Something is wrong with your drawing that is throwing off any analysis. Here is what a 45x20 foot lawn looks like with a head-to-head throw

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This shows a big gap in the middle. Fix the inconsistencies and I can give you a better picture of what is going on with the bulk of the water at the edges. At this point it looks like your dry spot should be where your wet spot is.

Good for you for noticing that most of the water goes to the ends of the sprinkler throw. That's why I opted to go with an oscillator type sprinkler. The back and forth sweep of the jets gives just about perfect coverage.

Thanks - I was just guessing at the size based on my lot - I haven't measured it at the moment.

Enclosed is are 2 photos taken while I was mowing it yesterday. I am mowing it with a push reel mower at 3" high, it is pretty plush. The center as can be seen is pretty green and tall.

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Can anyone see anything I should do? Thanks!

Perhaps you need to change the nozzles in your sprinkler heads to provide more thorough coverage between the heads, since you are saying that most of the water seems to be thrown to the ends of the arc. What type of irrigation system is this.....Rain Bird, Toro, or Hunter? It certainly appears that the greenest grass is where the most overlap occurs.

If it were me, I would want to have more heads installed with smaller nozzles, which would provide more even coverage.

Our heads are a Hunter PGJ

So my thinking is to reduce the radius of the two bottom corner units quite a bit - it seems you can see those units radius pattern in the center green lush are of the grass. I fill also reduce the top corners a tiny bit...

If that doesn't work I will look into getting some different nozzles and try again.

I think if I can reduce the overlap in the center then it will allow me to increase the watering time a bit and give me better color on the fringes????

Great pictures. You need to do something ASAP or your fescue at the edges will be more gone than it is. I would suggest a stopgap measure of using a hose and good oscillator sprinkler. The good ones do not have that mechanical linkage you see on the cheap ones. Those linkages will bind up and freeze the sprinkler in about 1 season. I've had one of the turbo models for 5 years and it's still going strong. The good oscillators cost upwards of $16 (on sale) and upwards of $20 during the season. Oscillators put out a very even spread of water and do it very slowly so it will sink in. Mine take 8 hours to get an inch of water out.

Who installed your sprinkler system? It does seem like they mis calculated the coverage.

Where are you on the central coast? To me that means from Santa Barbara to San Francisco.

I would agree that doing some type of manual watering as suggested above is immediately necessary. Those edges don't look good.

If you reduce the radius of the bottom heads, then you will not be getting the head to head coverage needed with the top row of heads. Again, more sprinkler heads with smaller coverage areas will provide more even coverage of the entire area.

But for now, the oscillating sprinkler seems to be needed.