[LVAS] February Observer's Challenge and Supplemental

Fri Mar 5 18:49:47 PST 2010

MONTHLY OBSERVER’S CHALLENGE
Las Vegas Astronomical Society
Compiled by:
Roger Ivester, Boiling Springs, North Carolina
&
Fred Rayworth, Las Vegas, Nevada
With special assistance from:
Rob Lambert, Las Vegas, Nevada
February 2010
NGC-2903 Galaxy in Leo
Plus the winter supplemental
M-105, NGC-3384, NGC- 3389 Galaxy Trio in Leo
Introduction
The purpose of the observer’s challenge is to encourage the pursuit of visual observing.  It is open to everyone that is interested, and if you are able to contribute notes, drawings, or photographs, we will be happy to include them in our monthly summary.  Observing is not only a pleasure, but an art.  With the main focus of amateur astronomy on astrophotography, many times people tend to forget how it was in the days before cameras, clock drives, and GOTO.  Astronomy depended on what was seen through the eyepiece.  Not only did it satisfy an innate curiosity, but it allowed the first astronomers to discover the beauty and the wonderment of the night sky.
Before photography, all observations depended on what the astronomer saw in the eyepiece, and how they recorded their observations.  This was done through notes and drawings and that is the tradition we are stressing in the observers challenge.  By combining our visual observations with our drawings, and sometimes, astrophotography (from those with the equipment and talent to do so), we get a unique understanding of what it is like to look through an eyepiece, and to see what is really there.  The hope is that you will read through these notes and become inspired to take more time at the eyepiece studying each object, and looking for those subtle details that you might never have noticed before.  Each new discovery increases one’s appreciation of the skies above us.  It is our firm belief that careful observing can improve your visual acuity to a much higher level that just might allow you to add inches to your telescope.  Please consider this at your next observing session, as you can learn to make details jump out.  It is also a thrill to point out details a new observer wouldn’t even know to look for in that very faint galaxy, star cluster, nebula, or planet.
NGC-2903 Bright Galaxy in Leo
            NGC-2903 is a barred spiral galaxy in Leo.  It was discovered by William Herschel on 16 November, 1784.  At approximate mag. 9.7, it provides an easy target for most any telescope.  It is amazing that Charles Messier missed this galaxy as two of the comets discovered by him passed quite close to it.
            Though it is face-on, it carries a slightly oblong appearance.  It provides a wealth of features that can be seen, especially with larger backyard telescopes.
Celestial Sampler by Sue French, Sky Publishing, Cambridge Massachusetts 2005
NGC-2903 is faintly visible through a 50mm finder.  With her 4.1” (105mm) refractor at 87X, this is a very nice galaxy about 8' by 4' in angular size.  The outer halo is faint, but there is considerable brightening toward the center.  Some dark patches in the oval core hint at spiral structure, and a stellar nucleus spot can be seen south of the center.  A bright patch in the galaxy's north-eastern spiral arms bears its own designation, NGC-2905.  It looked like a double nebula to its discoverer, William Herschel, who observed from southern England in the late 18th century.  It will take at least an 8” scope to catch sight of NGC-2905.
Deep-Sky Wonder's by Walter Scott Houston, selections and commentary by Stephen O'Meara, Sky Publishing Corp
NGC-2903 is a big 9th mag. spiral about 4° SW of Epsilon Leonis.  It seems distinctly oval, but not as much as the catalog dimensions 11' x 4.6' suggest.  At mag. 9, it should be visible even in a good 2” finder.  Long exposure photographs show it as a single galaxy, but this object's ownership of two NGC numbers, 2903 and 2905, is a reminder that early visual observers thought otherwise.  In his Cycle of Celestial Objects, Smyth tells us that William Herschel described it in 1784 as "a double nebula, each having a seeming nucleus, with their apparent nebulosities running into each other."  William's son, John, and Smyth had some difficulty in making this out with his 6” refractor.  "The upper or south part is better defined than the lower, it requires, however, the closest attention and most patient watching, to make it a bi-central object."  It would be interesting to view NGC-2903 with a long-focus instrument at medium to high magnification, gradually reducing the aperture until the object becomes nearly invisible in the hope of inducing the "double" appearance.  “I myself have never been able to see such an appearance, despite experiments with various apertures.  Has any reader of this column observed NGC-2903 as double?”
He always wondered why Charles Messier missed this galaxy, especially since he catalogued fainter ones in nearby Virgo.  Ron Morales of Tucson, Arizona, found it "easy and impressive" as seen with an 8” reflector.  California amateur Tokuo Nakamoto reports seeing a faint oval halo surrounding the "much brighter" center of NGC-2903 with his 14” reflector.  Years ago in Kansas, Walter viewed the galaxy with a 10” reflector at 120X.  The arms were rather ill-defined, but several knots of material dotted the extensions around the core.  These knots were bright clouds of ionized hydrogen (called H-II regions) similar to the Orion Nebula within our own galaxy.  Photographers might try recording NGC-2903 with a series of exposures.  Long ones should show the galaxy's arms in all of their splendor, but shorter exposures may better reveal the knots and the nucleus.  Astronomers have identified over 70 such glowing clouds within NGC-2903.  In the 1960's he saw several of them with the 20” Clark refractor at Connecticut's Wesleyan University.  They gave the galaxy a mottled appearance.
Celestial Harvest by James Mullaney
One of the best galaxies missed by Messier and a fine sight in small telescopes.  "Elongated, faint, with a double nucleus," thus the dual designation NGC-2903-5 that's sometimes given.  Actually a star cloud lying just 1' N of the nucleus.  But it's not exactly an obvious object in average backyard scopes.
M-105, NGC-3384, NGC- 3389 Galaxy trio in Leo
            M-105, or NGC-3379 is the brightest galaxy in the Leo 1 M-96 group.  At mag. 9.3, it dominates the field of view that also includes NGC-3384 and NGC-3389.  Together they make a very interesting trio.  If using an eyepiece with a wide enough field, one can also bring M-96 into the edge of the field.  M-105 was a late addition to the Messier catalogue as it was actually discovered by Pierre Méchain in 1781.  It is a bright elliptical galaxy known to house a super-massive black hole.  NGC-3384 is a lenticular galaxy discovered by William Herschel in 1784 and comes in at a mag. 10.9.  The faintest of the three is NGC-3389 which comes it at mag. 12.4 and is by far, the most challenging to see visually.  It usually requires a 10” scope or larger to see.
Celestial Sampler by Sue French, Sky Publishing, Cambridge Massachusetts 2005
In her 4.1” scope at 87X, she can see M-105 and another galaxy, NGC-3384, just to its east-northeast.  Their centers are a mere 8' apart.  On M-105, the same instrument at medium to high power shows a tiny, bright nucleus embedded in a slightly oval glow that fades gradually toward the periphery.  NGC-3384 looks like a smaller, dimmer version of M-105.  Close inspection reveals a very faint third galaxy, NGC-3389, only 11' east-southeast of M-105.  NGC-3384 is a member of the Leo I Group, but NGC-3389 is generally thought to be a background galaxy.
Observing Handbook and Catalogue Of Deep-Sky Objects, by Christian Luginbuhl and Brian Skiff, Cambridge University Press
M-105 is easily visible in a 6cm (2.4”) in the same low-power field with M-95 and M-96. 15cm (6”) shows a stellar nucleus in the center of a bright circular spot.  In 25cm (10”) the brightness increases evenly up to a sub-stellar nucleus:  the core and halo are not clearly delineated.  The overall size is 1'.5 x 1'.2, elongated E-W.  With 30cm (12”) it grows to 4' x 3', elongated in pa 80°.  The smoothly textured halo is moderately concentrated to the core, which shows strong, sharp concentration to a bright 10' nucleus.
NGC-3384 in 15cm (6”) this object appears similar to M-105, though it is slightly smaller.  The nucleus is stellar. 25cm (10”) shows it 3' x 1', elongated NE-SW, and clearly fainter than M-105.  The core is circular, about 40" across, with a stellar nucleus.  A mag. 13 star lies 2'.3 SE of center.  In 30cm (12”) the halo is very elongated, extending to 5'.5 x 1'.75 in pa 50°.  It is abruptly concentrated to circular central regions and a more nearly stellar nucleus than M-105.
NGC-3389:  This galaxy is discernable in 15cm (6”) as a faint uniform glow a little smaller than its nearby companions.  A faint stellar center is visible in 25cm (10”):  the halo extends to 2' x 1', elongated ESE-WNW.  30cm (12”) shows the un-concentrated halo to 3' x 1'.5 in position angle 110°.  No nucleus is discernable even at high power, though the middle parts show some mottling.  A mag. 13.5 star is visible 2'.7 NNE.
Observations/Drawings/Photos
Roger Ivester (see Rogers Pictures 003.jpg):  Observer from North Carolina
NGC-2903
Observations using a 10” reflector at 142X in a moderately light polluted backyard from the foothills of western North Carolina, presents NGC-2903 as bright, very elongated with a brighter core.  The orientation is NNE-SSW.  The texture of this galaxy is very uneven with mottling noted.  Conditions on this night didn’t allow the observation of the bright patch just north of the central region for certain.  This bright patch carries the designation of NGC-2905.
Please see sketch using 142X with a field of 0.46° / 28' arc minutes.  The sketch was made using a white charcoal pencil on black card stock (see Rogers NGC-2903.jpg).
M105
M-105 appears very bright, round, a brightening toward the central region and a stellar nucleus when observed with the 10”.  A faint surrounding halo is very easy to see.  This galaxy is well concentrated and the overall texture is very even.  M-105 is the brightest of the group which includes NGC-3384 and NGC-3389, and is the most western of the three galaxies.
Please see sketch using 142X with a FOV of 0.46° /  28' arc minutes.  The sketch was made using a white charcoal pencil on black card stock (see Rogers M-105 Group.jpg).
NGC-3384
When observed through the 10” at 142X, the second brightest galaxy of this group, NGC-3384, appears bright and is elongated NE-SW.  This galaxy is NE of M-105 and has a similar appearance, but is smaller and fainter.  The core or central region of NGC-3384 is well concentrated, and with careful attention a stellar nucleus and a faint halo can be seen.
NGC-3389
NGC-3389 lies SE of M-105 and is the faintest of the trio of galaxies.  When observed with the 10” at 142X, this galaxy is poorly concentrated and can be difficult if conditions are not good.  It is also elongated with an orientation of SE-NW.  Little or no central brightness could be seen.  This galaxy appears as a mostly faint elongated glow.
Fred Rayworth (see Freds At Sawmill.jpg):  Observer from Nevada
He first observed NGC-2903 in 1984 with his home-built 8” f/9.44 Newtonian.  He was even able to see it through streetlights in the neighborhood near Torrejon Air Base, Spain where he lived at the time.  For this challenge, he observed from Valley of Fire State Park Visitor’s Center.  The skies were iffy at best.  Though he could see all the brightest stars in Leo, when he looked through the eyepiece, the background was not black, and everything in that part of the sky appeared dim and unremarkable.  He observed the challenge supplemental under the same conditions.
It was a nice, medium-sized oval that appeared mostly round and face-on, but had a slight oval appearance to it.  It had a concentrated center with just a touch of lumpiness.  He noticed no significant stars in or around the galaxy and saw no distinctive sign of NGC-2905.  With the very bright background, the galaxy appeared drab as if he were looking at it through a heavy haze from downtown Las Vegas (even though Las Vegas was a good 30 miles in the opposite direction, as the crow flies) (see Freds NGC-2903.jpg).
The M-105 trio was much more interesting.  The first time he’d seen M-105 was in 1987 and that was right after he built his 16” f/6.4 reflector.  With a brand new enhanced coating on the mirror, he was able to cut through some serious atmosphere despite being at 50’ above sea level, and located on Incirlik Air Base in Turkey.
For the challenge, he observed it from Valley of Fire under the same conditions as NGC-2903.  However, in this case, not only did he get M-105, NGC-3384 and NGC-3389, in the same field he was also able to squeeze in M-96.  That was, as he’d call it, a “four bagger” and he accomplished it with a 26mm Orion Q-70 eyepiece.
M-105 was a bright, dense oval with no distinguishing features.  NGC-3384 was almost as bright, but had a more distinct oval shape.  NGC-3389 was very hard to pick out as just a shapeless gray ghost of a smudge.  At the other side of the field, M-96 seemed almost a twin to M-105, but had a slightly narrower oval shape to it (see Freds M-105 Group.jpg).
Overall, despite being a poor night in that part of the sky, he had a great time and was glad for the opportunity to go out.  The last time he’d been out was around Thanksgiving.
Rob Lambert:  Observer from Nevada
He first observed NGC-2903 on February 21, 2009 and then again almost a year later on February 13, 2010.  Using his Mallincam VSS astro-video camera, he observed this month’s challenge object through his Orion ST120 and 10” LX200GPS.  The ST120 with focal reduction to f/2.5 presents a 1.5° FOV at 32X.  The LX200 with focal reduction to f/3.2 presents a 0.5° FOV at 100X and at f/5.0 presents a 0.3° FOV at 160X.  Although the skies were clear at the Valley of Fire observing site just outside of Las Vegas, the transparency wasn’t all that great due to the recent rains and higher than normal humidity in the air.  In the accompanying images, north is toward the bottom right corner with west toward the bottom left corner.
Through the ST120 at approximately 32X, NGC-2903 hints at being a barred spiral with a counterclockwise rotation.  It has an obvious bright core with somewhat less brighter bars extending NNE and SSW from the core.  The NNE bar appears to be brighter than the opposite bar and may be the location of the star forming region known as NGC-2905.  At this lower magnification, there wasn’t much detail to be seen in the spiral arms (see Robs NGC-2903-ST120-32X.jpg).
At 100X in the LX200, NGC-2903 presents a very bright elongated irregular core and mottled halo with more detail in its spiral arms and bar.  The central bar cuts diagonally across the galaxy’s NNE-SSW axis at almost a 45° angle.  The northern bar has a large bright nodule at the end of it and two smaller ones that follow the curve of the spiral.  It must be this area that is the star forming region recognized as NGC-2905.  The southern bar appears to have only one smaller bright nodule near the end of the arm.  The galaxy has two distinct major arms radiating from each end of the bar (see Robs NGC-2903-LX200-100X.jpg).  At 160X, a couple of fainter minor arms squeezed in between the two major ones begin to become more distinct.  All of the arms are more tightly wound than in other spiral galaxies the group has observed.  They are fairly distinct closer in to the body of the galaxy, but become diffuse and faint as they extend away from the galaxy.  The arms are more prominent on the east side of the galaxy than on the west (see Robs NGC-2903-LX200-160X.jpg).
On the next trip to a dark site, he’ll see if less focal reduction will reveal more distinction in the minor arms of the galaxy.
Dave Blanchette:  Observer from Nevada
A 12 minute exposure of NGC-2903 is attached.  No stacking, just some contrast adjustment.  Taken through 12" Meade LX200, f/6.3 focal reducer.  He did try without the focal reducer, but the seeing really wasn't up to it (see Daves NGC-2903.jpg).
Dr. James Dire:  (see Jim Dire.jpg) Observer from North Carolina
NGC-2903 is a fine barred spiral galaxy located to the west of the sickle of Leo.  The galaxy is 1.5° due south of the 4th mag. red star Lambda Leonis.  This 9th mag. galaxy measures 11.8 by 5.1 arcminutes.  The image shown here was taken with an Orion 190mm f/5.3 Maksutov-Newtonian using an SBIG ST-2000XCM CCD camera.  The exposure was 40 minutes.  Even with this short focal length, the galaxies central bar is quite apparent.  As usual for barred spiral galaxies, the spiral arms tend to originate at the ends of the bar.  There are roughly two spiral arms coming from each end of the bar, however only one spiral arm from each end appear distinct and wrapped 180° around the galaxy.  The galaxy lies 34 million light years away.  It has significant star formation occurring in the spiral arms as evident by the abundant number of short-lived blue giant stars and bright red hydrogen gas regions (see Jims NGC-2903 Labeled.jpg).
A great trio of galaxies in constellation Leo consists of M-105 (mag. 9.27, size 4.8 x 4.2 arcmin), NGC-3384 (mag. 9.96, size 5.3 x 2.4 arcmin) and, NGC-3373 (mag. 12.05, size 2.7 x 1.2 arcmin).  M-105 is visually the brightest and largest of the three galaxies, but not by much over NGC-3384.  Both M-105 and NGC-3384 are elliptical galaxies.  These galaxies tend to exhibit a bright central core with a halo of starlight surrounding them.  M-105 is a relatively spherical elliptical galaxy, while NGC-3384 is very elongated.  Both of these galaxies are between 34 and 38 million light years away and are part of the Leo I galaxy group.  The third galaxy in the group, NGC-3373, is a spiral galaxy.  This galaxy is fainter than the other two since it is located roughly twice as far away.
The trio image was taken with an Orion 190mm f/5.3 Maksutov-Newtonian using an SBIG ST-2000XCM CCD camera.  The exposure was 30 minutes.  The faint stars located in the halos of the two elliptical galaxies and within the spiral arms of NGC-3373 are actually faint foreground stars located in our galaxy.  The trio can be found in the middle of Leo, slightly more than 1.5° south of 5.5 mag. star 52 Leonis (see Jims M-105 Group.jpg).
Frank Barrett:  Observer from North Carolina (www.celestialwonders.com)
On Feb 19, 2010, Frank took this photo of NGC-2903 from his observatory in Gastonia, NC.  He used a Meade 10” LX200R, with a 2800mm focal length, at f/11.  The exposure was four hours of luminance along with three hours of color using an SBIG STL-11000M camera.  His mount is a Losmandy G11 with an Ovision worm upgrade (see Franks NGC-2903.jpg)
References
(Submitted by Roger Ivester)
Celestial Sampler by Sue French, Sky Publishing, Cambridge Massachusetts 2005
Deep-Sky Wonder's by Walter Scott Houston, selections and commentary by Stephen O'Meara, Sky Publishing Corp
Celestial Harvest by James Mullaney
Observing Handbook and Catalogue Of Deep-Sky Objects, by Christian Luginbuhl and Brian Skiff, Cambridge University Press 		 	   		  
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