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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. Swift-BAT trigger 150131 is not a GRB
  2. GRB050807(=H3889): An X-Ray Rich GRB Localized by HETE
  3. Ongoing activity of SGR 1806-20: an intermediate burst 050811
  4. GRB050803: CrAO optical observations, no OT candidate
  5. Detection of an intermediate burst from SGR 1806-20 on August 8
  6. GRB 050730: WSRT Radio Observations
  7. GRB 050803: PROMPT BVRcIc Observations
  8. GRB 050807: ROTSE-III Optical Limits
  9. GRB 050730, optical observation
  10. GRB050805b: CrAO optical limit
  11. GRB050805a : Null detection report
  12. GRB050730, optical observations
  13. GRB050803, optical observations
  14. Swift-BAT trigger 149118 is very likely not a GRB
  15. Retraction of Swift Trigger 149131 (GRB 050805B)
  16. GRB 050805b: OHP optical limits
  17. GRB 050805b: TAROT optical limits
  18. GRB050805b: MASTER optical observations
  19. Possible GRB 050805B: Swift-BAT trigger 149131 may be a burst
  20. GRB050805a: MASTER optical candidat
  21. Swift-BAT trigger 149118 is probably not a GRB
  22. GRB050802: TNG optical observations
  23. GRB050803: Radio Observation
  24. GRB 050803: RTT150 optical observations
  25. GRB050801: Radio Observation
  26. GRB050730: Radio Detection
  27. GRB050803: CrAO optical observations, possible OT candidate
  28. GRB050803: Optical/UV Upper Limits from Swift-UVOT
  29. GRB 050803: Keck Observations
  30. GRB 050803: Swift-BAT refined analysis
  31. GRB 050802.422: Fading of the afterglow and detection of the host
  32. GRB050803: MASTER further analys
  33. GRB 050803, optical observations
  34. GRB 050803: Magellan Observations
  35. GRB 050803: early Swift XRT analysis results
  36. GRB 050803: TAROT optical limits
  37. GRB050803: MASTER optical observations
  38. GRB050802: Tentative absorption redshift
  39. GRB050803: Swift-BAT detection of a very long burst
  40. GCN GRB observation 050713A
  41. GRB050730: FORS1 and UVES/VLT low- and high-resolution spectroscopy
  42. GRB 050802: Swift/UVOT optical and UV detections
  43. GRB050802: CrAO optical observations
  44. GRB050801: Unchanged decay slope
  45. GRB050802 radio non-detection
  46. GRB 050730: OHP optical observations
  47. GRB 050802: early Swift XRT analysis results
  48. GRB 050802: Swift/UVOT observations
  49. GRB 050802 : Lulin Optical follow-up observation
  50. GRB 050802: Swift-BAT refined analysis
  51. GRB050801: Optical photometry and decay index
  52. GRB 050802: XRT position
  53. GRB 050802: Swift Gamma-ray Burst
  54. GRB050801: Swift/UVOT Optical and UV detections
  55. GRB 050730: Preliminary Analysis of MIKE Spectrum
  56. GCN 050801: early Swift XRT analysis results
  57. GRB 050801: Swift-BAT refined analysis
  58. GRB 050801, SMARTS optical/IR afterglow observations
  59. GRB 050801, afterglow observations
  60. GRB 050730, corrected photometry and break?
  61. GRB 050801: ROTSE-III Early Afterglow Break
  62. GRB050801: Swift-BAT detection of a burst
  63. GRB050801: GCN XRT position is incorrect
  64. GRB 050801: ROTSE-III Detection of Possible Counterpart
  65. GRB 050730: XRT refined analysis
  66. Correction to GCN Circ 3476 on GRB050525A
  67. GRB 050730: early TAROT optical observations
  68. GRB 050726: PROMPT Rc Observations
  69. GRB 050730: RTT150 optical observations
  70. Swift/UVOT photometry of GRB050730
  71. GRB 050730, spectra and optical photometry
  72. GRB050730: Refined BAT analysis of the Swift-BAT burst
  73. GRB 050730: Swift XRT afterglow observations
  74. GRB 050730 XMM-Newton observation
  75. GRB 050730: PROMPT VRcIc Observations
  76. GRB050730, afterglow observations
  77. GRB050730: confirmation of redshift
  78. GRB 050730: Redshift Measurement based on Magellan/MIKE Observations
  79. GRB 050730, SMARTS optical/IR afterglow observations
  80. GRB 050730 : Planned XMM-Newton observation
  81. GRB050730: Liverpool Telescope optical observations
  82. GRB 050730, optical candidate
  83. GRB050730: Swift-BAT detection of a weak burst
  84. GRB 050713A: Swift XRT extended light curve
  85. GRB 050709: PROMPT Rc Observations
  86. GRB050713b: Maidanak optical observations
  87. GRB 050724: Secure Host Redshift from Keck
  88. GRB 050724: WHT optical observations
  89. GRB050726: Swift UVOT observations
  90. GRB 050724: Chandra Observations of the X-ray Afterglow
  91. GRB050724: Refined Radio Position
  92. GRB050713: analysis of the XMM-Newton observation
  93. GRB 050724, SMARTS optical/IR afterglow observations
  94. GRB 050726, SMARTS optical/IR observations
  95. Swift-BAT trigger 147918 is not a real GRB
  96. GRB 050727: RTT150 optical observations
  97. GRB050724: VLT observations of the variable source
  98. GRB050727: KAIT optical limit
  99. GRB050709: Second Epoch Chandra Observation
  100. GRB 050726: PROMPT Rc Observations

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