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

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