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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"

20966 results found.

  1. GRB 050408: Subaru Observations
  2. GRB 050408: WIDGET simultaneous optical observations
  3. GRB 050408: SOAR UBVRc Observations
  4. GRB 050408: Properties of the Host Galaxy
  5. GRB 050408: Mercator Optical Observations
  6. GRB050408: Radio Observations
  7. GRB 050408, SMARTS optical/IR afterglow observations
  8. GRB 050408, optical observations
  9. GRB 050408 Optical Observations
  10. GRB 050408: Emission and absorption redshift
  11. GRB 050408: Mercator Optical Observations
  12. GRB 050408: Magellan astrometry and photometry
  13. GRB 050408: First Optical observations with TFOSC at the RTT150
  14. GRB 050408, optical observations
  15. GRB 050408 optical candidate
  16. GRB050408: MASTER optical observations
  17. GRB050401: Radio Detection
  18. Swift-UVOT Optical Counterpart Candidate to XRF 050406
  19. GRB 050406: Magellan optical observations
  20. GRB 050406: Early observations with Swift-UVOT
  21. GRB050401: Radio observation at 610 MHz with GMRT
  22. GRB050401, radio observation at 4.8 GHz and 8.64 GHz
  23. GRB 050401 Optical Observations
  24. GRB050401: TNG R-band observation
  25. GRB 050402A: IR Observations
  26. GRB 050402: Early observations with Swift-UVOT
  27. Swift Trigger 113225: P60 Observations
  28. GRB 050401: Optical afterglow confirmed
  29. GRB 050401: Optical afterglow candidate
  30. GRB050331: No Afterglow Detected
  31. GRB 050331: Swift UVOT Source
  32. GRB050319: radio observation
  33. GRB 050326: Early observations with Swift-UVOT
  34. GRB 050326: Swift XRT Position
  35. GRB050326: delayed XRT observation
  36. GRB050319, optical observations
  37. GRB050319, color indices
  38. GRB050319: optical observation, March 20-22
  39. GRB050319: RTT150 Optical Observations
  40. GRB 050319: ROTSE-III Refined Analysis
  41. GRB 050318: Swift-BAT refined analysis
  42. GRB050319: VLA Observations
  43. GRB 050319 R band observations
  44. GRB 050319: Swift-UVOT detection of the afterglow
  45. GRB050319: Radio Observations
  46. GRB 050319: NIR afterglow candidate
  47. GRB 050319:Near IR afterglow
  48. GRB 050318: Absorption redshift from Magellan
  49. GRB 050319 : Confirmation of optical afterglow decay
  50. GRB 050319: Detection of Possible Optical Counterpart
  51. GRB 050318: Swift/UVOT detection of afterglow emission
  52. GRB 050318: Magellan optical afterglow identification
  53. RXTE Observations of GRB050318
  54. GRB 050315, SMARTS optical afterglow decay
  55. GRB050316: MASTER before, simultanious and follow up optical
  56. GRB050316: MASTER optical observations
  57. GRB 050315: Swift-BAT further refined analysis
  58. GRB 050315, SMARTS optical/IR afterglow observations
  59. GRB 050315 I-band observations
  60. GRB050315: Radio afterglow
  61. GRB 050315: Absorption redshift
  62. GRB 050315: Optical afterglow identification
  63. Non-detection of GRB050315 in ATCA Radio Observations
  64. GRB 050315: Swift XRT Position
  65. GRB 050219b: Gemini/GNIRS near-infrared spectroscopy
  66. GRB 050315: Early Observations with Swift/UVOT
  67. Swift-BAT detection of GRB 050315
  68. GRB050223: No XMM-Newton OM detection of afterglow emission
  69. GRB 050306: Radio Observations
  70. GRB 050306: optical afterglow
  71. Swift-BAT trigger 107873: No Swift XRT counterpart
  72. GRB050309: Early optical limit from P60
  73. Swift-BAT trigger 107873 (GRB050309): possible X-ray counterparts
  74. Swift 107873: P60 Optical Observations
  75. GRB 050306: CORRECTION to date of observation
  76. GRB 050306: R-band observations
  77. GRB 050306: No Swift UVOT Optical Counterpart Detected
  78. GRB 050306: REM optical-infrared observations
  79. GRB 050306: Possible X-ray Afterglow Position from the Swift
  80. GRB 050306: TAROT optical observations
  81. GRB050215B: Late-Time Swift UVOT Observations
  82. PROMPT VRcIc Observations of GRB 050223
  83. XRF/GRB 050215B: Radio Observations
  84. GRB 050219b: candidate NIR afterglow
  85. GRB 050223: optical observations
  86. GRB050223: No Swift UVOT Detection of Afterglow Emission
  87. GRB050223: ROTSE-III Optical Observations
  88. GRB 050223: Swift XRT Position
  89. HETE-2 Observations of GRB 050215b (=U11570): A Likely X-Ray Flash
  90. GRB050219b: CORRECTION to time of UVOT observations
  91. GRB050215b: Faulkes North and SDSS limits on UKIRT candidate
  92. GRB050219b: No Swift UVOT Detection of Afterglow Emission
  93. GRB 050219a: Optical observations from LCO
  94. GRB 050219b: Optical and near-IR observations from LCO
  95. GRB050219b: No Swift UVOT Detection of Afterglow Emission
  96. GRB 050219b: CORRECTION: Swift XRT Position
  97. GRB 050219b: Swift XRT Position
  98. GRB 050219a, optical observations
  99. GRB 050219a: Refined XRT position
  100. GRB050219a: No Swift UVOT Detection of Afterglow Emission

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