Aperture Mask: Yes. Pluto: Not so much.

Got home from the trustees meeting last night to a glorious clear sky. On a Monday? Really?

I made an aperture mask for my dob over the weekend and was itching to try it out. The idea behind the mask is that on bright targets cutting out a bit of light and diffraction from the secondary struts should improve clarity, even though the aperture is reduced (350 to 160 in this instance).

And so after failing to resist temptation I was setup by 11:20:

Jupiter: Disappeared behind neighbors house. Need to catch it in the gap between house and apple tree 1.

Saturn: Seeing dreadful without mask: boiling away with no clarity at all. With the mask: same but dimmer. Hmmm.

Pluto: Spent ages looking for this. Definitely in the right place. Pluto formed a triangle asterism with two other faint stars. I upped the magnification to dim the sky glow and there was definitely something there. Wobbled the scope – that helped. Averted vision- didn’t make much difference. So- I’ve looked at Pluto but not seen it! Beginning to regret doing this on a work night…

Jupiter again. Behind apple tree 1. That moved quick! Damn!

Izar: At last- some success. Successively improved views moving from Baader zoom to binoviewers to adding aperture mask. In the final view the stars were pinpoint sharp and well separated with the companion showing a lovely blue.

Double double: the same experience. The 2 pairs were easily separated in all 3 configurations, but the binoviewers plus aperture mask gave the best view.

M13: Too dim for the mask, the best view was in the binoviewers- resolving all the way to the core and seemingly spherical, even though at that distance you don’t really have depth perception!

Jupiter again: Gotcha! Just before it snuck behind apple tree 2… Definitely a better view with the aperture mask- slightly dimmer but with much more clarity. 6 bands plus the GRS were clearly visible, with some detailing on the bands, plus the moons spread out as clear disks 3 to one side and one on the other.

Well worth the fatigue today!

Very pleased with the aperture mask- it’s not often an astro upgrade is almost free. It’s only really good for bright objects and with the binoviewers I had to velcro 4kgs onto the bottom of the tube to balance it- bit well worth the hassle!

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