Yesterday there was a segment about the Atlanta Motor Speedway lighting system from WSB-TV news.  The reporter showed us the big 1500 Watts MH BT-56 bulb with arc tube in 45 degree angle with matte black dome.  Has anyone seen such specimen in the wild?

https://www.wsbtv.com/news/local/henry-county/nascar-returns-atlanta-motor-speedway-under-lights/2OOFMQJNRNAFVLN7KWKXYALIHU/

 I've never seen them like that before.  I'd assume it's to help cut the glare ?  I used to go to the spring race at AMS for close to 20 years . I quit going when they moved the date to latter in the season .

The closest I've seen are these which were located in a park but were also built by Musco. Interestingly the lamps are slightly different too in regards to the shape and location of the black paint on the lamp.

I suppose the base luminaire for these is pretty customizable and are build to order. In my example, a few had the external glare control baffle and one has different reflector inserts. Finally one has fully clear lamp, although that might have been a spot replacement. 

 I did notice that the ones in the video I linked don't look to have the entire top coated . I wonder if they custom make the lamps specifically for different applications ?

 I've seen ones like in your link at a local go cart track . 

I wonder too, and how many variations of those Z framed MH lamps existed.

Unfortunately it seems like all the details on the MH systems had been purged from Musco's website.

 I wonder where the speedway gets their lamps , ballasts , etc. ??

Apparently Musco sells replacement parts directly and also service agreements. I suppose there might also be non OEM lamps. Ballasts you can probably just use any core and coil kit IMO.

https://www.musco.com/replacement-parts/

 Makes sense !

Thanks for the video link, wide-lite 1000

Joe, looks like half coated matte black on the top of the bulb
Also, thanks for the light fixture link here as well, Joe I can see that it has the same light bulb as shown at the video presentation as well.

 No problem !