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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 021004: Optical observations, AUDE network
  2. GRB 021004 - VLA Radio Observations
  3. GRB 021004 - Unusual Radio-to-Submm Spectrum
  4. GRB 021004: optical spectroscopy
  5. IPN triangulation of GRB021007 (annulus)
  6. XRF 020903 spectrum
  7. GRB 021004: HST/STIS spectroscopic observations
  8. GRB021004: optical observations and predicted break time
  9. GRB021004: BVRc photometry
  10. GRB 021004 redshift
  11. GRB021004 radio observation
  12. GRB021004: restart of optical decay
  13. GRB 021004: Optical Decay
  14. GRB 021004 continued IR fading
  15. HETE fluences for GRB021004
  16. GRB 021004, spectroscopic observations
  17. GRB021004: not fading anymore?
  18. GRB 021004: Optical Photometry at 2.5 Days
  19. GRB 021004: polarimetric observations
  20. GRB 021004: V-band Polarimetric Observations
  21. GRB021004: Update Bisei photometric data
  22. GRB 021004: Optical Decay
  23. GRB021004, astrometric position
  24. GRB021004, Optical Observations
  25. IRAM Millimeter detection of GRB 021004
  26. GRB 021004: Optical observations at RIKEN
  27. GRB 021004 radio observation
  28. GRB 021004: Optical Observations
  29. GRB021004: continued fading
  30. GRB 021004: Optical Photometry at 1.5 Days
  31. GRB021004, Optical Observations
  32. GRB021004, BVRcIc field photometry
  33. GRB 021004: Optical observations
  34. GRB 021004: optical counterpart
  35. GRB 021004, optical observations
  36. GRB021004: Optical Spectroscopy
  37. GRB 021004: Optical Observations
  38. GRB 021004, SPM optical observations
  39. GRB 021004, optical observations
  40. GRB 021004 radio search
  41. GRB 021004: radio observations
  42. GRB 021004: steepening of the optical decay slope
  43. GRB021004: Upper limits from recent and historical observations
  44. XRF020903, BVRI field photometry
  45. GRB021004: optical observations at Nyrola
  46. GRB021004: Absorption redshift
  47. GRB021004(=H2380): Revised Localization with HETE Soft X-ray
  48. GRB021004: optical observations at Bisei
  49. GRB 021004: Kyoto observation
  50. GRB021004(=H2380): A Long GRB Localized by HETE in Near-Real Time
  51. GRB021004: Optical Afterglow
  52. XRF020903: TNG and Asiago photometry
  53. GRB 020903: Optical observations at RIKEN
  54. XRF 020903: Correction to GCN 1560
  55. XRF 020903: VRI observations
  56. IPN triangulation of GRB020926 (single large error box)
  57. GRB 020903: correction to GCN 1557
  58. XRF 020903: R band observations
  59. XRF 020903: Archival Optical Images
  60. Radio Observations of XRF 020903: The Missing Link
  61. XRF 020903: Supernova
  62. IPN triangulation of GRB020926 (two large error boxes)
  63. GRB020924 (ecliptic latitude-only localization)
  64. IPN triangulation of GRB020923 (two error boxes)
  65. IPN annulus for GRB020923
  66. IPN triangulation of GRB020914B
  67. Improved IPN position for GRB020918 (two large error boxes)
  68. IPN annulus for GRB020914B
  69. IPN triangulation of GRB020918 (annulus)
  70. IPN triangulation of GRB020911 (2 large error boxes)
  71. IPN triangulation of GRB020914 - clarification and additional information
  72. IPN triangulation of GRB020914
  73. GRB 020305: HST/STIS observations
  74. Confirmation of IPN error box for GRB020910
  75. IPN triangulation of GRB020910
  76. IPN GCN Circulars now to be issued without restriction
  77. Single IPN error box for GRB020904
  78. XRF 020903: optical observation at Kyoto
  79. GRB020322 : HST/STIS observations
  80. XRF 020903: Optical observations
  81. IPN triangulation of GRB020904
  82. XRF 020903: Optical observations
  83. IPN detection of a burst from SGR1900+14
  84. XRF 020903, optical observations
  85. GRB020903(=H2314): An X-Ray Flash Localized by HETE
  86. INTEGRAL GRBs added to GCN
  87. GRB020813: optical observation
  88. GRB020812: optical observation
  89. GRB020819(=H2275): Revised Localization with HETE Soft X-ray
  90. SGR1900+14 burst localized by HETE
  91. GRB020813: High-resolution optical spectroscopy
  92. GRB020819: optical observations at Bisei
  93. GRB020812: negative optical observations
  94. GRB 020812: optical observation at Kyoto University
  95. Second epoch K band imaging of GRB 020819
  96. GRB020813, Baade 6.5m data now available
  97. GRB 020813 : HST observations
  98. Confirming no variability for GRB02081
  99. GRB020819 : Optical observations at KISO
  100. GRB 020812: early time optical observation at Ouda Station

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