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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. GRB050824: Maidanak optical limits
  2. GRB050820A: RTT150 optical observations
  3. GRB050827: RTT150 optical observations
  4. GRB 050827: Swift-BAT refined analysis
  5. GRB050827: Swift-BAT detection of a burst
  6. Subaru Observations of GRB050724
  7. GRB 050826: Optical Candidate
  8. GRB050824, HETE-2 Observation
  9. GRB 050826: Swift XRT preliminary analysis results
  10. GRB 050826: BAT refined analysis
  11. GRB050826: Swift/UVOT early upper limits
  12. GRB050824: First 2 hours of power low optical decay?
  13. GRB 050826: Swift XRT position
  14. GRB050826: Swift-BAT detection of a long burst
  15. GRB050824: MASTER final analysis of the OT observations
  16. Possible GRB050825:MASTER optical observations
  17. Swift-BAT trigger 152038 is definitely not a GRB
  18. GRB050824: CORRECTION to UVOT observing times
  19. Swift-BAT trigger 152038 is probably not a GRB
  20. GRB050824: Swift/UVOT detection of fading afterglow
  21. GRB050824: decay of the XRT light curve and updated X-ray spectrum
  22. GRB050824, I-band imaging
  23. GRB050824: Radio Observations
  24. GRB 050824: Spectroscopic redshift from the VLT
  25. GRB 050822: refined XRT analysis
  26. GRB 050824: XRT refined analysis and possible afterglow detection
  27. GRB 050824: BAT refined analysis of a soft weak burst
  28. GRB050824: MASTER:OT decay
  29. GRB050824: MASTER observation OT
  30. GRB050805a: MASTER optical candidat
  31. GRB 050824: ROTSE-III Optical Limits
  32. GRB050824: Swift-BAT detection of a burst
  33. GRB 050824 optical candidate
  34. GRB050820A: RTT150 optical observations
  35. GRB050820a: PROMPT RcIc Observations
  36. GRB050815: Maidanak optical observation
  37. XRF050509c: Radio upper limits from GMRT
  38. VLT/UVES spectroscopy of GRB050820
  39. GRB050822: Swift/UVOT upper limits
  40. GRB 050820A BAT observations of second, larger episode of emission
  41. GRB050813: Maidanak I-band observations
  42. GRB 050822: Swift-BAT refined analysis
  43. GRB050525, GRB050607, GRB050802 BVRcIc field photometry
  44. GRB050820B at FRAM
  45. GRB050820A: RTT150 optical observations
  46. GRB 050820a - corrections to GCN 3846
  47. Swift/UVOT UV Photometry of GRB 050820B
  48. GRB 050822: ROTSE-III Prompt Optical Limits
  49. GRB 050822: Swift detection of a long burst
  50. Correction to Eiso calculation in GCN 3835 on GRB 050820A
  51. GRB050820A: Radio Observation
  52. GRB050825a - very long GRB like GRB041219a? (Konus-Wind observation)
  53. GRB050820a BVRcIc field photometry
  54. GRB050820B XMM-Newton observation
  55. GRB 050820a: NIR Observations by WIRO
  56. GRB 050820B: Swift XRT position
  57. GRB050820B: Planned XMM-Newton observation
  58. GRB050820B: Refined analysis of the Swift-BAT burst
  59. GRB050820B: BAT-Swift detection of a bright GRB
  60. Swift/UVOT photometry of GRB050820
  61. GRB050820: refined XRT analysis
  62. GRB 050820: Early RAPTOR detections
  63. GRB 050820 Swift-BAT refined analysis
  64. GRB 050820: P60 Temporal Decay Index
  65. GRB 050820: High Resolution Spectroscopy from Keck
  66. GRB050819: refined XRT analysis
  67. GRB050819: RTT150 optical observations
  68. GRB 050820: Swift detection of a GRB
  69. GRB050820: Optical afterglow from P60
  70. GRB 050819 Swift-BAT refined analysis
  71. GRB050819: Swift XRT position
  72. GRB050819: Swift-BAT detection of a weak burst
  73. Swift-BAT trigger 150993 is not a GRB
  74. Swift Trigger 150823 is HETE J1900.1-2455
  75. GRB 050817: Optical observations
  76. GRB 050815: Radio Observation
  77. GRB050814: Radio Observation
  78. GRB050817: Negative Optical Observations
  79. GRB050817: Swift-BAT Detection of a burst
  80. GRB 050814: continued fading
  81. GRB050815: Optical afterglow detection by Swift UVOT
  82. GRB050815: XRT refined analysis
  83. GRB 050813: Radio Observations
  84. GRB050815: Refined analysis of the Swift-BAT burst
  85. GRB 050815: ROTSE-III Optical Limits
  86. GRB050815: Swift XRT afterglow localization
  87. GRB050815: Swift-BAT detection of a burst
  88. GRB 050730: Third Epoch WSRT Radio Observations
  89. GRB050814: Fading red source
  90. GRB 050813: Gemini Spectra Revisited
  91. GRB050814: P60 Optical Afterglow Candidate
  92. GRB 050813: Non-fading of afterglow candidate
  93. GRB 050814: XRT refined analysis
  94. GRB050814: SWIFT/UVOT observation
  95. GRB050814: Refined analysis of the Swift-BAT burst
  96. GRB050813: Gemini Imaging
  97. GRB 050813: Gemini spectroscopy and redshifts of galaxies B and C
  98. GRB 050814: Swift XRT Afterglow Localization
  99. GRB 050814: Swift detection of a burst
  100. GRB 050813: Magellan detection of a high redshift galaxy cluster

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