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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 031203: Radio detection
  2. GRB 031203: Further reports on December 4 observations
  3. GRB 031203: IR NTTobservations do not confirm REM detection
  4. GRB031203 : Optical Observation of Lulin Observatory
  5. GRB 031203: z ~ 10 or Fragmented Dust in the Circumburst Environment?
  6. GRB 031203: Apparent Spectral Break
  7. GRB031203: Planned XMM-Newton observation II
  8. GRB 031203: IR REM Observations
  9. GRB031203: Optical Observations
  10. GRB 031203 XMM-Newton observation
  11. GRB 031203: Optical/IR SMARTS Observations
  12. GRB031203: Planned XMM-Newton observation
  13. IPN triangulation of GRB031127A and B (quasi-simultaneous; large error boxes)
  14. GRB 031203: further analysis of INTEGRAL data
  15. GRB 031203: A long GRB detected with INTEGRAL
  16. IPN triangulation of GRB031201 (large error box)
  17. IPN triangulation of GRB031130 (large error box)
  18. GRB031111A, prompt optical observations
  19. GRB 030329: Planned XMM-Newton Observation
  20. IPN triangulation of GRB031120 (two large error boxes)
  21. GRB 031111B (= H2925) : Kyoto Optical Observation
  22. IPN/HETE localization of GRB031109 (=H2917; large error box)
  23. IPN detection of activity from SGR1806-20
  24. GRB 031111, Radio observations
  25. IPN triangulation of GRB031114 (large error box)
  26. IPN triangulation of GRB031107 (two large error boxes)
  27. GRB 031111: Optical observations
  28. GRB 031111, optical observations
  29. SN 2003jd (SN/GRB?) -- X-ray Observations
  30. HETE Prompt GRB Spectral Analyses
  31. IPN triangulation of GRB031111 (=H2924): small error box
  32. XRF031109 (=H2919): A very long XRF localized by HETE
  33. IPN triangulation of GRB031108 (large error box)
  34. GRB031026: 1.2mm upper limit with MAMBO at the IRAM 30m
  35. GRB030929/SN2003jd association unlikely based on IPN localiztion
  36. IPN triangulation of GRB031027 (small error box)
  37. IPN triangulation of GRB031026B (large error box)
  38. Lulin optical follow-up observations of GRB031026
  39. SN 2003jd (SN/GRB?), Radio Observations
  40. SN 2003jd (SN/GRB?) - possible association with GRB 030929
  41. GRB 031026: Further Ic Observations
  42. GRB 031026 (=H2882): Evidence for High Redshift from Prompt
  43. Peculiar Type Ic SN 2003jd (SN/GRB?), optical spectrum
  44. IPN triangulation of GRB031024 (single error box)
  45. GRB031026 (=H2882): A Long, Hard Spectrum Burst Localized by HETE
  46. GRB 031026: Ic Observations
  47. GRB031026 : KISO optical follow-up observation
  48. IPN triangulation of GRB031024 (annulus)
  49. IPN triangulation of GRB031020 (large error box)
  50. GRB030329: radio observations at RT-22 (CrAO)
  51. IPN triangulation of GRB031016 (two large error boxes)
  52. IBAS alert 1180 refers to a burst from SGR 1806-20
  53. HETE Prompt GRB Light Curves and Color-Color Diagrams
  54. IPN triangulation of GRB031014 (annulus)
  55. Ongoing Bursting Activity from SGR 1806-20 detected with IBAS
  56. XRF 030824: additional observations at CFHT
  57. SGR1806-20 bursts on 031008. Helicon detection and small error box.
  58. IPN triangulation of GRB031008 (annulus)
  59. SGR 1806-20 bursts with INTEGRAL and IBAS announcement on Soft Gamma-Ray Repeaters
  60. IPN detection of continued activity from SGR1806-20
  61. IPN triangulation of GRB031007 (two large error boxes)
  62. XRF 030723: Subaru Optical Observations
  63. IPN triangulation of GRB031004B (annulus)
  64. IPN triangulation of GRB031004A (short/hard; annulus)
  65. IPN triangulation of GRB030929 (short/hard; annulus)
  66. A burst from SGR 1806-20 detected with IBAS
  67. XRF 030824: Early follow-up observation at Kiso observatory
  68. XRF 030824: observations at CFHT
  69. IPN triangulation of GRB030926 (short/hard; large error box)
  70. IPN triangulation of GRB030922B (large error box)
  71. XRF 030723: Detection of the likely host galaxy
  72. XRF030824 (=H2821): An X-Ray Flash Localized by the HETE WXM
  73. XRF030823 (=H2818): An X-Ray Flash Localized by the HETE WXM and SXC
  74. IPN triangulation of GRB030922A (large error box)
  75. IPN triangulation of GRB030921 (large error box)
  76. IPN triangulation of GRB030919 (large error box)
  77. GRB030922 triangulation (annulus)
  78. GRB030913: Subaru Optical Observations
  79. GRB 030913: ROTSE-3c Optical Observations
  80. GRB030913: OT's limit by MASTER
  81. GRB030921 triangulation (annulus)
  82. GRB030913, candidate afterglow observations
  83. GRB 030913, optical candidate
  84. GRB030913: AAVSO optical observations
  85. GRB 030913, BOOTES observations
  86. GRB030913 (=H2849): Confirmation of the Flight Localization
  87. IPN triangulation of GRB030916 (possible short/hard GRB; large error box)
  88. GRB030913 (=H2849): TAROT Observations
  89. GRB030913: wide field imaging (7 sq.deg) of the error box by MASTER
  90. Magellan Observations of GRB030725 (=H2779)
  91. GRB030913 (=H2849): A GRB Possibly Localized by HETE
  92. IPN triangulation of GRB030908 (annulus)
  93. GRB 030913: Optical limit at RIKEN
  94. XRF 020427: Gemini-South Spectroscopic Observations of the Host
  95. XRF030824: Optical observations
  96. IPN triangulation of GRB030903 (large error box)
  97. IBAS detection of bursts from SGR 1806-20
  98. Radio Observations of SGR1806-20
  99. IPN triangulation of GRB030831 (annulus)
  100. IPN triangulation of GRB030830 (large error box)

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