A Workout for a Dark Sky Observatory

You might remember from prior posts that I have a working relationship with the Northeast Kingdom Astronomy Foundation and their Northern Skies Observatory. They recently installed their permanent mount, a single arm design by Astrometric Instruments of Westborough, Massachusetts.  This replaced a temporary mount that had been used until their new one was completed. The result is a stable platform for their 17″ Planewave RC with excellent tracking.

The 17" RC telescope of the Northern Skies Observatory

The 17″ RC telescope of the Northern Skies Observatory

This is what astronomy teachers do on vacation: work some more!  My goal for the night was to take a series of long, deep-sky images to show the performance of the instrument under dark, clear skies. I wanted to get at least an hour on the Horsehead Nebula, blast through a series of short integrations on the Orion Nebula, then go into the sky of galaxies and image through Virgo and Leo. The March night selected was very clear. There were some evaporating clouds in the early afternoon, and the skies became so stable that contrails disappeared rapidly and barely moved across the sky due to winds. The night was so clear that I was struggling to deal with two activities at the same time:  Taking flats! AND taking a good long look for Comet PanSTARRS which was perhaps visible low in the west after sunset. Well, no comet debut, but the flats came out just fine!

Walking into the observatory and setting up was a simple matter of following the directions set forth by Sidney Wanzer and others in their protocol docs. We had the whole place up and running in no time. As the dome came to ambient temperatures, Kate (my daughter and helper for the night) said our thanks and goodbyes to David Magnus (who met us for the startup procedure), then set up both our workstation and sleep area (two sleeping bags on the warm-room floor).

NSO Warm Room

The Northern Skies Observatory Warm Room. Workstations to control the telescope and imager are on the right.

As the sun set, we worked through the taking of flats. I did these manually to keep the pixel values up to about 65% of full well capacity. Nothing beats a good signal to noise ratio! As darkness fell, and we finished up the last of the luminance (clear) flats, stars started showing up on the flats. Time to run out and look for the comet: no joy… but that was ok, as you can see from an earlier post. We saw it later on the next week. We did wait for it to get solidly dark and were thrilled to see the winter Milky Way and another joyous surprise: the zodiacal light! That is something we do not see from Exeter, ever. Any light pollution at all, and it is not visible. For those not in the know, the zodiacal light is the reflected sunlight off of dust in the planetary orbital plane of our solar system!  How is that for neat?!

zodiacal light

The zodiacal light looking west after sunset from Peacham, Vermont, March 2013. Nikon D7000 12mm 30sec.

Time to get to work!  The first target was the brightest, and with the diminishing glow, M-42 was that target. We took a slew of short integrations to nail down the fine inner structure, and did this is in H-Alpha, red, green and blue. The result was a stunning final shot. Good tidings indeed. As with all images on this blog: click to enlarge.

Imaging workstation NSO

The NSO warm room workstation as images of M-42 are being taken. I kept my laptop (right) to plan the evening and to take notes.


M-42, the Orion Nebula, as an Ha, R, G, B color composite using luminance layering techniques in Photoshop.

Time to work on fainter subjects. The horsehead has been a favorite of many astronomers down through the ages. It is faint. It is lovely. Back in the days of Wallace and Provin, astrophotographers would use this nebula as a benchmark of their abilities. If one could guide accurately enough to take an exposure long enough (well over an hour) to get a good shot of this, then you had arrived.  CCDs made this target a bit easier with their higher quantum efficiency, but images of over an hour are still needed to do justice. Autoguiders and better mounts made this even easier. Now, at the NSO, the combination of an excellent mount and autoguiding made this a matter of waiting!  Kate and I took a slew of images, over an hour each in Ha, R, G, and B. The end to imaging the horsehead came when it got too low to the horizon.


IC434 the Horsehead Nebula in Orion. This is an Ha, R, G, B color composite using luminance layering methods in Photoshop.

That done, some galaxies were rising in the east as the winter Milky Way started to set in the west. It was time to think outside of our spiral and into the realm of millions of light-years. It was also time to make a small dinner of peanut butter, banana and Nutella sandwiches. Below you can see the remaining images, all lovely.


M-95, galaxy. An LRGB color composite.

NGC3628, M-65, M-66

This group of three galaxies in Leo offered an interesting challenge: would they all fit in one image? Yes! Here are NGC 3628, M-65 and M-66.


A closeup of NGC3628 from the previous image.


A closeup of M-65 from the previous image.


A closeup of M-66 from the previous image.

We didn’t have enough time in the night to do justice to the remaining targets, so these are all monochrome, luminance shots, of some of the prettier spring time galaxies:


M-91 galaxy. A monochrome luminance shot through a clear filter.


M-96 galaxy. A monochrome luminance shot through a clear filter.


This is the last target of that night, M-104 the Sombrero Galaxy.

The end came as we got towards the later half of the midnight hour: the telescope and dome became unslaved, and we, being too tired, decided to call it a night and wrap ourselves up in our sleeping bags. The end result: fabulous, deep images with a great new mount and minimal technical effort. These images all took some time to assemble, though, and that is an art (perhaps also a blog post for the future) unto itself. If you want some guidance on image processing, might I recommend a couple of ideas:

  • The Handbook of Astronomical Image Processing by Richard Berry and James Burnell. It is a tome, but really helps once one has read the whole thing. Do it. Don’t be shy.
  • Check out the work by Robert Gendler and his luminance layering methods.
  • Buy Adobe Photoshop, then take a few astronomy-centered classes on how to use it.





About johnb

- Director of Grainger Observatory, Phillips Exeter Academy. - Variable-star-crazed astronomer, but have done research in other areas. - Drummer, archer, pilot, chef, friend, pet owner, husband, father, Train-nut.
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