NGC 2244 - The Rosette Nebula

The Rosette Nebula -- a stunning emission nebula associated with the star cluster NGC 2244 -- is a complex and challenging target, worthy of repeated efforts.

Appearing in the constellation Monoceros (the Unicorn, east of Orion), the nebula and cluster are estimated to be about 5,000 light years distant, spanning a diameter of about 130 light years.

For astro-imagers, capturing the detail of the swirling gas clouds and the numerous bok globules (dark nebulae composed of dust and gas found in many emission nebulae), while preserving the Rosette's glorious colors, usually requires combining multiple images shot through a variety of filters.

The Rosette covers a wide area of sky. Each of the below images was taken with the ASI1600 through the 72mm refractor.

The above image was my first try this season, taken in September. It comprises 12, 360-second exposures through the Ha filter and 10, 180-second exposures through the R, G and B filters.

This month, I returned to the Rosette, capturing just over two and a half hours (31, 300-second sub-exposures) through the Ha filter, producing the above image. Ha brings out an incredible amount of detail of the nebula's structure.

I then captured an hour and 15 minutes of 300-second sub-exposures through the OIII filter, combining them with the previous Ha data to create the above HOO palette image. This narrowband-only exposure keeps the general color of the nebula, while revealing a lot of subtle detail. Total exposure time is 3 hours and 45 minutes.

Last weekend, I captured 2.5 hours of RGB data (10, 300-second sub-exposures per channel), which I then combined with the existing 2.5 hours of Ha data, creating the above image. Total exposure time for this image is about five hours.

Time and weather permitting, the next step will be to obtain more OIII data and possible SII data, creating a better HOO palette image and a separate SHO palette image -- and then combining the SHO an RGB data for a final image for the season.

November Highlights

The weather has not been especially kind to stargazing so far this month, but I have managed to spend a few clear nights imaging.

NGC 2264 - The Cone Nebula and Christmas Tree Cluster

The constellation Monoceros - the Unicorn - to the east of Orion has a number of interesting objects within its borders. The Rosette Nebula (NGC 2244) is one, the below complex is another.

NGC 2264 refers to both the Cone Nebula (the dark conical projection toward the lower middle of the image) and the Christmas Tree cluster (which looks like the outline, in blue-white stars, of an upside down Christmas tree, in the middle-to lover part of the image). Also apparent in the image is the Fur Nebula, which appear as undulating waves of red toward the upper middle of the image.

This image, taken with the ASI1600 is composed of 17, 360-second images taken through the Ha filter and 10, 300-second images, taken through the R, G and B filters, using the 72mm telescope. Total exposure time is four hours and 12 minutes.  The image has been cropped to concentrate on the objects at the center. I will take the time to image these objects with the higher-magnification 127mm next month.

M42 - The Great Orion Nebula

This massive stellar nursery is so bright that is one of the few nebula visible to the naked eye. When you look at Orion, the nebula appears as the fuzzy area south of the three-star belt. sometimes called the sword of Orion.

The above image is RGB only -- true color. The image comprises 10, 180-second images taken through the R, G and B filters, using the 72mm refractor. Total exposure time is two and one half hours. The ASI1600 did a nice job capturing detail in both the Orion Nebula and the Running Man Nebula (Sh2-279) which appears to the right of Orion Nebula and appears mostly in blue.

This is the same RGB image as above, but with 50 minutes of Ha (10 x 180 seconds) added in. The Ha data enhances the nebula and shows the sweeping waves of hydrogen gas that surround the entire nebula complex.

IC 1805 - The Heart Nebula

Appearing in Perseus, the Heart Nebula is an extended emission nebula with an unmistakable shape. It was first recorded by William Herschel in 1787 and is located about 7,500 light years from Earth.

The above image comprises two hours of Ha data (20x300s) and 2.5 hours of RGB (10x300s, per channel), for a total exposure time of 4.5 hours. It was taken with the ASI1600 through the 72mm refractor.

IC 434 - The Horsehead Nebula

It is always impossible to resist this object. I had produced an excellent image last month, but decided to go back this month to get better color data.

The above image combines two hours of Ha data (20x360 seconds) taken in September, with three hours of RGB color data (12x300 seconds, per channel), taken this month. Total exposure time is five hours.

The Fall Sky

Cooler autumn nights usually make for better imaging -- assuming the sky is clear, of course. This offers an excellent opportunity to capture the gems of the Fall and Winter (after midnight) skies.

M1 - The Crab Nebula

This supernova remnant shines relatively brightly in Taurus. It can be seen as a small smudge of light in even modest telescopes. Long-exposure imaging brings out the filamentary structure. But it looks nothing like a crab.

This image is composed of  20, 180-second images taken through the Ha filter and 10, 180-second exposures taken through the R, G and B filters, using the ASI1600 and the 72ED.  I'm a little surprised the image came out so well using the 72mm scope. In coming weeks, I will re-image this target with the 127mm scope, which seems like a much better match to M1's apparent size.

M45 - The Pleiades

No fall can go by without taking the opportunity to image the Seven Sisters. This cluster in Taurus immediately draws the eye as soon as it rises and is an irresistible target for binoculars or small scopes.

The above image comprises 12, 300-second sub-exposures shot through the R, G and B filters for a total exposure time of three hours.

NGC 891 - Silver Sliver Galaxy

This is a spiral galaxy, probably much like our own Milky Way, seen edge-on. It appears in the constellation Andromeda and is estimated to be about 27 million light years distant.

This image is composed of 11, 180-second sub-exposures taken with R, G and B filters through the ASI1600 and the 127mm refractor.

M31 - The Andromeda Galaxy

Like the Pleiades, M31 is almost an obligatory image to take every year. That does nothing to diminish the majesty of the magnificent spiral galaxy just 2.3 million light years away. M31 is now thought to be a truly massive galaxy, roughly twice the size of our Milky Way with a diameter of more than 200,000 light years (compared to 100,000 for the Milky Way) and home to a trillion stars.

This image is composed of 45 minutes of exposures shot through the L, R, G and B filters using the ASI1600 and 72ED. Total exposure time is three hours.

IC405 - The Flaming Star Nebula

This colorful emission and reflection nebula complex, which surrounds a blue-colored star in Auriga, always makes for a dramatic image.

Taken through the 127mm scope, this image combines 10, 180-second sub-exposures taken through the Ha, R, G and B filters. The total exposure time is two hours.

IC 405 and IC 410

IC 405 (above) appears in the sky close to IC 410, though the two are not really close together. IC 405 is estimated to be about 1,500 light years distant, while IC 410 is much farther away at about 12,000 light years. Nevertheless, the two nebula look fantastic when imaged in the same field of view.

This is a two panel mosaic taken through the 72mm scope with the ASI1600. Each panel is an HaRGB image with a total exposure time of about two hours.