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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. GRB030324 optical observation
  2. GRB030131, BVRcIc field photometry
  3. Possible GRB030323 localized by INTEGRAL
  4. IPN triangulation of GRB030325 (final analysis)
  5. GRB030323: Detection on 2003/03/24
  6. IPN triangulation of GRB030326 (single small error box)
  7. GRB 030323: SARA Optical Observations
  8. IPN triangulation of GRB030325 (single small error box)
  9. GRB030324, optical observations
  10. GRB030324, optical observations
  11. IPN triangulation of GRB030325 (two small error boxes)
  12. GRB 030324: TAROT optical observations
  13. GRB030323: V, R, I photometry
  14. GRB 030324 (HETE #2641): Optical observations
  15. GRB030324, Optical Observations
  16. GRB030323: Upper limits from recent and historical observations.
  17. GRB030323 (=H2640): A Faint, Long GRB Localized by the HETE WXM and SXC
  18. GRB030324 (=H2641): A Long GRB Localized in Real Time by the HETE WXM
  19. GRB030324 (=H2641): A Long GRB Localized in Real Time by the HETE WXM
  20. VLT/FORS2 spectra of GRB 030323
  21. GRB030323, ROTSE-III detection of possible optical counterpart
  22. GRB030323, optical observations
  23. GRB030324, BVRcIc field photometry
  24. GRB030323, possible optical counterpart
  25. GRB030323, BVRcIc field calibration
  26. GRB 030324 optical observations
  27. GRB 030320: Optical Observations
  28. GRB 030324, optical observations
  29. IPN triangulation of GRB030320B (annulus)
  30. IPN triangulation of GRB030320 (small error box)
  31. IPN triangulation of GRB030320
  32. Possible GRB 030320 localized by INTEGRAL
  33. GRB030226, addendum to GCN 1892
  34. IPN upper limit to a GRB associated with SN2003L
  35. IPN triangulation of GRB030317 (annulus)
  36. IPN triangulation of GRB030307 (annulus)
  37. GRB 030227: Optical limit at RIKEN
  38. GRB 030226 Optical observations
  39. IPN triangulation of GRB030306 (single small error box - REVISED)
  40. GRB030226: Optical observations at Asiago
  41. IPN triangulation of GRB030306 (single small error box)
  42. IPN triangulation of GRB030306 (two small error boxes)
  43. IPN triangulation of GRB030306 (intense; annulus only so far)
  44. GRB 030226: Optical observations
  45. GRB030226: Analysis of Chandra data
  46. IPN triangulation of GRB030304 (annulus)
  47. GRB 030227: Optical observations
  48. GRB030226, BVRc observations
  49. Chandra detection of the X-ray afterglow of GRB 030226
  50. GRB 030226, further optical/NIR imaging
  51. GRB030227, optical observations
  52. GRB 030226: Ic Observations
  53. GRB030227: Kiso optical upper limit
  54. IPN triangulation of GRB030301 (annulus)
  55. IPN triangulation of GRB030228 (annulus)
  56. GRB030227, BVRcIc field photometry
  57. GRB030226, BVRcIc field calibration
  58. GRB 030227 optical afterglow
  59. 030302: NOT A GRB
  60. 030228: NOT A GRB
  61. GRB 030228, optical observations
  62. GRB 030226: Steep Decline
  63. GRB 030227: Confirmed Optical Afterglow (S1-A)
  64. GRB 030226: R band polarimetric observations
  65. GRB 030226: Optical observations
  66. GRB 030227: fading of candidate optical afterglow 'S1-A'
  67. GRB030227:Optical observations
  68. GRB 20030226: Upper limits from recent and historical observations
  69. GRB 030227, possible optical counterpart of XMM-Newton source
  70. GRB030227 - faint tentative OT candidate
  71. GRB 030226, optical observations
  72. XMM-Newton observation of GRB030227
  73. GRB030227: Kiso optical observations
  74. GRB 030227: Kyoto optical observation
  75. GRB 030226, optical light curve
  76. GRB 030226 spectroscopy
  77. GRB030227: refined INTEGRAL position
  78. GRB030227 localized by INTEGRAL
  79. Possible break in the GRB 030226 light curve
  80. GRB 030226 : Predicted light curve
  81. GRB030226: optical observation
  82. IPN triangulation of GRB030225 (annulus)
  83. GRB 030226: Confirmed decay index
  84. GRB030226: ESI spectroscopy
  85. GRB030226 (=U10893): A Long GRB Localized by the HETE WXM and SXC
  86. GRB 030226 simultaneous optical observations
  87. Two absorption systems in GRB 030226
  88. GRB 030226, optical observations
  89. GRB030226: optical observations and refined redshift
  90. GRB030226: Optical decay index
  91. GRB 030226 Optical Spectra and R,I,z' Imaging
  92. GRB 030226, optical observations
  93. GRB 030226: Optical afterglow
  94. GRB030226: Candidate optical afterglow
  95. GRB 030217: Optical Observations at 4, 5, and 6 Days
  96. IPN triangulation of GRB030223 (annulus)
  97. IPN triangulation of GRB030220 (annulus)
  98. GRB: Non-Referencing of GCN Circulars.
  99. IPN triangulation of GRB030218 (annulus)
  100. GRB030217: optical observations

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