. GRB/XRF040912,optical observations
  57. GRB 040912, BVRI observations
  58. Optical observations of GRB/XRF 040912 = HETE 3557
  59. An intense burst from SGR1806-20
  60. GRB040912 : Kiso Optical follow-up observation
  61. IBAS GRB Alerts 1978-1980
  62. Optical observations of field of GRB040912
  63. HETE 3557: Optical observations
  64. GRB040912 (= H3557): A Long GRB or XRF Localized by HETE
  65. GRB 040827: XMM-Newton data
  66. GRB040903 - A XRF?
  67. GRB040827: analysis of the XMM-Newton observation
  68. GRB040903, REM near-IR observation
  69. GRB 040903 - INTEGRAL data analysis
  70. IBAS Alert 1974. Not a real GRB
  71. Very bright burst detected from SGR 1806-20
  72. ROTSE-III Rapid Response to possible GRB 040903 (INTEGRAL #1972)
  73. Possible GRB 040903 - further analysis
  74. Possible GRB 040903 detected with INTEGRAL
  75. GRB 040827 - Radio Observations
  76. XMM-Newton Images of GRB 040827
  77. GRB040825A: Optical observations
  78. GRB040825A: Optical observations
  79. GRB 040827: optical and NIR observations at the VLT
  80. GRB 040827: UKIRT - 2nd epoch K-band imaging
  81. GRB 040827: 2nd epoch of Magellan K-band imaging
  82. GRB 040827: K imaging - no evidence of variability
  83. GRB 040827: Detection of NIR afterglow
  84. GRB 040827: Possible detection of optical afterglow
  85. GRB 040827: RTT150 optical observations
  86. GRB040827 XMM-Newton observation
  87. GRB040825A: optical limit before GRB
  88. MASTER: GRB040827 possible OT
  89. GRB 040825B: Optical observations
  90. GRB040827 optical observations
  91. GRB 040827 : Planned XMM-Newton observation
  92. GRB 040827 - Refined position
  93. GRB 040827 : peak flux
  94. GRB 040827 - A long GRB detected by INTEGRAL
  95. GRB040825B, BVRcIc field photometry
  96. GRB040825A, BVRcIc field photometry
  97. GCN GRB OBSERBATION REPORT
  98. GRB 040825A,optical observations
  99. Increase of SGR 1806-20 activity
  100. GRB040825A: optical observations

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