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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. GRB050820a: PROMPT RcIc Observations
  2. GRB050815: Maidanak optical observation
  3. XRF050509c: Radio upper limits from GMRT
  4. VLT/UVES spectroscopy of GRB050820
  5. GRB050822: Swift/UVOT upper limits
  6. GRB 050820A BAT observations of second, larger episode of emission
  7. GRB050813: Maidanak I-band observations
  8. GRB 050822: Swift-BAT refined analysis
  9. GRB050525, GRB050607, GRB050802 BVRcIc field photometry
  10. GRB050820B at FRAM
  11. GRB050820A: RTT150 optical observations
  12. GRB 050820a - corrections to GCN 3846
  13. Swift/UVOT UV Photometry of GRB 050820B
  14. GRB 050822: ROTSE-III Prompt Optical Limits
  15. GRB 050822: Swift detection of a long burst
  16. Correction to Eiso calculation in GCN 3835 on GRB 050820A
  17. GRB050820A: Radio Observation
  18. GRB050825a - very long GRB like GRB041219a? (Konus-Wind observation)
  19. GRB050820a BVRcIc field photometry
  20. GRB050820B XMM-Newton observation
  21. GRB 050820a: NIR Observations by WIRO
  22. GRB 050820B: Swift XRT position
  23. GRB050820B: Planned XMM-Newton observation
  24. GRB050820B: Refined analysis of the Swift-BAT burst
  25. GRB050820B: BAT-Swift detection of a bright GRB
  26. Swift/UVOT photometry of GRB050820
  27. GRB050820: refined XRT analysis
  28. GRB 050820: Early RAPTOR detections
  29. GRB 050820 Swift-BAT refined analysis
  30. GRB 050820: P60 Temporal Decay Index
  31. GRB 050820: High Resolution Spectroscopy from Keck
  32. GRB050819: refined XRT analysis
  33. GRB050819: RTT150 optical observations
  34. GRB 050820: Swift detection of a GRB
  35. GRB050820: Optical afterglow from P60
  36. GRB 050819 Swift-BAT refined analysis
  37. GRB050819: Swift XRT position
  38. GRB050819: Swift-BAT detection of a weak burst
  39. Swift-BAT trigger 150993 is not a GRB
  40. Swift Trigger 150823 is HETE J1900.1-2455
  41. GRB 050817: Optical observations
  42. GRB 050815: Radio Observation
  43. GRB050814: Radio Observation
  44. GRB050817: Negative Optical Observations
  45. GRB050817: Swift-BAT Detection of a burst
  46. GRB 050814: continued fading
  47. GRB050815: Optical afterglow detection by Swift UVOT
  48. GRB050815: XRT refined analysis
  49. GRB 050813: Radio Observations
  50. GRB050815: Refined analysis of the Swift-BAT burst
  51. GRB 050815: ROTSE-III Optical Limits
  52. GRB050815: Swift XRT afterglow localization
  53. GRB050815: Swift-BAT detection of a burst
  54. GRB 050730: Third Epoch WSRT Radio Observations
  55. GRB050814: Fading red source
  56. GRB 050813: Gemini Spectra Revisited
  57. GRB050814: P60 Optical Afterglow Candidate
  58. GRB 050813: Non-fading of afterglow candidate
  59. GRB 050814: XRT refined analysis
  60. GRB050814: SWIFT/UVOT observation
  61. GRB050814: Refined analysis of the Swift-BAT burst
  62. GRB050813: Gemini Imaging
  63. GRB 050813: Gemini spectroscopy and redshifts of galaxies B and C
  64. GRB 050814: Swift XRT Afterglow Localization
  65. GRB 050814: Swift detection of a burst
  66. GRB 050813: Magellan detection of a high redshift galaxy cluster
  67. GRB050813: RTT150 optical observations
  68. GRB 050813: I-band observations
  69. GRB050813, SDSS pre-burst observations
  70. GRB 050813: KAIT optical limit
  71. GRB 050813: Swift-BAT refined analysis
  72. GRB 050813: Photometry of object in XRT error circle
  73. GRB050813: SWIFT/UVOT observation
  74. GRB 050813: Swift XRT afterglow localization
  75. RBO GRB 050714A and GRB 050716 observations
  76. GRB 050813: Possible Short Swift-BAT GRB
  77. GRB050813 (Swift 150139): P60 Observations
  78. Swift-BAT trigger 150131 is not a GRB
  79. GRB050807(=H3889): An X-Ray Rich GRB Localized by HETE
  80. Ongoing activity of SGR 1806-20: an intermediate burst 050811
  81. GRB050803: CrAO optical observations, no OT candidate
  82. Detection of an intermediate burst from SGR 1806-20 on August 8
  83. GRB 050730: WSRT Radio Observations
  84. GRB 050803: PROMPT BVRcIc Observations
  85. GRB 050807: ROTSE-III Optical Limits
  86. GRB 050730, optical observation
  87. GRB050805b: CrAO optical limit
  88. GRB050805a : Null detection report
  89. GRB050730, optical observations
  90. GRB050803, optical observations
  91. Swift-BAT trigger 149118 is very likely not a GRB
  92. Retraction of Swift Trigger 149131 (GRB 050805B)
  93. GRB 050805b: OHP optical limits
  94. GRB 050805b: TAROT optical limits
  95. GRB050805b: MASTER optical observations
  96. Possible GRB 050805B: Swift-BAT trigger 149131 may be a burst
  97. GRB050805a: MASTER optical candidat
  98. Swift-BAT trigger 149118 is probably not a GRB
  99. GRB050802: TNG optical observations
  100. GRB050803: Radio Observation

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