wimvb

Yes, you can. That does sound like a lot of string and chewing gum. What about this: indi & kstars/ekos & phd2 on a raspberry pi; eqdir cable from RPi to mount (no synscan); usb cable to imaging & guide cams; connect to RPi over wifi using windows remote desktop on you pc? And if you don't want to use ekos, you can use ccdciel & cdc on your laptop. You can keep phd on the RPi in order to keep wifi communications down. With everything running on a Raspberry Pi, an imaging session won't get interrupted in case you lose wifi connection between the RPi and PC.

Today, my digital copy of Rogelio Bernal Andreo's book arrived. This version of his book has 407 pages (excluding the reference guide) packed with information from this famous astrophotographer. After a first casual reading, I must say I like this book a lot. It provides what Warren Keller's book, in my opinion, is missing: in depth descriptions of how pixinsight tools can be used in a workflow. How pixinsight methods and scripts can be used to get a job done, rather than describing what a method/script does. While Keller's book is an excellent first reference of the various tools, Andreo's book goes further by using those tools on images. The perspective is shifted from methods descriptions to image processing. Rather surprisingly, this book is not only about Pixinsight. One chapter is dedicated to integrating a sequential workflow within Pixinsight with a parallel workflow using PS or GIMP. This chaper only provides an overview of such a workflow. It could be expanded upon, in my opinion. The printed version is expected to arrive just before summer, and will also contain a long reference of pixinsight methods, the digital version of which will be sent separately to those who have preordered the book.

Now you've lost me. How can those be just your flats? Or is this the light stack without darks & bias frames? Anyway, if you load all your subs into a shared dropbox/google directory, I can run them through PixInsight.

I agree with that. I recently saw a post (can't remember where, not necessarily here), where the culprit was the micro sd card. In other cases, usb connections and power cables were found to create artefacts. None of these causes are easy to diagnose. But any hardware issues must show up in single subs.

That sounds like a good idea. I don't know if large LP filters, similar to daytime UV filters, are available. They might be expensive. A few years ago, I was in very much the same position as you are now: where to go from here? In my case, I was stuck with an old dslr, that wouldn't connect to a computer anymore, and a mount that leaped like a frog. I bit the proverbial bullet(s), and first invested in a better mount, and later in a better camera. Both investments improved my data considerably. My latest investments, moving to a dark site and building an obsy, had the same impact, but are probably out if reach for many. What can I say, I was a lucky punk. (to paraphrase Dirty Harry) In the end only you can decide how large investments you can make, or justify. But this hobby does cost, no point denying that.

Calibrate the frames from last year with darks and flats from last year, and the frames from this year with darks and flats from this year. Then stack/integrate all frames together.

I think you pretty much summed it up: You tried to shoot with a non-modified dslr in a light polluted area, near a full moon. That's a sure recipe for imaging an overexposed star field. I think that if you try the same two weeks from now (no moon), with a light pollution filter, you will get better results. Just make sure you point your 42 mm lens at the Milky Way. And take many exposures. It's the total integration time that counts. Edit: point at the Milky Way, because for a wide field, this is the most interesting part of the sky, imo.

Yes, but there is a Goldilocks zone: unusual but large enough to show detail. Very nice image btw, Göran.

Thanks. I'm sure it will be worth the effort. There are many galaxies in this area of the sky.

In my image, seeing the tidal stream is like "you see it, if you believe it". But the small dwarfs are definitely there, and even these are super faint at magnitude 26.5 M/arcsec. My luminance just isn't flat enough to be able to pull more out of it.

Thank you. I measured sky darkness a while ago at about mag 20.5, and fortunately there are no glaring lights from neighbours. The only disturbing light is from all the LED indicators on my gear.

Thank you.

Thank you. I would if I could. But unfortunately I don't know anything about Meade gear.

Ngc 4206, 4216, and 4222 are three galaxies in the Virgo cluster. They are located at a distance of approximately 50 - 60 Mly. The most interesting is the one in the middle. Ngc 4216 is a barred spiral galaxy of type SAB(s)b, and is one of the larger galaxies in the Virgo cluster. Ngc 4216 forms a pair with the smaller galaxy just above it in this image, VCC 165 (LEDA 39247). The galaxy is subject to ongoing research after it was found to have several tidal star streams. These streams are likely the result of accretion events where satellite galaxies are being drawn into the main galaxy. What is particularly intruiging is the fact that one of the tidal streams contains three dwarf galaxies, two of which are visible and indicated in the annotated image. It has been speculated that these dwarfs, rather than being absorbed by ngc 4216, may be forming in the tidal stream. (S. Paudel et al., The Astrophysical Journal, 767:133 (11pp), 2013 April 20) Annotated superstretched luminance image: A, B dwarf galaxies in the tidal structure (F) of ngc 4216 Acquisition details: Skywatcher MN190 DS on SW AZ-EQ6 with off axis guider Camera: ZWO ASI174MM-Cool with ZWO LRGB filters L: 65 x 4 minutes; R 55 x 4 mins, G, 44 x 4 mins, B 30 x 4 mins (total integration time: just shy of 13 hours) Processed in PixInsight.

I combined the unstretched r, g, and b images to create a colour image. I then used colour calibration (PI photometric color calibration) and arcsinh stretch (is also available for PS). I desaturated the background protecting the galaxy and stars. I processed the luminance separately: gradient removal (DBE in PixInsight) deconvolution (sharpening) stretch using histogram transform (levels in PS) HDR compression to get more contrast in the dust lanes of the galaxy Then I combined the L with the RGB Topped off with star reduction.

in PixInsight: I think that the main problem is lack of data. How much was the total integration time?

To see if a master flat works, you can try to calibrate a single flat frame with your master flat and dark/bias. That should give you a perfectly calibrated and flat image with only some noise. Flat frames need to be calibrated with either bias (ccd, dslr) or darks (cmos), or they won't work properly.

0.87" rms at a pixelscale of 5.9"/pixel. That's good guiding.

I don't think that pixelscale matters much at your focal length. The same goes for fov; both are large enough at your fl to provide plenty of stars to guide on. The 174mm doesn't have a bayer matrix, and should be more sensitive because of that.

Here's my attempt in PixInsight. Your image has very strong gradients. Also, the background intensity of the subs and integrated image is quite high, so you should probably decrease your exposure time or use a light pollution filter.

Welcome to the forum, and what a nice way to introduce yourself. Great image.

J103559.74+520235.9: z=0.741221 J103600.4+520218: z=0.66256 Z for QSO's doesn't always translate directly to distance, as is the case with galaxies. I've seen QSO z values in excess of 5.

When you are in the market for a new camera, use a fov calculator to compare sensors. http://astronomy.tools/calculators/field_of_view/ Also, for deep sky work, always go for a cooled camera. Dark frames need to match light frames in temperature, which is much easier to do if you can set the temperature of the camera.

If you have a skywatcher mount with synscan hand controller, you can do an "all star" polar alignment. As rom v 4 (I believe), it's included in the HC firmware. It's much easier than drift align if you're new to this game, and good enough for a mobile setup.

Beauty is in the eyes of the beholder. There is some very interesting physics going on here.