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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. GRB021004: High-resolution optical spectroscopy
  2. IPN triangulation of GRB021013 (annulus)
  3. XRF 020903: flattening of the optical light curve.
  4. GRB021004, UBVRcIc field photometry update
  5. IPN triangulation of GRB021008 (single error box)
  6. GRB021004: Optical Observations
  7. GRB 021004 submm observations
  8. IPN triangulation of GRB021008B (annulus)
  9. IPN triangulation of GRB021008 (two small error boxes)
  10. GRB021004 Chandra HETG Observations
  11. GRB 021004: Optical/NIR Observations
  12. GRB 021004: Additional V-band Polarimetric Observations
  13. GRB021004: optical observation
  14. GRB 021004: Host Galaxy Star Formation Rate
  15. GRB 021004 submm observations
  16. GRB 021004: WC wind?
  17. IPN triangulation of GRB021008
  18. GRB021004: NIR and Optical observations
  19. GRB 021004: Optical measurement at OHP
  20. GRB 021004: Optical observations, AUDE network
  21. GRB 021004 - VLA Radio Observations
  22. GRB 021004 - Unusual Radio-to-Submm Spectrum
  23. GRB 021004: optical spectroscopy
  24. IPN triangulation of GRB021007 (annulus)
  25. XRF 020903 spectrum
  26. GRB 021004: HST/STIS spectroscopic observations
  27. GRB021004: optical observations and predicted break time
  28. GRB021004: BVRc photometry
  29. GRB 021004 redshift
  30. GRB021004 radio observation
  31. GRB021004: restart of optical decay
  32. GRB 021004: Optical Decay
  33. GRB 021004 continued IR fading
  34. HETE fluences for GRB021004
  35. GRB 021004, spectroscopic observations
  36. GRB021004: not fading anymore?
  37. GRB 021004: Optical Photometry at 2.5 Days
  38. GRB 021004: polarimetric observations
  39. GRB 021004: V-band Polarimetric Observations
  40. GRB021004: Update Bisei photometric data
  41. GRB 021004: Optical Decay
  42. GRB021004, astrometric position
  43. GRB021004, Optical Observations
  44. IRAM Millimeter detection of GRB 021004
  45. GRB 021004: Optical observations at RIKEN
  46. GRB 021004 radio observation
  47. GRB 021004: Optical Observations
  48. GRB021004: continued fading
  49. GRB 021004: Optical Photometry at 1.5 Days
  50. GRB021004, Optical Observations
  51. GRB021004, BVRcIc field photometry
  52. GRB 021004: Optical observations
  53. GRB 021004: optical counterpart
  54. GRB 021004, optical observations
  55. GRB021004: Optical Spectroscopy
  56. GRB 021004: Optical Observations
  57. GRB 021004, SPM optical observations
  58. GRB 021004, optical observations
  59. GRB 021004 radio search
  60. GRB 021004: radio observations
  61. GRB 021004: steepening of the optical decay slope
  62. GRB021004: Upper limits from recent and historical observations
  63. XRF020903, BVRI field photometry
  64. GRB021004: optical observations at Nyrola
  65. GRB021004: Absorption redshift
  66. GRB021004(=H2380): Revised Localization with HETE Soft X-ray
  67. GRB021004: optical observations at Bisei
  68. GRB 021004: Kyoto observation
  69. GRB021004(=H2380): A Long GRB Localized by HETE in Near-Real Time
  70. GRB021004: Optical Afterglow
  71. XRF020903: TNG and Asiago photometry
  72. GRB 020903: Optical observations at RIKEN
  73. XRF 020903: Correction to GCN 1560
  74. XRF 020903: VRI observations
  75. IPN triangulation of GRB020926 (single large error box)
  76. GRB 020903: correction to GCN 1557
  77. XRF 020903: R band observations
  78. XRF 020903: Archival Optical Images
  79. Radio Observations of XRF 020903: The Missing Link
  80. XRF 020903: Supernova
  81. IPN triangulation of GRB020926 (two large error boxes)
  82. GRB020924 (ecliptic latitude-only localization)
  83. IPN triangulation of GRB020923 (two error boxes)
  84. IPN annulus for GRB020923
  85. IPN triangulation of GRB020914B
  86. Improved IPN position for GRB020918 (two large error boxes)
  87. IPN annulus for GRB020914B
  88. IPN triangulation of GRB020918 (annulus)
  89. IPN triangulation of GRB020911 (2 large error boxes)
  90. IPN triangulation of GRB020914 - clarification and additional information
  91. IPN triangulation of GRB020914
  92. GRB 020305: HST/STIS observations
  93. Confirmation of IPN error box for GRB020910
  94. IPN triangulation of GRB020910
  95. IPN GCN Circulars now to be issued without restriction
  96. Single IPN error box for GRB020904
  97. XRF 020903: optical observation at Kyoto
  98. GRB020322 : HST/STIS observations
  99. XRF 020903: Optical observations
  100. IPN triangulation of GRB020904

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