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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. GRB 030226: Ic Observations
  2. GRB030227: Kiso optical upper limit
  3. IPN triangulation of GRB030301 (annulus)
  4. IPN triangulation of GRB030228 (annulus)
  5. GRB030227, BVRcIc field photometry
  6. GRB030226, BVRcIc field calibration
  7. GRB 030227 optical afterglow
  8. 030302: NOT A GRB
  9. 030228: NOT A GRB
  10. GRB 030228, optical observations
  11. GRB 030226: Steep Decline
  12. GRB 030227: Confirmed Optical Afterglow (S1-A)
  13. GRB 030226: R band polarimetric observations
  14. GRB 030226: Optical observations
  15. GRB 030227: fading of candidate optical afterglow 'S1-A'
  16. GRB030227:Optical observations
  17. GRB 20030226: Upper limits from recent and historical observations
  18. GRB 030227, possible optical counterpart of XMM-Newton source
  19. GRB030227 - faint tentative OT candidate
  20. GRB 030226, optical observations
  21. XMM-Newton observation of GRB030227
  22. GRB030227: Kiso optical observations
  23. GRB 030227: Kyoto optical observation
  24. GRB 030226, optical light curve
  25. GRB 030226 spectroscopy
  26. GRB030227: refined INTEGRAL position
  27. GRB030227 localized by INTEGRAL
  28. Possible break in the GRB 030226 light curve
  29. GRB 030226 : Predicted light curve
  30. GRB030226: optical observation
  31. IPN triangulation of GRB030225 (annulus)
  32. GRB 030226: Confirmed decay index
  33. GRB030226: ESI spectroscopy
  34. GRB030226 (=U10893): A Long GRB Localized by the HETE WXM and SXC
  35. GRB 030226 simultaneous optical observations
  36. Two absorption systems in GRB 030226
  37. GRB 030226, optical observations
  38. GRB030226: optical observations and refined redshift
  39. GRB030226: Optical decay index
  40. GRB 030226 Optical Spectra and R,I,z' Imaging
  41. GRB 030226, optical observations
  42. GRB 030226: Optical afterglow
  43. GRB030226: Candidate optical afterglow
  44. GRB 030217: Optical Observations at 4, 5, and 6 Days
  45. IPN triangulation of GRB030223 (annulus)
  46. IPN triangulation of GRB030220 (annulus)
  47. GRB: Non-Referencing of GCN Circulars.
  48. IPN triangulation of GRB030218 (annulus)
  49. GRB030217: optical observations
  50. IPN triangulation of GRB030217 (small error box)
  51. IPN triangulation of GRB030215C (annulus)
  52. IPN triangulation of GRB030217 (annulus)
  53. IPN triangulation of GRB030216 (annulus)
  54. IPN triangulation of GRB030215A and GRB030215B (annuli)
  55. GRB030115, WSRT radio observations - correction to GCN 1864
  56. GRB 030131: marginal optical detection
  57. GCN/INTEGRAL Mistake Fixed
  58. GRB030115, WSRT radio observations
  59. IPN triangulation of GRB030206 (annulus)
  60. IPN triangulation of GRB030208 (annulus)
  61. GRB 030204: Optical Observations
  62. GRB030204 field photometry
  63. GRB020819: Kiso R and I band observations
  64. GRB 030204: Correction to GCN 1856
  65. GRB030131: Candidate Optical Afterglow
  66. GRB 030115: Optical Observations
  67. GRB 030204, optical observations
  68. IPN triangulation of GRB030204 (small error box)
  69. IPN triangulation of GRB030202 (annulus)
  70. GRB 030131, optical observations
  71. GRB030131: Kiso optical limit for corrected position
  72. GRB030131: Optical limits for corrected position
  73. GRB 030131: afterglow candidate
  74. GRB 030115, late-time optical observations
  75. GRB030131: corrected INTEGRAL position
  76. Type Ic SN2003L (SN/GRB?), optical spectrum
  77. GRB030131: Kiso Observations
  78. GRB 020819: Host galaxy at Radio Position
  79. IPN triangulation of GRB030131 - CORRECTION
  80. GRB 020819: afterglow candidate
  81. IPN triangulation of GRB030131
  82. GRB030131: Optical limit
  83. GRB 030131 optical observations
  84. GRB030131: refined position
  85. GRB 030131 optical observations
  86. A long GRB detected by INTEGRAL
  87. GRB030115: 1.2 mm upper limits with MAMBO @ IRAM 30m
  88. Type Ic SN2003L (SN/GRB?) Radio Observations
  89. IPN triangulation of GRB030127 (annulus)
  90. GRB030115 submm upper limit
  91. IPN triangulation of GRB030119 (two large error boxes)
  92. GRB 030115: Further IR observations with IRSF/SIRIUS
  93. IPN triangulation of GRB030117 (two large error boxes)
  94. Publicizing GRB Discoveries - A Message from NASA HQ
  95. GRB 030115: Radio detection of IR candidate
  96. GRB 030115, simultaneous observations by BOOTES-1
  97. GRB 030115: IR observations with IRSF/SIRIUS
  98. IPN triangulation of GRB030115C (large error box)
  99. GRB030115: R-band counterpart of IR candidate
  100. GRB030115, afterglow candidate

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