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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"

36156 results found.

  1. GRB 050827: Swift XRT preliminary analysis results
  2. IBAS Alerts 2641 and 2642: not a real GRB
  3. Swift Trigger #152652 is not a GRB
  4. GRB 050827 : OSN 1.5m optical observations
  5. GRB 050827: P200 NIR Observations
  6. GRB 050827: Optical Limit
  7. GRB 050827: XRT possible afterglow detection
  8. GRB 050826 : Lulin R band observation
  9. GRB050824: Maidanak optical limits
  10. GRB050820A: RTT150 optical observations
  11. GRB050827: RTT150 optical observations
  12. GRB 050827: Swift-BAT refined analysis
  13. GRB 050826: Optical Candidate
  14. GRB050824, HETE-2 Observation
  15. GRB 050826: Swift XRT preliminary analysis results
  16. GRB 050826: BAT refined analysis
  17. GRB050824: First 2 hours of power low optical decay?
  18. GRB 050826: Swift XRT position
  19. GRB050826: Swift-BAT detection of a long burst
  20. GRB050824: MASTER final analysis of the OT observations
  21. Possible GRB050825:MASTER optical observations
  22. Swift-BAT trigger 152038 is definitely not a GRB
  23. Swift-BAT trigger 152038 is probably not a GRB
  24. GRB050824: decay of the XRT light curve and updated X-ray spectrum
  25. GRB050824, I-band imaging
  26. GRB050824: Radio Observations
  27. GRB 050824: Spectroscopic redshift from the VLT
  28. GRB 050822: refined XRT analysis
  29. GRB 050824: XRT refined analysis and possible afterglow detection
  30. GRB 050824: BAT refined analysis of a soft weak burst
  31. GRB050824: MASTER:OT decay
  32. GRB050824: MASTER observation OT
  33. GRB050805a: MASTER optical candidat
  34. GRB 050824: ROTSE-III Optical Limits
  35. GRB050824: Swift-BAT detection of a burst
  36. GRB 050824 optical candidate
  37. GRB050820A: RTT150 optical observations
  38. GRB050820a: PROMPT RcIc Observations
  39. GRB050815: Maidanak optical observation
  40. XRF050509c: Radio upper limits from GMRT
  41. VLT/UVES spectroscopy of GRB050820
  42. GRB 050820A BAT observations of second, larger episode of emission
  43. GRB050813: Maidanak I-band observations
  44. GRB 050822: Swift-BAT refined analysis
  45. GRB050525, GRB050607, GRB050802 BVRcIc field photometry
  46. GRB050820B at FRAM
  47. GRB050820A: RTT150 optical observations
  48. GRB 050820a - corrections to GCN 3846
  49. Swift/UVOT UV Photometry of GRB 050820B
  50. GRB 050822: ROTSE-III Prompt Optical Limits
  51. GRB 050822: Swift detection of a long burst
  52. Correction to Eiso calculation in GCN 3835 on GRB 050820A
  53. GRB050820A: Radio Observation
  54. GRB050825a - very long GRB like GRB041219a? (Konus-Wind observation)
  55. GRB050820a BVRcIc field photometry
  56. GRB 050820a: NIR Observations by WIRO
  57. GRB 050820B: Swift XRT position
  58. GRB050820B: Refined analysis of the Swift-BAT burst
  59. GRB050820B: BAT-Swift detection of a bright GRB
  60. GRB050820: refined XRT analysis
  61. GRB 050820: Early RAPTOR detections
  62. GRB 050820 Swift-BAT refined analysis
  63. GRB 050820: P60 Temporal Decay Index
  64. GRB 050820: High Resolution Spectroscopy from Keck
  65. GRB050819: RTT150 optical observations
  66. GRB 050820: Swift detection of a GRB
  67. GRB 050819 Swift-BAT refined analysis
  68. GRB050819: Swift XRT position
  69. GRB050819: Swift-BAT detection of a weak burst
  70. Swift-BAT trigger 150993 is not a GRB
  71. Swift Trigger 150823 is HETE J1900.1-2455
  72. GRB 050817: Optical observations
  73. GRB 050815: Radio Observation
  74. GRB050814: Radio Observation
  75. GRB050817: Negative Optical Observations
  76. GRB 050814: continued fading
  77. GRB 050813: Radio Observations
  78. GRB050815: Refined analysis of the Swift-BAT burst
  79. GRB 050815: ROTSE-III Optical Limits
  80. GRB050815: Swift XRT afterglow localization
  81. GRB 050730: Third Epoch WSRT Radio Observations
  82. GRB050814: Fading red source
  83. GRB 050813: Gemini Spectra Revisited
  84. GRB 050813: Non-fading of afterglow candidate
  85. GRB 050814: XRT refined analysis
  86. GRB050814: Refined analysis of the Swift-BAT burst
  87. GRB050813: Gemini Imaging
  88. GRB 050813: Gemini spectroscopy and redshifts of galaxies B and C
  89. GRB 050814: Swift XRT Afterglow Localization
  90. GRB 050814: Swift detection of a burst
  91. GRB 050813: Magellan detection of a high redshift galaxy cluster
  92. GRB050813: RTT150 optical observations
  93. GRB 050813: I-band observations
  94. GRB050813, SDSS pre-burst observations
  95. GRB 050813: KAIT optical limit
  96. GRB 050813: Swift-BAT refined analysis
  97. GRB 050813: Photometry of object in XRT error circle
  98. GRB 050813: Swift XRT afterglow localization
  99. RBO GRB 050714A and GRB 050716 observations
  100. GRB 050813: Possible Short Swift-BAT GRB

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