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Hubble already has (from the Hubble legacy archive): How should we interpret this? The intensities don't seem to match.

DSS2 shows a hint of a partial ring in the red channel. As the ring shows even with an NBZ filter, it shouldn't be too difficult to get a better image of it. The reason nobody has imaged the galaxy this way before is probably because it is small and not very interesting (apart from the ring). With a slower scope, it would take quite a few hours of integration time to reveal this feature.

I use astroberry on a raspberry pi 4, so am not bound to zwo gear, as you will with an asiair (ie, dedicated camera, filter wheel, focuser). I have used INDI on several devices and with several operating systems, and find Astroberry on a RPi4 the most stable solution. Easy to connect from any web browser, and not a major learning curve.

Note that objects that appear opaque in visible light, can be quite transparent in IR light, and vice versa (look at the guys glasses). This image was taken with a camera that is sensitive to 7.5 - 13 um light. https://www.spitzer.caltech.edu/image/sig08-004-hands-in-a-bag-color-visible-vs-infrared-light That is also why you should never take darks with just a plastic lens cap on.

Great image, Göran. Even if it is likened to a flatulent amphibian.

Not so much that I was tempted to grab the hacksaw https://www.astrobin.com/331604/F/?nc=&nce=

In AP the mount is probably more important than the optics (but of course, garbage in, garbage out). It pays off to spend some money on improving the mount. Since the mount is such an important part of any AP setup, it should not be overlooked in an upgrade. I have the 150PDS, not the 130PDS or the 6” photon. But it seems to me that if shown images taken with either, you’d have a hard time figuring out which scope was used, apart from the slightly different fov due to the difference in focal length. The main issue people have with the 130PDS, is that the focuser draw tube may protrude too far into the light path, resulting in diffraction artefacts around bright stars. I have no idea if the 6” photon has similar issues, but it’s worth investigating, imo. The price difference between the scopes isn’t that much, unless you want a carbon tube.

The 150PDS and its little brother are both good scopes for AP. The 130PDS has its own thread in the beginner’s imaging section. F/5 scopes are less fussy about perfect collimation and focus than F/4, so have a slight advantage in the field. The 150PDS is larger/heavier than the 130PDS and more sensitive to wind. If you save a few £ on the scope, you can use that to eg upgrade the mount with a belt. This will improve tracking accuracy.

Here's my attempt Dynamic Crop DBE Photometric Colour Calibration including background neutralisation Multiscale Median Transformation noise reduction och chrominance only (removes colour mottle) (cloned) arcsinh stretch star removal (M33_galaxy) contrast enhancement and colour saturation on M33_galaxy Histogram transformation on the cloned image (M33_stars) (cloned again) star removal on the second clone (M33_starless) combination of three images in PixInsight: M33_galaxy + M33_stars - M33_starless I had to separate the image in its colour components and realign those components in order to remove the chromatic aberration and dispersion effects

Imho you shouldn't use the screen transfer function as a permanent stretch. The STF calculates the histogram stretch depending on image statistics. Its aim is to show what's in the image, without concern for aestethics. Choose the stretch based on what you want the image to look like. With a colour image, I usually start with a colour preserving stretch, such as masked stretch or arcsinh stretch. I then apply a moderate histogram stretch, mainly to adjust the black level and increase contrast. After that, I only apply curves stretches. The exact choice of which stretch to use, and which settings for a certain stretch, should depend on the image.

Thank you, Alan. Glad you like it. I used the RGB only for the stars, so I didn't need much signal.

Not much to say about this one. Sharpless 2-188 is planetary nebula in the constellation Cassiopeia, at a distance of approximately 850 ly. This is an HaRGB image, with the data collected during a full moon. 144 minutes of Ha and about 3 hours of RGB for the stars. Imaged with the SW 190MN and ASI294MM. Processed in PixInsight.

Ha ha! That would be the second of this model flying across the sky. And the other also got a banged up look eventually.

Great image, Göran. Now the real question is, what make and model are we talking about? Obviously some sort of sedan.

Not really an issue. Once the oag is installed and is focused (I use a Bahtinov mask and a zwo helical focuser), it just sits there.

The 190MN is a very nice scope, and if I had the place and money, I would love to get a "second serving" (on its own mount). But the OP mentions easy to collimate. With a few years experience, I can vouch that this scope is not straightforward to collimate at all. But if you get it aligned properly it's a gem. @ollypenrice, I'm about to remedy the mechanics part. In August I ordered a 2" FeatherTouch focuser for my scope. The original is just too unreliable with its built in extension tube. Unfortunately FeatherTouch focusers have a long lead time. Astroshop informed me a month ago that I shouldn't expect delivery before new year.

Have you seen this?

It says price to be determined, so they probably just had to enter something into the database. And they could hardly enter $ 0.01. This is an IR camera, and InGaAs sensors aren't cheap. So even when they do set a price, it will be high per mm2 sensor area. An interesting development though, and I eagerly await results with this camera.

Love it! I think you can safely darken the background slightly. In PI I would use an S-curve with the upper half linear, ie the S restricted to the lower half of the curve.

I've heard of/seen truss tube telescopes, but never truss tube observatories. 😉 Seriously though, good luck with the build. I'll keep following this thread.

Use the filter wheel unidirectionally (can be set in the driver) and alternate between l, r, g, and b during the night. At least if you don't need to refocus between filters. That way, if the weather doesn't cooperate, you at least have a full colour set every night. And also, if for some reason one night's subs are bad, you can still create an image with what you have. At my site, fwhm may drift during one night, but most often, there is more variation between nights than within the same night. Collecting all colours during a night gives me more consistent results.

I have the ASI294MM Pro with zwo filter wheel and oag. This camera has much better specs at bin 2 than bin 1, and 4x smaller file size. Just check the ZWO product page. Smaller file size means faster download, and a lot faster image processing during stacking. In my experience, cmos cameras give best results if you stack many subs, so having smaller files does make a difference in processing speed and storage. I believe that ZWO reduce amp glow by powering down unnecessary circuitry on the chip and in the camera during exposure. This circuitry is then only turned on during read out. The camera has star burst amp glow, which needs matching darks to calibrate out. I have found that a low temperature isn't a must and run it at -10 C during autumn and at -20 C during winter. The most important thing is to keep the temperature stable and below ambient, or calibration may not work properly. For LRGB I use the camera at 0 gain, offset 8, and for narrow band 200 gain, offset 30. Exposure times at f/5.3 are 180s for L, 300s for RGB and 240s for Ha (7nm) at a Bortle 4/5 site. The exposures are long enough to drown fixed pattern "noise", while also short enough to avoid overexposing any but the brightest stars. Hope this helps.

He doesn't have safety goggles

In some of these galaxies, such as And XXX, the classification is done by photometric study of individual red giant stars. And XXX was discovered in 2012 as a local star density increase of only 8 such stars. Being roughly at the same distance as the Andromeda galaxy itself, this means that single stars need to be resolved. This is too much to demand from a 7.5” telescope situated in the Northern European climate. But if the stars create a diffuse patch, it may be possible to record it.

Neutral Hydrogen is only ”visible” in mm wave data, ie through radio astronomy. Stellar streams consist of stars, and should be visible in optical wavelengths. Like the dutch national coat of arms says: I will persevere. (Once the sky clears.)