wimvb

Thanks, guys. This is the only orientation where I see a clear primate head, although at times, it looks like Chewbacca. I guess I should print the other orientation and hang it on a wall. @Laurin Dave: I gather you visit that other forum as well.

Ngc 2175 is a star cluster, associated with an emission nebula in the constellation Orion. The nebula goes by the popular name Monkey Head nebula. There is some debate whether the nebula has its own ngc number (ngc 2174) or whether this number is a double in the catalogue, so that the star cluster actually has two ngc numbers. The nebula and cluster are about 6 400 lightyears distant. The nebula has an angular width of about 40 arc minutes. This means that it's a big monkey, with a skull that is about 75 light years across. The data for this image was collected in February of this year. I could only spend a few hours each night on this target, as it was setting early in the night. This also affected the guiding. Details: Ha 68 x 5 mins (Baader 7 nm, 31 mm filter) R 32 x 2.5 mins (Optolong 31 mm LRGB filter set) G 30 x 2.5 mins B 38 x 2.5 mins Total integration time just over 10 hours Gear: MN190 on a SW AZ-EQ6 mount with an ASI294MM camera Software: Ekos/Kstars for capture and PixInsight for processing

Not exactly bank-breaking expensive. But since it can't darken the sky, it's basically just a nice gadget. About a year ago, I built a Sky Quality Meter and "calibrated" it using Göran's Unihedron. According to that, I have a sky magnitude of about 20.5 - 20.7 at best. But it seems to me that this year (haven't measured it), the sky hasn't been that dark. Most likely, high clouds are to blame. We just haven't had one of thos crisp, clear skies this year.

Very nice, with lovely detail. Is that gso scope a newtonian or a RC?

This article from Sky and Telescope, written by Jerry Lodriguss, relates integration time to sky brightness. https://skyandtelescope.org/astronomy-blogs/astrophotography-benefits-dark-skies/ This should be relevant to the discussion in this thread.

What, no galaxies allowed?

I wonder if that combination can introduce heat currents and what effect these would have on star shapes, similar to heat currents in open tube telescopes such as Newtonians or RC.

Sorry, my bad. I really thought non integer values were possible. I never drizzle my data, so I’m not that familiar with the process. drizzle 2x is the best you can do. Follow up with deconvolution to get detail back, because, as I wrote earlier, drizzle by itself is not a guarantee that you get more detail.

There are several members on this forum who have a RASA (Göran Nilsson, @gorann gets excellent results with his), but they are best combined with an osc camera. Obviously, a filter wheel will be too much of an obstruction, so if you want to use it with a mono camera you will need a filter drawer and change filters manually.

If you collect data with a new moon and with a full moon about, you should expect more noise in the full moon subs. If you then integrate first the new moon stack, and then the full stack, you may very well end up with the results you show here. That's one explanation. I don't know the inner workings of dss, but the image integration routine of pixinsight normalizes the calibrated lights to a reference frame during integration. The brightness (and I assume also the noise) in the stacked image varies if you use a different calibrated reference. Dss does, most likely, something similar. This is also a possible explanation for your results.

That’s simply because you’re not an expert yet. Letting someone with more experience work with your data can help to ensure that at least the data acquisition is ok. I used this approach myself, and used the experts result as inspiration, something to thrive for. AP should be a passtime and a fun activity, not a contest. The only ”contest” I have is the one where I try to beat my own previous achievements. I usually end up being the winner in that contest. 😉

+1 for letting someone else process your data. And you can also process other's data. Eg, the IKI observatory data that is published here on sgl. This gives you the opportunity to compare your results to others.

You had me wondering whether that gear in the front was the latest user interface of StarTools.

Once you have good PA, you don't want to move the mount anymore, and you definitely don't want anything else to move the mount either. Ie, you want to bolt it down. Question is, how would you do that remotely? Leave it unbolted and you have a wobbly mount. But if you want to do it, you can just put an eq mount on top of an alt-az mount.

Don't think so

Demand your money back.

Could be. But above all, collect much data. Drizzle will inevitably decrease signal to noise ratio, and if you want to apply deconvolution, you need a low noise image to start with. The image data you posted here, has maximum pixel values less than 1 (scale 0 ... 1), so you can safely increase the sub exposure time.

There is a real difference in star profile in your image. The 2x drizzle image is in principle oversampled, and the non-drizzled is undersampled imo. Applying drizzle doesn't necessarily mean that you gain detail, it means that the detail is distributed over more pixels. But there is a difference in post processing. The oversampled image allows you to do a more aggressive deconvolution, reclaiming some of the detail that is lost to seeing. So there is an advantage to process the drizzled image. But that advantage comes at a cost; your image file is 1.2 GB, four times larger than the non-drizzled image. This not only eats hard drive space, but also slows down the processing. What I would do with this image is first crop the drizzled version to maybe 1/4 size, and then start processing it. In terms of image geometry, this is equivalent to taking an image with a smaller sensor camera which also has smaller pixels. Here are the star profiles for the drizzled and non-drizzled images Btw, if you drizzle an image, you don't need integer drizzle values. You could drizzle 1.5 x or even slightly less.

The bottom right doesn't look like light pollution. Does it show in your calibration masters (flats and/or darks)? If do, it's setup related. The other gradients are due to light pollution or the moon being close. Which of course, is also light pollution. These are easy to remove with dbe.

Open that post in another tab in your browser. Copy the address and paste in a post here. That's it. It will link automatically.

Good one. (Both are good, actually.)

The moon is just another bright light bulb in the sky. As with sunlight, moonlight will turn the sky blue, just less so than sunlight. And as with daytime b/w imaging, using a red filter will suppress that blue, giving more contrast. That's why Ha imaging works during a full moon. Using a red filter with a mono camera will also work to some extent. But if you plan to image blue nebulosity (reflection nebula or Oiii), you better wait for the moon to be out of the way.

Time to get the "bible" of astrophotography: https://www.firstlightoptics.com/books/making-every-photon-count-steve-richards.html

They don't, but life is easier if you leave them the same. You can alter exposure time, but you may need to take new darks. You can rotate or shift the camera, but you will need new flats and will lose area in the final image, because you need to crop the stacking edges. Once you manage plate solving in the field, your pointing accuracy will be much better and you can keep more of the subs in the final image. One way to get repeatable framing is to align your camera with RA and DEC. To do so, take a 30 s exposure. While the exposure is running, move the mount at sidereal rate in RA only. This will create star trails in the RA direction. Rotate your camera "into" the trails, ie until the trails are parallell with either the long side or the short side of your camera sensor. If you do this, any misalignment is only a shift in RA or DEC, which is much easier to correct.

But unintentionally, you cast a much wider eye on the sky. To the left side in your image, is an area with a very nice distant galaxy cluster [SPD2011] 9429 I have indicated its brightest members, two galaxies with a redshift of 0.132. This puts them at (don't start swearing now) 1.7 billion light years distant. To show them better, I took a crop from your image, inverted and superstretched it.