wimvb

And I realise that I sort of promised to do a write up on my work flow. I’ll try to squeeze that in somewhere this weekend.

I have abandoned LHE in favour of MMT (Multiscale Median Transform). LHE increased noise in my images, and didn't give me the same control that MMT does. With MMT I can increase sharpening or local contrast (which is the same thing) exactly where I want it. It can even control colour saturation locally (by selecting Chrominance as the target). I used MMT on my version of the IKI M81/82 dataset to get better definition in the arms of M81. I didn't need to use any sort of noise reduction (having 100 hrs of data helps). I must admit that I've never used MMT on such a rich star field as this image. It is very possible that MMT won't give any better results, because it will fatten stars, so these will need to be protected.

Nice catch, Olly. It looks like you also caught a few galaxies in your new photon hoover.

Ouch! that's tough. Get well soon!

A bit of reflection on the subject (poor pun) leads me to the conclusion that the reflection spot on the screen closest to the incident laser beam is from the surface closest to the laser. The reflection furthest from the incident laser beam is from the deepest reflecting surface (= sensor). Unless there are multiple reflections, ie the beam reflecting back and forth between two surfaces. And this is something which I hope, will never occur.

So how will you know which reflection is which?

Or this way: https://www.sxccd.com/support/maintenance-information/aligning-the-ccd-in-an-sxvr-camera/

@gorann, actually it is the reflecting surface (sensor) that determines the location and movement of the spot. It's similar to a laser collimator test rig. If during a full rotation of the sensor, the spot does not change, the sensor is perpendicular to the rotation axis. You only need to make sure that the rotation axis is perpendicular to the front plate of the camera.

Nothing like the one I made. I used gray duct tape instead 😉 Btw, the finder scope may have stray light entering, being white on the inside.

That definitely sounds like it's the rejection settings in dss. I've had this with pixinsight sometimes, and adjusting the rejection parameter for high rejection, solved it.

You can actually use PixInsight for capture, stacking and processing. PI has a client for the INDI platform, which allows mount and camera control. Unfortunately not developed past the rudimentary functionality, and I wouldn't recommend it for gear control and capture.

I agree. There are three options. The first is that you download a sub to your computer and stretch it hard. Use this stretched test image to reframe. In this case the brightest stars in the upper half of your image need to be close to the very top of your frame, if you want to catch the whole arc. The second option is to download an image with the same object from the net and use this as a reference. Again, use stars as a guide. The third option is to use a stellarium program to frame the target. I frequently use the online resource aladin. You need to know your approximate field of view (easy to get from a processed image such as the one in your first post). https://aladin.u-strasbg.fr/AladinLite/ And of course, you can go all in, and control your gear by computer, plate solving etc.

Combining data from several sessions is quite common, but there are a few things you needto pay attention to. 1. Try to keep the camera attached to the scope. If this isn't possible, align the sensor edge with RA and DEC. This makes reframing easier. To align the sensor, start a 30 s exposure. About 5 s in, press the RA button on the hc, with slew rate at 1x sidereal, until the exposure ends. This will create a star trail. After the exposure view the result. Turn the camera into the trail. Repeat until star trails are parallell to the sensor's edge. 2. Use platesolving software if youcan. If you can't, note the position of brighter stars near the frame edge, and align these as close to the previous sessions position as possible. 3. Allow for mismatch between sessions and keep the main target clear from any edge. Btw, if I were you, I'd reframe the veil and reshoot, or use the data you have and create a mosaic.

That’s a very fine coathanger. Thanks for sharing.

You will probably need to relax the rejection criteria a bit. As always: experiment. 😁

Even if it’s a focusing issue, you should still check your stacking parameters. Changing the rejection settings can improve the star shapes.

How was the proverbial pudding (wherein the proof lies)?

Gently clean the front only. You can use the wonder fluid. Or ”soften” the dirt with isopropanol first and the clean with wonderfluid. There’s no need to take the corrector off. But if you plan to do that in the future, make markings on it and the tube so you know how to put it back.

With the ultimate you’ll be more future proof. If you have a refractor and guide, you’ll need two dew heater ports at least. And if you ever want a smaller scope piggybacked on a larger, you need another one. If budget and size are not a problem, take the bigger one.

I think you will find it difficult to keep the cables perfectly straight, and you may end up with Drechsler’s solution.

Very likely so. Unless you go extremely deep in L, you may never see dust bunnies. A RASA is most likely combined with an osc camera, so you won’t get in a situation where you collect L only. Unless you go for a quad scope rig with permanently mounted LRGB filters. I know that Göran keeps his gear so tidy that he never(?) uses flats. The little vignetting that he has can be dealt with in postprocessing.

I'd say, pollution: yes. Pollination: no. Pollen is nasty stuff that can destroy the coating on optics. And it's much harder to remove than regular dust.

That’s part of reflector territory. Imo, you have to either accept it or you fight it. I’ve accepted it. At least there are no spikes to worry about.

According to the article, galaxy Mrk 1486 is at a distance of 500 ly. That’s less than half the distance of the dumbbell nebula, another polluter.

Swedish license plates have a combination of three letter followed by three digits. Meeting a deep sky object up close isn’t very uncommon. NGC, LDN, LBN