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

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