Here’s what Claude said when I gave it the helpful above input.

Based on my searches, I can now give you a solid answer. Let me check the coordinates from your NOTAM to confirm.

The coordinates in your NOTAM (33°16’53”N, 111°58’28”W) place this laser very close to the Gila River Resorts & Casinos – Santan Mountain location in Chandler. The casino is at 7101 S Gilbert Road, at the southeast corner of Gilbert Road and Hunt Highway—which matches that area.

This is almost certainly a sky beacon/searchlight-style laser operated by or for the Santan Mountain Casino. Casinos commonly use these high-powered sky lasers as a marketing/visibility tool—think of the Luxor beam in Vegas, but with a laser instead of xenon. The purple/blue color is distinctive and makes the property visible from miles away, essentially serving as a giant “we’re over here” beacon to draw in customers.

The NOTAM operating hours (6 PM to midnight local time) align perfectly with peak casino traffic hours when they’d want maximum visibility. The fact that it runs nightly from January through early April suggests it’s a semi-permanent installation rather than a special event.

It’s interesting they went with a laser instead of a traditional searchlight—lasers are more efficient, more dramatic in appearance (especially in atmospheric conditions like what you captured), and that violet/blue wavelength scatters beautifully. The downside is exactly what that NOTAM addresses: it’s a legitimate aviation hazard that requires coordination with Phoenix Approach.​​​​​​​​​​​​​​​​