Observatory axis N/S or E/W?

[Mokusatsu (Australia)]

All else being equal, such as the horizons on all sides are about equal, light pollution isn't significantly different in any particular direction, there's plenty of space to put it anywhere I'd like to put it, and there are no other geographical quirks of my site to consider...

Should I align my rectangular roll off roof observatory such that the long axis, and therefore preferred view of horizons, goes north-south, or east-west?

Anyone got any strongly held views? I'm thinking favour north-south because I figure objects will rotate into view e-w anyway, and perhaps arguably I'm exposing less wall to direct midday sunlight, but is there a compelling counterargument for E-W?

[xelasnave]

Have the diagonal go North South so your scope has the best clearance maybe?
Alex

[glend (Glen)]

It doesn't really matter, provided you have clearance for your scope to get down as low as you wish. Many imagers do not bother imaging below 40 degrees altitude due to atmospheric effects. Everything rises in the East and in the Southern hemisphere the sky rotates around the south celestial pole. My personal preference is north south Long axis alignment for my observatory, with my mount more towards the Southern end of the observatory, giving me room for my workstation area in the northern end. Roof rolls off to the north, and can be stopped over my workstation, an important factor on damp nights. Importantly your wall height and pier height must provide you with the ability to reach down to the altitude you desire, and you must have swing, slew, room for all your gear within the narrow dimension.

[LonelySpoon (Neville)]

I've got a dome, so the issue doesn't occur, but if making a ROR I'd do E/W so I'd get a clear view of the circumpolar region and to the North, without the edge og the roof in the way.

To the west is upslope for me so probably roll that way.

Neville
LSO

[oska (John)]

I'm going with EW orientation and low sides so I can get more of the northern targets. I figured the higher targets all goes over head eventually but the low north stuff, even if it's decidedly average, is also available.

[gregbradley]

Best to stand on the site where you are going to build your observatory and look at the sky that is exposed in different directions. There are a lot of targets in the Large Magellanic Cloud that you would want to be able to image as often as possible.

Also consider the predominant wind direction. It would be good to be able to roll your roof in such a way as to shelter from that wind. If you live in a windy area that could give you an extra 20 nights or more of imaging time where the wind is neutralised.

Greg.

[AlexN]

I would consider where the best/your most frequent imaging targets are.

For me' I dont point west often. I typically image a target as it rises in the east, do the flip and then 2hrs.

There's a lot of good stuff in the Northern sky between 30~40⁰ up. The southern sky is worth keeping. There's lots in there. So for me, I'd roll off west.