~Deep Space Images by Annie Morris~
It's been a few years since I have blogged and in that time we have moved to Idaho, we bought some acreage in pretty dark skies (though by a small town for convenience), I built my dome observatory (Star Stalker Observatory), and so many other things. I thought about going back and writing a blog about the observatory build ... that might come down the line ... for tonight I wanted to share how an excerpt of how my brain operates when I am imaging. I typed these up last night around 4:30am in my first imaging session in a couple months (thanks to endless clouds whenever the moon was away) to answer the "How's did it go" text I knew I would get in the morning. Normally I completely adjust my schedule and operate on the opposite of the rest of the world, but due to a few factors recently I couldn't entirely swap my schedule before this week's imaging runs. As such, I went into the week of imaging knowing that I would be tired until I adjusted.
More rambling later, on to my Internal dialogue:
I started imaging at 10pm, I should have 6.5 hrs of data to check. Yay!
Wait, I have been checking each image as it comes through every 15 min, I don't need to check them again.
I should check them again *checks them* Hrmm, how do I only have 4.5 hrs of data *scratches head*
Oh, right, I had it focus every so often and that takes time. I also threw out 5 frames as my guider occasionally loses its mind for a second and ruins a 15 min frame, and I paused at 2 am for a bit as I put the slide off roof back on, ok, makes sense.
Waiiiiitt ..... is 900seconds REALLY 15 min *looks skeptically at clock and giant countdown timer on imaging software* ok, fine, time is still time.
I need sleep.
I really need to adjust my polar alignment again, I have some overall drift even with guiding ... not tonight, during next bright moon when I can't image *remembers that I have said this every single time I have imaged for the past year and never remembers to actually do this come full moon, puts into calendar*
Yay, new sub just came through *instantly checks it as I have every single frame that has come in since 10pm* Yay, pretty. Stars look good. No airplane in the frame. Yippee.
Want to sleep. Is it sunrise yet? No? Dangit. I mean, Yay, more imaging time. But dangit, I am tired.
Ok, forecast is supposed to be good for next 3-4 nights. Stay on target whole time? *does internal calculations about total exposure time for each filter* Yeah, stay on target. If I lose about as many hours for focus and other tasks as tonight I should have 30hrs of data by the end of the week, that should be a nice picture.
Definitely too tired, giving up for the night, and by that I mean I will definitely be spending the next hour doing calibration and shut down tasks and wiping down the electronics cause the dew is bad. So I can sleep in an hour. Yay. *goes back to the observatory, gets some calibration frames going, transfers files from the night to the network drive, dries off what needs to be and closes up dome.*
So, yeah, that is roughly how my brain works when working non-stop all night. Data last night looked decent and tonight's session is currently going and looking even better than last nights. I should have ~13 hours of Hydrogen-Alpha data on the Flaming Star Nebula (IC 405) after this evening with, hopefully, 3 more nights ahead of me. Here's to clear skies ahead!
The Charlotte Observer and Raleigh News and Observer just published my article about the latest IDA Dark Sky Park, Staunton River State Park. This new Silver-tiered Dark Sky Park is a fantastic resource to all those in the region. Make a trip up to view their skies, they are well worth it!
I just recently got a great deal on a couple Astrodon 3nm filters (H-alpha and OIII) which I am very excited about. I have had 12nm filters for a while now (Astronomik), which I have loved and are great filters, but I have always wanted to get some narrower wavelength filters for all the narrowband I tend to image. Cutting out extraneous light should greatly improve the signal I am getting in my images as well as allowing me to image a bit further into moon's cycle. While I plan on comparing these for a while during various conditions and will do additional writeups with photos, I got to image through the new filters for the first time at the Staunton River Star Party this past week and was mightily impressed with the 3nm filters.
I did some initial comparisons using Messier 16, the Eagle Nebula, the last evening out. The skies there were lovely (Sky Quality Meter (SQM) reading of 21.08 that night) and we were doing a public observing night as well, which gave an opportunity to introduce imaging and astronomy to adults and kids alike. I decided on 10 min exposures for all 4 filters and refocused between each filter with the Moonight Focuser. This time around I did not do a whole lot to compare, as I wanted to get onto my proper imaging for the night as it was the light night of the Star Party and the skies were so great, so I will do much better testing soon with many more #s and calculations, and exposure times.
To start, here is the setup and details for these comparisons:
Imaging scope: Orion EON80ED
Camera: Atik 314L+
Filters: Astronomik Ha 12nm, Astronomik OIII 12nm, Astrodon Ha 3nm, Astrodon OIII 3nm
Exposure time: 600s
Calibration: Darks and Flats
Location: Staunton River State Park, Virginia
Sky Quality Meter reading: 21.08
Date: 25 November 2014
To start off, Hydrogen-Alpha 600 second single sub, unstretched comparison
At first glance, the stars appear slightly larger in the 12nm as well as the overall background levels are higher (mean pixel stat value of 709 vs 540), although with a single unstretched sub it is hard to tell whether there is will be a noticeable difference in the nebulosity and overall image but it does appear as if there is more in the image already. With that said, on to stretching.
For the stretches I used only levels and curves and as opposed to doing identical stretches with the levels on both (which would have resulted with a much brighter/washed out image with the 12nm due to the extra light let in), I adjusted the levels to keep the background of both images comparable and any curves I used, I did identically on both. I determined this would be the fairest way to compare the final results in the filters.
After the stretches, the difference is very noticeable. While the physical size of the stars is similar (with the 12nm only being slightly larger), the brightness of the stars (especially the fainter stars) is noticeably less. Stretching to similar overall background levels brings out much more nebulosity in the 3nm filter vs the 12nm even though the exposure times were identical. The amount of nebulosity that is shown in a single 10 min exposure without having to do extreme stretching and risk introducing extra noise and without having to worry about stars bloating was just amazing.
I really wanted to see just how much was in there by having cut all the other wavelengths out so I did an inverted image comparison for a portion of the image where I removed the stars and used ONLY levels to do a linear stretch. Here is the result:
The difference in contrast and extent of nebulosity between the two filters was quite impressive on this single exposure. While I cannot fault the Astronomik 12nm filter as I have gotten great results out of it, the narrower passband of the Astrodon 3nm just shows the advantages of going narrower.
I also did the same comparisons with the OIII filters, here are those images:
The initial star difference in the single unstretched sub is the main thing that is noticeable in this comparison, now on to the stretch:
The comparison shows similar effects as the Ha: slightly smaller, although comparable, star size but with a noticeable difference in brightness for fainter stars creating the appearance of a less dense star field and increasing the nebulosity to star contrast, lower overall background light levels which allow for a higher nebulosity to background ration through. The result is more nebulosity, more contrast, and smaller-appearing/less bright. stars.
While I need to do more extensive comparisons, I am really impressed so far. I realize that the 3nm Ha filter will also cut out the NII line that the 12nm filter will allow through, which might be a reason to use the wider passband filter on certain targets. However, the advantages of the 3nm over the 12nm, despite the price jump, make it well worthwhile.
I have gotten several requests as to how I processed my latest M42. Before I go into that I want to mention that my processing of this was done using Adobe Photoshop CS5 and includes a few different processes layered together. This is snowballed a little by M42 and its high dynamic range from the core to the outer dust, which adds layering to avoid blowing out the core.
I will include photos as I go so you can see how the steps progress. I started with several stacks as I took multiple exposure lengths. I took 5 different sets and ended up making 2 master stacks: one for the core with the 60s and 120s exposures, one with the 480s, 600s, and the 900s exposures for the rest. I would normally use each set as its own process and layer the 5 together but started with the two to try to save time and it turned out well so didn't go back and do the individual stack processes.
Here are the two master stacks:
|Long Exposure Stack|
I started with a process of the core stack. I didn't focus on stretching it too much as I was just going for the detail in the core as the other stack would cover all the rest of the detail. A few levels, curves, and the enhance dust lanes action from my set and here is the final core stretch:
I finally got a chance to shoot the Orion Nebula for the first time since I started imaging. After months and months of clouds and full moons during the only clear evenings I got a perfect evening. By far the best skies I have had here at the house since we moved here 3 years ago. I have had the scope set for Comet ISON (which didn't make its trip around the sun) so instead of putting my regular configuration back on, I decided to use my Nikon D7000 to shoot M42. I did a variety of sub-exposure times to compensate for the high range of lighting in this region so have subs ranging from 60 seconds to 15 minutes with a total of 8 hours. Instead of going into how I layered all of those to get the detail from core to dust I want to show just how much dust really was captured.
I started off using my normal processing steps (i.e. stack, run through my Photoshop Action set, color correct, some manual stretching, possibly GradientXTerminator, a few other actions, noise reduction) I did these and then used a plugin I have and occasionally use for my normal photography business called Color Efex Pro. There are a few of the steps in there I have found useful for certain astrophotography targets so gave them a try. Using Detail Extractor, Tonal Contrast, and Pro Contrast I was able to tweak out a bit more of the dust and get a nice looking final image (you can see higher res on my website).