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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: SARA afterglow observations
  2. GRB041006, optical observation in CrAO
  3. Search for SN light in XRF 040912 with MEGACAM
  4. GRB 040916: Afterglow Color at Early Times
  5. GRB 041006 Optical afterglow observations
  6. IBAS GRB Alert # 2010
  7. GRB 041006: BR observations with VATT
  8. GRB 041006: Redshift confirmed
  9. GRB041006: Liverpool Telescope optical observations
  10. GRB 041006: Colour measurement
  11. GRB041006: break in the light curve
  12. GRB 041006: Radio Observations
  13. GRB041006, further submilllimetre observations
  14. GRB 041006 : optical follow-up observation at Lulin Observatory
  15. SUBJECT: GRB 041006 : Optical follow-up observation at TAROT
  16. GRB041006: Optical photometry and spectroscopy at TNG
  17. GRB 041006: presice astrometry
  18. GRB041006 (= H3570): Chandra Observations In Progress
  19. GRB 041006 : optical observation at Bisei
  20. GRB041006, optical I observation
  21. GRB041006 (=HETE3570): optical observations
  22. ROTSE-IIIa Observations of GRB 041006
  23. GRB041006, optical observation
  24. GRB041006, submillimetre observations
  25. GRB041006: MASTER optical observations
  26. GRB041006,optical observation
  27. GRB 041006: Optical decay
  28. GRB 041006 (=H3570): An X-Ray Rich GRB Localized in Real Time by HETE
  29. Konus-Wind observation of a series SGR 1806-20 bursts on 041005
  30. GRB041006: Fading of optical afterglow candidate
  31. GRB 041006 : Optical follow-up observation at KISO
  32. GRB 041006: Finding chart
  33. GRB 041006: Optical afterglow candidate
  34. Bursts from SGR 1806-20: Preliminary INTEGRAL results
  35. Very strong outburst from SGR 1806-20 detected with INTEGRAL
  36. XRF 020903: Observations of the Host Galaxy (authors)
  37. XRF 020903: Observations of the Host Galaxy
  38. SGR 1806-20 still active
  39. GRB 040924: Second Epoch WSRT Radio Observations
  40. radio observations, GRB 040924
  41. IBAS Alert 1991. Not a real GRB
  42. GRB040929,optical observation
  43. GRB040929: MASTER optical observations
  44. Konus-Wind and Helicon-Coronas-F observations of GRB040924
  45. GRB040924,optical observation
  46. GRB040924, RTT150 optical observation
  47. GRB040924,optical observation
  48. GRB 040924: detection of possible host galaxy by Subaru
  49. GRB040924, RTT150 optical observation
  50. GRB040924: KAIT observations
  51. GRB040924: Afterglow magnitude at t=17.5hr
  52. GRB 040924: WSRT Radio Observations
  53. GRB 040924: NIR finding chart
  54. GRB040924 : Optical candidate observations at Lulin observatory
  55. GRB040924 : Optical candidate observations at Lulin observatory
  56. GRB 040924: Subaru NIR observation
  57. GRB040924: Optical afterglow properties
  58. GRB 040924: RTT150 optical observations
  59. GRB 040924, optical follow-up
  60. GRB040924: MASTER: OT decay
  61. GRB040924: MASTER Optical observations
  62. IPN triangulation of GRB040924 (H3564)
  63. GRB 040924(=H3564): A Short, Bright GRB Localized in Real Time by HETE
  64. GRB040924 (H3564): Optical afterglow candidate
  65. XRF 040912: Radio Observations
  66. XRF 040916: Radio Observations
  67. GRB040912(=H3557): Chandra Candidate X-ray Afterglow
  68. XRF040916: continuing decay of OT
  69. TAROT Observations of GRB 040916 (HETE #3558)
  70. GRB040912(=H3557): Candidate Optical Afterglow
  71. XRF040916, optical observations
  72. XRF040916: Optical Transient Candidate by Subaru
  73. GRB040916 optical limits 17 min after GRB
  74. XRF 040912, identification of CXO sources
  75. XRF 040912 (=H3557): Spectral and Temporal Properties
  76. XRF040916, Ic observations
  77. XRF040916: optical follow-up observations
  78. XRF040912, BVRcIc field calibration
  79. XRF040916, BVRcIc field calibration
  80. GRB040916: Archival optical observations
  81. XRF 040916, optical follow-up
  82. GRB040912(=H3557): Observations with the Chandra X-ray Observatory
  83. GRB040916: Optical observations
  84. ROTSE-IIIb Observations of GRB 040916 (HETE #3558)
  85. GRB040916 (= H3558): Improved Localization from HETE WXM
  86. GRB040916 (= H3558): A Long XRF Localized by HETE
  87. GRB040912 (= H3557): Chandra Observations Scheduled
  88. GRB 040912: Optical Observations
  89. GRB/XRF040912,optical observations
  90. GRB 040912, BVRI observations
  91. Optical observations of GRB/XRF 040912 = HETE 3557
  92. An intense burst from SGR1806-20
  93. GRB040912 : Kiso Optical follow-up observation
  94. IBAS GRB Alerts 1978-1980
  95. Optical observations of field of GRB040912
  96. HETE 3557: Optical observations
  97. GRB040912 (= H3557): A Long GRB or XRF Localized by HETE
  98. GRB 040827: XMM-Newton data
  99. GRB040903 - A XRF?
  100. GRB040827: analysis of the XMM-Newton observation

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