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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. GRB050820B at FRAM
  2. GRB050820A: RTT150 optical observations
  3. GRB 050820a - corrections to GCN 3846
  4. Swift/UVOT UV Photometry of GRB 050820B
  5. GRB 050822: ROTSE-III Prompt Optical Limits
  6. GRB 050822: Swift detection of a long burst
  7. Correction to Eiso calculation in GCN 3835 on GRB 050820A
  8. GRB050820A: Radio Observation
  9. GRB050825a - very long GRB like GRB041219a? (Konus-Wind observation)
  10. GRB050820a BVRcIc field photometry
  11. GRB050820B XMM-Newton observation
  12. GRB 050820a: NIR Observations by WIRO
  13. GRB 050820B: Swift XRT position
  14. GRB050820B: Planned XMM-Newton observation
  15. GRB050820B: Refined analysis of the Swift-BAT burst
  16. GRB050820B: BAT-Swift detection of a bright GRB
  17. Swift/UVOT photometry of GRB050820
  18. GRB050820: refined XRT analysis
  19. GRB 050820: Early RAPTOR detections
  20. GRB 050820 Swift-BAT refined analysis
  21. GRB 050820: P60 Temporal Decay Index
  22. GRB 050820: High Resolution Spectroscopy from Keck
  23. GRB050819: refined XRT analysis
  24. GRB050819: RTT150 optical observations
  25. GRB 050820: Swift detection of a GRB
  26. GRB050820: Optical afterglow from P60
  27. GRB 050819 Swift-BAT refined analysis
  28. GRB050819: Swift XRT position
  29. GRB050819: Swift-BAT detection of a weak burst
  30. Swift-BAT trigger 150993 is not a GRB
  31. Swift Trigger 150823 is HETE J1900.1-2455
  32. GRB 050817: Optical observations
  33. GRB 050815: Radio Observation
  34. GRB050814: Radio Observation
  35. GRB050817: Negative Optical Observations
  36. GRB050817: Swift-BAT Detection of a burst
  37. GRB 050814: continued fading
  38. GRB050815: Optical afterglow detection by Swift UVOT
  39. GRB050815: XRT refined analysis
  40. GRB 050813: Radio Observations
  41. GRB050815: Refined analysis of the Swift-BAT burst
  42. GRB 050815: ROTSE-III Optical Limits
  43. GRB050815: Swift XRT afterglow localization
  44. GRB050815: Swift-BAT detection of a burst
  45. GRB 050730: Third Epoch WSRT Radio Observations
  46. GRB050814: Fading red source
  47. GRB 050813: Gemini Spectra Revisited
  48. GRB050814: P60 Optical Afterglow Candidate
  49. GRB 050813: Non-fading of afterglow candidate
  50. GRB 050814: XRT refined analysis
  51. GRB050814: SWIFT/UVOT observation
  52. GRB050814: Refined analysis of the Swift-BAT burst
  53. GRB050813: Gemini Imaging
  54. GRB 050813: Gemini spectroscopy and redshifts of galaxies B and C
  55. GRB 050814: Swift XRT Afterglow Localization
  56. GRB 050814: Swift detection of a burst
  57. GRB 050813: Magellan detection of a high redshift galaxy cluster
  58. GRB050813: RTT150 optical observations
  59. GRB 050813: I-band observations
  60. GRB050813, SDSS pre-burst observations
  61. GRB 050813: KAIT optical limit
  62. GRB 050813: Swift-BAT refined analysis
  63. GRB 050813: Photometry of object in XRT error circle
  64. GRB050813: SWIFT/UVOT observation
  65. GRB 050813: Swift XRT afterglow localization
  66. RBO GRB 050714A and GRB 050716 observations
  67. GRB 050813: Possible Short Swift-BAT GRB
  68. GRB050813 (Swift 150139): P60 Observations
  69. Swift-BAT trigger 150131 is not a GRB
  70. GRB050807(=H3889): An X-Ray Rich GRB Localized by HETE
  71. Ongoing activity of SGR 1806-20: an intermediate burst 050811
  72. GRB050803: CrAO optical observations, no OT candidate
  73. Detection of an intermediate burst from SGR 1806-20 on August 8
  74. GRB 050730: WSRT Radio Observations
  75. GRB 050803: PROMPT BVRcIc Observations
  76. GRB 050807: ROTSE-III Optical Limits
  77. GRB 050730, optical observation
  78. GRB050805b: CrAO optical limit
  79. GRB050805a : Null detection report
  80. GRB050730, optical observations
  81. GRB050803, optical observations
  82. Swift-BAT trigger 149118 is very likely not a GRB
  83. Retraction of Swift Trigger 149131 (GRB 050805B)
  84. GRB 050805b: OHP optical limits
  85. GRB 050805b: TAROT optical limits
  86. GRB050805b: MASTER optical observations
  87. Possible GRB 050805B: Swift-BAT trigger 149131 may be a burst
  88. GRB050805a: MASTER optical candidat
  89. Swift-BAT trigger 149118 is probably not a GRB
  90. GRB050802: TNG optical observations
  91. GRB050803: Radio Observation
  92. GRB 050803: RTT150 optical observations
  93. GRB050801: Radio Observation
  94. GRB050730: Radio Detection
  95. GRB050803: CrAO optical observations, possible OT candidate
  96. GRB050803: Optical/UV Upper Limits from Swift-UVOT
  97. GRB 050803: Keck Observations
  98. GRB 050803: Swift-BAT refined analysis
  99. GRB 050802.422: Fading of the afterglow and detection of the host
  100. GRB050803: MASTER further analys

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