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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. GRB 021008, optical observations
  2. GRB021016(=H2397): A Long GRB Localized by HETE
  3. IPN triangulation of GRB021016 (area corrected)
  4. IPN triangulation of GRB021016 (small error box)
  5. GRB021004: Optical Observations
  6. IPN triangulation of GRB021014 (large error box)
  7. IPN triangulation of GRB021013 (single error box)
  8. GRB 021004: optical spectroscopy on Oct 11
  9. IPN triangulation of GRB021013 (two small error boxes)
  10. GRB021004: High-resolution optical spectroscopy
  11. IPN triangulation of GRB021013 (annulus)
  12. XRF 020903: flattening of the optical light curve.
  13. GRB021004, UBVRcIc field photometry update
  14. IPN triangulation of GRB021008 (single error box)
  15. GRB021004: Optical Observations
  16. GRB 021004 submm observations
  17. IPN triangulation of GRB021008B (annulus)
  18. IPN triangulation of GRB021008 (two small error boxes)
  19. GRB021004 Chandra HETG Observations
  20. GRB 021004: Optical/NIR Observations
  21. GRB 021004: Additional V-band Polarimetric Observations
  22. GRB021004: optical observation
  23. GRB 021004: Host Galaxy Star Formation Rate
  24. GRB 021004 submm observations
  25. GRB 021004: WC wind?
  26. IPN triangulation of GRB021008
  27. GRB021004: NIR and Optical observations
  28. GRB 021004: Optical measurement at OHP
  29. GRB 021004: Optical observations, AUDE network
  30. GRB 021004 - VLA Radio Observations
  31. GRB 021004 - Unusual Radio-to-Submm Spectrum
  32. GRB 021004: optical spectroscopy
  33. IPN triangulation of GRB021007 (annulus)
  34. XRF 020903 spectrum
  35. GRB 021004: HST/STIS spectroscopic observations
  36. GRB021004: optical observations and predicted break time
  37. GRB021004: BVRc photometry
  38. GRB 021004 redshift
  39. GRB021004 radio observation
  40. GRB021004: restart of optical decay
  41. GRB 021004: Optical Decay
  42. GRB 021004 continued IR fading
  43. HETE fluences for GRB021004
  44. GRB 021004, spectroscopic observations
  45. GRB021004: not fading anymore?
  46. GRB 021004: Optical Photometry at 2.5 Days
  47. GRB 021004: polarimetric observations
  48. GRB 021004: V-band Polarimetric Observations
  49. GRB021004: Update Bisei photometric data
  50. GRB 021004: Optical Decay
  51. GRB021004, astrometric position
  52. GRB021004, Optical Observations
  53. IRAM Millimeter detection of GRB 021004
  54. GRB 021004: Optical observations at RIKEN
  55. GRB 021004 radio observation
  56. GRB 021004: Optical Observations
  57. GRB021004: continued fading
  58. GRB 021004: Optical Photometry at 1.5 Days
  59. GRB021004, Optical Observations
  60. GRB021004, BVRcIc field photometry
  61. GRB 021004: Optical observations
  62. GRB 021004: optical counterpart
  63. GRB 021004, optical observations
  64. GRB021004: Optical Spectroscopy
  65. GRB 021004: Optical Observations
  66. GRB 021004, SPM optical observations
  67. GRB 021004, optical observations
  68. GRB 021004 radio search
  69. GRB 021004: radio observations
  70. GRB 021004: steepening of the optical decay slope
  71. GRB021004: Upper limits from recent and historical observations
  72. XRF020903, BVRI field photometry
  73. GRB021004: optical observations at Nyrola
  74. GRB021004: Absorption redshift
  75. GRB021004(=H2380): Revised Localization with HETE Soft X-ray
  76. GRB021004: optical observations at Bisei
  77. GRB 021004: Kyoto observation
  78. GRB021004(=H2380): A Long GRB Localized by HETE in Near-Real Time
  79. GRB021004: Optical Afterglow
  80. XRF020903: TNG and Asiago photometry
  81. GRB 020903: Optical observations at RIKEN
  82. XRF 020903: Correction to GCN 1560
  83. XRF 020903: VRI observations
  84. IPN triangulation of GRB020926 (single large error box)
  85. GRB 020903: correction to GCN 1557
  86. XRF 020903: R band observations
  87. XRF 020903: Archival Optical Images
  88. Radio Observations of XRF 020903: The Missing Link
  89. XRF 020903: Supernova
  90. IPN triangulation of GRB020926 (two large error boxes)
  91. GRB020924 (ecliptic latitude-only localization)
  92. IPN triangulation of GRB020923 (two error boxes)
  93. IPN annulus for GRB020923
  94. IPN triangulation of GRB020914B
  95. Improved IPN position for GRB020918 (two large error boxes)
  96. IPN annulus for GRB020914B
  97. IPN triangulation of GRB020918 (annulus)
  98. IPN triangulation of GRB020911 (2 large error boxes)
  99. IPN triangulation of GRB020914 - clarification and additional information
  100. IPN triangulation of GRB020914

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