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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. IPN detection of continued SGR1900+14 activity
  2. GRB021125 refined position
  3. IPN triangulation of GRB021115 (annulus)
  4. IPN triangulation of GRB021125B (two large error boxes)
  5. IPN triangulation of GRB021119 (large error box)
  6. IPN triangulation of GRB021125B (annulus)
  7. Improved IPN error box for GRB021125
  8. IPN BURST POSITION
  9. IPN triangulation of GRB021125 (INTEGRAL BURST)
  10. GRB021125 : A long GRB localized by INTEGRAL
  11. IPN confirmation of the reactivation of SGR1900+14
  12. IPN detection of possible reactivation of SGR1900+14
  13. GRB021113, SPI ACS observation
  14. IPN triangulation of GRB021119 (annulus)
  15. GRB 021112: Afterglow or Variable Star?
  16. GRB021113: optical observations at Bisei
  17. GRB 021113: Evidence for a Dark Optical Afterglow
  18. GRB 021112, Radio Observations
  19. GRB021112, BVRI field photometry
  20. GRB 021112: Variable Source in R-band search
  21. GRB021112: Optical Observations
  22. GRB021113: Kiso Observations
  23. IPN triangulation of GRB021109 (portion of annulus)
  24. IPN triangulation of GRB021113 (=H2449; annulus)
  25. IPN triangulation of GRB021108 (CORRECTION; TWO LARGE ERROR BOXES)
  26. GRB 021113: Optical observations
  27. GRB 021112: RAPTOR Observations
  28. GRB 021113: Optical Observations
  29. GRB 021113: Optical Observations
  30. GRB021113 (=H2449): A Long GRB Localized by HETE
  31. GRB 021112: Optical Observations
  32. GRB 021112: R-band search
  33. IPN triangulation of GRB021108 (large error box)
  34. GRB021112 (=H2448): A Long GRB Localized by HETE
  35. GRB 021016: Optical Observations
  36. IPN triangulation of GRB021109 (annulus)
  37. IPN triangulation of GRB021108 (annulus)
  38. GRB021004: Near infrared spectroscopy
  39. GRB021104: Optical Observations
  40. IPN triangulation of GRB021104 (annulus)
  41. GRB021104(=H2434): A Long, X-Ray-Rich GRB Localized by HETE
  42. IPN triangulation of bursts from SGR1900+14, November 1-2, 2002
  43. SGR1900+14 activity, November 2-4, 2002
  44. Spectropolarimetry of GRB021004
  45. GRB021104: Optical observations
  46. GRB021104: optical observations
  47. GRB021104: Candidate present in DSS
  48. GRB021104: possible optical afterglow
  49. IPN triangulation of GRB021102 (annulus)
  50. Detection of activity from SGR 1900+14 with the RXTE/PCA
  51. IPN triangulation of a burst from SGR1900+14 on November 01, 2002
  52. IPN triangulation of a burst from SGR1900+14 on October 29 2002
  53. IPN triangulation of GRB021025 (portion of annulus)
  54. IPN triangulation of GRB021027 (single large error box)
  55. GRB021004, late-time optical observations
  56. IPN triangulation of GRB021027 (two large error boxes)
  57. GRB 021023: Infrared Imaging
  58. IPN triangulation of GRB021027 (annulus)
  59. GRB 021023: Curious K-band Source(s) Just Outside of IPN Localization
  60. IPN triangulation of GRB021025 (annulus)
  61. IPN triangulation of SGR1900+14, October 22 2002
  62. GRB 021004: optical observations
  63. IPN triangulation of GRB021023 (small error boc)
  64. GRB021004: Optical Observations
  65. GRB 020813; likely host galaxy.
  66. IPN triangulation of GRB021020 (smaller error box)
  67. GRB021021(=XRF 021021): An X-ray Flash Localized by HETE
  68. IPN triangulation of GRB021020
  69. GRB 021008, radio observations
  70. GRB 021016, optical observations
  71. GRB 021004: VRI observations at TNG: possible break
  72. GRB021016, optical observations
  73. SGR1900+14: burst on October 10 2002
  74. GRB 021008, optical observations
  75. GRB021016(=H2397): A Long GRB Localized by HETE
  76. IPN triangulation of GRB021016 (area corrected)
  77. IPN triangulation of GRB021016 (small error box)
  78. GRB021004: Optical Observations
  79. IPN triangulation of GRB021014 (large error box)
  80. IPN triangulation of GRB021013 (single error box)
  81. GRB 021004: optical spectroscopy on Oct 11
  82. IPN triangulation of GRB021013 (two small error boxes)
  83. GRB021004: High-resolution optical spectroscopy
  84. IPN triangulation of GRB021013 (annulus)
  85. XRF 020903: flattening of the optical light curve.
  86. GRB021004, UBVRcIc field photometry update
  87. IPN triangulation of GRB021008 (single error box)
  88. GRB021004: Optical Observations
  89. GRB 021004 submm observations
  90. IPN triangulation of GRB021008B (annulus)
  91. IPN triangulation of GRB021008 (two small error boxes)
  92. GRB021004 Chandra HETG Observations
  93. GRB 021004: Optical/NIR Observations
  94. GRB 021004: Additional V-band Polarimetric Observations
  95. GRB021004: optical observation
  96. GRB 021004: Host Galaxy Star Formation Rate
  97. GRB 021004 submm observations
  98. GRB 021004: WC wind?
  99. IPN triangulation of GRB021008
  100. GRB021004: NIR and Optical observations

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