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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. IPN triangulation of GRB030304 (annulus)
  2. GRB 030227: Optical observations
  3. GRB030226, BVRc observations
  4. Chandra detection of the X-ray afterglow of GRB 030226
  5. GRB 030226, further optical/NIR imaging
  6. GRB030227, optical observations
  7. GRB 030226: Ic Observations
  8. GRB030227: Kiso optical upper limit
  9. IPN triangulation of GRB030301 (annulus)
  10. IPN triangulation of GRB030228 (annulus)
  11. GRB030227, BVRcIc field photometry
  12. GRB030226, BVRcIc field calibration
  13. GRB 030227 optical afterglow
  14. 030302: NOT A GRB
  15. 030228: NOT A GRB
  16. GRB 030228, optical observations
  17. GRB 030226: Steep Decline
  18. GRB 030227: Confirmed Optical Afterglow (S1-A)
  19. GRB 030226: R band polarimetric observations
  20. GRB 030226: Optical observations
  21. GRB 030227: fading of candidate optical afterglow 'S1-A'
  22. GRB030227:Optical observations
  23. GRB 20030226: Upper limits from recent and historical observations
  24. GRB 030227, possible optical counterpart of XMM-Newton source
  25. GRB030227 - faint tentative OT candidate
  26. GRB 030226, optical observations
  27. XMM-Newton observation of GRB030227
  28. GRB030227: Kiso optical observations
  29. GRB 030227: Kyoto optical observation
  30. GRB 030226, optical light curve
  31. GRB 030226 spectroscopy
  32. GRB030227: refined INTEGRAL position
  33. GRB030227 localized by INTEGRAL
  34. Possible break in the GRB 030226 light curve
  35. GRB 030226 : Predicted light curve
  36. GRB030226: optical observation
  37. IPN triangulation of GRB030225 (annulus)
  38. GRB 030226: Confirmed decay index
  39. GRB030226: ESI spectroscopy
  40. GRB030226 (=U10893): A Long GRB Localized by the HETE WXM and SXC
  41. GRB 030226 simultaneous optical observations
  42. Two absorption systems in GRB 030226
  43. GRB 030226, optical observations
  44. GRB030226: optical observations and refined redshift
  45. GRB030226: Optical decay index
  46. GRB 030226 Optical Spectra and R,I,z' Imaging
  47. GRB 030226, optical observations
  48. GRB 030226: Optical afterglow
  49. GRB030226: Candidate optical afterglow
  50. GRB 030217: Optical Observations at 4, 5, and 6 Days
  51. IPN triangulation of GRB030223 (annulus)
  52. IPN triangulation of GRB030220 (annulus)
  53. GRB: Non-Referencing of GCN Circulars.
  54. IPN triangulation of GRB030218 (annulus)
  55. GRB030217: optical observations
  56. IPN triangulation of GRB030217 (small error box)
  57. IPN triangulation of GRB030215C (annulus)
  58. IPN triangulation of GRB030217 (annulus)
  59. IPN triangulation of GRB030216 (annulus)
  60. IPN triangulation of GRB030215A and GRB030215B (annuli)
  61. GRB030115, WSRT radio observations - correction to GCN 1864
  62. GRB 030131: marginal optical detection
  63. GCN/INTEGRAL Mistake Fixed
  64. GRB030115, WSRT radio observations
  65. IPN triangulation of GRB030206 (annulus)
  66. IPN triangulation of GRB030208 (annulus)
  67. GRB 030204: Optical Observations
  68. GRB030204 field photometry
  69. GRB020819: Kiso R and I band observations
  70. GRB 030204: Correction to GCN 1856
  71. GRB030131: Candidate Optical Afterglow
  72. GRB 030115: Optical Observations
  73. GRB 030204, optical observations
  74. IPN triangulation of GRB030204 (small error box)
  75. IPN triangulation of GRB030202 (annulus)
  76. GRB 030131, optical observations
  77. GRB030131: Kiso optical limit for corrected position
  78. GRB030131: Optical limits for corrected position
  79. GRB 030131: afterglow candidate
  80. GRB 030115, late-time optical observations
  81. GRB030131: corrected INTEGRAL position
  82. Type Ic SN2003L (SN/GRB?), optical spectrum
  83. GRB030131: Kiso Observations
  84. GRB 020819: Host galaxy at Radio Position
  85. IPN triangulation of GRB030131 - CORRECTION
  86. GRB 020819: afterglow candidate
  87. IPN triangulation of GRB030131
  88. GRB030131: Optical limit
  89. GRB 030131 optical observations
  90. GRB030131: refined position
  91. GRB 030131 optical observations
  92. A long GRB detected by INTEGRAL
  93. GRB030115: 1.2 mm upper limits with MAMBO @ IRAM 30m
  94. Type Ic SN2003L (SN/GRB?) Radio Observations
  95. IPN triangulation of GRB030127 (annulus)
  96. GRB030115 submm upper limit
  97. IPN triangulation of GRB030119 (two large error boxes)
  98. GRB 030115: Further IR observations with IRSF/SIRIUS
  99. IPN triangulation of GRB030117 (two large error boxes)
  100. Publicizing GRB Discoveries - A Message from NASA HQ

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