Documenting the setup of my new telescope

[Devin-M]

…a nice, modest rig…

 

[DennisN]

…a nice, modest rig…

It's just the bare-bones.

 

[collinsmark]

I've got more data!

Here's M100 (a.k.a., NGC 4321, "The Blowdryer Galaxy," "The Mirror Galaxy") with about 37 hours of data and a lot more care with post-processing. (It's the same target as before, just with more data and more care.)

Not only did I gather more L, R, G, B data, but I also gathered and integrated some Hα data giving a "punch" to the nebulous regions in the galaxy.

Figure 1. M100 with about 37 hours of data from the new telescope.

Also, here's a 100% crop of the image showing more detail.

Figure 2. 100% crop.

Equipment (dew mitigation accessories not listed, since they're not part of the optical/imaging train):
Celestron C14 EdgeHD telescope*
SkyWatcher EQ8-R Pro mount*
Celestron 0.7x Focal reducer* (for C14 EdgeHD)
Off-axis guider (OAG) with guide camera
Baader LRGB filter set*
Antila 3nm Hα filter*
ZWO ASI6200MM-Pro Main Camera

*first light

Software:
N.I.N.A.
PHD2 Guiding
PixInsight with
o RC-Astro Plugins
o SkyPixels "GAME" plugin

Acquisition/Integration:
Location: San Diego, USA
Bortle Class 7 (maybe 8 ) skies
All subframes binned 2×2
Stacked using drizzle algorithm
L: 532×60 sec = 8.67 hrs
R: 439×60 sec = 7.27 hrs
G: 426×60 sec = 7.10 hrs
B: 472×60 sec = 7.87 hrs
Hα: 16×300 sec + 30×600 sec = 6.33 hours
Total integration time: 37.43 hours

For comparison, here's an image of M100 from the Hubble Space Telescope (HST):

Figure 3. Image from HST (not an image from my telescope!) for comparison (Source: https://science.nasa.gov/mission/hu...night-sky/hubble-messier-catalog/messier-100/ ).


Here's my speculation as to why M100 is called "The Blowdryer Galaxy" (taken from my post in "Our Beautiful Universe" PF thread https://www.physicsforums.com/threads/our-beautiful-universe-photos-and-videos.800540/post-7081032)

I speculate that there was an amateur astronomer out one night observing M100, perhaps with a group of guests, and the poor sap's corrector plate fogged up from dew. Naturally, the observer scrambled inside to grab a hairdryer and extension cord to warm up the sky-facing optics. I mean, we've all done it. Everyone present thereafter started calling M100 "The Blowdryer Galaxy." This time though, the name stuck and slowly spread to others. That's just my speculation: I have no solid evidence or source as to how this object got its nickname, but that's my guess. If anybody can find a credible reference as to how this galaxy got its "Blowdryer" nickname, let me know.​

Fighting dew is a real thing. Every amateur astronomer must deal with this, whether it's for an astrophotography setup, scientific setup, or even visual observing with eyepieces. It's always a battle with dew.

When buying a first telescope, the seller usually doesn't emphasize how important dew mitigation is. But the buyer will find out the hard way once their objective fogs up after only a few hours of observing. At the very least invest in a dew shield if your telescope doesn't already have one attached (most refractors come with a dew shield built in, most Schmit-Cassegrains [SCTs] do not. Maybe it's not such a big of deal with Newtonians.) If your scope has a built in dew shield, make sure it's extended when the telescope is in use. Consider getting a dew strap or two along with a dew controller. Don't forget about the finderscope -- that can fog up too.

Of course, as a last resort, there's always the hairdryer. But if you find yourself in that situation, it's already too late.

About half the peripherals by weight on the new telescope involve dew mitigation.

Figure 4. New telescope's dew mitigation. The "Dew Heater Controller" is part of the power distribution box (Pegasus Astro Ultimate Power Box V2) that does other things too (12 V power distribution and USB hub).

 

[Vanadium 50]

That's really pretty.

It looks (and should look) quite blue. How accurate are the colors?

 

[collinsmark]

That's really pretty.

It looks (and should look) quite blue. How accurate are the colors?

That's an important question worthy of discussion. The answer isn't simple.

If I had to give a short answer it's this: the color saturation that I used in this image is higher than what would normally be used in a terrestrial photograph. And the color saturation that I used in my photo is substantially less than what was used by whoever processed the Hubble (HST) photograph (shown in the above post for comparison).

The full answer is complicated and nuanced. As a general rule-of-thumb, when it comes to making pretty pictures in astrophotography, color detail is fair-game. The person processing the photo has full creative license to choose the color mapping (i.e., which filters map to which color channel), color saturation, white balance, etc., all without sacrificing scientific merit. It's perfectly acceptable to be creative with colors when processing astrophotos.

It's also acceptable to attempt to remove optical imperfection artifacts that were caused by Earth's atmosphere or optical imperfections in the telescope. Examples are removal of halos caused by narrowband filters, gradients caused by anything that causes artificial gradients (Moon, light pollution, vingetting of optics, etc.) and diffration artifacts. Global sharpening is also acceptable. Sometimes the detail is still in the data, but just needs a little coaxing out with sharpening algorithms. That's totally fine.

Nonlinear editing should be used sparingly, but sometimes acceptable such as dodging a galaxy's core, and/or applying HDR masking techniques to bring out the detail in what would otherwise be blown highlights, so long as the detail is present in the original data (i.e., not already blown-out in the subs).

What's not acceptable (more than highly frowned upon) is to add luminosity details and structures that don't exist in the original data at all. That's not cool.

But when it comes to color detail, almost anything is fair game, so long as some level of consistency is maintained across the image. It's fine for an astrophotographer to get creative with color.

Take the Hubble (HST) image (linked to in the above post) as an example. It's extremely blue and also highly color saturated. This was done solely by the choices made by the astrophotographer processing the data. It's way more blue than what our naked eyes would see if the galaxy was bright enough. But it's all totally fine, since its just color choices which are fair game.

For my image of M100, I waffled back and forth for days, trying to get the colors to look right. I probably spent more time on this one than any other target I've ever worked on to get the color balance the way I wanted it. The image posted here was what I decided on in the end. But given more time I probably would have waffled some more.

If M100 was bright enough to see the colors clearly with the naked eye, it probably would look more washed out, and maybe less blue and more beige than what's displayed in my final result. But if I chose colors such that the whole image to look washed out and beige, the viewer would miss out on some of the subtle color variations that actually do exist in the galaxy.