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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. VLT spectra of GRB 021211 revisited
  2. GRB021219: a long GRB localized by INTEGRAL
  3. GRB021211: APO optical observations
  4. IPN detection of continued activity from SGR1806-20
  5. IPN triangulation of GRB021215 (large error box)
  6. IPN triangulation of GRB021214 (annulus)
  7. XRF 020903 : HST observations
  8. GRB 021201: Optical Observations
  9. GRB 021211, optical observations
  10. GRB 021211: CTIO observations
  11. GRB021211: Measurement of Early Time Afterglow
  12. VLT spectrum of GRB 021211
  13. IPN triangulation of GRB021211B (two large error boxes)
  14. GRB 021211: early break in light curve
  15. GRB021211, BVRI field photometry
  16. GRB021211: Optical observations in CrAO
  17. GRB 021211, IR observations
  18. GRB 021211, optical observations
  19. GRB 021211: Optical Observations
  20. GRB021211: Kiso Observations
  21. GRB021204: Kiso Observations
  22. GRB 021201, optical observations
  23. GRB 021211: Radio Observations
  24. GRB021211: Optical observations
  25. GRB 021201 (short/hard), NOT observations
  26. SUB-MM SEARCH FOR GRB 021211
  27. Chandra observation of the IPN error box of GRB021201 (short/hard)
  28. GRB 021211 Milagro GeV/TeV Observations
  29. GRB 021211, R- and I-band observations
  30. GRB021211 - Upper limits from recent and historical observations
  31. GRB021211, OT at 108 s
  32. GRB021211 (HETE2493), OT at 143 sec
  33. GRB 021204: I-band Observations
  34. GRB021211 (=H2493): A Bright, Long GRB Localized by HETE-2 in Near-Real Time
  35. HETE 2493: Optical observations
  36. HETE 2493: Optical observations
  37. HETE 2493: Optical candidate
  38. GRB 021204: Optical Observations at RIKEN
  39. GRB 021125: Radio Observations
  40. IPN triangulation of GRB021206 (small error box)
  41. IPN triangulation of GRB021206 (exceptionally bright; annulus only)
  42. IPN detection of renewed activity from SGR1806-20
  43. IPN triangulation of GRB021205 (large error box)
  44. GRB 021104, GRB 021112 and GRB 021113 - Milagro GeV/TeV Observations
  45. GRB021201, BVRcIc field photometry
  46. GRB 021201, Radio Observations
  47. GRB 021201: Optical Observations
  48. GRB 021201: BOOTES simultaneous optical observations
  49. IPN triangulation of GRB021201 (short/hard burst, small error box)
  50. Radio Catalog of GRB Afterglows
  51. GRB021004, late time optical observations
  52. GRB021004 Chandra Observation
  53. IPN detection of continued SGR1900+14 activity
  54. GRB021125 refined position
  55. IPN triangulation of GRB021115 (annulus)
  56. IPN triangulation of GRB021125B (two large error boxes)
  57. IPN triangulation of GRB021119 (large error box)
  58. IPN triangulation of GRB021125B (annulus)
  59. Improved IPN error box for GRB021125
  60. IPN BURST POSITION
  61. IPN triangulation of GRB021125 (INTEGRAL BURST)
  62. GRB021125 : A long GRB localized by INTEGRAL
  63. IPN confirmation of the reactivation of SGR1900+14
  64. IPN detection of possible reactivation of SGR1900+14
  65. GRB021113, SPI ACS observation
  66. IPN triangulation of GRB021119 (annulus)
  67. GRB 021112: Afterglow or Variable Star?
  68. GRB021113: optical observations at Bisei
  69. GRB 021113: Evidence for a Dark Optical Afterglow
  70. GRB 021112, Radio Observations
  71. GRB021112, BVRI field photometry
  72. GRB 021112: Variable Source in R-band search
  73. GRB021112: Optical Observations
  74. GRB021113: Kiso Observations
  75. IPN triangulation of GRB021109 (portion of annulus)
  76. IPN triangulation of GRB021113 (=H2449; annulus)
  77. IPN triangulation of GRB021108 (CORRECTION; TWO LARGE ERROR BOXES)
  78. GRB 021113: Optical observations
  79. GRB 021112: RAPTOR Observations
  80. GRB 021113: Optical Observations
  81. GRB 021113: Optical Observations
  82. GRB021113 (=H2449): A Long GRB Localized by HETE
  83. GRB 021112: Optical Observations
  84. GRB 021112: R-band search
  85. IPN triangulation of GRB021108 (large error box)
  86. GRB021112 (=H2448): A Long GRB Localized by HETE
  87. GRB 021016: Optical Observations
  88. IPN triangulation of GRB021109 (annulus)
  89. IPN triangulation of GRB021108 (annulus)
  90. GRB021004: Near infrared spectroscopy
  91. GRB021104: Optical Observations
  92. IPN triangulation of GRB021104 (annulus)
  93. GRB021104(=H2434): A Long, X-Ray-Rich GRB Localized by HETE
  94. IPN triangulation of bursts from SGR1900+14, November 1-2, 2002
  95. SGR1900+14 activity, November 2-4, 2002
  96. Spectropolarimetry of GRB021004
  97. GRB021104: Optical observations
  98. GRB021104: optical observations
  99. GRB021104: Candidate present in DSS
  100. GRB021104: possible optical afterglow

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