Hello all,

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This Saturday night will be the peak night of the famous Perseids meteor shower, one of the year's best!? Even better is that the Moon will not present any problems this year!? The broad traditional annual maximum is predicted on August 12/13, between 07h UT and 14h UT (which translates to between 3am and 10am EDT).? Under very dark skies and ideal viewing circumstances, the rates could surpass one meteor per minute during the early morning hours of the 13th.? In areas affected by light pollution, or obstructions (such as buildings or trees) the rates will be lower.? These meteors are known for producing good numbers of colourful meteors, and fireballs.? The Perseids can be enjoyed from nightfall onwards, although rates generally increase during the hours after midnight.

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Here's a good article to learn more...

This year's shower might have a couple of additional surprises:

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1) ?A weak filament is expected to cross Earth on August 13, around 03h UT (11pm EDT), according to ?meteor dynamicist Peter Jenniskens. ?(A filament is thought to be an accumulation of meteoroids in a mean-motion resonance.)

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2) ?There is also the possibility of enhanced activity on the following night Sunday August 13/14, between 01h UT and 0245h UT (between 9pm and 10:45pm EDT). Meteor dynamicist Jeremie Vaubaillon predicts that the Earth will encounter a very old trail of dust released in 68 BC.? It is definitively worth monitoring although a prediction of the activity level is essentially impossible.? Back on the morning of August 14 2021, I was fortunate to observe an unexpected strong outburst with a ZHR of more than 100 above the basic level, about a day and a half after the nodal maximum!? So if your skies are clear Saturday and/or Sunday night, give the Perseids a try! :)

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Clear skies!

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- Pierre

I've built a number of computers throughout the years and I always recommend Noctua fans. They also have anti-vibration mounts that work very well and are easy to install if you don't want to go with the McMaster Carr grommet route. I'm sure they could also be doubled-up with the grommets for extra vibration dampening.?

Richard?

On Fri, Apr 21, 2023 at 11:15?AM Attilla Danko <danko@...> wrote:

>Vibrations

There are at least 3 ways

- expensive anti vibration fans. example
<>

- rubbery gromets, "vibration damping bushings" around the mounting
screws. example: <>

- mount fan switch near eyepiece and turn off while observing at high
power. Turn back on while not looking or observing at low power.

I've used all three methods -- except for the switch near the eyepice.
All 3 work. Though running down the ladder to flip the fan switch on
my mirror box was annoying.


attilla danko, ,? danko@...,
attilladanko@...

On Fri, Apr 21, 2023 at 10:56?AM Tony Kourlas via
<tonykourlas=[email protected]> wrote:
>
> Thanks for sharing that. Great presentation btw.
>
> Blowing air across top of mirror from back to front makes a lot of sense. I've seen designs where they place a fan in each corner of the mirror box and blow air towards the center of the mirror... seemed to me this would just cause a different kind of turbulence. And while your suggested approach does involve some serious hacking of the pristine starmaster furniture... its better than waiting 2 hours for mirror to cool with a back-blowing fan. I'll probably give it I go when I retire next year... trick will be to eliminate any vibrations.
>

>Vibrations

There are at least 3 ways

- expensive anti vibration fans. example
<>

- rubbery gromets, "vibration damping bushings" around the mounting
screws. example: <>

- mount fan switch near eyepiece and turn off while observing at high
power. Turn back on while not looking or observing at low power.

I've used all three methods -- except for the switch near the eyepice.
All 3 work. Though running down the ladder to flip the fan switch on
my mirror box was annoying.


attilla danko, ,? danko@...,
attilladanko@...

On Fri, Apr 21, 2023 at 10:56?AM Tony Kourlas via
<tonykourlas=[email protected]> wrote:
>
> Thanks for sharing that. Great presentation btw.
>
> Blowing air across top of mirror from back to front makes a lot of sense. I've seen designs where they place a fan in each corner of the mirror box and blow air towards the center of the mirror... seemed to me this would just cause a different kind of turbulence. And while your suggested approach does involve some serious hacking of the pristine starmaster furniture... its better than waiting 2 hours for mirror to cool with a back-blowing fan. I'll probably give it I go when I retire next year... trick will be to eliminate any vibrations.
>