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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').
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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. XRF 030723: Subaru Optical Observations
  2. IPN triangulation of GRB031004B (annulus)
  3. IPN triangulation of GRB031004A (short/hard; annulus)
  4. IPN triangulation of GRB030929 (short/hard; annulus)
  5. A burst from SGR 1806-20 detected with IBAS
  6. XRF 030824: Early follow-up observation at Kiso observatory
  7. XRF 030824: observations at CFHT
  8. IPN triangulation of GRB030926 (short/hard; large error box)
  9. IPN triangulation of GRB030922B (large error box)
  10. XRF 030723: Detection of the likely host galaxy
  11. XRF030824 (=H2821): An X-Ray Flash Localized by the HETE WXM
  12. XRF030823 (=H2818): An X-Ray Flash Localized by the HETE WXM and SXC
  13. IPN triangulation of GRB030922A (large error box)
  14. IPN triangulation of GRB030921 (large error box)
  15. IPN triangulation of GRB030919 (large error box)
  16. GRB030922 triangulation (annulus)
  17. GRB030913: Subaru Optical Observations
  18. GRB 030913: ROTSE-3c Optical Observations
  19. GRB030913: OT's limit by MASTER
  20. GRB030921 triangulation (annulus)
  21. GRB030913, candidate afterglow observations
  22. GRB 030913, optical candidate
  23. GRB030913: AAVSO optical observations
  24. GRB 030913, BOOTES observations
  25. GRB030913 (=H2849): Confirmation of the Flight Localization
  26. IPN triangulation of GRB030916 (possible short/hard GRB; large error box)
  27. GRB030913 (=H2849): TAROT Observations
  28. GRB030913: wide field imaging (7 sq.deg) of the error box by MASTER
  29. Magellan Observations of GRB030725 (=H2779)
  30. GRB030913 (=H2849): A GRB Possibly Localized by HETE
  31. IPN triangulation of GRB030908 (annulus)
  32. GRB 030913: Optical limit at RIKEN
  33. XRF 020427: Gemini-South Spectroscopic Observations of the Host
  34. XRF030824: Optical observations
  35. IPN triangulation of GRB030903 (large error box)
  36. IBAS detection of bursts from SGR 1806-20
  37. Radio Observations of SGR1806-20
  38. IPN triangulation of GRB030831 (annulus)
  39. IPN triangulation of GRB030830 (large error box)
  40. GRB 030824: Candidate Follow-Up
  41. INTEGRAL ToO OBSERVATIONS OF SGR1806-20: CALL FOR CORRELATED OBSERVATIONS
  42. IPN triangulation of GRB030827 (large error box)
  43. GRB 030823 observation at Ouda
  44. XRF030824: Second-epoch Palomar observations
  45. XRF030824: optical observations
  46. IPN triangulation of GRB030822 (annulus)
  47. GRB030823: optical observations
  48. GRB030823: Palomar observations
  49. XRF030824: Palomar observations
  50. GRB 030824: Candidate Afterglow (or Variable/Flare Star?)
  51. GRB030823: optical observation at Tokyo Tech
  52. RAPTOR observations of GRB030823
  53. Lulin follow-up observations of GRB030823
  54. IPN triangulation of GRB030821 (=H2814; refined error box)
  55. GRB 030821(=H2814): A Faint, Long GRB Localized by the HETE WXM and the IPN
  56. Summary of recent IPN and HETE detections of SGR bursts
  57. IPN triangulation of GRB030814 (annulus)
  58. Clarification of GCN 2354 on SGR1806-20
  59. IPN detection of continued activity from SGR1806-20
  60. 030813 SGR event (Konus-Wind observation)
  61. GRB 030817 = H2808 TAROT optical observations
  62. SGR 1808-20 (=H2802): A Possible new SGR
  63. GRB 021206 Optical Observations
  64. IPN triangulation of GRB030808 (two large error boxes)
  65. IPN triangulation of GRB030806 (large burst; large error box)
  66. XRF030723(=H2777): Chandra Fading X-ray Afterglow Confirmed
  67. IPN/HETE summary of recent bursts from SGR1806-20
  68. XRF 030723: Detection of a rebrightening in the optical afterglow
  69. GRB030725: Optical observations
  70. XRF030723, BVRcIc field photometry update
  71. IPN triangulation of GRB030801 (large error box)
  72. GRB021206 optical counterpart upper limit
  73. IPN triangulation of GRB030731 (annulus)
  74. IBAS GRB Alerts 1011-1017 NOT CONFIRMED
  75. XRF030723: Re-analysis of ROTSE-III early images
  76. IPN triangulation of GRB030725 (=H2779; small error box)
  77. XRF030723 (=H2777): Second Epoch Magellan Observations
  78. GRB 030725: optical observations.
  79. GRB030725, optical transient observations
  80. IPN triangulation of GRB030726 (large error box)
  81. IPN triangulation of GRB030722 (large error box)
  82. IPN triangulation of GRB030721 (large error box)
  83. XRF030723 Radio Observations
  84. XRF 030723: confirmation of fading optical counterpart
  85. XRF030723(=H2777): Chandra Observations
  86. XRF 030723: VLT spectra
  87. Magellan Observations of XRF030723 (=H2777)
  88. GRB030723: Upper limits from historical observations
  89. GRB030725, possible optical transient
  90. XRF030723: Palomar observations and proposed counterpart
  91. GRB030725 (=H2779): A Bright GRB Localized by HETE
  92. XRF030723: optical observations
  93. XRF030723 (= H2777): Chandra Observations Scheduled
  94. XRF030723, BVRcIc field photometry correction
  95. XRF030723, ROTSE-III Early Observations
  96. XRF030723, BVRcIc field photometry
  97. XRF 030723, optical observations
  98. XRF030723, optical observations
  99. XRF 030723, optical observations
  100. XRF030723 (=H2777): An X-ray Flash Localized by the HETE WXM and

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