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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. GRB030226, addendum to GCN 1892
  2. IPN upper limit to a GRB associated with SN2003L
  3. IPN triangulation of GRB030317 (annulus)
  4. IPN triangulation of GRB030307 (annulus)
  5. GRB 030227: Optical limit at RIKEN
  6. GRB 030226 Optical observations
  7. IPN triangulation of GRB030306 (single small error box - REVISED)
  8. GRB030226: Optical observations at Asiago
  9. IPN triangulation of GRB030306 (single small error box)
  10. IPN triangulation of GRB030306 (two small error boxes)
  11. IPN triangulation of GRB030306 (intense; annulus only so far)
  12. GRB 030226: Optical observations
  13. GRB030226: Analysis of Chandra data
  14. IPN triangulation of GRB030304 (annulus)
  15. GRB 030227: Optical observations
  16. GRB030226, BVRc observations
  17. Chandra detection of the X-ray afterglow of GRB 030226
  18. GRB 030226, further optical/NIR imaging
  19. GRB030227, optical observations
  20. GRB 030226: Ic Observations
  21. GRB030227: Kiso optical upper limit
  22. IPN triangulation of GRB030301 (annulus)
  23. IPN triangulation of GRB030228 (annulus)
  24. GRB030227, BVRcIc field photometry
  25. GRB030226, BVRcIc field calibration
  26. GRB 030227 optical afterglow
  27. 030302: NOT A GRB
  28. 030228: NOT A GRB
  29. GRB 030228, optical observations
  30. GRB 030226: Steep Decline
  31. GRB 030227: Confirmed Optical Afterglow (S1-A)
  32. GRB 030226: R band polarimetric observations
  33. GRB 030226: Optical observations
  34. GRB 030227: fading of candidate optical afterglow 'S1-A'
  35. GRB030227:Optical observations
  36. GRB 20030226: Upper limits from recent and historical observations
  37. GRB 030227, possible optical counterpart of XMM-Newton source
  38. GRB030227 - faint tentative OT candidate
  39. GRB 030226, optical observations
  40. XMM-Newton observation of GRB030227
  41. GRB030227: Kiso optical observations
  42. GRB 030227: Kyoto optical observation
  43. GRB 030226, optical light curve
  44. GRB 030226 spectroscopy
  45. GRB030227: refined INTEGRAL position
  46. GRB030227 localized by INTEGRAL
  47. Possible break in the GRB 030226 light curve
  48. GRB 030226 : Predicted light curve
  49. GRB030226: optical observation
  50. IPN triangulation of GRB030225 (annulus)
  51. GRB 030226: Confirmed decay index
  52. GRB030226: ESI spectroscopy
  53. GRB030226 (=U10893): A Long GRB Localized by the HETE WXM and SXC
  54. GRB 030226 simultaneous optical observations
  55. Two absorption systems in GRB 030226
  56. GRB 030226, optical observations
  57. GRB030226: optical observations and refined redshift
  58. GRB030226: Optical decay index
  59. GRB 030226 Optical Spectra and R,I,z' Imaging
  60. GRB 030226, optical observations
  61. GRB 030226: Optical afterglow
  62. GRB030226: Candidate optical afterglow
  63. GRB 030217: Optical Observations at 4, 5, and 6 Days
  64. IPN triangulation of GRB030223 (annulus)
  65. IPN triangulation of GRB030220 (annulus)
  66. GRB: Non-Referencing of GCN Circulars.
  67. IPN triangulation of GRB030218 (annulus)
  68. GRB030217: optical observations
  69. IPN triangulation of GRB030217 (small error box)
  70. IPN triangulation of GRB030215C (annulus)
  71. IPN triangulation of GRB030217 (annulus)
  72. IPN triangulation of GRB030216 (annulus)
  73. IPN triangulation of GRB030215A and GRB030215B (annuli)
  74. GRB030115, WSRT radio observations - correction to GCN 1864
  75. GRB 030131: marginal optical detection
  76. GCN/INTEGRAL Mistake Fixed
  77. GRB030115, WSRT radio observations
  78. IPN triangulation of GRB030206 (annulus)
  79. IPN triangulation of GRB030208 (annulus)
  80. GRB 030204: Optical Observations
  81. GRB030204 field photometry
  82. GRB020819: Kiso R and I band observations
  83. GRB 030204: Correction to GCN 1856
  84. GRB030131: Candidate Optical Afterglow
  85. GRB 030115: Optical Observations
  86. GRB 030204, optical observations
  87. IPN triangulation of GRB030204 (small error box)
  88. IPN triangulation of GRB030202 (annulus)
  89. GRB 030131, optical observations
  90. GRB030131: Kiso optical limit for corrected position
  91. GRB030131: Optical limits for corrected position
  92. GRB 030131: afterglow candidate
  93. GRB 030115, late-time optical observations
  94. GRB030131: corrected INTEGRAL position
  95. Type Ic SN2003L (SN/GRB?), optical spectrum
  96. GRB030131: Kiso Observations
  97. GRB 020819: Host galaxy at Radio Position
  98. IPN triangulation of GRB030131 - CORRECTION
  99. GRB 020819: afterglow candidate
  100. IPN triangulation of GRB030131

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