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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. GRB041016: MASTER: Optical observations
  2. GRB 041015: Optical Observations at Rikubetsu
  3. GRB041006: Near Infrared observations
  4. GRB 041016: Optical limit
  5. GRB 041015 R band observations
  6. GRB040924, BVRcIc field calibration
  7. GRB041015: MASTER: Optical observations
  8. GRB041015,optical observation
  9. GRB041006: Fading X-ray Afterglow Observed with Chandra
  10. GRB 041015: Optical limit at Osaka University
  11. GRB041015 : Optical follow-up at Kiso
  12. GRB 041015 - A long GRB detected by INTEGRAL
  13. GRB 041006 R observations in Loiano
  14. GRB041006: VLT observations of the afterglow and host galaxy
  15. GRB041006: Optical observations and Potential host galaxy
  16. GRB041006, BVRcIc field calibration
  17. GRB 040924: VLT spectroscopy
  18. GRB 041006: SARA afterglow observations
  19. GRB041006, optical observation in CrAO
  20. Search for SN light in XRF 040912 with MEGACAM
  21. GRB 040916: Afterglow Color at Early Times
  22. GRB 041006 Optical afterglow observations
  23. IBAS GRB Alert # 2010
  24. GRB 041006: BR observations with VATT
  25. GRB 041006: Redshift confirmed
  26. GRB041006: Liverpool Telescope optical observations
  27. GRB 041006: Colour measurement
  28. GRB041006: break in the light curve
  29. GRB 041006: Radio Observations
  30. GRB041006, further submilllimetre observations
  31. GRB 041006 : optical follow-up observation at Lulin Observatory
  32. GRB 041006 : Optical follow-up observation at TAROT
  33. GRB041006: Optical photometry and spectroscopy at TNG
  34. GRB 041006: presice astrometry
  35. GRB041006 (= H3570): Chandra Observations In Progress
  36. GRB 041006 : optical observation at Bisei
  37. GRB041006, optical I observation
  38. GRB041006 (=HETE3570): optical observations
  39. ROTSE-IIIa Observations of GRB 041006
  40. GRB041006, optical observation
  41. GRB041006, submillimetre observations
  42. GRB041006: MASTER optical observations
  43. GRB041006,optical observation
  44. GRB 041006: Optical decay
  45. GRB 041006 (=H3570): An X-Ray Rich GRB Localized in Real Time by HETE
  46. Konus-Wind observation of a series SGR 1806-20 bursts on 041005
  47. GRB041006: Fading of optical afterglow candidate
  48. GRB 041006 : Optical follow-up observation at KISO
  49. GRB 041006: Finding chart
  50. GRB 041006: Optical afterglow candidate
  51. Bursts from SGR 1806-20: Preliminary INTEGRAL results
  52. Very strong outburst from SGR 1806-20 detected with INTEGRAL
  53. XRF 020903: Observations of the Host Galaxy (authors)
  54. XRF 020903: Observations of the Host Galaxy
  55. SGR 1806-20 still active
  56. GRB 040924: Second Epoch WSRT Radio Observations
  57. radio observations, GRB 040924
  58. IBAS Alert 1991. Not a real GRB
  59. GRB040929,optical observation
  60. GRB040929: MASTER optical observations
  61. Konus-Wind and Helicon-Coronas-F observations of GRB040924
  62. GRB040924,optical observation
  63. GRB040924, RTT150 optical observation
  64. GRB040924,optical observation
  65. GRB 040924: detection of possible host galaxy by Subaru
  66. GRB040924, RTT150 optical observation
  67. GRB040924: KAIT observations
  68. GRB040924: Afterglow magnitude at t=17.5hr
  69. GRB 040924: WSRT Radio Observations
  70. GRB 040924: NIR finding chart
  71. GRB040924 : Optical candidate observations at Lulin observatory
  72. GRB040924 : Optical candidate observations at Lulin observatory
  73. GRB 040924: Subaru NIR observation
  74. GRB040924: Optical afterglow properties
  75. GRB 040924: RTT150 optical observations
  76. GRB 040924, optical follow-up
  77. GRB040924: MASTER: OT decay
  78. GRB040924: MASTER Optical observations
  79. IPN triangulation of GRB040924 (H3564)
  80. GRB 040924(=H3564): A Short, Bright GRB Localized in Real Time by HETE
  81. GRB040924 (H3564): Optical afterglow candidate
  82. XRF 040912: Radio Observations
  83. XRF 040916: Radio Observations
  84. GRB040912(=H3557): Chandra Candidate X-ray Afterglow
  85. XRF040916: continuing decay of OT
  86. TAROT Observations of GRB 040916 (HETE #3558)
  87. GRB040912(=H3557): Candidate Optical Afterglow
  88. XRF040916, optical observations
  89. XRF040916: Optical Transient Candidate by Subaru
  90. GRB040916 optical limits 17 min after GRB
  91. XRF 040912, identification of CXO sources
  92. XRF 040912 (=H3557): Spectral and Temporal Properties
  93. XRF040916, Ic observations
  94. XRF040916: optical follow-up observations
  95. XRF040912, BVRcIc field calibration
  96. XRF040916, BVRcIc field calibration
  97. GRB040916: Archival optical observations
  98. XRF 040916, optical follow-up
  99. GRB040912(=H3557): Observations with the Chandra X-ray Observatory
  100. GRB040916: Optical observations

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