) of [*HST*]{}/ACS on 2006 May 21 (90 d after $B$ maximum) and on 2006 December 25 (308 d after $B$ maximum), respectively (GO–10991; PI, Arlin Crotts). At $t = 90$ d, the SN was imaged in F435W (1480 s), F555W (1080 s), and F775W (1080 s), while at $t = 308$ d, the SN was again observed in the same three bandpasses, with the exposure times of 920 s, 520 s, and 520 s, respectively.

The standard [*HST*]{} pipeline was employed to pre-process the images and remove cosmic-ray hits. In Figure 1 we show the pre- and post-explosion [*HST*]{} images of SN 2006X in the F555W filter. This pre-discovery image does not reveal any significant source brighter than 24.0 mag in F555W, excluding the possibility of a significant star cluster at the location of SN 2006X. Neither of the two post-discovery images exhibits any resolved LE arcs or rings around SN 2006X. The magnitudes of SN 2006X were measured from the [*HST*]{} ACS images with both the Dolphot method (Dolphin 2000) and the Sirianni procedure (Sirianni et al. 2005), and the mean photometry is given in Table 1.

Keck Optical Spectrum
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Observations of nebular-phase spectra provide an alternative way to explore the possibility of an LE around SNe, as the scattered, early-phase light will leave a noticeable imprint on the nebular spectra (e.g., Schmidt et al. 1994; Cappellaro et al. 2001) when the SN becomes dimmer. Two very late-time spectra of SN 2006X taken at t $\approx$ 277 and 307 days after $B$ maximum were published by W07 (see their Fig. 19), which were obtained by the Keck telescopes at the W. M. Keck Observatory: one with the Low Resolution Imaging Spectrometer (LRIS; Oke et al. 1995) mounted on the 10 m Keck I telescope, and the other with the Deep Extragalactic Imaging Multi-Object Spectrograph (DEIMOS) mounted on the 10 m Keck II telescope. In the following analysis we focus on the LRIS spectrum taken at $t \approx 277$ d because of its wider wavelength coverage.

Data Analysis
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Late-Time Light Curves
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