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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 030328: Optical observations
  2. Re: GRB 030328: Finding chart
  3. GRB 030328: Finding chart
  4. GRB 030328: Optical afterglow candidate
  5. GRB030323 optical observations
  6. GRB030324 optical observation
  7. GRB030131, BVRcIc field photometry
  8. Possible GRB030323 localized by INTEGRAL
  9. IPN triangulation of GRB030325 (final analysis)
  10. GRB030323: Detection on 2003/03/24
  11. IPN triangulation of GRB030326 (single small error box)
  12. GRB 030323: SARA Optical Observations
  13. IPN triangulation of GRB030325 (single small error box)
  14. GRB030324, optical observations
  15. GRB030324, optical observations
  16. IPN triangulation of GRB030325 (two small error boxes)
  17. GRB 030324: TAROT optical observations
  18. GRB030323: V, R, I photometry
  19. GRB 030324 (HETE #2641): Optical observations
  20. GRB030324, Optical Observations
  21. GRB030323: Upper limits from recent and historical observations.
  22. GRB030323 (=H2640): A Faint, Long GRB Localized by the HETE WXM and SXC
  23. GRB030324 (=H2641): A Long GRB Localized in Real Time by the HETE WXM
  24. GRB030324 (=H2641): A Long GRB Localized in Real Time by the HETE WXM
  25. VLT/FORS2 spectra of GRB 030323
  26. GRB030323, ROTSE-III detection of possible optical counterpart
  27. GRB030323, optical observations
  28. GRB030324, BVRcIc field photometry
  29. GRB030323, possible optical counterpart
  30. GRB030323, BVRcIc field calibration
  31. GRB 030324 optical observations
  32. GRB 030320: Optical Observations
  33. GRB 030324, optical observations
  34. IPN triangulation of GRB030320B (annulus)
  35. IPN triangulation of GRB030320 (small error box)
  36. IPN triangulation of GRB030320
  37. Possible GRB 030320 localized by INTEGRAL
  38. GRB030226, addendum to GCN 1892
  39. IPN upper limit to a GRB associated with SN2003L
  40. IPN triangulation of GRB030317 (annulus)
  41. IPN triangulation of GRB030307 (annulus)
  42. GRB 030227: Optical limit at RIKEN
  43. GRB 030226 Optical observations
  44. IPN triangulation of GRB030306 (single small error box - REVISED)
  45. GRB030226: Optical observations at Asiago
  46. IPN triangulation of GRB030306 (single small error box)
  47. IPN triangulation of GRB030306 (two small error boxes)
  48. IPN triangulation of GRB030306 (intense; annulus only so far)
  49. GRB 030226: Optical observations
  50. GRB030226: Analysis of Chandra data
  51. IPN triangulation of GRB030304 (annulus)
  52. GRB 030227: Optical observations
  53. GRB030226, BVRc observations
  54. Chandra detection of the X-ray afterglow of GRB 030226
  55. GRB 030226, further optical/NIR imaging
  56. GRB030227, optical observations
  57. GRB 030226: Ic Observations
  58. GRB030227: Kiso optical upper limit
  59. IPN triangulation of GRB030301 (annulus)
  60. IPN triangulation of GRB030228 (annulus)
  61. GRB030227, BVRcIc field photometry
  62. GRB030226, BVRcIc field calibration
  63. GRB 030227 optical afterglow
  64. 030302: NOT A GRB
  65. 030228: NOT A GRB
  66. GRB 030228, optical observations
  67. GRB 030226: Steep Decline
  68. GRB 030227: Confirmed Optical Afterglow (S1-A)
  69. GRB 030226: R band polarimetric observations
  70. GRB 030226: Optical observations
  71. GRB 030227: fading of candidate optical afterglow 'S1-A'
  72. GRB030227:Optical observations
  73. GRB 20030226: Upper limits from recent and historical observations
  74. GRB 030227, possible optical counterpart of XMM-Newton source
  75. GRB030227 - faint tentative OT candidate
  76. GRB 030226, optical observations
  77. XMM-Newton observation of GRB030227
  78. GRB030227: Kiso optical observations
  79. GRB 030227: Kyoto optical observation
  80. GRB 030226, optical light curve
  81. GRB 030226 spectroscopy
  82. GRB030227: refined INTEGRAL position
  83. GRB030227 localized by INTEGRAL
  84. Possible break in the GRB 030226 light curve
  85. GRB 030226 : Predicted light curve
  86. GRB030226: optical observation
  87. IPN triangulation of GRB030225 (annulus)
  88. GRB 030226: Confirmed decay index
  89. GRB030226: ESI spectroscopy
  90. GRB030226 (=U10893): A Long GRB Localized by the HETE WXM and SXC
  91. GRB 030226 simultaneous optical observations
  92. Two absorption systems in GRB 030226
  93. GRB 030226, optical observations
  94. GRB030226: optical observations and refined redshift
  95. GRB030226: Optical decay index
  96. GRB 030226 Optical Spectra and R,I,z' Imaging
  97. GRB 030226, optical observations
  98. GRB 030226: Optical afterglow
  99. GRB030226: Candidate optical afterglow
  100. GRB 030217: Optical Observations at 4, 5, and 6 Days

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