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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: Optical observations at Asiago
  2. IPN triangulation of GRB030306 (single small error box)
  3. IPN triangulation of GRB030306 (two small error boxes)
  4. IPN triangulation of GRB030306 (intense; annulus only so far)
  5. GRB 030226: Optical observations
  6. GRB030226: Analysis of Chandra data
  7. IPN triangulation of GRB030304 (annulus)
  8. GRB 030227: Optical observations
  9. GRB030226, BVRc observations
  10. Chandra detection of the X-ray afterglow of GRB 030226
  11. GRB 030226, further optical/NIR imaging
  12. GRB030227, optical observations
  13. GRB 030226: Ic Observations
  14. GRB030227: Kiso optical upper limit
  15. IPN triangulation of GRB030301 (annulus)
  16. IPN triangulation of GRB030228 (annulus)
  17. GRB030227, BVRcIc field photometry
  18. GRB030226, BVRcIc field calibration
  19. GRB 030227 optical afterglow
  20. 030302: NOT A GRB
  21. 030228: NOT A GRB
  22. GRB 030228, optical observations
  23. GRB 030226: Steep Decline
  24. GRB 030227: Confirmed Optical Afterglow (S1-A)
  25. GRB 030226: R band polarimetric observations
  26. GRB 030226: Optical observations
  27. GRB 030227: fading of candidate optical afterglow 'S1-A'
  28. GRB030227:Optical observations
  29. GRB 20030226: Upper limits from recent and historical observations
  30. GRB 030227, possible optical counterpart of XMM-Newton source
  31. GRB030227 - faint tentative OT candidate
  32. GRB 030226, optical observations
  33. XMM-Newton observation of GRB030227
  34. GRB030227: Kiso optical observations
  35. GRB 030227: Kyoto optical observation
  36. GRB 030226, optical light curve
  37. GRB 030226 spectroscopy
  38. GRB030227: refined INTEGRAL position
  39. GRB030227 localized by INTEGRAL
  40. Possible break in the GRB 030226 light curve
  41. GRB 030226 : Predicted light curve
  42. GRB030226: optical observation
  43. IPN triangulation of GRB030225 (annulus)
  44. GRB 030226: Confirmed decay index
  45. GRB030226: ESI spectroscopy
  46. GRB030226 (=U10893): A Long GRB Localized by the HETE WXM and SXC
  47. GRB 030226 simultaneous optical observations
  48. Two absorption systems in GRB 030226
  49. GRB 030226, optical observations
  50. GRB030226: optical observations and refined redshift
  51. GRB030226: Optical decay index
  52. GRB 030226 Optical Spectra and R,I,z' Imaging
  53. GRB 030226, optical observations
  54. GRB 030226: Optical afterglow
  55. GRB030226: Candidate optical afterglow
  56. GRB 030217: Optical Observations at 4, 5, and 6 Days
  57. IPN triangulation of GRB030223 (annulus)
  58. IPN triangulation of GRB030220 (annulus)
  59. GRB: Non-Referencing of GCN Circulars.
  60. IPN triangulation of GRB030218 (annulus)
  61. GRB030217: optical observations
  62. IPN triangulation of GRB030217 (small error box)
  63. IPN triangulation of GRB030215C (annulus)
  64. IPN triangulation of GRB030217 (annulus)
  65. IPN triangulation of GRB030216 (annulus)
  66. IPN triangulation of GRB030215A and GRB030215B (annuli)
  67. GRB030115, WSRT radio observations - correction to GCN 1864
  68. GRB 030131: marginal optical detection
  69. GCN/INTEGRAL Mistake Fixed
  70. GRB030115, WSRT radio observations
  71. IPN triangulation of GRB030206 (annulus)
  72. IPN triangulation of GRB030208 (annulus)
  73. GRB 030204: Optical Observations
  74. GRB030204 field photometry
  75. GRB020819: Kiso R and I band observations
  76. GRB 030204: Correction to GCN 1856
  77. GRB030131: Candidate Optical Afterglow
  78. GRB 030115: Optical Observations
  79. GRB 030204, optical observations
  80. IPN triangulation of GRB030204 (small error box)
  81. IPN triangulation of GRB030202 (annulus)
  82. GRB 030131, optical observations
  83. GRB030131: Kiso optical limit for corrected position
  84. GRB030131: Optical limits for corrected position
  85. GRB 030131: afterglow candidate
  86. GRB 030115, late-time optical observations
  87. GRB030131: corrected INTEGRAL position
  88. Type Ic SN2003L (SN/GRB?), optical spectrum
  89. GRB030131: Kiso Observations
  90. GRB 020819: Host galaxy at Radio Position
  91. IPN triangulation of GRB030131 - CORRECTION
  92. GRB 020819: afterglow candidate
  93. IPN triangulation of GRB030131
  94. GRB030131: Optical limit
  95. GRB 030131 optical observations
  96. GRB030131: refined position
  97. GRB 030131 optical observations
  98. A long GRB detected by INTEGRAL
  99. GRB030115: 1.2 mm upper limits with MAMBO @ IRAM 30m
  100. Type Ic SN2003L (SN/GRB?) Radio Observations

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