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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. GRB021211, BVRI field photometry
  2. GRB021211: Optical observations in CrAO
  3. GRB 021211, IR observations
  4. GRB 021211, optical observations
  5. GRB 021211: Optical Observations
  6. GRB021211: Kiso Observations
  7. GRB021204: Kiso Observations
  8. GRB 021201, optical observations
  9. GRB 021211: Radio Observations
  10. GRB021211: Optical observations
  11. GRB 021201 (short/hard), NOT observations
  12. SUB-MM SEARCH FOR GRB 021211
  13. Chandra observation of the IPN error box of GRB021201 (short/hard)
  14. GRB 021211 Milagro GeV/TeV Observations
  15. GRB 021211, R- and I-band observations
  16. GRB021211 - Upper limits from recent and historical observations
  17. GRB021211, OT at 108 s
  18. GRB021211 (HETE2493), OT at 143 sec
  19. GRB 021204: I-band Observations
  20. GRB021211 (=H2493): A Bright, Long GRB Localized by HETE-2 in Near-Real Time
  21. HETE 2493: Optical observations
  22. HETE 2493: Optical observations
  23. HETE 2493: Optical candidate
  24. GRB 021204: Optical Observations at RIKEN
  25. GRB 021125: Radio Observations
  26. IPN triangulation of GRB021206 (small error box)
  27. IPN triangulation of GRB021206 (exceptionally bright; annulus only)
  28. IPN detection of renewed activity from SGR1806-20
  29. IPN triangulation of GRB021205 (large error box)
  30. GRB 021104, GRB 021112 and GRB 021113 - Milagro GeV/TeV Observations
  31. GRB021201, BVRcIc field photometry
  32. GRB 021201, Radio Observations
  33. GRB 021201: Optical Observations
  34. GRB 021201: BOOTES simultaneous optical observations
  35. IPN triangulation of GRB021201 (short/hard burst, small error box)
  36. Radio Catalog of GRB Afterglows
  37. GRB021004, late time optical observations
  38. GRB021004 Chandra Observation
  39. IPN detection of continued SGR1900+14 activity
  40. GRB021125 refined position
  41. IPN triangulation of GRB021115 (annulus)
  42. IPN triangulation of GRB021125B (two large error boxes)
  43. IPN triangulation of GRB021119 (large error box)
  44. IPN triangulation of GRB021125B (annulus)
  45. Improved IPN error box for GRB021125
  46. IPN BURST POSITION
  47. IPN triangulation of GRB021125 (INTEGRAL BURST)
  48. GRB021125 : A long GRB localized by INTEGRAL
  49. IPN confirmation of the reactivation of SGR1900+14
  50. IPN detection of possible reactivation of SGR1900+14
  51. GRB021113, SPI ACS observation
  52. IPN triangulation of GRB021119 (annulus)
  53. GRB 021112: Afterglow or Variable Star?
  54. GRB021113: optical observations at Bisei
  55. GRB 021113: Evidence for a Dark Optical Afterglow
  56. GRB 021112, Radio Observations
  57. GRB021112, BVRI field photometry
  58. GRB 021112: Variable Source in R-band search
  59. GRB021112: Optical Observations
  60. GRB021113: Kiso Observations
  61. IPN triangulation of GRB021109 (portion of annulus)
  62. IPN triangulation of GRB021113 (=H2449; annulus)
  63. IPN triangulation of GRB021108 (CORRECTION; TWO LARGE ERROR BOXES)
  64. GRB 021113: Optical observations
  65. GRB 021112: RAPTOR Observations
  66. GRB 021113: Optical Observations
  67. GRB 021113: Optical Observations
  68. GRB021113 (=H2449): A Long GRB Localized by HETE
  69. GRB 021112: Optical Observations
  70. GRB 021112: R-band search
  71. IPN triangulation of GRB021108 (large error box)
  72. GRB021112 (=H2448): A Long GRB Localized by HETE
  73. GRB 021016: Optical Observations
  74. IPN triangulation of GRB021109 (annulus)
  75. IPN triangulation of GRB021108 (annulus)
  76. GRB021004: Near infrared spectroscopy
  77. GRB021104: Optical Observations
  78. IPN triangulation of GRB021104 (annulus)
  79. GRB021104(=H2434): A Long, X-Ray-Rich GRB Localized by HETE
  80. IPN triangulation of bursts from SGR1900+14, November 1-2, 2002
  81. SGR1900+14 activity, November 2-4, 2002
  82. Spectropolarimetry of GRB021004
  83. GRB021104: Optical observations
  84. GRB021104: optical observations
  85. GRB021104: Candidate present in DSS
  86. GRB021104: possible optical afterglow
  87. IPN triangulation of GRB021102 (annulus)
  88. Detection of activity from SGR 1900+14 with the RXTE/PCA
  89. IPN triangulation of a burst from SGR1900+14 on November 01, 2002
  90. IPN triangulation of a burst from SGR1900+14 on October 29 2002
  91. IPN triangulation of GRB021025 (portion of annulus)
  92. IPN triangulation of GRB021027 (single large error box)
  93. GRB021004, late-time optical observations
  94. IPN triangulation of GRB021027 (two large error boxes)
  95. GRB 021023: Infrared Imaging
  96. IPN triangulation of GRB021027 (annulus)
  97. GRB 021023: Curious K-band Source(s) Just Outside of IPN Localization
  98. IPN triangulation of GRB021025 (annulus)
  99. IPN triangulation of SGR1900+14, October 22 2002
  100. GRB 021004: optical observations

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