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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/FORS2 spectra of GRB 030323
  2. GRB030323, ROTSE-III detection of possible optical counterpart
  3. GRB030323, optical observations
  4. GRB030324, BVRcIc field photometry
  5. GRB030323, possible optical counterpart
  6. GRB030323, BVRcIc field calibration
  7. GRB 030324 optical observations
  8. GRB 030320: Optical Observations
  9. GRB 030324, optical observations
  10. IPN triangulation of GRB030320B (annulus)
  11. IPN triangulation of GRB030320 (small error box)
  12. IPN triangulation of GRB030320
  13. Possible GRB 030320 localized by INTEGRAL
  14. GRB030226, addendum to GCN 1892
  15. IPN upper limit to a GRB associated with SN2003L
  16. IPN triangulation of GRB030317 (annulus)
  17. IPN triangulation of GRB030307 (annulus)
  18. GRB 030227: Optical limit at RIKEN
  19. GRB 030226 Optical observations
  20. IPN triangulation of GRB030306 (single small error box - REVISED)
  21. GRB030226: Optical observations at Asiago
  22. IPN triangulation of GRB030306 (single small error box)
  23. IPN triangulation of GRB030306 (two small error boxes)
  24. IPN triangulation of GRB030306 (intense; annulus only so far)
  25. GRB 030226: Optical observations
  26. GRB030226: Analysis of Chandra data
  27. IPN triangulation of GRB030304 (annulus)
  28. GRB 030227: Optical observations
  29. GRB030226, BVRc observations
  30. Chandra detection of the X-ray afterglow of GRB 030226
  31. GRB 030226, further optical/NIR imaging
  32. GRB030227, optical observations
  33. GRB 030226: Ic Observations
  34. GRB030227: Kiso optical upper limit
  35. IPN triangulation of GRB030301 (annulus)
  36. IPN triangulation of GRB030228 (annulus)
  37. GRB030227, BVRcIc field photometry
  38. GRB030226, BVRcIc field calibration
  39. GRB 030227 optical afterglow
  40. 030302: NOT A GRB
  41. 030228: NOT A GRB
  42. GRB 030228, optical observations
  43. GRB 030226: Steep Decline
  44. GRB 030227: Confirmed Optical Afterglow (S1-A)
  45. GRB 030226: R band polarimetric observations
  46. GRB 030226: Optical observations
  47. GRB 030227: fading of candidate optical afterglow 'S1-A'
  48. GRB030227:Optical observations
  49. GRB 20030226: Upper limits from recent and historical observations
  50. GRB 030227, possible optical counterpart of XMM-Newton source
  51. GRB030227 - faint tentative OT candidate
  52. GRB 030226, optical observations
  53. XMM-Newton observation of GRB030227
  54. GRB030227: Kiso optical observations
  55. GRB 030227: Kyoto optical observation
  56. GRB 030226, optical light curve
  57. GRB 030226 spectroscopy
  58. GRB030227: refined INTEGRAL position
  59. GRB030227 localized by INTEGRAL
  60. Possible break in the GRB 030226 light curve
  61. GRB 030226 : Predicted light curve
  62. GRB030226: optical observation
  63. IPN triangulation of GRB030225 (annulus)
  64. GRB 030226: Confirmed decay index
  65. GRB030226: ESI spectroscopy
  66. GRB030226 (=U10893): A Long GRB Localized by the HETE WXM and SXC
  67. GRB 030226 simultaneous optical observations
  68. Two absorption systems in GRB 030226
  69. GRB 030226, optical observations
  70. GRB030226: optical observations and refined redshift
  71. GRB030226: Optical decay index
  72. GRB 030226 Optical Spectra and R,I,z' Imaging
  73. GRB 030226, optical observations
  74. GRB 030226: Optical afterglow
  75. GRB030226: Candidate optical afterglow
  76. GRB 030217: Optical Observations at 4, 5, and 6 Days
  77. IPN triangulation of GRB030223 (annulus)
  78. IPN triangulation of GRB030220 (annulus)
  79. GRB: Non-Referencing of GCN Circulars.
  80. IPN triangulation of GRB030218 (annulus)
  81. GRB030217: optical observations
  82. IPN triangulation of GRB030217 (small error box)
  83. IPN triangulation of GRB030215C (annulus)
  84. IPN triangulation of GRB030217 (annulus)
  85. IPN triangulation of GRB030216 (annulus)
  86. IPN triangulation of GRB030215A and GRB030215B (annuli)
  87. GRB030115, WSRT radio observations - correction to GCN 1864
  88. GRB 030131: marginal optical detection
  89. GCN/INTEGRAL Mistake Fixed
  90. GRB030115, WSRT radio observations
  91. IPN triangulation of GRB030206 (annulus)
  92. IPN triangulation of GRB030208 (annulus)
  93. GRB 030204: Optical Observations
  94. GRB030204 field photometry
  95. GRB020819: Kiso R and I band observations
  96. GRB 030204: Correction to GCN 1856
  97. GRB030131: Candidate Optical Afterglow
  98. GRB 030115: Optical Observations
  99. GRB 030204, optical observations
  100. IPN triangulation of GRB030204 (small error box)

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