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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. XRF 050522: Swift XRT refined analysis
  2. XRF050522: Radio Observations
  3. Swift/UVOT observation of XRF 050522
  4. GRB 050509A: Further I-band imaging
  5. GRB050522,optical observation
  6. GRB050520,optical observation
  7. XRF 050522: Continued NIR P200 Monitoring
  8. RBO Observations of GRB050522
  9. GRB050509b: optical observations
  10. Recent GRB BVRcIc field photometry
  11. GRB050520: Radio Observations
  12. XRF 050522: Swift XRT observation
  13. XRF050522, BVRcIc field photometry
  14. XRF 050522 : Lulin observations
  15. XRF050522: Optical Observations
  16. XRF050522: Near-infrared Observations
  17. XRF 050522: KAIT observations
  18. XRF 050522 detected with INTEGRAL
  19. GRB 050520: VLT/ULTRACAM observations
  20. Swift UVOT Observations of GRB 050520
  21. GRB 050520: Swift XRT refined analysis
  22. XRF050509C: Chandra Afterglow Detection
  23. XRF 050509c: Swift XRT Upper Limit
  24. XRF050509c: Radio Observations
  25. RBO Observations of GRB050520
  26. GRB 050520: P200 Observations
  27. GRB050520: Liverpool Telescope follow-up
  28. RBO Observations of GRB050520
  29. GRB 050520: TAROT optical limit
  30. GRB 050520: Swift XRT position
  31. GRB 050520: VLT/ULTRACAM observations
  32. GRB 050520: OSN optical observations
  33. GRB 050520: BART optical limit
  34. GRB 050520 - A long GRB detected with INTEGRAL
  35. No Swift-BAT Lightcurves in real-time for next 3 weeks
  36. Swift-BAT trigger 122203 is not a real GRB
  37. XRF 050509C: REM NIR and Optical refined analysis
  38. GRB 050504: Swift XRT afterglow candidate has faded
  39. XRF 050509c optical afterglow
  40. GRB 050509B and short GRB-SN association? (corrected)
  41. GRB 050509B and short GRB-SN association?
  42. GRB 050509B: Subaru Optical Observations
  43. GRB050502b: Early Observation
  44. GRB050509b, Bok telescope B-band imaging
  45. Refined Chandra analysis of GRB 050509b
  46. GRB050509b, SDSS pre-burst observations
  47. GRB 050509b: Keck/Chandra Cross-Correlation
  48. GRB 050509b: Keck/Chandra Cross-Correlation
  49. Chandra observation of GRB 050509b
  50. GRB 050509b: RAPTOR deep, early limits.
  51. GRB050509B: Optical/Infared observations
  52. GRB 050509b: Swift/UVOT follow-up measurements
  53. GRB 050509b Milagro GeV/TeV Observations
  54. GRB050509B: Optical observations at the Very Large Telescope
  55. GRB 050509b: No Optical Variability in XRT Error Circle
  56. GRB050416: Afterglow detection at 188 nm with Swift UVOT
  57. GRB 050509a: Swift-BAT refined analysis
  58. GRB 050509c: ROTSE-III Optical Limits
  59. GRB 050509B: WSRT Radio Observations
  60. GRB050509c: REM NIR and Optical observations (errata corrige to GCN 3400)
  61. GRB 050505, early TAROT observation
  62. GRB050509c (=H3751): An X-Ray Flash Localized By HETE
  63. GRB 050509b: Further Analysis of Keck LRIS Images
  64. GRB050509c: REM NIR and Optical observations
  65. GRB 050509b: Physical Properties of the Candidate Host galaxy
  66. GRB 050505: SARA Observations
  67. Swift UVOT Follow-up Observations of GRB 050509B
  68. GRB 050509B, Optical Observations
  69. GRB 050509B: Swift/XRT refined analysis
  70. GRB050509a: Swift UVOT observations
  71. GRB 050509b: Optical observations
  72. GRB 050509b: Precision Astrometry
  73. GRB 050509b: Possible Optical Counterpart
  74. Keck/DEIMOS Spectrum of Possible Host Galaxy for GRB050509b
  75. GRB 050509A: Optical observations
  76. GRB 050509b: Optical Counterpart Candidate
  77. GRB050509b: Radio Observations
  78. GRB 050509b: PAIRITEL and WIYN Observations
  79. GRB 050509b: Swift-BAT refined analysis of the short hard burst
  80. GRB 050509b: optical observations
  81. GRB 050509b: Swift XRT Position
  82. GRB 050509B: ROTSE-III Optical Limits
  83. Swift Detection of GRB050509b: A short duration burst
  84. GRB 050509a: Swift XRT Position
  85. Swift Detection of the Burst GRB050509
  86. Swift-BAT detection of GRB 050507
  87. GRB 050505: Keck I-band Magnitude
  88. GRB 050505: early time observations
  89. GRB 050505 - Faulkes Telescope North observations
  90. GRB 050502a: Swift XRT Upper Limit
  91. GRB 050505, simultaneous optical observation
  92. GRB050505: Infrared observations
  93. GRB 050505: Further Swift UVOT observations.
  94. GRB050505: AAVSO observations
  95. GRB050416A : 1 GHz limit from GMRT
  96. GRB 050505: Keck absorption spectrum and redshift (z=4.27)
  97. GRB 050505 UVOT
  98. GRB050505: Optical Afterglow Candidate
  99. GRB 050505: Swift XRT Position
  100. GRB050505 Swift-BAT refined analysis

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