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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"

36181 results found.

  1. XRF050522: Radio Observations
  2. GRB 050509A: Further I-band imaging
  3. GRB050522,optical observation
  4. GRB050520,optical observation
  5. XRF 050522: Continued NIR P200 Monitoring
  6. RBO Observations of GRB050522
  7. GRB050509b: optical observations
  8. Recent GRB BVRcIc field photometry
  9. GRB050520: Radio Observations
  10. XRF050522, BVRcIc field photometry
  11. XRF050522: Optical Observations
  12. XRF 050522: KAIT observations
  13. XRF 050522 detected with INTEGRAL
  14. GRB 050520: VLT/ULTRACAM observations
  15. Swift UVOT Observations of GRB 050520
  16. GRB 050520: Swift XRT refined analysis
  17. RBO Observations of GRB050520
  18. GRB 050520: P200 Observations
  19. GRB050520: Liverpool Telescope follow-up
  20. GRB 050520: TAROT optical limit
  21. GRB 050520: Swift XRT position
  22. GRB 050520: VLT/ULTRACAM observations
  23. GRB 050520: OSN optical observations
  24. GRB 050520: BART optical limit
  25. GRB 050520 - A long GRB detected with INTEGRAL
  26. Swift-BAT trigger 122203 is not a real GRB
  27. GRB 050504: Swift XRT afterglow candidate has faded
  28. XRF 050509c optical afterglow
  29. GRB 050509B and short GRB-SN association? (corrected)
  30. GRB 050509B and short GRB-SN association?
  31. GRB 050509B: Subaru Optical Observations
  32. GRB050502b: Early Observation
  33. GRB050509b, Bok telescope B-band imaging
  34. Refined Chandra analysis of GRB 050509b
  35. GRB050509b, SDSS pre-burst observations
  36. GRB 050509b: Keck/Chandra Cross-Correlation
  37. GRB 050509b: Keck/Chandra Cross-Correlation
  38. Chandra observation of GRB 050509b
  39. GRB 050509b: RAPTOR deep, early limits.
  40. GRB050509B: Optical/Infared observations
  41. GRB 050509b: Swift/UVOT follow-up measurements
  42. GRB 050509b Milagro GeV/TeV Observations
  43. GRB050509B: Optical observations at the Very Large Telescope
  44. GRB 050509b: No Optical Variability in XRT Error Circle
  45. GRB 050509a: Swift-BAT refined analysis
  46. GRB 050509c: ROTSE-III Optical Limits
  47. GRB 050509B: WSRT Radio Observations
  48. GRB050509c: REM NIR and Optical observations (errata corrige to GCN 3400)
  49. GRB 050505, early TAROT observation
  50. GRB050509c (=H3751): An X-Ray Flash Localized By HETE
  51. GRB 050509b: Further Analysis of Keck LRIS Images
  52. GRB050509c: REM NIR and Optical observations
  53. GRB 050509b: Physical Properties of the Candidate Host galaxy
  54. GRB 050505: SARA Observations
  55. Swift UVOT Follow-up Observations of GRB 050509B
  56. GRB 050509B, Optical Observations
  57. GRB 050509B: Swift/XRT refined analysis
  58. GRB 050509b: Optical observations
  59. GRB 050509b: Precision Astrometry
  60. GRB 050509b: Possible Optical Counterpart
  61. Keck/DEIMOS Spectrum of Possible Host Galaxy for GRB050509b
  62. GRB 050509A: Optical observations
  63. GRB 050509b: Optical Counterpart Candidate
  64. GRB 050509b: PAIRITEL and WIYN Observations
  65. GRB 050509b: Swift-BAT refined analysis of the short hard burst
  66. GRB 050509b: optical observations
  67. GRB 050509b: Swift XRT Position
  68. GRB 050509B: ROTSE-III Optical Limits
  69. GRB 050509a: Swift XRT Position
  70. Swift-BAT detection of GRB 050507
  71. GRB 050505: Keck I-band Magnitude
  72. GRB 050505: early time observations
  73. GRB 050505 - Faulkes Telescope North observations
  74. GRB 050502a: Swift XRT Upper Limit
  75. GRB 050505, simultaneous optical observation
  76. GRB 050505: Further Swift UVOT observations.
  77. GRB050505: AAVSO observations
  78. GRB050416A : 1 GHz limit from GMRT
  79. GRB 050505: Keck absorption spectrum and redshift (z=4.27)
  80. GRB 050505 UVOT
  81. GRB050505: Optical Afterglow Candidate
  82. GRB 050505: Swift XRT Position
  83. GRB 050502a: Optical Observations
  84. GRB 050416b:Swift XRT afterglow upper limits
  85. GRB 050416b:Swift XRT afterglow upper limits
  86. GRB 050504: Swift XRT position
  87. GRB050502: P200 Observations (Correction)
  88. GRB050502: P200 Observations
  89. GRB 050504 : R band observation at Lulin observatory
  90. Swift UVOT observation of GRB 050504
  91. GRB 050504, R band Observations
  92. GRB 050502b, V band Observations
  93. GRB050504: P60 Observations
  94. GRB 050504: A long GRB detected with INTEGRAL
  95. GRB (?) 050504: IR Observations, Intriguing Source
  96. GRB 050502b, Optical observations
  97. GRB050502a: P60 Observations (Correction)
  98. GRB050502a: P60 Observations
  99. Renewal of SGR 1806-20 activity
  100. GRB 050502a: RBO Observations

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