IC 405 image provided by Dr. James Dire from the Wildwood Pines Observatory in Earl, North Carolina

This month's challenge objects really define the "challenge" in our observer's challenge. IC 405 is a diffuse nebula surrounding the variable star AE Aurigae. It is about 1,500 light years away and is five light years across. It is believed, to have originated in the area around Orion's belt. Sources list the magnitude as around 6.0, but that is highly deceptive. Because it is dispersed so widely through an eyepiece, it is very difficult to spot, unless you have a large backyard telescope. It is much easier to spot in a photograph. 

The unusual open cluster NGC 1893 is embedded in IC 410. Both of these objects are close to IC 405 and can be seen by moving the telescope a few degrees to the southeast. The cluster has stars of wildly differing magnitudes, listed from as dim as 14.8 mag to as bright as 7.5 mag. It is challenging because it is in a relatively rich star field. On the other hand, IC 410 is extremely difficult to see visually. If visible at all, IC 410 appears as a faint lumpy haze in and around the cluster, but is much better seen in photos than visually. An O-3 or maybe a UHC may help bring it out.

The location of this month's challenge objects. 

Roger Ivester - LVAS Member from North Carolina

I believe the Observer's Challenge for March 2010 contains possibly two of the most difficult objects to date for the visual observer. All observations were made from my backyard in Boiling Spring, North Carolina, located in the western foothills of the state. My limiting naked eye magnitude on a good night averages between mag 5.0 and 5.5. On an exceptional night, it can go as high as mag 6.0. There are several unshielded streetlights in relative close proximity, but I use several methods to block as much direct light as possible. On occasions, I have had the opportunity to observe from some very dark skies located in the South Mountains, only 25 minutes from my home; however, it is far more convenient to set up in my backyard, especially when time is a factor.

The first object is IC 405, a diffuse nebulosity, also called the "Flaming Star Nebula". It is illuminated by the variable star, AE Aurigae. I attempted IC 405 with my 10-inch reflector on numerous occasions, but have never been able to see the nebula. This object is definitely best suited for the astrophotographer and not the visual observer. I am hopeful that someone with a very large scope, observing from a dark site will visually glimpse this illusive object.

The second object is the nebula, IC 410, which is illuminated by open cluster NGC 1893. This object is very difficult to view with most backyard or amateur scopes. With the 10-inch, there was a definite glow surrounding the cluster, but I could not say for certain that it was IC 410 or just scattered light within the optical system.

Open cluster NGC 1893 lies in a very rich star field, but was easy to see in my 4-inch refractor, using a magnification of 83X. With careful observation, 20 stars could be counted, but a number of fainter stars seem to be just beyond the limit of the small refractor. Walter Scout Houston of Deep-Sky Wonders, describes "a conspicuous 'Y' pattern, formed by four 8th magnitude stars." This is indeed one of the features that allows this object to stand out when using low power in the 4-inch. The 'Y' pattern is easily recognized in the following sketch, which was made with a 4-inch f/9.8 refractor with a magnification of 83X, field of view 0.72 degrees or 43 arcmin. North is at the top and east is to the right.

Fred Rayworth - LVAS Member from Las Vegas

Try as I might, I was not able to get out and observe these objects during the month of March. I could only wonder if I would be able to spot the nebulosity in either object, though I was confident I would be able to see NGC 1893.

I finally got an opportunity on the 8th of April. It was a lousy night for seeing, with a lot of light pollution coming off two barges in the middle of Lake Mead, along with the skyglow of Las Vegas. Because I went out by myself, I had to stay within cell phone range and chose Sunset Overview on the west shore of Lake Mead. I used my 16-inch Meade LightBridge along with a 26mm Orion Q-70 (70X), a 17mm Hyperion (101X), and an 8mm Hyperion (220X).

IC 405 and IC 410/NGC 1893 are next to each other in Auriga. I found them easily when the weird 'Y' shape of NGC 1893 stood out against the rather rich background. The two major objects were separated by a line of stars going roughly north to south. By using that line, I was able to switch back and forth between the two/three objects.

Starting with the more difficult object, IC 405, I zeroed in on AE Aurigae. Despite substantial light pollution from the glow of Las Vegas, I noticed a haze, which seemed a bit more intense than the surrounding glow of the sky. At 70X, it looked the best. I added an O-3 filter and there was no mistake that a nebula was lurking in the background. By sweeping around, I could tell a definite difference in the sky background. It was much darker to the south of AE Aurigae, while it faded fairly fast the further north it got from the star. There is another bright (though a bit dimmer) star next to AE Aurigae and the nebual filled in behind it also. I detected a slight lumpiness to the grayish cloud, but it was mostly concentrated around those two stars. I noticed on Megastar that the "official" nebula extended in a kind of "7" shape and I scanned the area, but saw no hint of anything beyond 1/2 degree of those two stars.

Crossing the "bridge" of stars to NGC 1893, I was quite surprised at how distinct that cluster was. At 70X, it was a grainy 'Y' with many different magnitude stars concentrated within the thick arms of that 'Y'. At 101X, I saw even more stars. At 220X, the cluster blended in with the background and didn't look like a 'Y' anymore. Even without a filter, I saw a blotch of gray "something" around one leg of the 'Y'. Backing off to 70X again, I plugged in the O-3 filter and there was no mistaking the few lumps of nebulosity that contrasted nicely with the background, yet it was still quite faint. I saw two distinct long lumps, both of which were to one side of the 'Y' and crossing just the tip of one arm of it. I scanned the area and didn't see any more lumps and whatever might have been there blended in with the background. At 101X and 220X, the nebulosity washed out, though I could still tell something was just there at 101X. Since the O-3 filter cuts out much of the starlight, in the drawing I show a combined view with and without the filter to show both objects in relation to each other.

Overall, I was quite surprised to see any nebulosity at all, especially since I could not see even mag 10 galaxies to the east a little while later; however, even with the skyglow in the west, I noticed six stars in the Trapezium for the first time. I chalked it up to just a inconsistent sky that night.

Rob Lambert - LVAS Member from Las Vegas

March was a difficult observing month for me.  It seemed that I could not get out on the nights that were clear and steady, and the sky condition of nights around the New Moon were were not conducive to capturing a good image of the Flaming Star Nebula. To even catch a hint of the nebula, I had to push my Mallincam integrations to 60 seconds, which is right at the limits of my Alt-Az mount with regard to field rotation. In my enclosed image, there is just a hint of the nebula all around AE Aurigae, but it appears somewhat more dense from the northeast to the northwest (north is at approximately the 2 o'clock position on the photo). Evidence of the nebula is seen more in the fuzziness of the stars rather than in an obvious visual presence. An interesting feature of this area is the formation of stars, which form a squared-off cup that opens to the upper right corner of the photo. The bottom of the cup is a straight row of four stars. AE Aurigae is the center star of the left side of the cup. It was this star formation that assured me that I was in the right area for observing the nebula. At five-second integrations, this formation was visible, but I couldn't see the nebula until I approached 60 seconds of integration. The attached image was captured with the Mallincam Variable Shutter System Video Camera through an Orion ST120, piggy-backed on an LX200GPS for alt-az tracking. I used a Mallincam Focal Reducer (MFR) 3 with 25mm of spacers to reduce the native f/5.0 ST120 to f/2.5, which results in an approximate FOV of 1.5 degrees.

Since my observations of IC-405 were not that impressive, I'll shed a little more light on the reference of AE Aurigae being a rogue star. AE Aurigae is not native to this area of the Auriga constellation. According to the research of Ronnie Hoogerwerf of the Leiden Observatory in the Netherlands, it actually originated in the heart of the Orion Nebula's Trapezium. It was supposedly violently ejected from the Trapezium as the result of a close encounter of two closely bound binary-star systems. It, like Mu Columbae, was flung away at high speed and it continues to move relatively rapidly through Auriga. As it moves through this particular piece of space, it is lighting up the nebulosity know as IC 405. Scientists estimate that the star will take another 20,000 years to leave this nebulous region, all the while greatly altering the cloud of dust surrounding it by pushing the nebula out of the way as the star travels through it.

Hopefully, the rest of the Spring observing will be better than that of March and early April.

David Blanchette - LVAS Member from Las Vegas

I took a single, 15-minute ISO 1600 exposure. I obviously need to start shooting flats.

This image was take at Amargosa airport under some of the best skies I've seen in a while. Zodiacal light was a nuisance, even at 9:30p.m., but appear to be clear of IC-405. I could not see the nebula visually.

Dr. James Dire - LVAS Member from North Carolina

IC 405, the Flaming Star Nebula is a large complex emission/reflection nebula located in the constellation Auriga. The nebula has an integrated magnitude of 10.0 and spans 30' by 19'. The surface brightness is very low and the nebula is very difficult to see visually, even in large aperture telescopes. Long exposure images show an extended comma-shaped gas cloud surrounding IC-405, which extends nearly 1.5 degrees from end to end. IC 405 is located 4 degrees due west of M36 and 3 degrees southwest of M38. The nebula is approximately 1.500 light years away and spans 5 light years of space.

The variable star AE Aurigae is the brightest star within the nebula. AE Aurigae is a mag 6, O-class star whose brightness various sporadically by 0.3 mag. AE Aurigae was born in the Orion Nebula, but it is hypothesized that 2.7 million years ago, it had a close encounter with the star Mu Columbae, which resulted in both stars being ejected from the area.

This image of IC 405 was taken with a SBIG ST-2000XCM CCD camera at prime focus on a 190mm (7.5-inch) Maksutov-Newtonian Astrograph. The exposure was four hours on January 10 and 13, 2010.

NGC 1893/IC 410 is an open star cluster embedded in a diffuse nebula. NGC 1893 is the designation of the star cluster while IC 410 is the nebula. This object is located 1.5 degrees southeast of IC 405. NGC 1893 is mag 7.5 and easily seen in binoculars. Estimates of the cluster's distance range from 10,000 to 20,000 light years. The cluster contains many hot O-type main sequence stars, several of which are mag 9. The cluster spans 25 arcminutes.

IC 410 is presumed to be at the same distance as NGC 1893. The nebula is 40' by 30' in size. An integrated magnitude for the nebula is difficult to obtain due to its diffuse nature and size, but the brighter regions are estimated to be near mag 12. This nebula is much more difficult to see visually than IC 405.

The image of IC 410 is the longest exposure I've taken to date, 5.5 hours over the nights of March 4-6, 2010. My image reached skyglow saturation prior to the end of 5.5 hours, so at some point, I failed to overcome increased signal-to-noise and probably could have obtained the same image with a shorter exposure.

Oh to have the dark skies of the Desert Southwest! The image of NGC 1893/IC 410 was obtained with the same equipment configuration as IC 405 from the Wildwood Pines Observatory in Earl, North Carolina.

Frank Barrett - LVAS Friend from North Carolina (www.celestialwonders.com)

I took this image of IC 405 from my observatory. I started this target much too late in the year for my tree-challenged horizon. Only 95 minutes of luminance was captured and the shot was planned to be a two-frame mosaic. I reused the color channels from an image I took in 2005 with the ST-2000XCM. Perhaps I will have to wait until next season to try this one again. It looks like there is a small galaxy in the upper right corner.

I took this image on March 3, 2005 from Gastonia, North Carolina. I used a Meade 10-inch LX200R, 2,800mm f/11 with an SBIG STL-11000m camera. My mount was a Losmandy G11 with an Ovision worm upgrade.

Buddy L. Barbee - LVAS Friend from North Carolina

It was Thursday, April 1, 2010 and my wife and I were camping for the Easter Holiday. We stayed at Hagan Stone Park near Greensboro, North Carolina. After spending the day packing the camper, driving to the campground, and setting up camp, I was pretty much worn out. Being very tired, I only set up the AT66ED for some solar viewing. It has really been fun watching the sunspots return once again.

After supper and couple hours of rest, I decided to do a little observing. The sky was beautiful after almost a month of cloudy skies or bad weather, so I decided to go after the March Observer's Challenge and see if it could be seen with a small telescope. Using the AT66ED and my 15mm Panoptic eyepiece (with a wide 2.5-degree field-of-view at 27X), I pointed the scope at the Flying Minnow Asterism in Aurgia. From there, I swept eastward until I found the open cluster NGC 1893. Having found the open cluster, I added my TeleVue Bandamate Nebustar filter to the eyepiece for a look see. The filter revealed faint puffy wisps of nebulosity all over and around the cluster. The nebula was really faint, but could be seen with both direct and averted vision. At only 27X, the cluster is a small, but fairly bright gray spot with four to five dim stars visible. I needed more magnification to see the cluster well. Using my 5mm Radian eyepiece with a 0.75-degree field-of-view at 80X, it was a very lovely, nicely detached open cluster. Some say the cluster is shaped like the letter Y. To me it looked more like a goblet. The 5mm eyepiece only has an exit pupil of 0.8mm, so both the nebustar and O-3 filters failed to show any nebulosity with the little scope. On the other hand, my Orion Sky Glow filter did show some nebulosity. There appeared to be a faint haze around three of the stars at the top of the goblet with a faint haze across the top and down the south side of the goblet as well. This haze began to appear after looking for a minute or two and was best seen with averted vision although some nebulosity could be seen with direct vision.

All in all, with the AT66ED, this cluster of 30 to 40 faint stars is best seen at 80X, but the nebula was best seen at 27X with the Nebustar filter. I believe this little scope does as well as or better than anyone would expect it to do. 

Other Notable Observations: 

Burnham's Celestial Handbook, Vol 1 - Robert Burnham, Jr. spends most of his time describing the movement of AE Aurigae; however, he does point out that IC 405 appears to be a random encounter rather than being associated with AE Aurigae. Since the star shot off from Orion's Belt area, it happened to plow through this nebulosity and light it up. 

Observing Handbook and Catalogue of Deep-Sky Objects, Christian Luginbuhl and Brian Skiff, Cambridge University Press - NGC 1893 illuminates IC 410, which is quite difficult to discern. A 6cm (2.4") shows the cluster elongated north to south with ten stars visible. Roughly 30 stars are visible in 15cm (6") with some stars trailing to the northeast. It is an obvious cluster in 25cm (10") despite the rich fields nearby. In the center is a nice pair along with a mag 9.5 star. A well-defined group of stragglers extends north and east, including another 30 stars. An equal pair of mag 9 stars lies isolated in a field 18' west of the cluster. 30cm (12") shows 25 stars, including ten brighter ones in a 15' x 18' area. 

Deep-Sky Wonders by Walter Scott Houston, Selections and Commentaries by Stephen O'Meara, Sky Publishing Corp - The cluster measures about 10 arc minutes across. Sky Catalogue 2000.0 lists it as having a total mag of 7.5, but he estimated it to be slightly fainter. It contains a conspicuous Y-pattern formed by four mag 8 stars. British amateur, Guy Hurst, comments that NGC 1893 is "very rich with a haze of unresolved stars." However, here is an interesting point. In small apertures, the cluster does show a haze of unresolved stars, but , as mentioned, NGC 1893 is involved with the nebula IC 410. "Like many observers, I have looked at the cluster, but not seen the nebula. Could the glow we attribute to stars just below our telescope's limit really be due to the nebula?"