Andromeda Galaxy all night exposure

[rdking647]

finally finished processing my andromeda galaxy photo from last week.
this is 7.25 hours of exposures,435 1 minute shots stacked together
taken just outside of austin

[MiHale]

1. Applauding your hard work.

Beautiful!

[mbusby]

3. The Andromeda galaxy....

...is also the only galaxy you can see with your naked eye, assuming you have a dark night and the moon is not up.

[rdking647]

21. there another one just on teh edge of visibility

the Triangulum galaxy (m33) is just on the edge of visibility if you have good eyes and very dark skies. . if your in the southern hemisphere the large and small Magellanic clouds are visible too.

of course my eyes are so bad and i live with so much light pollution i cant see andromeda with the naked eye anyway. im lucky i can see the north star

[CaliforniaPeggy]

4. Superb work! We are so lucky to have your ability here. Thank you! ♥

[berni_mccoy]

5. Nice work! You actually captured the banding in the arms of it

[Grumpy Old Guy]

6. Congratulations on a stunning accomplishment.

The dedication required for an image this magnigicent is huge. Bravo!

[ffr]

7. Sophisticated setup? How'd you manage to hold the camera focused on that while the earth moved?

[rdking647]

18. i use a celestron AVX telescope mount although there are other cheaper options

the celestron has goto capability and can handle a lot of weight. I also have a smaller Ioptron skyguider pro that can handle a simple camera and lens but doesnt have goto capability

[jaxexpat]

8. I love this stuff!

The universe is humbling.

[Moebym]

9. Stunning!

[hwmnbn]

10. WOW!!!!

Brilliant technological artwork.

[Mr. Sparkle]

11. Cool

We are probably looking at billions of intelligent alien life.

[CaptainTruth]

12. Awesome!!!

I can only imagine what your camera rig must look like.

[rdking647]

19. nothing super outrageous

i use an old sony a6000 camera with a 250mm f4.9 lens (a williams redcat.) you can do similar with an ordinary 70-200 lens
i mount it on a celestron avx telescope mount which can handle much more weight then the camera and lens but i like it because it has goto capability and a lot of what i shoot isnt naked eye visible here due to serious light pollution. Im just outsode of downtown in the first suburb across the austin city line.

[Traildogbob]

13. Amazing

Thank you for sharing.

[hollygolively]

14. Beautiful!

I toy with photography as a hobby. I know nighttime pictures are not easy.

[LittleGirl]

15. That's great! Nt

[electric_blue68]

16. Oh, That is SO Lovely! The majesty and mystery of Space

[Roy Rolling]

17. Wow, just wow

Stacking 435 images seems like a miracle.

[rdking647]

20. there is special software i use

I use a program called nebulosity to stack. I stack the photos with 2 sets of calibration photos in this case 50 shots with the lens cap on (called darks) and 50 with the camera pointed at a neutral surface called flats(i use an ipad with an all white webpage open)
using the darks and flats plus all the images lets me really stretch out the histogram to bring out the details

[yonder]

22. Nice work. I was going to ask how you keep an airplane, satellite or meteor

from ruining the exposure but think I have figured it out.

Unlike one, constant 8-hour exposure using guide stars for alignment, you have 435 exposures so you could throw out any one or several that picked up an "undesirable", right?

Even at 1 minute exposures, do you still have to use a clock drive/tracking star? That works out close to 15 arc-minutes of apparent movement (at the equator) for each shot so it seems like it would be necessary.

Finally, is the stacking process digital or do you have to eyeball and adjust each exposure (layer)?

In any case, fine work there, thanks for posting.

[rdking647]

23. yes you need a tracking device

the general rule of thumb is take 500/focal length (adjust for crop sensor or full frame) to get how long of an exposure you can take without star trails

stacking does a pretty good job of eliminating airplanes because the plane would only be in one exposure and the software can just treat it as noise and discard it.

as to the actual process the software can attempt to do it automatically . the success depends on how well you are polar aligned. for this shot i had to actually divide the total exposure into 2 parts. when an object crosses the celestial meridian a lot of mounts will stop tracking to prevent the camera from banging into the tripod as it moves. mine is one that stops. so after about 3 hours when andromeda crossed the meridian i moved the camera to the other side of the mount and started shooting again (whats called a meridian flip) so i had roughly 3 hours of exposure before the flip and 3 after. I stacked each set separately and then stacked the 2 results. i had a good enough alignment in each set to do an automatic stack and then had 2 manually stack the final 2 results.

even if i have to manually stack the software makes it fairly easy. I click on a brightish start in the image. and then go thru each individual frame and click on the same star. in some cases i have to use 2 stars to get a good stack. once i have the stars clicked the software then makes the stack and also uses the flats and darks to reduce noise and vignetting

[Grumpy Old Guy]

24. My head hurts just thinking about all that.

You sure put my single exposure astro shots to shame. Thanks for all the technical info.

[yonder]

25. Thanks for the detailed response. I think I get the gist of it, except for the processing part.

A couple more field questions if you don’t mind:

Once you are polar aligned (This retired surveyor would call it a back sight), can you adjust up mid-session or are you “locked in” to your original alignment till the end of session? In this case, two 3-hour sessions.

Do you always use Polaris or can you use another known object for alignment/tracking? It wobbles somewhat around the celestial pole anyway, so it seems like you should be able to use something else with an ephemeris and an accurate time. Or maybe the mount/timer device has a digital ephemeris?

How much coffee does it take? Just kidding though I imagine it’s a bit.

I’ve played around with getting into this before and your shot of M31 may have sent me over the edge. Thanks again.

[rdking647]

26. not sure if i understand what your asking but ill take a shot at answering

i have an app on my phone that shows me the offset of polaris from the celestial pole so i actually align to that instead of polaris itself. once aligned i dont touch the mount. I have a hand controller for the mount that will then slew the camera to whatever i choose to point at. i use 3 bright stars so that the mount knows exactly where the camera is pointing and then i can use teh hand controller to slew to whatever target i want to shoot.

I keep the mount set up in my backyard most of the time so polar aligning isnt much more than minor adjustments. they do make specialized equipment that makes aligning even easier and rather than having to use a 3 star alignment it takes a quick photo and compares it to known stars so it basically self aligns. I havent bought that equipment.

some people also add a second camera and lens to help make tracking even more accurate. the second camera points at a bright star and if there is any wobble in the mount it self corrects it. once again thats more equipment i havent bought yet
.

as to coffee,i shot from about 10:30 to 1:30 checkign the camera every 30 minutes or so to make sure it was doing what i wanted. then i swung around the meridian and started shooting again but went to bed and just let it shoot all night. by 5am it was getting light out so i also have a few hours of pure white shots too . woke up early,shot my dark frames and my flats and then went back to bed until. reasonable hour.


processing is the real PITA. the main software i use is something called pixinsight. the learning curve for it is extreme,it makes photoshop look like a piece of cake. ive barely scratched teh surface of what it can do and even after watching countless youtube videios im stiill a rookie at using it.

[yonder]

27. Yes thanks, that's helpful.

Your controller has a built-in digital ephemeris which allows your mount/telescope/camera setup to "slew" wherever you want....once it knows where it is at by that initial alignment/backsight.

I wasn't sure how you aligned to the CP without adjusting for the offset of Polaris - or if you just sighted it and called it good. Too much error. In pre-GPS days we would sight Polaris, the sun or other stars directly and use highly accurate time along with ephemeris tables for calculating correspondingly accurate azimuth. Also, your circle (RA?) is perpendicular to the CP while ours is perpendicular to gravity. Kind of the same thing and concepts but with different techniques and objectives.

I've got enough curiosity now to start nosing around to see if I can develop and sustain an interest in this hobby though your post processing comment has me a little leery. Field time is way more fun than time at a computer.

I wont bug you anymore with questions and once again rdking647, thanks for the info.

[rdking647]

28. ask away :)

[WhiteTara]

29. Thank you for sharing

This is an incredible photo. What patience on your part.

[HAB911]

30. Absolutely amazing