wimvb

Is the Ha data still linear (ie, not stretched)?

Throwing them all into the pot is better, it gives a better average and pixel rejection is more "reliable".

Looks like a reflection of the glass edge. What brand is it? You also have a band along the top and bottom.

Wow. There's a lot of structure in that core.

A very good image indeed, with warm colours. 30 hrs well spent. Did you process in Pixinsight? There is a tiny amount of ringing and a background structure in the full scale version that hint at deconvolution in PI.

I also noticed that. I would like to see more data points after the dec drift is restored. My suggestion: run the guiding assistant.

3500 for a laptop? That must be some beast.

Yes, that would be nice to have. It's just that the warm room of its obsy is so far away.

That seems rather small for an 8" telescope. It's easy to measure how much space you need. Set up your scope and swing it around. Mark the positions on the ground that are furthest from the center. Also measure the highest point it will reach. This will give you the absolute minimum dimensions of any enclosure. Add some margin, and space to move around the scope if you plan for a ror. The roll off shed that I used last season was about 3.5 x 4.2 x 7 ft, and had barely enough room for me to stand in an awkward position when needing to adjust the camera. And that was with a sw 150pds on an az-eq6. As for the roof construction, there are several options besides a roll off roof. Eg, a clam shell design saves space. Google around.

Excellent catch, Rodd. I agree that hdr composition is probably the way to go. Other dynamic range compression techniques will most likely do more harm than good.

Very nice! But I think you should change the topic title. 😉

Looks like dust to me. If you take flats, they should be at the same position. Look for dust on the inside of your lens.

Neither do imagers. 😉 An alternative would be to use false eyelashes as a brush. This post reminds me of a time long gone, when I started working for a Swedish electronics company. I noticed that the microscope eyepieces were quite dirty (in a cleanroom!), so I cleaned them with a tissue. They had black residue on them. After a moment it dawned on me that some of the ladies working there were wearing mascara. Over time cleanroom policy changed for the better. So did the quality of the devices (mostly prototypes) that were manufactured there.

Load limit, I believe. The eq5 is rated at 6.5 kg for imaging. The heq5 can handle 11 kg. But that's on paper only. Tracking accuracy depends very much on what you put on the mount, and where you put it. A newt, although lighter, will catch more wind than a frac. (im)proper balancing also affects tracking. If you decide for the heq5, concider the belt modded version, or do the belt mod afterwards. It's easy to do, and improves tracking.

As @JamesF I'm also spending more than saving atm. Building an observatory puts any astro saving/investment on hold. But I am window shopping. Rings + Losmandy plate for my MN190 Filters (dare I mention astrodon) and possibly a new filter wheel.

RMS stands for "root mean square", and is a standardised way of measuring average deviations. There is s ome math behind it, but I won't go into that here. In guiding, the star is kept at the same position, but it will deviate somewhat from that position. RMS is a measure of how much that deviation is, on average. This is correct. Seeing is how much a star twinkles. Due to air movement (not wind), the light from a star is deflected a tiny bit all the time. You get the same effect when you look at the moon through a high power eyepiece; craters seem to wiggle. Guiding can't keep up with these fast movements, so you set your guide camera exposure time to average out the twinkling as much as possible. That's why you need to set the guide cam exposure to several seconds. But despite this, guiding quality still depends on seeing. When you find that guiding is excellent, collect luminance. When guiding is poor, collect colour. This way you get the most out of your imaging time.

Excellent! That was time well spent. All 16 hrs. Thanks for sharing

https://www.firstlightoptics.com/books/making-every-photon-count-steve-richards.html http://deepskystacker.free.fr/english/faq.htm#lightdarkflatoffset Also have a look here: http://deepskystacker.free.fr/english/technical.htm#stackingmethods Providing links to good information makes more sense than rewriting that information. Also: get the book, it will be your best "bang for buck" in a long time. If you have any more questions, or don't understand the contents of the links provided, don't hesitate to ask them.

Flats contain a bias signal as well as dark current. The dark current is generally negligible, but the bias is not. Before you combine the flat frames into a master flat, you need to subtract the bias from them. When you calibrate the light frames, you also first need to subtract the bias as well as the dark signal. The stacking software takes care of this, as long as you provide the calibration files/masters.

@vlaiv is right on the money. You used flats that didn't properly calibrate the lights. This causes weird vignetting and leaves dust bunnies. You also have walking noise, the noisy streaks in the background. These can be reduced by using cosmetic correction and playing with the kappa rejection settings. The only sure way to remove this pattern is by dithering; move the mount in a random direction some 12 - 15 pixels between exposures. The bortle 8 sky doesn't help either; it causes gradients and a lot of noise. Once you remove the light pollution by adjusting the background, you're left with the light pollution noise. If you image from a site with light pollution, you need to increase the total integration time. For each hour of integration time from a magnitude 20 site, you need 2.5 hrs from a mag 19 site, 6.25 hrs from a mag 18 site, etc. I downloaded your master file, and to me it seems underexposed. I would expect to see more stars in the unstretched image. What was your single sub exposure time? Did you use a light pollution filter?

Unless it has an hdr setting, dss will calculate the average of all three exposures. In true hdr, you want the best out of each exposure, not just their average. What you probably should do is create a master for each exposure, aligned against one single reference. Then you do hdr composition in photoshop or any other processing software. I know that Pixinsight has a process for this, I'm not sure about other astro imaging software.

You can add the goto to your eq5 and invest in a short fl refractor, such as the 72ed or 80ed + field flattener. With your newtonian you also need to invest in a coma corrector for ap.

Depends on your intended use, space, and budget A roll off shed is easier and cheaper to build. Also smaller. A ror is more work, more expensive and (usually) larger. I used a roll off shed last season, but have now almost finished a ror. It's a LOT more work and expensive.

Generally, the DS are the imaging versions of the skywatcher newtonians. DS stands for dual speed and refers to the focuser. I have used the 150 P-DS on an eq3 goto with aluminium tripod, and in my opinion it's undermounted. The eq3 has a load limit of 5 kg, which is taken up by the scope only. You have no margin for camera, guidescope, etc. That being said, with some tlc, attention to balancing, and beefing up of the tripod, it's still a nice setup for a beginner. When you outgrow it, you can use the mount for a light weight grab & go setup with a photo lens and camera. The 130 P-DS has a shorter fl and is somewhat lighter than the 150 P-DS, so probably easier to guide. I believe that the DS models are also slightly shorter, so it's easier to reach focus with a camera. Not sure about this, though.

It uses online star catalogs; Vizier, etc. Then it reports stars that are "in the wrong position". It would be interesting to know what the cause of the error is. It may just be wrong entries in the catalogs.