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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').
  1. GRB 060413: Refined analysis of the Swift-BAT burst
  2. GRB 060413: Watcher UBVR observations
  3. GRB 060413: XRT refined analysis
  4. GRB 060413: No Optical Afterglow in Swift/UVOT TDRSS Data
  5. GRB 060413: Swift detection of a burst
  6. GRB060403: optical observations
  7. GRB 060403 Optical observations
  8. GRB 060403: MITSuME optical observation
  9. GRB060403: Optical Limit
  10. GRB060403: XRT refined analysis
  11. GRB 060403: Swift/UVOT upper limits
  12. HETE Triggers H4043 and H4044 Not Due to New Cosmic Source
  13. SGR 1900+14: BAT observations
  14. GRB 060403: Refined analysis of the Swift-BAT burst
  15. GRB060403: Swift XRT refined position
  16. Konus-Wind observation of the recent SGR 1900+14 activity. Will
  17. GRB 060403: Swift detection of a burst
  18. HETE trigger H4044: RTT150 optical observations
  19. GRB060331: Swift/UVOT upper limits
  20. H4044, a Repeat Outburst From The Source of H4043 (="GRB060331")
  21. Swift XRT observations of the HETE transient H4043
  22. HETE Trigger 4043: ROTSE-III Optical Limits
  23. Correction to Circular 4938, =H4043, an unusual high energy transient observed by HETE
  24. H4043, an unusual high-energy transient observed by HETE
  25. GRB 060322: LNA optical limit
  26. SGR 1900+14: bright burst detected by Konus-Wind on March 28
  27. INTEGRAL and XMM ToO observations of SGR1900+14
  28. SGR 1900+14: Swift-BAT detection of a cluster of outbursts
  29. SGR 1900+14: Swift-BAT detection of a bright outburst
  30. GRB 060218SN 2006aj: optical observations at Rozhen Observatory
  31. GRB 060323 : WIDGET simultaneous optical observations
  32. GRB 060323: Early optical observation at Xinglong
  33. GRB060218, optical observations
  34. GRB 060322: Confirmation of Swift XRT afterglow
  35. GRB 060211A: optical observation
  36. GRB060323: optical limit
  37. GRB060211B: optical observation
  38. SGR 1900+14: CORRECTION to GCN 4923
  39. SGR 1900+14: Refined Swift-BAT analysis of the renewed activity
  40. SGR 1900+14: Swift detection of renewed activity
  41. GRB060323: NOT optical observations
  42. GRB 060322: IAC80 optical observations
  43. GRB 060322: Swift XRT afterglow candidate
  44. GRB060323: P60 Observations
  45. GRB 060323: Swift/UVOT Observations
  46. GRB 060323: optical afterglow confirmed
  47. GRB060323: NOT observations
  48. GRB 060323: Optical Observations
  49. GRB 060323: Tautenburg OT candidate retraction
  50. GRB 060323: Refined analysis of the Swift-BAT burst
  51. GRB 060323: optical observations at TNG
  52. GRB 060323: Swift XRT refined analysis
  53. GRB 060323: BVRI observations at Tautenburg, aftreglow candidate
  54. GRB 060323: Swift/XRT position
  55. GRB 060322: Refined analysis of the Swift-BAT burst
  56. GRB060323, optical observation
  57. GRB060323 - SDSS Pre-Burst Observations
  58. GRB 060323: Swift detection of a burst with a possible optical afterglow
  59. GRB 060322: Swift-BAT detection of a 200-sec burst
  60. GRB060219: optical observation
  61. GRB060206: optical observation
  62. GRB060218/SN2006aj: optical observations
  63. GRB 060218/SN 2006aj, LNA optical observation
  64. GRB060218: Refined photometric calibration of comparison stars
  65. GRB 060319: WHT K-band candidate afterglow
  66. GRB 060319: IAC-80 optical observations
  67. GRB060319: Swift XRT refined analysis
  68. GRB060319: Swift/UVOT upper limits
  69. GRB 060319: Re-analysis of TNG data
  70. GRB060319: MASTER limit
  71. GRB 060319: Swift-BAT refined analysis
  72. GRB 060319 optical observations at TNG
  73. GRB060319 : Liverpool Telescope optical limit
  74. GRB060319: MASTER optical observation
  75. GRB060319 - SDSS Pre-burst Observations
  76. GRB060319: Swift/XRT position
  77. GRB 060319: Swift detection of a burst
  78. GRB060313: Radio Observations
  79. GRB 060313: early afterglow NIR upper limits with REM
  80. IBAS Alert n. 3221: not a GRB
  81. Konus-Wind observation of GRB 060313
  82. GRB060313: SSO 40inch Observations
  83. GRB 060313: Further analysis of the Swift-BAT bright short hard burst
  84. GRB 060313: PROMPT Observations
  85. GRB 060313: Swift/UVOT Observations
  86. GRB060313:Gemini South Observations
  87. GRB 060313: Swift-XRT team refined analysis
  88. GRB060313: optical observations of the afterglow candidate
  89. GRB 060313: Refined analysis of the Swift-BAT bright short hard burst
  90. GRB 060313, SMARTS optical counterpart?
  91. GRB 060313: Possible optical counterpart
  92. GRB 060313: Swift XRT position
  93. GRB 060313, SMARTS optical/IR observations
  94. GRB060313: optical and near infrared observations with REM
  95. GRB 060313: Swift-BAT detection of a bright short hard burst
  96. GRB060218: SARA Observations of SN2006aj
  97. GRB060312: Swift UVOT observation
  98. GRB 060312: Refined analysis of the Swift-BAT burst
  99. GRB 060218/SN 2006aj, high resolution spectra
  100. GRB 060312: Swift XRT team refined analysis

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