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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"

42254 results found.

  1. GRB 050408: Emission and absorption redshift
  2. GRB 050408: Mercator Optical Observations
  3. GRB 050408: Magellan astrometry and photometry
  4. GRB 050408: First Optical observations with TFOSC at the RTT150
  5. GRB 050408: steepening of the optical decay
  6. GRB 050408: Optical afterglow confirmed
  7. GRB 050408: opitcal observation
  8. GRB 050408, optical observations
  9. GRB 050408 optical candidate
  10. GRB 050408: Swift XRT Position
  11. GRB 050408: ROTSE-III Optical Limits
  12. GRB 050408 (=H3711): A Long X-Ray-Rich GRB Detected by HETE
  13. GRB050408: MASTER optical observations
  14. GRB050401: Radio Detection
  15. Swift-UVOT Optical Counterpart Candidate to XRF 050406
  16. GRB 050406: Magellan optical observations
  17. GRB 050406: early Swift XRT analysis results
  18. GRB 050406 BAT refined analysis
  19. GRB 050406: Early observations with Swift-UVOT
  20. GRB 050406: Swift XRT Position
  21. Swift-BAT detection of GRB 050406
  22. Konus-Wind observation of GRB 050401
  23. GRB050401: Radio observation at 610 MHz with GMRT
  24. GRB050401, radio observation at 4.8 GHz and 8.64 GHz
  25. GRB 050401: VLT spectroscopic redshift
  26. GRB 050401 Optical Observations
  27. GRB050401: Maidanak optical observation
  28. GRB 050401 BAT refined analysis
  29. Very questionable identity of Swift-BAT GRB050402 (Trig=113225)
  30. GRB050401: TNG R-band observation
  31. GRB 050402A: IR Observations
  32. GRB 050402: Early observations with Swift-UVOT
  33. Swift Trigger 113225: P60 Observations
  34. GRB050401: ROTSE-III Detection of Prompt Optical Counterpart
  35. GRB 050401: Optical afterglow confirmed
  36. GRB 050401: Optical afterglow candidate
  37. Swift-BAT detection of GRB 050401
  38. GRB 050401: Prompt XRT position
  39. GRB050331: No Afterglow Detected
  40. GRB 050331: Swift UVOT Source
  41. Swift-BAT detection of GRB 050331
  42. GRB 050331: Swift XRT Position
  43. GRB050319: radio observation
  44. Konus-Wind observation of GRB 050326
  45. GRB050326: optical limit
  46. GRB 050326: Early observations with Swift-UVOT
  47. GRB 050326 XMM-Newton observation
  48. GRB 050326 : Planned XMM-Newton observation
  49. GRB 050326: Swift XRT Position
  50. GRB050326: optical limit 33min before GRB
  51. GRB 050326 BAT refined analysis
  52. GRB050326: delayed XRT observation
  53. Swift-BAT detection of a bright GRB 050326
  54. GRB050319, optical observations
  55. GRB050319, color indices
  56. GRB050319: optical observation, March 20-22
  57. GRB050319: RTT150 Optical Observations
  58. Swift-BAT detection of a bright outburst from SGR1806-20
  59. GRB 050319: Absorption redshift from the Nordic Optical Telescope
  60. GRB 050319: ROTSE-III Refined Analysis
  61. GRB 050318: Swift-BAT refined analysis
  62. Refined Swift XRT positions for GRB050315, GRB050318 and GRB050319
  63. GRB050319: VLA Observations
  64. GRB050319: radio observation
  65. GRB 050319 R band observations
  66. GRB 050319: Swift-UVOT detection of the afterglow
  67. GRB 050315: Variability Analysis of Swift BAT Time History
  68. GRB050319: Radio Observations
  69. GRB 050319: NIR afterglow candidate
  70. GRB 050319:Near IR afterglow
  71. GRB050319: BR optical photometry
  72. GRB 050318: SWIFT-UVOT refined analysis
  73. GRB 050319: Optical observation
  74. GRB 050319 : Confirmation of optical afterglow decay
  75. GRB050319,optical observation
  76. Swift Detection of GRB 050319
  77. GRB 050319: Detection of Possible Optical Counterpart
  78. GRB 050318: Swift/UVOT detection of afterglow emission
  79. GRB 050318: Magellan optical afterglow identification
  80. GRB050318: Swift XRT position
  81. RXTE Observations of GRB050318
  82. Swift-BAT detection of GRB 050318
  83. GRB 050315, SMARTS optical afterglow decay
  84. GRB050223: analysis of the XMM-Newton observation
  85. GRB050316: MASTER before, simultanious and follow up optical
  86. GRB 050306: ROTSE-III early limits
  87. GRB050316: MASTER optical observations
  88. GRB 050315: Swift-BAT further refined analysis
  89. GRB 050315, SMARTS optical/IR afterglow observations
  90. GRB 050315 I-band observations
  91. GRB050315: Radio afterglow
  92. GRB 050315: Optical afterglow identification
  93. GRB 050315: Swift XRT Position
  94. GRB 050219b: Gemini/GNIRS near-infrared spectroscopy
  95. GRB 050315: Early Observations with Swift/UVOT
  96. Swift-BAT detection of GRB 050315
  97. GRB050223: No XMM-Newton OM detection of afterglow emission
  98. GRB 050306: Radio Observations
  99. GRB050306: 250 GHz upper limit with MAMBO at the IRAM 30m
  100. GRB050309: CONCAM pre-trigger and trigger coincident optical

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