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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"

42173 results found.

  1. GRB050827: RTT150 optical observations
  2. GRB 050827: Swift-BAT refined analysis
  3. GRB050827: Swift-BAT detection of a burst
  4. Subaru Observations of GRB050724
  5. GRB 050826: Optical Candidate
  6. GRB050824, HETE-2 Observation
  7. GRB 050826: Swift XRT preliminary analysis results
  8. GRB 050826: BAT refined analysis
  9. GRB050826: Swift/UVOT early upper limits
  10. GRB050824: First 2 hours of power low optical decay?
  11. GRB 050826: Swift XRT position
  12. GRB050826: Swift-BAT detection of a long burst
  13. Possible GRB050825:MASTER optical observations
  14. GRB050824: CORRECTION to UVOT observing times
  15. Swift-BAT trigger 152038 is probably not a GRB
  16. GRB050824: Swift/UVOT detection of fading afterglow
  17. GRB050824: decay of the XRT light curve and updated X-ray spectrum
  18. GRB050824, I-band imaging
  19. GRB050824: Radio Observations
  20. GRB 050822: refined XRT analysis
  21. GRB 050824: XRT refined analysis and possible afterglow detection
  22. GRB 050824: BAT refined analysis of a soft weak burst
  23. GRB050824: MASTER:OT decay
  24. GRB050824: MASTER observation OT
  25. GRB050805a: MASTER optical candidat
  26. GRB 050824: ROTSE-III Optical Limits
  27. GRB050824: Swift-BAT detection of a burst
  28. GRB 050824 optical candidate
  29. GRB050820A: RTT150 optical observations
  30. GRB050815: Maidanak optical observation
  31. XRF050509c: Radio upper limits from GMRT
  32. VLT/UVES spectroscopy of GRB050820
  33. GRB050822: Swift/UVOT upper limits
  34. GRB 050820A BAT observations of second, larger episode of emission
  35. GRB050813: Maidanak I-band observations
  36. GRB 050822: Swift-BAT refined analysis
  37. GRB050525, GRB050607, GRB050802 BVRcIc field photometry
  38. GRB050820B at FRAM
  39. GRB050820A: RTT150 optical observations
  40. GRB 050820a - corrections to GCN 3846
  41. GRB 050822: ROTSE-III Prompt Optical Limits
  42. GRB 050822: Swift detection of a long burst
  43. GRB050820A: Radio Observation
  44. GRB050825a - very long GRB like GRB041219a? (Konus-Wind observation)
  45. GRB050820a BVRcIc field photometry
  46. GRB050820B XMM-Newton observation
  47. GRB 050820a: NIR Observations by WIRO
  48. GRB 050820B: Swift XRT position
  49. GRB050820B: Planned XMM-Newton observation
  50. GRB050820B: Refined analysis of the Swift-BAT burst
  51. GRB050820B: BAT-Swift detection of a bright GRB
  52. GRB050820: refined XRT analysis
  53. GRB 050820 Swift-BAT refined analysis
  54. GRB 050820: P60 Temporal Decay Index
  55. GRB 050820: High Resolution Spectroscopy from Keck
  56. GRB050819: refined XRT analysis
  57. GRB050819: RTT150 optical observations
  58. GRB 050820: Swift detection of a GRB
  59. GRB050820: Optical afterglow from P60
  60. GRB 050819 Swift-BAT refined analysis
  61. GRB050819: Swift XRT position
  62. GRB050819: Swift-BAT detection of a weak burst
  63. Swift-BAT trigger 150993 is not a GRB
  64. Swift Trigger 150823 is HETE J1900.1-2455
  65. GRB 050817: Optical observations
  66. GRB 050815: Radio Observation
  67. GRB050814: Radio Observation
  68. GRB050817: Negative Optical Observations
  69. GRB050817: Swift-BAT Detection of a burst
  70. GRB 050814: continued fading
  71. GRB050815: Optical afterglow detection by Swift UVOT
  72. GRB050815: XRT refined analysis
  73. GRB050815: Refined analysis of the Swift-BAT burst
  74. GRB 050815: ROTSE-III Optical Limits
  75. GRB050815: Swift XRT afterglow localization
  76. GRB050815: Swift-BAT detection of a burst
  77. GRB 050730: Third Epoch WSRT Radio Observations
  78. GRB050814: Fading red source
  79. GRB 050813: Gemini Spectra Revisited
  80. GRB050814: P60 Optical Afterglow Candidate
  81. GRB 050813: Non-fading of afterglow candidate
  82. GRB 050814: XRT refined analysis
  83. GRB050814: SWIFT/UVOT observation
  84. GRB050814: Refined analysis of the Swift-BAT burst
  85. GRB050813: Gemini Imaging
  86. GRB 050813: Gemini spectroscopy and redshifts of galaxies B and C
  87. GRB 050814: Swift XRT Afterglow Localization
  88. GRB 050814: Swift detection of a burst
  89. GRB 050813: Magellan detection of a high redshift galaxy cluster
  90. GRB050813: RTT150 optical observations
  91. GRB 050813: I-band observations
  92. GRB050813, SDSS pre-burst observations
  93. GRB 050813: KAIT optical limit
  94. GRB050813: SWIFT/UVOT observation
  95. GRB 050813: Swift XRT afterglow localization
  96. RBO GRB 050714A and GRB 050716 observations
  97. GRB 050813: Possible Short Swift-BAT GRB
  98. Swift-BAT trigger 150131 is not a GRB
  99. GRB050807(=H3889): An X-Ray Rich GRB Localized by HETE
  100. Ongoing activity of SGR 1806-20: an intermediate burst 050811

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