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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"

20558 results found.

  1. GRB 050712: Swift detection of a weak burst
  2. GRB 050709: LCO40 Observations
  3. GRB050709, optical observations
  4. PROMPT Rc Observations of GRB 050709
  5. GRB 050525a: ARC 3.5-meter Optical and NIR Observations
  6. GRB 050525a: ARC 3.5-Meter SPIcam Field Calibration
  7. GRB 050626 optical observations
  8. GRB 050626: Swift XRT observations
  9. GRB 050701, optical observations
  10. GRB 050408: ARC 3.5-meter NIR Observations
  11. Swift UVOT observations of GRB 050701
  12. GRB 050607, radio observations
  13. H11603: An X-ray flare from V4641 Sgr, or a possible XRF
  14. GRB 050525A: Swift Late-Time Decay Rate
  15. GRB050525a: HST Observations
  16. CORRECTION: GRB050603 Swift UVOT Afterglow Observations
  17. H3800 and H3801 on 2005 June 11: two bursts from SGR1806-20 localized by HETE
  18. XRF 050509c: Optical monitoring
  19. XRF050509c: Radio Detection
  20. GRB 050416(a): Host Galaxy Redshift Determination
  21. GRB 050607: MDM Observation
  22. GRB 050607 optical decay
  23. GRB 050607: RTT150 optical observations
  24. GRB050607: refined analysis of prompt REM observations
  25. Swift/UVOT observations of GRB050607
  26. GRB 050607 : Lulin R-band observation
  27. GRB 050607: PROMPT VRcIc Observations
  28. GRB 050607: RAPTOR-S Early Optical Limits
  29. GRB 050525a, Mid-Infrared Observations
  30. GRB 050607: Optical decay and spectral slope
  31. GRB 050607: MDM Observations
  32. GRB 050607 - XRT refined data analysis
  33. Optical Afterglow of GRB 050607
  34. GRB050607: P60 Observations
  35. GRB050607: prompt REM observations
  36. GRB 050603: prediction of t_break
  37. GRB 050603 - XRT data analysis of the first day
  38. GRB 050603: Analysis of UVOT data
  39. GRB050603: Fading Afterglow observed by Swift UVOT
  40. GRB050603, submillimetre observations
  41. GRB 050603: Swift XRT Position
  42. GRB 050603: Swift-BAT refined analysis of a long three-spiked burst
  43. Swift/BAT Detection of GRB050603
  44. GRB 050408: jet break in the XRT light curve
  45. GRB 050525a, infrared observations
  46. GRB 050525a, SMARTS optical/IR afterglow observations
  47. GRB050528, XRT observations
  48. GRB050528: updated Liverpool Telescope limits
  49. Possible GRB050528: no candidate from Liverpool Telescope
  50. GRB050525a: Radio Observations
  51. GRB 050509b: refined XRT/Chandra afterglow position analysis
  52. GRB 050525: RTT150, Optical observations
  53. GRB 050525a: SARA Observations
  54. GRB 050525B: Swift-BAT observations
  55. GRB 050525a: MDM Observations
  56. GRB 050525 : Lulin optical afterglow observations
  57. GRB050525: Super-LOTIS observations
  58. GRB 050525a: Gemini/GMOS Spectra
  59. GRB050306: optical afterglow not confirmed
  60. GRB 050525A: BOOTES simultaneous optical observations
  61. GRB050525: Optical observations
  62. GRB 050525: TAROT observations of the early afterglow
  63. GRB 050525, infrared observations
  64. GRB 050525: observatons of the optical afterglow
  65. GRB 050525: Swift Detection of a Bright, Possibly Short Burst
  66. GRB 050525A: ROTSE-III Detection of Possible Counterpart
  67. XRF050522: NIR observations of XRT candidate
  68. XRF 050522: Swift XRT refined analysis
  69. XRF050522: Radio Observations
  70. XRF 050522: Continued NIR P200 Monitoring
  71. RBO Observations of GRB050522
  72. GRB050509b: optical observations
  73. GRB050520: Radio Observations
  74. XRF 050522: Swift XRT observation
  75. XRF050522, BVRcIc field photometry
  76. XRF 050522 : Lulin observations
  77. XRF050522: Optical Observations
  78. XRF050522: Near-infrared Observations
  79. XRF 050522: KAIT observations
  80. GRB 050520: VLT/ULTRACAM observations
  81. Swift UVOT Observations of GRB 050520
  82. XRF 050509c: Swift XRT Upper Limit
  83. XRF050509c: Radio Observations
  84. RBO Observations of GRB050520
  85. GRB 050520: P200 Observations
  86. RBO Observations of GRB050520
  87. GRB 050520: TAROT optical limit
  88. GRB 050520: Swift XRT position
  89. GRB 050520: VLT/ULTRACAM observations
  90. GRB 050520: OSN optical observations
  91. GRB 050504: Swift XRT afterglow candidate has faded
  92. XRF 050509c optical afterglow
  93. GRB 050509B and short GRB-SN association? (corrected)
  94. GRB 050509B and short GRB-SN association?
  95. GRB 050509B: Subaru Optical Observations
  96. GRB050509b, Bok telescope B-band imaging
  97. GRB050509b, SDSS pre-burst observations
  98. GRB 050509b: Keck/Chandra Cross-Correlation
  99. Chandra observation of GRB 050509b
  100. GRB050509B: Optical/Infared observations

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