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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"

16001 results found.

  1. GRB030329 optical observations
  2. GRB030329:optical observations by MASTER
  3. GRB 030329: optical observations
  4. GRB030329: Upper limits from recent and historical observations.
  5. GRB030329 (=H2652): A Long, Extremely Bright GRB Localized by the HETE WXM and SXC
  6. GRB 030329: Optical Afterglow Observations
  7. GRB 030329: precise position from Kyoto images
  8. GRB 030328 Optical Observations
  9. GRB 030328: Optical observations
  10. GRB 030328: optical observations
  11. GRB 030329: Optical afterglow fading
  12. GRB 030329: Optical afterglow candidate
  13. GRB 030329: Optical afterglow candidate
  14. GRB030328: optical spectroscopy at TNG
  15. GRB030328: optical photometry at the TNG
  16. VLT spectra of GRB 030328
  17. GRB 030328, optical spectroscopy
  18. GRB 030328, optical observations
  19. GRB030328 (=H2650): A Long, Bright GRB Localized by the HETE WXM and SXC
  20. GRB 030328: Optical observations
  21. GRB 030328: Finding chart
  22. GRB 030328: Optical afterglow candidate
  23. GRB030323 optical observations
  24. GRB030324 optical observation
  25. GRB030323: Detection on 2003/03/24
  26. GRB 030323: SARA Optical Observations
  27. GRB030324, optical observations
  28. GRB030324, optical observations
  29. GRB 030324: TAROT optical observations
  30. GRB 030324 (HETE #2641): Optical observations
  31. GRB030324, Optical Observations
  32. GRB030323: Upper limits from recent and historical observations.
  33. GRB030323 (=H2640): A Faint, Long GRB Localized by the HETE WXM and SXC
  34. GRB030324 (=H2641): A Long GRB Localized in Real Time by the HETE WXM
  35. GRB030324 (=H2641): A Long GRB Localized in Real Time by the HETE WXM
  36. GRB030323, ROTSE-III detection of possible optical counterpart
  37. GRB030323, optical observations
  38. GRB030323, possible optical counterpart
  39. GRB 030324 optical observations
  40. GRB 030320: Optical Observations
  41. GRB 030324, optical observations
  42. GRB 030227: Optical limit at RIKEN
  43. GRB 030226 Optical observations
  44. GRB030226: Optical observations at Asiago
  45. GRB 030226: Optical observations
  46. GRB 030227: Optical observations
  47. GRB030226, BVRc observations
  48. Chandra detection of the X-ray afterglow of GRB 030226
  49. GRB 030226, further optical/NIR imaging
  50. GRB030227, optical observations
  51. GRB 030226: Ic Observations
  52. GRB030227: Kiso optical upper limit
  53. GRB030227, BVRcIc field photometry
  54. GRB030226, BVRcIc field calibration
  55. GRB 030227 optical afterglow
  56. GRB 030228, optical observations
  57. GRB 030226: Steep Decline
  58. GRB 030227: Confirmed Optical Afterglow (S1-A)
  59. GRB 030226: R band polarimetric observations
  60. GRB 030226: Optical observations
  61. GRB 030227: fading of candidate optical afterglow 'S1-A'
  62. GRB030227:Optical observations
  63. GRB 20030226: Upper limits from recent and historical observations
  64. GRB 030227, possible optical counterpart of XMM-Newton source
  65. GRB030227 - faint tentative OT candidate
  66. GRB 030226, optical observations
  67. GRB030227: Kiso optical observations
  68. GRB 030227: Kyoto optical observation
  69. GRB 030226, optical light curve
  70. GRB 030226 spectroscopy
  71. GRB 030226 : Predicted light curve
  72. GRB030226: optical observation
  73. GRB030226 (=U10893): A Long GRB Localized by the HETE WXM and SXC
  74. GRB 030226 simultaneous optical observations
  75. GRB 030226, optical observations
  76. GRB030226: optical observations and refined redshift
  77. GRB030226: Optical decay index
  78. GRB 030226 Optical Spectra and R,I,z' Imaging
  79. GRB 030226, optical observations
  80. GRB 030226: Optical afterglow
  81. GRB030226: Candidate optical afterglow
  82. GRB 030217: Optical Observations at 4, 5, and 6 Days
  83. GRB030217: optical observations
  84. GRB 030131: marginal optical detection
  85. GRB 030204: Optical Observations
  86. GRB030131: Candidate Optical Afterglow
  87. GRB 030115: Optical Observations
  88. GRB 030204, optical observations
  89. GRB 030131, optical observations
  90. GRB030131: Kiso optical limit for corrected position
  91. GRB030131: Optical limits for corrected position
  92. GRB 030115, late-time optical observations
  93. Type Ic SN2003L (SN/GRB?), optical spectrum
  94. GRB 020819: Host galaxy at Radio Position
  95. GRB 020819: afterglow candidate
  96. GRB030131: Optical limit
  97. GRB 030131 optical observations
  98. GRB 030131 optical observations
  99. Type Ic SN2003L (SN/GRB?) Radio Observations
  100. GRB 030115, simultaneous observations by BOOTES-1

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