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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. GRB030328: Decay index
  3. GRB 030328: Optical observations
  4. GRB 030328: optical observations
  5. GRB 030329: Optical afterglow fading
  6. GRB 030329 follow-up
  7. GRB 030329: Optical afterglow candidate
  8. GRB 030329: OT candidate
  9. GRB 030329: Optical afterglow candidate
  10. GRB 030328: OT photometry
  11. GRB030328: optical spectroscopy at TNG
  12. GRB030328: optical photometry at the TNG
  13. VLT spectra of GRB 030328
  14. GRB 030328, optical spectroscopy
  15. GRB 030328, optical observations
  16. GRB030328 (=H2650): A Long, Bright GRB Localized by the HETE WXM and SXC
  17. GRB 030328: Optical observations
  18. Re: GRB 030328: Finding chart
  19. GRB 030328: Finding chart
  20. GRB 030328: Optical afterglow candidate
  21. GRB030323 optical observations
  22. GRB030324 optical observation
  23. GRB030131, BVRcIc field photometry
  24. Possible GRB030323 localized by INTEGRAL
  25. IPN triangulation of GRB030325 (final analysis)
  26. GRB030323: Detection on 2003/03/24
  27. IPN triangulation of GRB030326 (single small error box)
  28. GRB 030323: SARA Optical Observations
  29. IPN triangulation of GRB030325 (single small error box)
  30. GRB030324, optical observations
  31. GRB030324, optical observations
  32. IPN triangulation of GRB030325 (two small error boxes)
  33. GRB 030324: TAROT optical observations
  34. GRB030323: V, R, I photometry
  35. GRB 030324 (HETE #2641): Optical observations
  36. GRB030324, Optical Observations
  37. GRB030323: Upper limits from recent and historical observations.
  38. GRB030323 (=H2640): A Faint, Long GRB Localized by the HETE WXM and SXC
  39. GRB030324 (=H2641): A Long GRB Localized in Real Time by the HETE WXM
  40. GRB030324 (=H2641): A Long GRB Localized in Real Time by the HETE WXM
  41. VLT/FORS2 spectra of GRB 030323
  42. GRB030323, ROTSE-III detection of possible optical counterpart
  43. GRB030323, optical observations
  44. GRB030324, BVRcIc field photometry
  45. GRB030323, possible optical counterpart
  46. GRB030323, BVRcIc field calibration
  47. GRB 030324 optical observations
  48. GRB 030320: Optical Observations
  49. GRB 030324, optical observations
  50. IPN triangulation of GRB030320B (annulus)
  51. IPN triangulation of GRB030320 (small error box)
  52. IPN triangulation of GRB030320
  53. Possible GRB 030320 localized by INTEGRAL
  54. GRB030226, addendum to GCN 1892
  55. IPN upper limit to a GRB associated with SN2003L
  56. IPN triangulation of GRB030317 (annulus)
  57. IPN triangulation of GRB030307 (annulus)
  58. GRB 030227: Optical limit at RIKEN
  59. GRB 030226 Optical observations
  60. IPN triangulation of GRB030306 (single small error box - REVISED)
  61. GRB030226: Optical observations at Asiago
  62. IPN triangulation of GRB030306 (single small error box)
  63. IPN triangulation of GRB030306 (two small error boxes)
  64. IPN triangulation of GRB030306 (intense; annulus only so far)
  65. GRB 030226: Optical observations
  66. GRB030226: Analysis of Chandra data
  67. IPN triangulation of GRB030304 (annulus)
  68. GRB 030227: Optical observations
  69. GRB030226, BVRc observations
  70. Chandra detection of the X-ray afterglow of GRB 030226
  71. GRB 030226, further optical/NIR imaging
  72. GRB030227, optical observations
  73. GRB 030226: Ic Observations
  74. GRB030227: Kiso optical upper limit
  75. IPN triangulation of GRB030301 (annulus)
  76. IPN triangulation of GRB030228 (annulus)
  77. GRB030227, BVRcIc field photometry
  78. GRB030226, BVRcIc field calibration
  79. GRB 030227 optical afterglow
  80. 030302: NOT A GRB
  81. 030228: NOT A GRB
  82. GRB 030228, optical observations
  83. GRB 030226: Steep Decline
  84. GRB 030227: Confirmed Optical Afterglow (S1-A)
  85. GRB 030226: R band polarimetric observations
  86. GRB 030226: Optical observations
  87. GRB 030227: fading of candidate optical afterglow 'S1-A'
  88. GRB030227:Optical observations
  89. GRB 20030226: Upper limits from recent and historical observations
  90. GRB 030227, possible optical counterpart of XMM-Newton source
  91. GRB030227 - faint tentative OT candidate
  92. GRB 030226, optical observations
  93. XMM-Newton observation of GRB030227
  94. GRB030227: Kiso optical observations
  95. GRB 030227: Kyoto optical observation
  96. GRB 030226, optical light curve
  97. GRB 030226 spectroscopy
  98. GRB030227: refined INTEGRAL position
  99. GRB030227 localized by INTEGRAL
  100. Possible break in the GRB 030226 light curve

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