wimvb

Interesting discussion regarding standardised workflow. Are any of you familiar with the works and writings of Ansel Adams? He basically only used black and white film for his artistisc photography. (”When all else fails, you can use color.”) But he hardly used a standardised workflow, even though he introduced the zone system. Of which the fundamentals can be applied to astrophotography as well. Sort of. What I’m trying to say is, that image processing isn’t a one button affair. Even in camera you have to choose a white reference (sunny, cloudy, incadescent lighting, etc). If you want more than snapshots out of your photography, you need to apply colour corrections, red eye removal, smoothing, sharpening, hdr processing, etc etc. Definitely not a one button process.

I added 1 hr of Ha and used Vicent Peris' red continuum subtraction to add it to the red channel. This allowed me to push the Ha more without intorducing noise. Image added to the original post.

Astrophotography, like real estate, is about three things: location, location, and… location

Great! Access to a dark site helps.

Go for it! It would be interesting to see the comparison.

Thanks. The galaxy contains many young stars and is ”strong” in blue. Not exactly a full moon target.

ngc 4395 is a low surface brightness galaxy in the constellation Canes Venatici, approximately 14 million light-years from Earth. It is a Seyfert I spiral galaxy with an active nucleus which contains a low mass black hole (300 000 x solar mass). The galaxy lacks a central bulge that is common in spiral galaxies. Its diameter is approximately 50 000 light-years. This image contains a few galaxy clusters, the one at the upper left of ngc 4395 at a distance of approximately 3.6 billion light-years. Technical details: SkyWatcher 190MN on AZ-EQ6 with ZWO ASI294MM and Optolong LRGB filters L: 224 x 3 minutes RGB: 50/50/66 x 4 minutes Ha: 55 70 x 4 minutes Total integration time, 26 27 hours, processed in PixInsight With added Ha (one hour) and better Ha incorporation. I used Vicent Peris' Red Continuum Subtraction method to boost the Ha in the red channel without adding noise. (original)

https://aladin.u-strasbg.fr/AladinLite/ Is what I use. Most galaxies are quite small in a 1000 mm fl telescope. I try to frame them such that I get a bit extra in the final image. Usually there is something interesting hidden in the background.

Whenever Ekos has done a flip at the southern Meridian, it informs me that the next flip is due in 12 hours, not in 24. And how else, the next day, would the scope be in the same position as pre-flip?

The problem that I had with this configuration was that if I lost (wifi) connection between the server and the client, my imaging session would crash. Because of this I now run everything on a RPi4 and connect to the linux desktop with MS RDP. If I lose the connection, my session happily continues. Platesolving never takes more than 2-5 seconds with the newest StellarSolver.

PixInsight does 😜 but you already knew that

Yes, I saw that in your signature. You can extract luminance from the colour image while it is still linear and apply deconvolution to that. (This is what I meant by "clean luminance", as opposed to the rgb channels which also contain lightness or luminance information.) Then use LRGB combination to put the luminance back. You can even process the colour image just for colour, stretch the luminance for detail and reinsert it with LRGB combination. For deconvolution to give any benefit, you need a high signal to noise ratio. Like any other sharpening technique, deconvolution tends to increase noise.

I don't think it will make matters worse, because you will mask the background anyway. If you want to use deconvolution, it works best on clean luminance.

Pixinsighted Dynamic Crop DBE Background Neutralization Photometric Color Calibration Arcsinh stretch Curves Transformation Multiscale Median Transform with bias on L with mask to protect the stars How are your imaging conditions? Light pollution can be the cause of weird gradients. As can a lot of other things, of course.

Quite so. A lot of published research is based on sky surveys like SDSS and Gaia, zapping away in space, collecting spectra of almost anything up there. https://en.wikipedia.org/wiki/Gaia_(spacecraft)#Scientific_instruments

Looks good to me. I don't know APP, so can't really help with getting the colour right. Combining Ha with RGB in the linear stage worked best for me. https://www.astrobin.com/rff05g/

You made the right decision to use short exposures. Since the jet is very close to the core of M87, longer exposures will drown it in the light from the core. Last year I managed to capture it with 150 s exposures at 0 gain through a red filter (to increase contrast). https://www.astrobin.com/7oj8y8/B/

Almost, I think. With some finger force, I could tighten the thumbscrew that locks the extension tube a bit more. There was a very tiny amount of play there before. But it's not 100% solved. I saw a hint of it in a recent capture. The good thing is that both MoonLite and Starlight Instruments (Feather Touch) have focusers that can replace the stock focuser on the 190MN, if it comes to that.

Another star cluster, but this one has a bunch of galaxies in the background. Ngc 5466 is a globular star cluster in the constellation Boötes. Its distance to earth is approximately 52 000 light years, and its age 13.6 billion years. In 2006 a possible tidal stream was discovered that extends from this cluster towards Ursa Major. This image represents 3 hours of integration, 15 x 3 minutes exposures per channel in RGB. Telescope: SkyWatcher 190MN; camera: ZWO ASI294MM. When the weather clears up later this week, I plan to collect more data in order to clean up the background and pull out more detail. April 12: The weather has cleared up and I have collected more data, but only 2 hours worth. Nights are getting shorter and shorter up here. As I wrote before, there are plenty of faint galaxies in the background. The faintest one that I could find information on, has a redshift of 0.44, which puts it at a distance of 6 billion light years. Also interesting in this image is a small QSO next to the brightest star. This galaxy, with designation QSO B1404+286, is classified as a BL Lac object. According to F Massaro et al: "The most elusive and extreme subclass of active galactic nuclei (AGNs), known as BL Lac objects, shows features that can only be explained as the result of relativistic effects occurring in jets pointing at a small angle with respect to the line of sight." (F. Massaro et al 2020 ApJL 900 L34)

I took the liberty of downloading your image and apply colour calibration in PixInsight. As I only had a compressed jpeg image to work with, the result is (to say the least) not very good. But it shows what colour is in this image.

👍

Just stretch them gently. Avoid bloating them too much. Stars from refractors are easier than stars with spikes.

Starnet v2 is your help. Extract the stars from the RGB image, and put them into the starless NB image.

A short break from imaging galaxies, here is star cluster M67 in the constellation Cancer. This is one of the oldest open clusters tied to the Milky Way, and has been studied extensively. This image is an integration of 3 x 20 sub frames of 4 minutes each at gain 0 and -20 C, totalling 4 hours of exposure. Stacked and stretched in PixInsight. Gear as always: SkyWatcher 190MN on an AZ-EQ6 mount, with an ASI294MM camera and Optolong RGB filters.

Not much, really. Stars are bright, and you won’t be using the star background. Depending on gear, conditions and expectations, only few subs per colour.