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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. RBO GRB 050714A and GRB 050716 observations
  2. GRB 050813: Possible Short Swift-BAT GRB
  3. GRB050813 (Swift 150139): P60 Observations
  4. Swift-BAT trigger 150131 is not a GRB
  5. GRB050807(=H3889): An X-Ray Rich GRB Localized by HETE
  6. Ongoing activity of SGR 1806-20: an intermediate burst 050811
  7. GRB050803: CrAO optical observations, no OT candidate
  8. Detection of an intermediate burst from SGR 1806-20 on August 8
  9. GRB 050730: WSRT Radio Observations
  10. GRB 050803: PROMPT BVRcIc Observations
  11. GRB 050807: ROTSE-III Optical Limits
  12. GRB 050730, optical observation
  13. GRB050805b: CrAO optical limit
  14. GRB050805a : Null detection report
  15. GRB050730, optical observations
  16. GRB050803, optical observations
  17. Swift-BAT trigger 149118 is very likely not a GRB
  18. Retraction of Swift Trigger 149131 (GRB 050805B)
  19. GRB 050805b: OHP optical limits
  20. GRB 050805b: TAROT optical limits
  21. GRB050805b: MASTER optical observations
  22. Possible GRB 050805B: Swift-BAT trigger 149131 may be a burst
  23. GRB050805a: MASTER optical candidat
  24. Swift-BAT trigger 149118 is probably not a GRB
  25. GRB050802: TNG optical observations
  26. GRB050803: Radio Observation
  27. GRB 050803: RTT150 optical observations
  28. GRB050801: Radio Observation
  29. GRB050730: Radio Detection
  30. GRB050803: CrAO optical observations, possible OT candidate
  31. GRB050803: Optical/UV Upper Limits from Swift-UVOT
  32. GRB 050803: Keck Observations
  33. GRB 050803: Swift-BAT refined analysis
  34. GRB 050802.422: Fading of the afterglow and detection of the host
  35. GRB050803: MASTER further analys
  36. GRB 050803, optical observations
  37. GRB 050803: Magellan Observations
  38. GRB 050803: early Swift XRT analysis results
  39. GRB 050803: TAROT optical limits
  40. GRB050803: MASTER optical observations
  41. GRB050802: Tentative absorption redshift
  42. GRB050803: Swift-BAT detection of a very long burst
  43. GCN GRB observation 050713A
  44. GRB050730: FORS1 and UVES/VLT low- and high-resolution spectroscopy
  45. GRB 050802: Swift/UVOT optical and UV detections
  46. GRB050802: CrAO optical observations
  47. GRB050801: Unchanged decay slope
  48. GRB050802 radio non-detection
  49. GRB 050730: OHP optical observations
  50. GRB 050802: early Swift XRT analysis results
  51. GRB 050802: Swift/UVOT observations
  52. GRB 050802 : Lulin Optical follow-up observation
  53. GRB 050802: Swift-BAT refined analysis
  54. GRB050801: Optical photometry and decay index
  55. GRB 050802: XRT position
  56. GRB 050802: Swift Gamma-ray Burst
  57. GRB050801: Swift/UVOT Optical and UV detections
  58. GRB 050730: Preliminary Analysis of MIKE Spectrum
  59. GCN 050801: early Swift XRT analysis results
  60. GRB 050801: Swift-BAT refined analysis
  61. GRB 050801, SMARTS optical/IR afterglow observations
  62. GRB 050801, afterglow observations
  63. GRB 050730, corrected photometry and break?
  64. GRB 050801: ROTSE-III Early Afterglow Break
  65. GRB050801: Swift-BAT detection of a burst
  66. GRB050801: GCN XRT position is incorrect
  67. GRB 050801: ROTSE-III Detection of Possible Counterpart
  68. GRB 050730: XRT refined analysis
  69. Correction to GCN Circ 3476 on GRB050525A
  70. GRB 050730: early TAROT optical observations
  71. GRB 050726: PROMPT Rc Observations
  72. GRB 050730: RTT150 optical observations
  73. Swift/UVOT photometry of GRB050730
  74. GRB 050730, spectra and optical photometry
  75. GRB050730: Refined BAT analysis of the Swift-BAT burst
  76. GRB 050730: Swift XRT afterglow observations
  77. GRB 050730 XMM-Newton observation
  78. GRB 050730: PROMPT VRcIc Observations
  79. GRB050730, afterglow observations
  80. GRB050730: confirmation of redshift
  81. GRB 050730: Redshift Measurement based on Magellan/MIKE Observations
  82. GRB 050730, SMARTS optical/IR afterglow observations
  83. GRB 050730 : Planned XMM-Newton observation
  84. GRB050730: Liverpool Telescope optical observations
  85. GRB 050730, optical candidate
  86. GRB050730: Swift-BAT detection of a weak burst
  87. GRB 050713A: Swift XRT extended light curve
  88. GRB 050709: PROMPT Rc Observations
  89. GRB050713b: Maidanak optical observations
  90. GRB 050724: Secure Host Redshift from Keck
  91. GRB 050724: WHT optical observations
  92. GRB050726: Swift UVOT observations
  93. GRB 050724: Chandra Observations of the X-ray Afterglow
  94. GRB050724: Refined Radio Position
  95. GRB050713: analysis of the XMM-Newton observation
  96. GRB 050724, SMARTS optical/IR afterglow observations
  97. GRB 050726, SMARTS optical/IR observations
  98. Swift-BAT trigger 147918 is not a real GRB
  99. GRB 050727: RTT150 optical observations
  100. GRB050724: VLT observations of the variable source

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