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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').
  1. GRB030131, BVRcIc field photometry
  2. Possible GRB030323 localized by INTEGRAL
  3. IPN triangulation of GRB030325 (final analysis)
  4. GRB030323: Detection on 2003/03/24
  5. IPN triangulation of GRB030326 (single small error box)
  6. GRB 030323: SARA Optical Observations
  7. IPN triangulation of GRB030325 (single small error box)
  8. GRB030324, optical observations
  9. GRB030324, optical observations
  10. IPN triangulation of GRB030325 (two small error boxes)
  11. GRB 030324: TAROT optical observations
  12. GRB030323: V, R, I photometry
  13. GRB 030324 (HETE #2641): Optical observations
  14. GRB030324, Optical Observations
  15. GRB030323: Upper limits from recent and historical observations.
  16. GRB030323 (=H2640): A Faint, Long GRB Localized by the HETE WXM and SXC
  17. GRB030324 (=H2641): A Long GRB Localized in Real Time by the HETE WXM
  18. GRB030324 (=H2641): A Long GRB Localized in Real Time by the HETE WXM
  19. VLT/FORS2 spectra of GRB 030323
  20. GRB030323, ROTSE-III detection of possible optical counterpart
  21. GRB030323, optical observations
  22. GRB030324, BVRcIc field photometry
  23. GRB030323, possible optical counterpart
  24. GRB030323, BVRcIc field calibration
  25. GRB 030324 optical observations
  26. GRB 030320: Optical Observations
  27. GRB 030324, optical observations
  28. IPN triangulation of GRB030320B (annulus)
  29. IPN triangulation of GRB030320 (small error box)
  30. IPN triangulation of GRB030320
  31. Possible GRB 030320 localized by INTEGRAL
  32. GRB030226, addendum to GCN 1892
  33. IPN upper limit to a GRB associated with SN2003L
  34. IPN triangulation of GRB030317 (annulus)
  35. IPN triangulation of GRB030307 (annulus)
  36. GRB 030227: Optical limit at RIKEN
  37. GRB 030226 Optical observations
  38. IPN triangulation of GRB030306 (single small error box - REVISED)
  39. GRB030226: Optical observations at Asiago
  40. IPN triangulation of GRB030306 (single small error box)
  41. IPN triangulation of GRB030306 (two small error boxes)
  42. IPN triangulation of GRB030306 (intense; annulus only so far)
  43. GRB 030226: Optical observations
  44. GRB030226: Analysis of Chandra data
  45. IPN triangulation of GRB030304 (annulus)
  46. GRB 030227: Optical observations
  47. GRB030226, BVRc observations
  48. Chandra detection of the X-ray afterglow of GRB 030226
  49. GRB 030226, further optical/NIR imaging
  50. GRB030227, optical observations
  51. GRB 030226: Ic Observations
  52. GRB030227: Kiso optical upper limit
  53. IPN triangulation of GRB030301 (annulus)
  54. IPN triangulation of GRB030228 (annulus)
  55. GRB030227, BVRcIc field photometry
  56. GRB030226, BVRcIc field calibration
  57. GRB 030227 optical afterglow
  58. 030302: NOT A GRB
  59. 030228: NOT A GRB
  60. GRB 030228, optical observations
  61. GRB 030226: Steep Decline
  62. GRB 030227: Confirmed Optical Afterglow (S1-A)
  63. GRB 030226: R band polarimetric observations
  64. GRB 030226: Optical observations
  65. GRB 030227: fading of candidate optical afterglow 'S1-A'
  66. GRB030227:Optical observations
  67. GRB 20030226: Upper limits from recent and historical observations
  68. GRB 030227, possible optical counterpart of XMM-Newton source
  69. GRB030227 - faint tentative OT candidate
  70. GRB 030226, optical observations
  71. XMM-Newton observation of GRB030227
  72. GRB030227: Kiso optical observations
  73. GRB 030227: Kyoto optical observation
  74. GRB 030226, optical light curve
  75. GRB 030226 spectroscopy
  76. GRB030227: refined INTEGRAL position
  77. GRB030227 localized by INTEGRAL
  78. Possible break in the GRB 030226 light curve
  79. GRB 030226 : Predicted light curve
  80. GRB030226: optical observation
  81. IPN triangulation of GRB030225 (annulus)
  82. GRB 030226: Confirmed decay index
  83. GRB030226: ESI spectroscopy
  84. GRB030226 (=U10893): A Long GRB Localized by the HETE WXM and SXC
  85. GRB 030226 simultaneous optical observations
  86. Two absorption systems in GRB 030226
  87. GRB 030226, optical observations
  88. GRB030226: optical observations and refined redshift
  89. GRB030226: Optical decay index
  90. GRB 030226 Optical Spectra and R,I,z' Imaging
  91. GRB 030226, optical observations
  92. GRB 030226: Optical afterglow
  93. GRB030226: Candidate optical afterglow
  94. GRB 030217: Optical Observations at 4, 5, and 6 Days
  95. IPN triangulation of GRB030223 (annulus)
  96. IPN triangulation of GRB030220 (annulus)
  97. GRB: Non-Referencing of GCN Circulars.
  98. IPN triangulation of GRB030218 (annulus)
  99. GRB030217: optical observations
  100. IPN triangulation of GRB030217 (small error box)

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