Will every deep sky object go past the back of my house at night in a year? - Forums

Topic starter

Aug 27, 2022 · Edited: Aug 27, 2022

I have a concrete patio in the back of the house, facing west. Have a view of almost all (of half of) the sky. It's Bortle 3 and that patio is a great place to do astro photog from. There is about 3 feet of it not covered by a roof,enough for my mount, and it has a view of Polaris (just barely, but enough.)

Will that spot on the west side of the house allow me to photograph everything in the night sky thorough a given year, or will some objects be on the west side only during the day? I'm speaking of the Northern night sky, what I'd see at latitude 45 in an open field, which is not what I have, mainly because our house is in the middle of that field.

I have two long-timers on Cloudy Nights giving contradictory answers, and one is really adamant that he's right, saying I will be able to do all in a year, and kind of insulted me while complimenting me too ("I saw your image in the 'first photo' thread and I don't know how you've gotten this far without understanding how the stars move.") lol.

But here another guy answered that all DSOs will all pass west side of house during the year, but some only during day.

I have apps and websites, but really think there must just be a simple yes or no answer to this that someone with experience could tell me that I won't get from doing apps. I'm kind of aspergery too and this stuff isn't simple for me to grok. Nothing mechanical comes natural to me, and earth rotation is mechanics. I'm surprised I was able to get my mount working properly after not a lot of trying.

If I can do it all from west side and every object in northern hemisphere will be viable from there AT NIGHT at some point in the year , I don't need to pour a slab in the front (East) side of the house. I was going to do that to have two options.

EDIT:
I've spent hours looking at stellar apps and websites trying to figure this stuff out. I've got people here and on Cloudy Nights basically saying "use the app dummy". One of them in a rather aggressive way.

But even with that, it's not intuitive to me, which is why I'm asking. I would not ask this without trying to find the answer myself first, I should probably add that into the post too. I can't change the oil on my car either, but I can drive.

Thank you.

Jonny Bravo

Aug 27, 2022

Assuming you can see the entirety of the sky from north to south on the western half of the north-south line, then yes, every single visible DSO from your location will at some point be visible at night. For example, in the middle of the summer, you're not going to see Orion, Rosette, etc because they're in the sky during the daylight hours. However, come winter, those objects will be in the sky at night. They haven't changed positions… they're still at exactly the same RA/Dec coordinates.

I suggest you check out Stellarium (or some similar planetarium app) and watch how things progress throughout the year. Pick any object and watch through different months/days/hours to see where it is in the sky. You'll notice pretty quickly that objects in the sky during the day in the summer are correspondingly in the sky at night during the winter. Using Orion as an example, it crossed the meridian this morning at just about 8:13am east. It will be 10 Feb 2023 when Orion crosses the meridian at 8:13pm east.

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kuechlew

Aug 27, 2022 · Edited: Aug 27, 2022

Obviously you will not see the "entire sky" because based on your latitute part of the sky will never rise above the horizon.

The objects which rise above the horizon rise in the east and settle in the west due to earths rotation. The siderial day is 3 minutes 56 seconds shorter than the solar day, see: Sidereal Day | COSMOS (swin.edu.au). Therefore each object rises in the east and settles in the west 3 minutes 56 seconds earlier every day.
Therefore all objects rising above the horizon at your lattitude will eventually be visible in the western half of the sky during the night. I stress the recommendation to check with Stellarium with a horizon representing your exact view of the sky. Some will be very low in the sky not well located for AP.

Clear skies
Wolfgang

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Michael W. Dean

Topic starter

Aug 27, 2022 · Edited: Aug 27, 2022

Obviously you will not see the "entire sky" because based on your latitute part of the sky will never rise above the horizon.

The objects which rise above the horizon rise in the east and settle in the west due to earths rotation. The siderial day is 3 minutes 56 seconds shorter than the solar day, see: Sidereal Day | COSMOS (swin.edu.au). Therefore each object rises in the east and settles in the west 3 minutes 56 seconds earlier every day.
Therefore all objects rising above the horizon at your lattitude will eventually be visible in the western half of the sky during the night. I stress the recommendation to check with Stellarium with a horizon representing your exact view of the sky. Some will be very low in the sky not well located for AP.

Clear skies
Wolfgang

Thank you.

I've edited my post to add "'I'm speaking of the Northern night sky, what I'd see at latitude 45 in an open field, which is not what I have, mainly because our house is in the middle of that field."

I've spent hours looking at stellar apps and websites trying to figure this stuff out. I've got people here and on Cloudy Nights basically saying "use the app dummy". One of them in a rather aggressive way.

But even with that, it's not intuitive to me, which is why I'm asking. I would not ask this without trying to find the answer myself first, I should probably add that into the post too. I can't change the oil on my car either, but I can drive.

When you say "Some will be very low in the sky not well located for AP" I know that's true in general, and have a crappy photo I won't post that proves it, but do you mean moreso than if I had an open field? To be clear:

If my house was gone and I put my mount where my house is, instead of on the back porch where direct view to eastern sky is blocked by the house, is there anything I'd see some time of the year higher up in the east that with the house gone that I'll only see in the west but low?

kuechlew

Aug 27, 2022

Obviously you will not see the "entire sky" because based on your latitute part of the sky will never rise above the horizon.

The objects which rise above the horizon rise in the east and settle in the west due to earths rotation. The siderial day is 3 minutes 56 seconds shorter than the solar day, see: Sidereal Day | COSMOS (swin.edu.au). Therefore each object rises in the east and settles in the west 3 minutes 56 seconds earlier every day.
Therefore all objects rising above the horizon at your lattitude will eventually be visible in the western half of the sky during the night. I stress the recommendation to check with Stellarium with a horizon representing your exact view of the sky. Some will be very low in the sky not well located for AP.

Clear skies
Wolfgang

Thank you.

I've edited my post to add "'I'm speaking of the Northern night sky, what I'd see at latitude 45 in an open field, which is not what I have, mainly because our house is in the middle of that field."

I've spent hours looking at stellar apps and websites trying to figure this stuff out. I've got people here and on Cloudy Nights basically saying "use the app dummy". One of them in a rather aggressive way.

But even with that, it's not intuitive to me, which is why I'm asking. I would not ask this without trying to find the answer myself first, I should probably add that into the post too. I can't change the oil on my car either, but I can drive.

When you say "Some will be very low in the sky not well located for AP" I know that's true in general, and have a crappy photo I won't post that proves it, but do you mean moreso than if I had an open field? To be clear:

If my house was gone and I put my mount where my house is, instead of on the back porch where direct view to eastern sky is blocked by the house, is there anything I'd see some time of the year higher up in the east that with the house gone that I'll only see in the west but low?

As the objects rise in the east and set in the west they all cross the meridian at some point. This is the point when they are highest in the sky and best to photograph through the least amount of atmosphere. Based on their declination this point will be either in the South or in the North (or in the zenith ...) .

Clear skies
Wolfgang

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Willem Jan Drijfhout

Aug 27, 2022

As a general rule of thumb, you probably want to image objects only if they are more than 30 degrees above the horizon, whichever direction, N, E, S or W. If you go below that, you just have too much atmosphere you have to look through, causing all sorts of issues, generally degrading image quality. So if you have an obstruction by a house or a tree, that sticks out 25 degree from the horizon, it probably won't cost you too much valuable imaging time.

Like said above, East and West will present themselves at some point in the year. But anything on the Southern Hemisphere of course you will never see. So how can you see if an object is on the Southern Hemisphere? Take a look at an objects Declination (Dec), and if it's negative, be careful. From your latitude of 45 degrees, any object with Dec lower than around -20 will probably be hard to image for any significant amount of time at a high enough altitude to get a decent image.

If you want to get a feel for the obstructions on your horizon relative to the altitude, you may want to check out the app SkySafari. It has an Augmented Reality option, which shows you your horizon, imaged through the camera of your phone, with projected on that the sky with the gridlines of altitude and azimuth. Just walk around with the phone, and you get a pretty good understanding of your horizon obstructions.

Hope this helps.

CS, Willem Jan

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Jonny Bravo

Aug 27, 2022 · Edited: Aug 27, 2022

When you say "Some will be very low in the sky not well located for AP" I know that's true in general, and have a crappy photo I won't post that proves it, but do you mean moreso than if I had an open field? To be clear:

If my house was gone and I put my mount where my house is, instead of on the back porch where direct view to eastern sky is blocked by the house, is there anything I'd see some time of the year higher up in the east that with the house gone that I'll only see in the west but low?

No. The reason you'll often hear people talk about not imaging a target that is low to the horizon is because you have a lot more atmosphere to see through the closer to the ground the target is. Think about it like this: when you look directly up, you are looking through the least amount of atmosphere. Ever been somewhere with a very large asphalt parking lot during a very hot day? If you look across the parking lot, you'll see all kinds of wavering air. Close to the asphalt, the air is very disturbed and hard to see through. As you look further up, the air becomes more steady and easier to see through.

Same applies to astrophotography... except you're magnifying the impact because you're looking through a scope. This is why stars appear to twinkle. You can try this tonight assuming it's clear where you are. Go outside around 9:30 and look directly up, just past the meridian and you'll see Vega. Then, look to the west about 25 degrees above the horizon and you'll see Arcturus. I bet Arcturus is going to appear to be twinkling / jumping around far more than Vega. That jumpy/twinkling thing ... not so good for taking pictures where you need your mount to be able to track something the size of a dime at two miles away from you.

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Michael W. Dean

Topic starter

Aug 27, 2022

When you say "Some will be very low in the sky not well located for AP" I know that's true in general, and have a crappy photo I won't post that proves it, but do you mean moreso than if I had an open field? To be clear:

If my house was gone and I put my mount where my house is, instead of on the back porch where direct view to eastern sky is blocked by the house, is there anything I'd see some time of the year higher up in the east that with the house gone that I'll only see in the west but low?

not so good for taking pictures where you need your mount to be able to track something the size of a dime at two miles away from you.

Thank you for the reply. So no reason to put a slab in the east when I have a slab in the west it seems.

That dime / 2 miles seems oddly specific. Is that the actual ratio we're shooting.

I'm painfully aware of the effect of atmospheric conditions low in the sky. I live in a Bortle 3 but I'm surrounded by grain farms. 4 times a year there's harvest and there's a week where the sky is too dusty to see much in space. On a good night there's enough grain dust / dirt dust that things down low just don't look good. Not so much light pollution and not much actual pollution, but haze yes. Makes for nice sunsets, but not so nice for low imaging. Overhead looks great though. That's why everything I've imaged so far is in Cygnus. lol

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kuechlew

Aug 27, 2022

When you say "Some will be very low in the sky not well located for AP" I know that's true in general, and have a crappy photo I won't post that proves it, but do you mean moreso than if I had an open field? To be clear:

If my house was gone and I put my mount where my house is, instead of on the back porch where direct view to eastern sky is blocked by the house, is there anything I'd see some time of the year higher up in the east that with the house gone that I'll only see in the west but low?

not so good for taking pictures where you need your mount to be able to track something the size of a dime at two miles away from you.

Thank you for the reply. So no reason to put a slab in the east when I have a slab in the west it seems.

That dime / 2 miles seems oddly specific. Is that the actual ratio we're shooting.

I'm painfully aware of the effect of atmospheric conditions low in the sky. I live in a Bortle 3 but I'm surrounded by grain farms. 4 times a year there's harvest and there's a week where the sky is too dusty to see much in space. On a good night there's enough grain dust / dirt dust that things down low just don't look good. Not so much light pollution and not much actual pollution, but haze yes. Makes for nice sunsets, but not so nice for low imaging. Overhead looks great though. That's why everything I've imaged so far is in Cygnus. lol

You're imaging at around 5 arcseconds image scale. This translates into an approximately 3 inch large object in 2 miles distance - I hope I got the nonmetric units right ... (around 8 cm in 3.2 km distance for the metric part of the community). With more expensive equipment and good skies you can get into the 1 arcsecond region.

Clear skies
Wolfgang

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