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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. GRB050805a: MASTER optical candidat
  2. Swift-BAT trigger 149118 is probably not a GRB
  3. GRB050802: TNG optical observations
  4. GRB050803: Radio Observation
  5. GRB 050803: RTT150 optical observations
  6. GRB050801: Radio Observation
  7. GRB050730: Radio Detection
  8. GRB050803: CrAO optical observations, possible OT candidate
  9. GRB050803: Optical/UV Upper Limits from Swift-UVOT
  10. GRB 050803: Keck Observations
  11. GRB 050803: Swift-BAT refined analysis
  12. GRB 050802.422: Fading of the afterglow and detection of the host
  13. GRB050803: MASTER further analys
  14. GRB 050803, optical observations
  15. GRB 050803: Magellan Observations
  16. GRB 050803: early Swift XRT analysis results
  17. GRB 050803: TAROT optical limits
  18. GRB050803: MASTER optical observations
  19. GRB050802: Tentative absorption redshift
  20. GRB050803: Swift-BAT detection of a very long burst
  21. GCN GRB observation 050713A
  22. GRB050730: FORS1 and UVES/VLT low- and high-resolution spectroscopy
  23. GRB 050802: Swift/UVOT optical and UV detections
  24. GRB050802: CrAO optical observations
  25. GRB050801: Unchanged decay slope
  26. GRB050802 radio non-detection
  27. GRB 050730: OHP optical observations
  28. GRB 050802: early Swift XRT analysis results
  29. GRB 050802: Swift/UVOT observations
  30. GRB 050802 : Lulin Optical follow-up observation
  31. GRB 050802: Swift-BAT refined analysis
  32. GRB050801: Optical photometry and decay index
  33. GRB 050802: XRT position
  34. GRB 050802: Swift Gamma-ray Burst
  35. GRB050801: Swift/UVOT Optical and UV detections
  36. GRB 050730: Preliminary Analysis of MIKE Spectrum
  37. GCN 050801: early Swift XRT analysis results
  38. GRB 050801: Swift-BAT refined analysis
  39. GRB 050801, SMARTS optical/IR afterglow observations
  40. GRB 050801, afterglow observations
  41. GRB 050730, corrected photometry and break?
  42. GRB 050801: ROTSE-III Early Afterglow Break
  43. GRB050801: Swift-BAT detection of a burst
  44. GRB050801: GCN XRT position is incorrect
  45. GRB 050801: ROTSE-III Detection of Possible Counterpart
  46. GRB 050730: XRT refined analysis
  47. Correction to GCN Circ 3476 on GRB050525A
  48. GRB 050730: early TAROT optical observations
  49. GRB 050726: PROMPT Rc Observations
  50. GRB 050730: RTT150 optical observations
  51. Swift/UVOT photometry of GRB050730
  52. GRB 050730, spectra and optical photometry
  53. GRB050730: Refined BAT analysis of the Swift-BAT burst
  54. GRB 050730: Swift XRT afterglow observations
  55. GRB 050730 XMM-Newton observation
  56. GRB 050730: PROMPT VRcIc Observations
  57. GRB050730, afterglow observations
  58. GRB050730: confirmation of redshift
  59. GRB 050730: Redshift Measurement based on Magellan/MIKE Observations
  60. GRB 050730, SMARTS optical/IR afterglow observations
  61. GRB 050730 : Planned XMM-Newton observation
  62. GRB050730: Liverpool Telescope optical observations
  63. GRB 050730, optical candidate
  64. GRB050730: Swift-BAT detection of a weak burst
  65. GRB 050713A: Swift XRT extended light curve
  66. GRB 050709: PROMPT Rc Observations
  67. GRB050713b: Maidanak optical observations
  68. GRB 050724: Secure Host Redshift from Keck
  69. GRB 050724: WHT optical observations
  70. GRB050726: Swift UVOT observations
  71. GRB 050724: Chandra Observations of the X-ray Afterglow
  72. GRB050724: Refined Radio Position
  73. GRB050713: analysis of the XMM-Newton observation
  74. GRB 050724, SMARTS optical/IR afterglow observations
  75. GRB 050726, SMARTS optical/IR observations
  76. Swift-BAT trigger 147918 is not a real GRB
  77. GRB 050727: RTT150 optical observations
  78. GRB050724: VLT observations of the variable source
  79. GRB050727: KAIT optical limit
  80. GRB050709: Second Epoch Chandra Observation
  81. GRB 050726: PROMPT Rc Observations
  82. GRB050709: Second Epoch Chandra Observation
  83. GRB 050724: dust-scattered X-ray halo detected in SWIFT/XRT observation
  84. GRB050724: Further Radio Observations
  85. GRB 050726: early Swift XRT analysis results
  86. GRB050726: Swift-BAT detection of a weak burst
  87. GRB 050724: Optical Variability in Nearby Galaxy
  88. GRB 050724: J-band observations
  89. GRB 050724: GMOS Imaging and Spectroscopy
  90. GRB 050724: SWIFT XRT refined position
  91. RXTE ASM Detection of GRB050724
  92. GRB050724: Radio Observation
  93. GRB 050724: spectroscopy of object in the XRT error circle
  94. GRB 050724: Optical limit
  95. GRB 050724: optical and near-IR observations
  96. GRB 050724: Optical imaging/astrometry
  97. GRB 050724: RTT150 optical observations
  98. GRB 050724: Swift/UVOT Upper Limit
  99. GRB 050724: early Swift XRT analysis results
  100. GRB 050724 : Lulin early R-band monitoring observations

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