February 2023 – A Thousand Acres of Silphiums

The Rosette or Skull Nebula – Sh2-275/NGC 2246 (February 2023)

The Rosette, or Skull Nebula, one of the largest and spectacular star-forming regions in our sky. Can you make out the skull? It is looking downward around 8:00.

The Rosette or Skull Nebula (NGC 2237, Sh2-275)
My February target was the fantastic and grand Rosette Nebula, also known as the Skull Nebula for hopefully obvious reasons. This nebula is a gigantic cloud of predominantly ionized atomic hydrogen that lies in the Monoceros constellation, not too far from the Orion Molecular Cloud Complex. This object has a number of different catalogue designations given to different regions of the nebula (NGC 2237, 2238, 2239, 2246) and associated star clusters. The primary star cluster being NGC 2244 – the most central cluster that provides most of the illumination and stellar winds and radiation that illuminate and disperse the gaseous clouds that form the nebula. X-ray imaging has identified approximately 2500 young stars in this star-forming complex.

Space is Big
This nebula lies approximately 5,000 light years from earth and is roughly 130 light years in diameter. To get an idea how immense this nebula is, compare this to the Great Orion Nebula (M42), which is only 40 light years in diameter. With all this talk about light years, I wanted to explore this to get a better idea of what we’re talking about and try and wrap our heads around the scale of an object like this. A light year is roughly 5.88 trillion miles – the distance light travels in a year. Since I’m an American, I’ll keep everything in miles so that I can better understand. The diameter of this nebula is roughly 764 trillion miles. The fastest spacecraft ever recorded is the Parker Solar Probe, which reached a top speed of 364,660 mph. This comes to 3,194,421,600 miles this probe can traverse in a single year. Sounds like a lot, right? Well, to cover the 764 trillion miles to reach one end of this nebula to the other, it would take the Parker Probe 239,167 years! We probably don’t need to get into the amount of time it would take the Parker Probe to get to the nebula in the first place.

“Space is big. You just won’t believe how vastly, hugely, mind-bogglingly big it is.” Douglas Adams – A Hitchhiker’s Guide to the Galaxy

Collecting the data
I had anticipated this one being a little difficult to find. IT is found roughly on the line between two stars of the winter triangle – Betelgeuse, and Procyon. But, there are really no large magnitude stars in close proximity to help get it in the tight frame of my 300mm lens. I was please that it took me only about 10 minutes to get it in frame. However, because I was hoping to grab some of the much dimmer gases that can make up a sort of stem of this rose, I spent another 30 minutes trying to frame it just so. This turned out to be time wasted. In order to get this dim gas to show, much more integration time would be necessary than what I was able to collect on a single night.

Date and location
Imaged on the night of 17/18 February 2023 at Danville Conservation Area in Montgomery County, Missouri (Bortle 4).

Dark period: 19:10 – 05:19

Target period: 15:20 – 02:08; Zenith 20:44

Conditions
Clear skies over the course of the session. Temperature: 31° – 27° F. Winds forecasted to be 6-8 mph but seemed lower than this.

Equipment
Astro-modified Canon 7D mkii camera, Canon 300mm f/2.8 lens, Skywatcher Star Adventurer tracker without guiding on a William Optics Vixen Wedge Mount. Gitzo CF tripod, Canon shutter release cable, laser pointer to help find Polaris and sky targets, lens warmer to prevent dew and frost on lens, dummy battery to power camera, lithium battery generator to provide power to camera and dew heater, right-angle viewfinder to aid in polar alignment.

Imaging Details
Lights taken (ISO 3200, f/2.8, 25 second exposures) 779. 61 frames dropped due to poor focus, 217 frames dropped due to tracker error, 10% frames dropped in stacking instructions. A total of 450 frames used in integration for a total of 3.13 hours.
Darks: 39 taken at the exposure time listed above.
Bias and Flats: Not taken. Removed most vignetting and some chromatic aberration while converting RAW images to TIF.

Processing
RAW files converted to TIF in Canon DPP, stacked in Astro Pixel Processor, GraXpert for gradient removal, StarNet++ for separating stars from nebulosity, Photoshop CS6 for stretching, recombining stars and nebulosity and other cosmetic adjustments.

This one was a bit tougher than I expected, mainly due to the StarNet software not wanting to work the first several times I tried. I captured more of the hydrogen alpha in the surrounding regions than this image depicts but, because it was so faint, nasty artifacts appeared during the stretch. I was forced to leave much of this out of the final image due to this. I think in order to do this properly I would need much more total integration time.

Problems and learnings
This one went about how I had expected except for one thing. I was devastated to learn that I had not acquired critical focus for roughly the first 45 minutes of imaging. This was even more of a blow as this time coincided with the object being at or near its zenith, meaning I lost some of the best potential data gathering of the night.

I have also been collecting some data on how many subs I throw away due to errors in tracking. In this case, 35% of the subs I took were thrown away, which seems to be close to my average when using this lens at these exposure times. I dropped the exposure time to 25 seconds in order to help reduce this but I think this issue is mostly due to the tracker being at or above its limit in regards to payload and focal length. For this reason, I am investigating a new tracker that should meet my needs nicely for a 1-2 minute exposure with the above kit and a keeper rate of greater than 90%. Keeping my fingers crossed for that company bonus this year. 😉

Conclusion
This is another very popular and relatively easy object that most astrophotographers tackle early on. Overall I’m pleased with the outcome. I like the detail and the colors but I think that better processing might bring these out better even with the data I have here. Always learning. This object is better imaged in December or January, when more time with it can be had in a single night. I look forward to trying this one again someday.

Sedge Wren – August 2022

birds, Nesting Birds of Missouri, wildlife, wildlife photography

A cooperative Sedge Wren from August of last year.

Insect’s of Horn’s Prairie Grove LWR

location spotlight, macro, native plants, WGNSS Field Trips, wildlife, wildlife photography

Part of the Horn’s Prairie Grove LWR with obedient plant blooming in the foreground and joe pye weed behind.

The WGNSS Entomology and Nature Photography Groups had a splendid treat in July of 2022 when we jointly visited Horn’s Prairie Grove Land Water Reserve (LWR) near Ramsey IL. This 40 acre patch represents part of the less than 1% of the remaining southern till plain prairie ecosystem that was nearly wiped from the planet due to land conversion for farming. Even better, about 30 acres are original “virgin” prairie, (the largest intact remnant prairie in IL) meaning these spots were never touched by the plow. Even better still, at this location there lies five different types of prairie habitat: seep/wetland, dry hillside, mesic, black soil and savanna.

Keith Horn, owner and guide to Horn’s Prairie Grove LWR

The story of this land is interesting. The current owners, Keith and Patty Horn, purchased the land in 2001 as “junk land” from an old farmer who’s family had owned since the 1870s. They liked the fact that the majority of the land was in a “wild” state. The untouched 30 acres had been used as a wild hay field, being cut almost yearly. They had noticed some nice wildflowers in bloom but did not realize what they had until a few years into a wildlife habitat improvement plan that included periodic burning. Every year they noticed more and more species in bloom. They have sought help in identifying the plant species here and the current list is now at 619 species, including six native orchid species! Bravo to the Horns for identifying what they had and taking the steps to see their land improved. This remnant prairie could have been destroyed in the blink of an eye if it had fallen into the wrong hands.

Although most of us were simply thrilled to be in such high quality habitat, the primary purpose of the trip was to check out the arthropod life. Unfortunately, in late July, we were there on a truly miserable day of weather. The heat and humidity created a heat index that was well above the safety zone. This meant not many of us had the nerve to do a great deal of walking and searching, especially much after lunch time.