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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. IPN triangulation of GRB030922B (large error box)
  2. XRF 030723: Detection of the likely host galaxy
  3. XRF030824 (=H2821): An X-Ray Flash Localized by the HETE WXM
  4. XRF030823 (=H2818): An X-Ray Flash Localized by the HETE WXM and SXC
  5. IPN triangulation of GRB030922A (large error box)
  6. IPN triangulation of GRB030921 (large error box)
  7. IPN triangulation of GRB030919 (large error box)
  8. GRB030922 triangulation (annulus)
  9. GRB030913: Subaru Optical Observations
  10. GRB 030913: ROTSE-3c Optical Observations
  11. GRB030913: OT's limit by MASTER
  12. GRB030921 triangulation (annulus)
  13. GRB030913, candidate afterglow observations
  14. GRB 030913, optical candidate
  15. GRB030913: AAVSO optical observations
  16. GRB 030913, BOOTES observations
  17. GRB030913 (=H2849): Confirmation of the Flight Localization
  18. IPN triangulation of GRB030916 (possible short/hard GRB; large error box)
  19. GRB030913 (=H2849): TAROT Observations
  20. GRB030913: wide field imaging (7 sq.deg) of the error box by MASTER
  21. Magellan Observations of GRB030725 (=H2779)
  22. GRB030913 (=H2849): A GRB Possibly Localized by HETE
  23. IPN triangulation of GRB030908 (annulus)
  24. GRB 030913: Optical limit at RIKEN
  25. XRF 020427: Gemini-South Spectroscopic Observations of the Host
  26. XRF030824: Optical observations
  27. IPN triangulation of GRB030903 (large error box)
  28. IBAS detection of bursts from SGR 1806-20
  29. Radio Observations of SGR1806-20
  30. IPN triangulation of GRB030831 (annulus)
  31. IPN triangulation of GRB030830 (large error box)
  32. GRB 030824: Candidate Follow-Up
  33. INTEGRAL ToO OBSERVATIONS OF SGR1806-20: CALL FOR CORRELATED OBSERVATIONS
  34. IPN triangulation of GRB030827 (large error box)
  35. GRB 030823 observation at Ouda
  36. XRF030824: Second-epoch Palomar observations
  37. XRF030824: optical observations
  38. IPN triangulation of GRB030822 (annulus)
  39. GRB030823: optical observations
  40. GRB030823: Palomar observations
  41. XRF030824: Palomar observations
  42. GRB 030824: Candidate Afterglow (or Variable/Flare Star?)
  43. GRB030823: optical observation at Tokyo Tech
  44. RAPTOR observations of GRB030823
  45. Lulin follow-up observations of GRB030823
  46. IPN triangulation of GRB030821 (=H2814; refined error box)
  47. GRB 030821(=H2814): A Faint, Long GRB Localized by the HETE WXM and the IPN
  48. Summary of recent IPN and HETE detections of SGR bursts
  49. IPN triangulation of GRB030814 (annulus)
  50. Clarification of GCN 2354 on SGR1806-20
  51. IPN detection of continued activity from SGR1806-20
  52. 030813 SGR event (Konus-Wind observation)
  53. GRB 030817 = H2808 TAROT optical observations
  54. SGR 1808-20 (=H2802): A Possible new SGR
  55. GRB 021206 Optical Observations
  56. IPN triangulation of GRB030808 (two large error boxes)
  57. IPN triangulation of GRB030806 (large burst; large error box)
  58. XRF030723(=H2777): Chandra Fading X-ray Afterglow Confirmed
  59. IPN/HETE summary of recent bursts from SGR1806-20
  60. XRF 030723: Detection of a rebrightening in the optical afterglow
  61. GRB030725: Optical observations
  62. XRF030723, BVRcIc field photometry update
  63. IPN triangulation of GRB030801 (large error box)
  64. GRB021206 optical counterpart upper limit
  65. IPN triangulation of GRB030731 (annulus)
  66. IBAS GRB Alerts 1011-1017 NOT CONFIRMED
  67. XRF030723: Re-analysis of ROTSE-III early images
  68. IPN triangulation of GRB030725 (=H2779; small error box)
  69. XRF030723 (=H2777): Second Epoch Magellan Observations
  70. GRB 030725: optical observations.
  71. GRB030725, optical transient observations
  72. IPN triangulation of GRB030726 (large error box)
  73. IPN triangulation of GRB030722 (large error box)
  74. IPN triangulation of GRB030721 (large error box)
  75. XRF030723 Radio Observations
  76. XRF 030723: confirmation of fading optical counterpart
  77. XRF030723(=H2777): Chandra Observations
  78. XRF 030723: VLT spectra
  79. Magellan Observations of XRF030723 (=H2777)
  80. GRB030723: Upper limits from historical observations
  81. GRB030725, possible optical transient
  82. XRF030723: Palomar observations and proposed counterpart
  83. GRB030725 (=H2779): A Bright GRB Localized by HETE
  84. XRF030723: optical observations
  85. XRF030723 (= H2777): Chandra Observations Scheduled
  86. XRF030723, BVRcIc field photometry correction
  87. XRF030723, ROTSE-III Early Observations
  88. XRF030723, BVRcIc field photometry
  89. XRF 030723, optical observations
  90. XRF030723, optical observations
  91. XRF 030723, optical observations
  92. XRF030723 (=H2777): An X-ray Flash Localized by the HETE WXM and
  93. GRB030723, optical observations
  94. Konus-Wind detection of the bursts from SGR1806-20 region
  95. IBAS GRB Alerts 969 970
  96. SGR 1806-20, submm observations
  97. H2768, H2770, and H2771: Three Bursts from SGR1806-20
  98. IPN triangulation of GRB030717 (annulus)
  99. RXTE PCA Observations of SGR1806-20 Region
  100. GRB030329: Subaru Optical Spectroscopy

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