TheSkySearchers

Hello - First post.

At the moment, getting my feet wet in astrophotography.

Let me identify my 'credentials' and equipment. I'll try to be sufficiently complete so that 'you' have the information necessary to answer my questions, while trying to avoid appearing arrogant.
I am an experienced, (55+ years), amateur photographer. I have several Canon DSLR bodies and lenses. I recently purchased a Sky-Watcher 2i Pro kit to facilitate my interest in taking "deep space" pictures. I am a novice "astronomer". I have sufficient education, (12 years post-secondary science), to understand 'complex' solutions. I live in Alaska, approximately 50 miles north of Anchorage. I am fortunate to have a nice southern view of the sky from the deck of my house, (Bortle 5), from which I would like to take night-time pictures.

Unfortunately, my view is of the southern sky, and my house, behind me and therefore to the north, blocks Polaris. Which in turn precludes aligning the Sky-Watcher on Polaris, from my deck. Which leads to my question:

Since technically, all stars have a geometric relationship to Polaris, (and each other), based on the latitude, longitude, date, and time of the observer, it seems to me that given sufficiently precision latitude, longitude, date, and time values, I should be able to align the Sky-Watcher on any other star visible to me.
Is that correct??

If I am correct in the above assumption, is it feasible to perform such a non-Polaris alignment with the hardware I have - Sky-Watcher 2i Pro Kit?

And finally, if it is feasible, would "you" be so kind to provide instruction on how to perform that alignment?

Thanks in advance.

Paul

Welcome to the forum.

In theory, it can be done. Many of the popular polar alignment software tools do it. However, the actual calculations to do it are non-trivial, and the mount setup would be difficult to manage with sufficient precision, since you cannot use the polar scope.

Your best bet may be to purchase one of the software tools, along with whatever camera it needs.

Welcome to the forum

NINIA has a three point polar alignment process currently in beta, it is free software. If you're interested in the math calculations, I've attached the PDF that lays it out. As Kathy has noted, the math is not trivial, good luck!

First of all welcome to the forum. On this forum, we leave arrogance outside the front door. We strive to be friendly first then provide expert guidance if we can.

Yes, you can align your mount, but it ain't easy. The first thing you do is to step back from your deck till you can see Polaris. Now draw a line down from Polaris with your eyes down to see where it crosses an identifiable feature on the south wall of your house. Now make a mark (a piece of tape, a tiny bit of white paint, or something else your spouse will find acceptable) to remember where this point is. Now you have a very good approximation of true north which gives you a mark where to point the R.A. axis of your mount. I had to do this when I lived in Hawaii because Polaris was so low, it didn't make it above the trees.

Now you can use any number of free software titles to refine your pointing. Personally, I use the "drift align" feature in the free guiding software PHD2. This should get you where you need to go.

Cheers

I'll have a look at the pdf and PHD2 (now apparently on "3"), chris_g and JayTee. Thanks!

Paul

PS - Had a look at the pdf. Just what I was looking for! Thanks!

Paul

Software will not help because you can't control your tracker from a computer. So you should have bought a mount instead. For instance the AVX has the type of polar alignment that you want built-in (ASPA), and generally, computer controlled mounts can use various types of software for polar alignment. I don't see how you can get polar aligned accurately enough for your tracker, sorry.

You can still do drift alignment with a tracker. It will simply not be easy as most trackers do not allow for extremely precise micro adjustments. Here's s good explanation of the drift method.
https://explorescientificusa.com/pages/ ... ift-method

And PHD2 is still on 2, 2.6.10dev3 is the most recent verstion.

It can be done with NINA TPPA software in manual mode. As long as NINA can connect to the camera and plate solve, you can move the mount/tracker on the RA axis by hand. Point the mount to true North using a compass app on your cell phone that shows true North based on GPS location, such as compass steel. Then start NINA TPPA in manual mode and follow the instructions. It works.

Henk, I totally missed that he's using a tracker. Thanks for pointing that out.

For Gitano. There is an alternative if you're willing to be a bit creative and supply a little elbow grease. There is Celestron GT Goto mount for sale on CN https://www.cloudynights.com/classified ... nd-tripod/

That mount attaches to this wedge and it will give you some very decent images for not much $$$. Read this article:
viewtopic.php?f=24&t=3129

Cheers,

SkyHiker-The Adventurer 2i has 1-axis numerical ("computer") control capability, and with the addition if an "autoguide", and some alignment software, Polaris alignment isn't mandatory. I can post the YouTube video link here if that's kosher.

Thanks to AstroBee, chris_g, and JayTee for the links. I will pursue them. Re PHD 2 or 3: I was at a site that referenced PHD3, so I figured it had moved on. Dudnt matter to me what the number is.

Thanks to everyone that responded. I have stumbled around and made my first "astrophotograph" using the stacking method. Made a crude stab at aligning "blind" using an app on my phone. Didn't prevent streaking with just a 30s exposure, so "that won't work", but I think with the above suggestions, I'll be able to get my act together sufficiently to take pictures with which I will be satisfied. I've already seen 'cool stuff' in this picture. (Which, seems much darker here, than on my computer screen.)

Thanks again.

Paul

Besides the latitude, you have the same Bortle level too.

I can see polaris, but I still align my mount using the kind of markers @JayTee talks about.
Makes polar alignment quick, when it's "almost there" to begin with.

I noticed the latitude right away, turboscrew. We should be experiencing the same diurnal light/dark cycles.

Elsewhere, away from the convenience and warmth of my house, seeing Polaris isn't an issue. It's just that I have a great scene in front of my deck where Orion spend most if the night suspended above the Chugach mountains. If I could get polar alignment, it'd be a great location for beginning astrophotography. I'll keep an eye out for your posts here at TSS to learn what I can from an experienced sky searcher at the same latitude.

Paul

gitano wrote: ↑Thu Jan 06, 2022 6:47 am SkyHiker-The Adventurer 2i has 1-axis numerical ("computer") control capability, and with the addition if an "autoguide", and some alignment software, Polaris alignment isn't mandatory. I can post the YouTube video link here if that's kosher.

Thanks to AstroBee, chris_g, and JayTee for the links. I will pursue them. Re PHD 2 or 3: I was at a site that referenced PHD3, so I figured it had moved on. Dudnt matter to me what the number is.

Your could try Drift Alignment using the camera.
https://www.cloudynights.com/articles/c ... vice-r2760

gitano wrote: ↑Thu Jan 06, 2022 6:47 am SkyHiker-The Adventurer 2i has 1-axis numerical ("computer") control capability, and with the addition if an "autoguide", and some alignment software, Polaris alignment isn't mandatory. I can post the YouTube video link here if that's kosher.

I watched the video and it is mentioned that the autoguide capability pushes the system to its limits, and that it only guides in RA. Chris is probalby right that Nina can do it (assuming that Nina does not use its internal model in the calculations - plate solving ought to be enough, I just don't know what Nina requires internally).

So in theory you might be able to do it with Nina or drift alignment. I would be practical and go to a place where Polaris is visible and use it there with the polar scope. Having to drag a laptop along and retrieving images from a DSLR for plate solving (that's the camera that you want to use for PA, right?) is probably a bad idea. I have never plate solved with a DSLR but I suspect it will take very long to get the images and to view the corrections as you tweak the controls. Plate solving is best done with a dedicated astro camera and a USB3 port.

ARock and SkyHiker - I wouldn't try drift alignment without a separate guide scope and camera. As for "going somewhere Polaris is visible": Sure. However, "somewhere Polaris is visible" is not my Bortle 4 deck that's just off of my living room. (I just got a new, more accurate Bortle score.) Right now, in The Great White North, it's -12F/-24C. Besides being 'uncomfortable' while trying to manipulate sophisticated camera and astronomy equipment, (especially when compared to my living room), those temps also render equipment "hesitant" to perform as designed. While I learn the ropes of astrophotography, I'd like to be able to make mistakes without an EXCESSIVE amount of the attendant 'penalty' associated with prep, travel, setup, etc., and then getting it wrong. "Doing it" from my living room allows me to learn without wasting as much time AND other resources. (To say nothing of also diminishing the amount of my use of 'sailor talk'. ) Please believe me when I say that at 70YO, I appreciate that 1) There are no free lunches, and 2) ALL forms of education/learning have some cost/fee to them.

Paul

SkyHiker wrote: ↑Thu Jan 06, 2022 6:54 pm

gitano wrote: ↑Thu Jan 06, 2022 6:47 am SkyHiker-The Adventurer 2i has 1-axis numerical ("computer") control capability, and with the addition if an "autoguide", and some alignment software, Polaris alignment isn't mandatory. I can post the YouTube video link here if that's kosher.

I watched the video and it is mentioned that the autoguide capability pushes the system to its limits, and that it only guides in RA. Chris is probalby right that Nina can do it (assuming that Nina does not use its internal model in the calculations - plate solving ought to be enough, I just don't know what Nina requires internally).

So in theory you might be able to do it with Nina or drift alignment. I would be practical and go to a place where Polaris is visible and use it there with the polar scope. Having to drag a laptop along and retrieving images from a DSLR for plate solving (that's the camera that you want to use for PA, right?) is probably a bad idea. I have never plate solved with a DSLR but I suspect it will take very long to get the images and to view the corrections as you tweak the controls. Plate solving is best done with a dedicated astro camera and a USB3 port.

It's not theory, at least not in my backyard, it's practical application done every time I set up.

NINA plate solves with my DSLR in about 3 seconds with a 10 second sub using ASTAP as well as APT using ASTAP. ASPS also blind solves with my DSLR in about 30 seconds. The only time I have issues plate solving with the DSLR is when I use the L-eNhane filter. Then I have to turn up the ISO to 6400 and change the exposure to 30. Then it all works fine. My DSLR is a Canon and both NINA and APT fully supports saving the image to the PC or flash card or both. No need to take the image off the flash card and transfer it manually to the PC. Nikon does this as well though I've never used a Nikon so I can't attest to it

I polar align every time I set up using NINA since I can't see Polaris. I used Compass Steel to get true north, then set up my path bricks for my tripod as you suggested Henk. I'm within 30 arc minutes before starting TPPA and within 1 arc minute in both axis within 5 minutes. Three point polar alignment can be accomplished starting from almost any position in the sky, no need for Polaris.

chris_g wrote: ↑Thu Jan 06, 2022 7:51 pm

SkyHiker wrote: ↑Thu Jan 06, 2022 6:54 pm

gitano wrote: ↑Thu Jan 06, 2022 6:47 am SkyHiker-The Adventurer 2i has 1-axis numerical ("computer") control capability, and with the addition if an "autoguide", and some alignment software, Polaris alignment isn't mandatory. I can post the YouTube video link here if that's kosher.

I watched the video and it is mentioned that the autoguide capability pushes the system to its limits, and that it only guides in RA. Chris is probalby right that Nina can do it (assuming that Nina does not use its internal model in the calculations - plate solving ought to be enough, I just don't know what Nina requires internally).

So in theory you might be able to do it with Nina or drift alignment. I would be practical and go to a place where Polaris is visible and use it there with the polar scope. Having to drag a laptop along and retrieving images from a DSLR for plate solving (that's the camera that you want to use for PA, right?) is probably a bad idea. I have never plate solved with a DSLR but I suspect it will take very long to get the images and to view the corrections as you tweak the controls. Plate solving is best done with a dedicated astro camera and a USB3 port.

It's not theory, at least not in my backyard, it's practical application done every time I set up.

NINA plate solves with my DSLR in about 3 seconds with a 10 second sub using ASTAP as well as APT using ASTAP. ASPS also blind solves with my DSLR in about 30 seconds. The only time I have issues plate solving with the DSLR is when I use the L-eNhane filter. Then I have to turn up the ISO to 6400 and change the exposure to 30. Then it all works fine. My DSLR is a Canon and both NINA and APT fully supports saving the image to the PC or flash card or both. No need to take the image off the flash card and transfer it manually to the PC. Nikon does this as well though I've never used a Nikon so I can't attest to it

I polar align every time I set up using NINA since I can't see Polaris. I used Compass Steel to get true north, then set up my path bricks for my tripod as you suggested Henk. I'm within 30 arc minutes before starting TPPA and within 1 arc minute in both axis within 5 minutes. Three point polar alignment can be accomplished starting from almost any position in the sky, no need for Polaris.

Cool! Just what I was hoping to hear.

Paul

gitano wrote: ↑Thu Jan 06, 2022 5:24 pm I noticed the latitude right away, turboscrew. We should be experiencing the same diurnal light/dark cycles.

Elsewhere, away from the convenience and warmth of my house, seeing Polaris isn't an issue. It's just that I have a great scene in front of my deck where Orion spend most if the night suspended above the Chugach mountains. If I could get polar alignment, it'd be a great location for beginning astrophotography. I'll keep an eye out for your posts here at TSS to learn what I can from an experienced sky searcher at the same latitude.

Paul

I'm, actually, not very experienced, but I know about the special circumstances at these latitudes.
And I'm planning to try AP as soon as I get my gear sorted out.
At the moment, my CEM120 is being fixed in Germany.
I haven't even listed any AP stuff, because I haven't had a change to try anything out yet.

Just an update, Ivo from APT, Astro Photography Tool, has said they will start developing a Polar Alignment routine that doesn't need Polaris next week.