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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 041015 R band observations
  2. GRB040924, BVRcIc field calibration
  3. GRB041015: MASTER: Optical observations
  4. GRB041015,optical observation
  5. GRB041006: Fading X-ray Afterglow Observed with Chandra
  6. GRB 041015: Optical limit at Osaka University
  7. GRB041015 : Optical follow-up at Kiso
  8. GRB 041015 - A long GRB detected by INTEGRAL
  9. GRB 041006 R observations in Loiano
  10. GRB041006: VLT observations of the afterglow and host galaxy
  11. GRB041006: Optical observations and Potential host galaxy
  12. GRB041006, BVRcIc field calibration
  13. GRB 040924: VLT spectroscopy
  14. GRB 041006: SARA afterglow observations
  15. GRB041006, optical observation in CrAO
  16. Search for SN light in XRF 040912 with MEGACAM
  17. GRB 040916: Afterglow Color at Early Times
  18. GRB 041006 Optical afterglow observations
  19. IBAS GRB Alert # 2010
  20. GRB 041006: BR observations with VATT
  21. GRB 041006: Redshift confirmed
  22. GRB041006: Liverpool Telescope optical observations
  23. GRB 041006: Colour measurement
  24. GRB041006: break in the light curve
  25. GRB 041006: Radio Observations
  26. GRB041006, further submilllimetre observations
  27. GRB 041006 : optical follow-up observation at Lulin Observatory
  28. GRB 041006 : Optical follow-up observation at TAROT
  29. GRB041006: Optical photometry and spectroscopy at TNG
  30. GRB 041006: presice astrometry
  31. GRB041006 (= H3570): Chandra Observations In Progress
  32. GRB 041006 : optical observation at Bisei
  33. GRB041006, optical I observation
  34. GRB041006 (=HETE3570): optical observations
  35. ROTSE-IIIa Observations of GRB 041006
  36. GRB041006, optical observation
  37. GRB041006, submillimetre observations
  38. GRB041006: MASTER optical observations
  39. GRB041006,optical observation
  40. GRB 041006: Optical decay
  41. GRB 041006 (=H3570): An X-Ray Rich GRB Localized in Real Time by HETE
  42. Konus-Wind observation of a series SGR 1806-20 bursts on 041005
  43. GRB041006: Fading of optical afterglow candidate
  44. GRB 041006 : Optical follow-up observation at KISO
  45. GRB 041006: Finding chart
  46. GRB 041006: Optical afterglow candidate
  47. Bursts from SGR 1806-20: Preliminary INTEGRAL results
  48. Very strong outburst from SGR 1806-20 detected with INTEGRAL
  49. XRF 020903: Observations of the Host Galaxy (authors)
  50. XRF 020903: Observations of the Host Galaxy
  51. SGR 1806-20 still active
  52. GRB 040924: Second Epoch WSRT Radio Observations
  53. radio observations, GRB 040924
  54. IBAS Alert 1991. Not a real GRB
  55. GRB040929,optical observation
  56. GRB040929: MASTER optical observations
  57. Konus-Wind and Helicon-Coronas-F observations of GRB040924
  58. GRB040924,optical observation
  59. GRB040924, RTT150 optical observation
  60. GRB040924,optical observation
  61. GRB 040924: detection of possible host galaxy by Subaru
  62. GRB040924, RTT150 optical observation
  63. GRB040924: KAIT observations
  64. GRB040924: Afterglow magnitude at t=17.5hr
  65. GRB 040924: WSRT Radio Observations
  66. GRB 040924: NIR finding chart
  67. GRB040924 : Optical candidate observations at Lulin observatory
  68. GRB040924 : Optical candidate observations at Lulin observatory
  69. GRB 040924: Subaru NIR observation
  70. GRB040924: Optical afterglow properties
  71. GRB 040924: RTT150 optical observations
  72. GRB 040924, optical follow-up
  73. GRB040924: MASTER: OT decay
  74. GRB040924: MASTER Optical observations
  75. IPN triangulation of GRB040924 (H3564)
  76. GRB 040924(=H3564): A Short, Bright GRB Localized in Real Time by HETE
  77. GRB040924 (H3564): Optical afterglow candidate
  78. XRF 040912: Radio Observations
  79. XRF 040916: Radio Observations
  80. GRB040912(=H3557): Chandra Candidate X-ray Afterglow
  81. XRF040916: continuing decay of OT
  82. TAROT Observations of GRB 040916 (HETE #3558)
  83. GRB040912(=H3557): Candidate Optical Afterglow
  84. XRF040916, optical observations
  85. XRF040916: Optical Transient Candidate by Subaru
  86. GRB040916 optical limits 17 min after GRB
  87. XRF 040912, identification of CXO sources
  88. XRF 040912 (=H3557): Spectral and Temporal Properties
  89. XRF040916, Ic observations
  90. XRF040916: optical follow-up observations
  91. XRF040912, BVRcIc field calibration
  92. XRF040916, BVRcIc field calibration
  93. GRB040916: Archival optical observations
  94. XRF 040916, optical follow-up
  95. GRB040912(=H3557): Observations with the Chandra X-ray Observatory
  96. GRB040916: Optical observations
  97. ROTSE-IIIb Observations of GRB 040916 (HETE #3558)
  98. GRB040916 (= H3558): Improved Localization from HETE WXM
  99. GRB040916 (= H3558): A Long XRF Localized by HETE
  100. GRB040912 (= H3557): Chandra Observations Scheduled

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