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

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