Identify SMD Cap

[Photoman]

I was wondering if anyone can identify the circled SMD cap?
I read the marking as ASO.  Its in parallel with a 51.1k resistor which is spot on.
I cant seem to get any reading in circuit for the cap.

The cap and resistor is the feedback for a OSI UDT-455HS Photodiode Amplifier Hybrid sensor.
I have a suspicion that the cap might be causing some instability in the sensors amplifier.

I will remove it but there's always the chance it will crack or fly off in to low earth orbit.
I like to get some replacements just in case.

If it helps the schematics I have (for a simpler earlier version) say its can be a 4.7pF, 10pF or 15pF.
The rails are +-12v.

Thanks!

[Jeff eelcr]

I hate to say it but I usually remove and measure, hopefully not damaging the part in the process.
Jeff

[Photoman]

I got lucky removing it...only lost it once and it bounced in the right direction.
It was a 4.7pF cap.  I found it interesting that ASO is written on both sides.
Im guessing part of that is the tolerance.  I found a spec sheet from AVX thats close.
It lists A as +-0.05pF.  Unfortunately DigiKey is out of stock so I bought the tolerance they had in stock.