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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"

16161 results found.

  1. GRB 050412: Early Optical/Ultraviolet Observations with
  2. GRB 050412: Optical limit
  3. GRB 050412: LCO Optical Observations
  4. GRB 050412: Optical observations
  5. GRB050412: optical limit before and during GRB
  6. GRB 050412: LCO optical observations
  7. GRB050412: ROTSE-III Optical Limits
  8. GRB 050412: IR and Optical observations
  9. GRB050408: Radio Observations
  10. GRB 050401: Optical limit
  11. GRB 050408: Optical limit
  12. GRB 050410: Early Optical/Ultraviolet Observations with Swift/UVOT
  13. GRB 050410, optical observations
  14. GRB 050408: Early Optical/Ultraviolet Observations with Swift/UVOT
  15. GRB 050410 R band Optical Observations
  16. GRB 050410, optical observations
  17. GRB050410: MASTER optical observations
  18. GRB 050410: Early observations with Swift-UVOT
  19. Swift-BAT detection of GRB 050410
  20. GRB 050408: WIDGET simultaneous optical observations
  21. GRB 050408: SOAR UBVRc Observations
  22. GRB 050408: Properties of the Host Galaxy
  23. GRB 050408: Mercator Optical Observations
  24. GRB050408: Radio Observations
  25. GRB 050408: Swift XRT analysis
  26. GRB 050408, SMARTS optical/IR afterglow observations
  27. GRB 050408: Optical limit at 20 min after the burst
  28. GRB 050408, optical observations
  29. GRB050408: REM NIR and Optical observation
  30. GRB 050408: Moderate-resolution Gemini Spectroscopy
  31. GRB 050408,optical observation
  32. GRB 050408 Optical Observations
  33. GRB 050408: Emission and absorption redshift
  34. GRB 050408: Mercator Optical Observations
  35. GRB 050408: First Optical observations with TFOSC at the RTT150
  36. GRB 050408: steepening of the optical decay
  37. GRB 050408: Optical afterglow confirmed
  38. GRB 050408, optical observations
  39. GRB 050408 optical candidate
  40. GRB 050408: ROTSE-III Optical Limits
  41. GRB 050408 (=H3711): A Long X-Ray-Rich GRB Detected by HETE
  42. GRB050408: MASTER optical observations
  43. GRB050401: Radio Detection
  44. Swift-UVOT Optical Counterpart Candidate to XRF 050406
  45. GRB 050406: Magellan optical observations
  46. GRB 050406: Early observations with Swift-UVOT
  47. Swift-BAT detection of GRB 050406
  48. GRB050401: Radio observation at 610 MHz with GMRT
  49. GRB 050401: VLT spectroscopic redshift
  50. GRB 050401 Optical Observations
  51. GRB050401: Maidanak optical observation
  52. GRB 050401 BAT refined analysis
  53. GRB050401: TNG R-band observation
  54. GRB 050402: Early observations with Swift-UVOT
  55. GRB050401: ROTSE-III Detection of Prompt Optical Counterpart
  56. GRB 050401: Optical afterglow confirmed
  57. GRB 050401: Optical afterglow candidate
  58. GRB050331: No Afterglow Detected
  59. GRB 050331: Swift UVOT Source
  60. GRB050326: optical limit
  61. GRB 050326: Early observations with Swift-UVOT
  62. GRB050326: optical limit 33min before GRB
  63. GRB050319, optical observations
  64. GRB050319, color indices
  65. GRB050319: optical observation, March 20-22
  66. GRB050319: RTT150 Optical Observations
  67. GRB 050319: Absorption redshift from the Nordic Optical Telescope
  68. GRB 050318: Swift-BAT refined analysis
  69. Refined Swift XRT positions for GRB050315, GRB050318 and GRB050319
  70. GRB050319: VLA Observations
  71. GRB050319: radio observation
  72. GRB 050319 R band observations
  73. GRB 050319: Swift-UVOT detection of the afterglow
  74. GRB050319: Radio Observations
  75. GRB 050319: NIR afterglow candidate
  76. GRB 050319:Near IR afterglow
  77. GRB050319: BR optical photometry
  78. GRB 050319: Optical observation
  79. GRB 050319 : Confirmation of optical afterglow decay
  80. GRB050319,optical observation
  81. GRB 050319: Detection of Possible Optical Counterpart
  82. GRB 050318: Swift/UVOT detection of afterglow emission
  83. GRB 050318: Magellan optical afterglow identification
  84. GRB 050315, SMARTS optical afterglow decay
  85. GRB050223: analysis of the XMM-Newton observation
  86. GRB050316: MASTER before, simultanious and follow up optical
  87. GRB 050306: ROTSE-III early limits
  88. GRB050316: MASTER optical observations
  89. GRB 050315: Swift-BAT further refined analysis
  90. GRB 050315, SMARTS optical/IR afterglow observations
  91. GRB 050315 I-band observations
  92. GRB050315: Radio afterglow
  93. GRB 050315: Optical afterglow identification
  94. GRB 050219b: Gemini/GNIRS near-infrared spectroscopy
  95. GRB 050315: Early Observations with Swift/UVOT
  96. GRB050223: No XMM-Newton OM detection of afterglow emission
  97. GRB 050306: Radio Observations
  98. GRB050306: 250 GHz upper limit with MAMBO at the IRAM 30m
  99. GRB050309: CONCAM pre-trigger and trigger coincident optical
  100. GRB 050306: optical afterglow

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