Late 1960's: bright, white, cylinder-shaped light; no noise, shown twice--a few seconds each time on rooftop.

My parents, now in their 70’s, had, what they think, was a UFO sighting back sometime between August 1967-July 1971 (they are unsure of the exact year).  They do know it was during the summer (July or August).  They lived in Washougal, WA, USA.  It occurred sometime between 10pm-midnight.
My parents had gone to bed.  It was a hot summer night (no AC in those days), so the upstairs windows were all open.  My brother and I (infant-toddler age) were in our own beds in our own room.  My father was asleep in bed, my mother awake in the same bed.  All of a sudden, my mom saw a very bright, white light out their second story bedroom window. She got up to look out the window and saw a perfect circle of light, cylindrical-shaped, that filled up the side roof of the next-door neighbor’s house.  Because of the way the neighbor’s house was/is situated, no on else in the neighborhood would have been able to see the shape of the light, only the brightness.  There was no sound at all.  She said the first light lasted a few seconds. She woke my dad up and then the light shone again, for a few seconds as well this second time.  They both saw it and said the light was a very distinct, perfect circle that came from the sky, down into a cylinder-shape onto the roof.  To this day, they bo! th report the exact same thing—a bright, white circle of light that had no “edging or haziness” to it.  It is still very clear in their minds.
They both were trying to come up with some plausible explanation for this—an airplane?  A helicopter? But, they said there was not a sound—total silence.  My mom called the Washougal Police Department to report this and see if anyone else had seen this.  The police department said there were no other reports of this or any other kind of aircraft around that night (she said she felt crazy even calling at all, but felt compelled).
Now, if you knew my parents, you would understand why they have never talked about this with anyone other than myself.  They are skeptical by nature, don’t necessarily “believe” in UFO’s, are religious, pragmatic, and not prone to “stories.”  When I asked them if I had their permission to report this sighting, they agreed. They also agreed to be interviewed.  They are getting older and I think they figure that if people are going to think they’re “crazy”, then it might as well be now.  Ha!  This is the first time I have written the story out or shared it with anyone.  I don’t know if I am even reporting to the correct agency or not, but here it is.  I don’t know if it’s “too late” or if this is anything of interest to anyone, but I feel that it’s better late than never.
Thank you.
P.S.--On a crazier side-note, when I was in my late thirties, doctors happened to discover that I only have one kidney.  I went my whole life (and had three healthy pregnancies) without this knowledge.  They said that on the side where there is no kidney, there is a little empty “sack”—“Most likely you were born this way, we don’t know.”  Strange.  I’m sure it’s coincidence and “stolen kidneys” are a complete myth, but it has, on occasion, caused me to say, “Hmmm.”
Witness indicates that the date of the sighting is approximate.  PD