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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: Optical Observations
  2. IPN triangulation of GRB021014 (large error box)
  3. IPN triangulation of GRB021013 (single error box)
  4. GRB 021004: optical spectroscopy on Oct 11
  5. IPN triangulation of GRB021013 (two small error boxes)
  6. GRB021004: High-resolution optical spectroscopy
  7. IPN triangulation of GRB021013 (annulus)
  8. XRF 020903: flattening of the optical light curve.
  9. GRB021004, UBVRcIc field photometry update
  10. IPN triangulation of GRB021008 (single error box)
  11. GRB021004: Optical Observations
  12. GRB 021004 submm observations
  13. IPN triangulation of GRB021008B (annulus)
  14. IPN triangulation of GRB021008 (two small error boxes)
  15. GRB021004 Chandra HETG Observations
  16. GRB 021004: Optical/NIR Observations
  17. GRB 021004: Additional V-band Polarimetric Observations
  18. GRB021004: optical observation
  19. GRB 021004: Host Galaxy Star Formation Rate
  20. GRB 021004 submm observations
  21. GRB 021004: WC wind?
  22. IPN triangulation of GRB021008
  23. GRB021004: NIR and Optical observations
  24. GRB 021004: Optical measurement at OHP
  25. GRB 021004: Optical observations, AUDE network
  26. GRB 021004 - VLA Radio Observations
  27. GRB 021004 - Unusual Radio-to-Submm Spectrum
  28. GRB 021004: optical spectroscopy
  29. IPN triangulation of GRB021007 (annulus)
  30. XRF 020903 spectrum
  31. GRB 021004: HST/STIS spectroscopic observations
  32. GRB021004: optical observations and predicted break time
  33. GRB021004: BVRc photometry
  34. GRB 021004 redshift
  35. GRB021004 radio observation
  36. GRB021004: restart of optical decay
  37. GRB 021004: Optical Decay
  38. GRB 021004 continued IR fading
  39. HETE fluences for GRB021004
  40. GRB 021004, spectroscopic observations
  41. GRB021004: not fading anymore?
  42. GRB 021004: Optical Photometry at 2.5 Days
  43. GRB 021004: polarimetric observations
  44. GRB 021004: V-band Polarimetric Observations
  45. GRB021004: Update Bisei photometric data
  46. GRB 021004: Optical Decay
  47. GRB021004, astrometric position
  48. GRB021004, Optical Observations
  49. IRAM Millimeter detection of GRB 021004
  50. GRB 021004: Optical observations at RIKEN
  51. GRB 021004 radio observation
  52. GRB 021004: Optical Observations
  53. GRB021004: continued fading
  54. GRB 021004: Optical Photometry at 1.5 Days
  55. GRB021004, Optical Observations
  56. GRB021004, BVRcIc field photometry
  57. GRB 021004: Optical observations
  58. GRB 021004: optical counterpart
  59. GRB 021004, optical observations
  60. GRB021004: Optical Spectroscopy
  61. GRB 021004: Optical Observations
  62. GRB 021004, SPM optical observations
  63. GRB 021004, optical observations
  64. GRB 021004 radio search
  65. GRB 021004: radio observations
  66. GRB 021004: steepening of the optical decay slope
  67. GRB021004: Upper limits from recent and historical observations
  68. XRF020903, BVRI field photometry
  69. GRB021004: optical observations at Nyrola
  70. GRB021004: Absorption redshift
  71. GRB021004(=H2380): Revised Localization with HETE Soft X-ray
  72. GRB021004: optical observations at Bisei
  73. GRB 021004: Kyoto observation
  74. GRB021004(=H2380): A Long GRB Localized by HETE in Near-Real Time
  75. GRB021004: Optical Afterglow
  76. XRF020903: TNG and Asiago photometry
  77. GRB 020903: Optical observations at RIKEN
  78. XRF 020903: Correction to GCN 1560
  79. XRF 020903: VRI observations
  80. IPN triangulation of GRB020926 (single large error box)
  81. GRB 020903: correction to GCN 1557
  82. XRF 020903: R band observations
  83. XRF 020903: Archival Optical Images
  84. Radio Observations of XRF 020903: The Missing Link
  85. XRF 020903: Supernova
  86. IPN triangulation of GRB020926 (two large error boxes)
  87. GRB020924 (ecliptic latitude-only localization)
  88. IPN triangulation of GRB020923 (two error boxes)
  89. IPN annulus for GRB020923
  90. IPN triangulation of GRB020914B
  91. Improved IPN position for GRB020918 (two large error boxes)
  92. IPN annulus for GRB020914B
  93. IPN triangulation of GRB020918 (annulus)
  94. IPN triangulation of GRB020911 (2 large error boxes)
  95. IPN triangulation of GRB020914 - clarification and additional information
  96. IPN triangulation of GRB020914
  97. GRB 020305: HST/STIS observations
  98. Confirmation of IPN error box for GRB020910
  99. IPN triangulation of GRB020910
  100. IPN GCN Circulars now to be issued without restriction

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