M102 by Jim Gianoulakis

Our M102 is not the duplicate of M101 that is common to the original Messier catalog.  Many common references list M101 and M102 as the same galaxy but in this case, it is NGC 5866, which many consider a better candidate for M102.  It makes for a more complete list even if it isn’t necessarily historically accurate.  Any controversy aside, this M102 is an excellent subject.  NGC 5866 was discovered by either Pierre Méchain or Charles Messier in 1781.  It is one of two galaxies called the Spindle Galaxy (the other one is NGC 3115 in Sextans).

NGC 5866 has an extended dust lane which can be seen edge-on.  This is highly unusual for a lenticular galaxy.  Lenticular galaxies are galaxies that are somewhere between being elliptical or spiral galaxies.  They have used up or lost most of their interstellar matter and have very little ongoing star formation.  There may, however, be significant dust within their disks.  This type of galaxy may be hard to distinguish from an elliptical galaxy.

In the case of NGC 5866, it is possible that it is really a spiral galaxy misidentified as lenticular because of its acute edge-on angle to the Earth.  In this case, the dust lane would not be that unusual.

NGC 5866 is one of the brightest of a small galaxy group that includes spiral galaxies NGC 5879 and NGC 5907.  This group may be a sub-clump of the M51 and M101 group, although some think these three groups are separate.

The challenge for the smaller scopes is to see the smudge of the galaxy.  For the larger scopes, it is to see the dark lane and more details surrounding it.

Observations/Drawings/Photos

Jim Gianoulakis: LVAS Member from Las Vegas, Nevada

This month's observer's challenge target is spiral galaxy NGC 5866 in Draco.  This object always generates a question among observers.  Is this galaxy Messier's 102nd object?  That depends on who one asks.  Some astronomical historians argue that M102 is a duplicate observation of spiral galaxy M101 in Ursa Major.  Others say the evidence points to this galaxy, NGC 5866.

Whether or not Messier meant NGC 5866 to be his 102nd entry, this lens-shaped galaxy shows up nicely through a 4-inch telescope as a bright streak with a brilliant center.  It shines at mag. 9.9 and measures 6.6' by 3.2'.  On the best nights, larger scopes reveal a thin dust lane extending almost as long as the galaxy.

To find NGC 5866, point a scope 4.1° south-southwest of mag. 3.3 Iota (?) Draconis.

Astronomy magazine contributing editor Stephen James O'Meara makes a good case that M102 is simply a more refined observation of M101.  I therefore call M102 the Fool's Gold Galaxy because, if one thinks they’ve found it when they’re observing NGC 5866, the joke's on them.

NGC 5866 is a bright lenticular galaxy in the constellation of Draco, the largest member of a small galaxy group.  A rough distance estimate is 35 million light years, with a diameter of about 50,000 light years.

Lenticular galaxies are disk-shaped like spiral galaxies, but mostly consist of old or middle-aged stars, like elliptical galaxies.  Some have prominent dust lanes.  NGC 5866’s dust lane is “buried” inside a large outer envelope that makes the galaxy look something like an elliptical on long photographic exposures.  Strangely, the dust lane is tilted slightly from the plane of the rest of the galaxy.  Also, there is some new star formation in this galaxy near the outer edge of the disk.

About the photo:

The photo of NGC 5866 is composed of 48 sub-frames of five minutes each.  Twelve frames each through red, green, blue, and luminance filters, for a total of four hours total exposure.  All frames were calibrated with darks, flats and bias frames.  The frames were stacked with Deep Sky Stacker, aligned with Nebulosity 2 and processed in Photoshop.  The images were taken through an Astro-Tech 8-inch RC on an Atlas EQ-G mount.  The camera used was a QSI 583 WSG.

Roger Ivester: LVAS Member from North Carolina

It has been a very difficult spring for observing in the foothills of western North Carolina, due to clouds, rain, and as of late, heat and haze.  On the night of June 25th, I was able to observe under excellent conditions using my 10-inch reflector.  NGC 5866 was very easy to locate, using low power.  The galaxy appeared bright, elongated, with two stars flanking the NW end.  When increasing the magnification to 200X and finally 290X, a third, fainter star could be seen relatively easy, SSW of the SE end of the galaxy.  At the higher magnification, the galaxy was presented as elongated, lens shaped, with a brighter and more concentrated core being noted.

With the use of 200X, I was very surprised to see the faint and small mag. 14.9 galaxy, NGC 5862, located to the SSW of NGC 5866.  The fainter galaxy appeared as little more than a faint blur when using averted vision.  It could not be held constantly, with the shape and size being indeterminable.

The sketch of NGC 5866 was made using a blank 5 X 8 note card, with only the use of a No. 2 graphite pencil.  The color was inverted for a negative image, using my copier/scanner.  The magnification was 290X with a 0.28° field of view.

Rob Lambert: LVAS President from Las Vegas, Nevada

My observation of M102 or NGC 5866 did little to confirm, in my mind, its status as an edge-on lenticular or spiral galaxy.  I, too, was torn as to whether it was spiral or lenticular, although it did appear to have more of a halo instead of a disk.  However, I didn’t think I was imagining the dust lane that was stretching across the center of the central bulge, which was angled somewhat from the southeast to northwest.  The galaxy definitely had a central bulge that was much brighter than its disk/halo.  I always have a difficult time determining which way is up when trying to determine the directional orientation of objects, and M102 was no different.  My Starry Night Pro didn't help much either.  In fact, Starry Night Pro showed M102 and NGC 5866 as being different objects, but showed M102 as being the object I observed.  Assuming that I had NGC 5866/M102 oriented correctly, it appeared to be oriented north-south with north being toward the lower right corner of my image. 

There appeared to be two foreground stars overlaid on the southwestern end of the galaxy.  I was just able to detect NGC 5867 on the western side of M102's central bulge.  I wasn't able to detect any of the many other galaxies that are clearly visible in Hubble images.  Although there does appear to be another galaxy visible between the two stars on the eastern side of M102, I couldn't find a labeled photo that would confirm that it was a galaxy and provide its designation.  What I would’ve given for one of Jim Dire's well-labeled photos of this region of the sky!

Fred Rayworth: LVAS Member and AL Coordinator from Las Vegas, Nevada

I had two chances to look at M102 this year, both from Desert Springs Preserve near Corn Creek just north of Las Vegas.  Unfortunately, both trips were not under the best observing conditions.  The skies were dark but the air was thick with dust.  Still, I was able to get two mediocre observations using my 16-inch f/4.5 reflector.

On May 7, 2011 I saw a sharp oval between two stars.  I noticed no other particularly distinctive features.  The sky didn’t lend itself to allowing for detailed observing so I considered myself lucky to see even that much.  The galaxy stood out even though the background was bright.  I saw it best that night at 86X, although I tried 133X and even 220X and neither magnification drew any improvement.  I was aware that there might be some fainter stars embedded within the halo but I never saw a hint of them at any magnification.

My second attempt was the evening of July 2, 2011.  The sky looked promising but once again, the conditions seemed to be a repeat of the May 7^th evening and they proved to be true.  By the time the public outreach was over and I was able to concentrate on M-102, the skies were already fading.  I saw a clone of what I witnessed in May.  However, I seemed to get the best view at 133X this time.  The edges of the oval were a bit more defined and filled out more toward the two stars framing it.  Because of the wide field of view of the eyepiece, I was able to squeeze in the area where the faint mag. 14.9 NGC 5870 was supposed to be.  I looked for the star it sits next to and scanned for it over and over again and spotted just a hint that something was there.  However, I couldn’t for sure say with certainty that I actually saw it as the background was getting brighter as time wore on. Just in case, I pointed it out in my drawing.  I didn’t add it to my database as I doesn’t think it was a good enough observation to count.  I also tried for the much fainter mag. 15.2 galaxy that lies just north of it but given the brightening sky, there was no way I was going to spot that.

I soon noticed that the brighter stars developed nebulae around them, a sure indication that the monsoon moisture was moving in, even though it couldn’t be seen directly.  It was time to quit for the night.

Buddy L. Barbee: LVAS Friend from North Carolina

This observation was made Friday, April 28, 2011 from my families' beach house at Oak Island,  NC.  I was using my 4-inch refractor with a 10mm eyepiece.  The weather was almost perfect with a clear sky having a naked eye limiting (NELM) of 5.1, but it turned out that the transparency was less than average for this site.  It was a comfortable 65° F with winds between 10 to 15 mph, while the humidity was a moderate 55%.

I began my star hop at Edasich, Iota Draco, using a 24mm eyepiece with a magnification of 37X and a true field-of-view of 1.83°.  Moving the telescope approximately two and a half fields-of-view to the southwest, I located a small dim hazy spot.  After verifying this to be the correct star field with my atlas, I started upping the magnification until I got the best view possible of M102.  After settling on the 10mm eyepiece with a magnification of 88X and a true field-of-view of 0.68°, the galaxy appeared to be a small lens-shaped gray spot that was a little brighter in the center.  M102 appeared to be about 4 arc minutes long by 1 arc minute wide.  The galaxy's long axis was oriented a little west of northwest to a little east of southeast.  The surface of the galaxy appeared to be mottled a little, and was not a smooth gray misty spot.  With the 4-inch refractor, I was surprised by how faint this galaxy appeared.

There were several stars visible around the galaxy. One was a mag. 11.5 star approximately 1 minute to the north of the galaxy's core and another was a mag. 12.0 star approximately1 minute southwest of the galaxy's core.  This mag. 12.0 star was only visible with averted vision.  There was also a bright mag. 7.5 star located 10 arc minutes southwest of the galaxy.  Also of note was a mag. 6 star just outside of my field-of-view, approximately 30 arc minutes to the northeast.

NOTE: On June 3, 2011, I viewed this galaxy once again with my 10-inch Dob while attending the East Coast Star Party on the Outer Banks of NC.  It was a comfortable 70° F with the wind blowing 5 to 15 mph.  The sky was clear with a naked eye limiting magnitude of 5.7.

With the 10-inch Dob and a 13mm eyepiece for a magnification of 92X and a true field-of-view of 0.88°, this view was almost identical to the view through the 4-inch refractor.  Except for the galaxy being brighter and the dim stars next to M102 being visible with direct vision, one would think it was the same view.  I was trying to see the dust lane with the larger aperture though, so I upped the magnification until I reached 240X with a 5mm eyepiece and still couldn’t see it.  I guess that seeing the dust lane will take either darker skies or a larger telescope.

Dr. James Dire: LVAS Friend from Hawaii

M102 in Draco is a mag. 10 edge-on galaxy that is classified as a lenticular galaxy (cross between a spiral galaxy and elliptical galaxy).  It has a prominent dust lane typical of spiral galaxies, but it has an ellipsoidal shape (like a football), characteristic of elliptical galaxies.  Because it is edge-on, spiral arms cannot be seen, if they exist.

Historically, there has been ambiguity as to which galaxy was originally classified as M102, but today that assignment is given to NGC 5866.  Some early 18th and 19th century astronomers claimed M102 was a duplication of M101.  Truly it may never be known.  Regardless, NGC 5866 is a good addition to Messier’s original list.

M102 is roughly 6.3 ´ 2.8 arc minutes in size, which makes it easy to spy at mag. 9.9 in small telescopes.  James could easily see it in my 70mm refractor as a faint blur and it was a delight in my 102mm APO.  However, a larger telescope is required to see its’ dust lane.  Based on gravitational interactions with other galaxies in the NGC 5866 group, it is estimated that M102 has the mass of one trillion suns, much more massive than the Milky Way.

My image of M102 was taken the night of June 4, 2011 at the KEASA observatory at Barking Sands on the island of Kauai.  It was a 60 minute exposure taken with a 70mm f/6 achromatic refractor using a hydrogen-beta filter (12 nm bandpass).  The image was taken with an SBIG ST-2000XCM CCD camera and covers a field of view 1° ´ 1.5°.

The wide field of view duplicated what might be seen in a finder scope or binoculars, or at low power in a rich-field Newtonian telescope.  However, the image captures stars down to mag. 16.  There are several fainter, smaller galaxies in the image down to mag. 15.

Sue French: LVAS Friend and Observer from New York

3-15-1980, 10:55 pm EDT - 6-inch f/8 Newtonian, 43X.  Seeing:  Fair.  Transparency:  Good - Very faint hazy patch, small, somewhat elongated.  Brighter in a large part of the central area.  Star near edge.

5-13-1991, 12:00 am EDT - 14 X 70 binoculars.  Seeing:  Good.  Transparency:  Very good - Quite small, very faint, elongated galaxy.  Near one point of a right triangle of nearly equal magnitude field stars.  Shares field with a bright star in Boötes.

4-17-2002, 12: 05 am EDT - 105/610 mm apochromat.  Seeing:  Fair.  Transparency:  Fair - 27X:  Small, bright, elongated, with star at north side of northwest end.  Located outside the faintest corner of a right triangle of fairly bright, nearly equal magnitude stars.  Bright star south in field of view. - 87X:  A fainter star is now visible at the south side of the northwest end.  Galaxy runs southeast-northwest with a length to width ratio of about 3 to 1.  Bright elongated core, with some patchiness in the southeast.  Length approximately equal to the distance between the bracketing stars ( 2.4' ). - 127X:  Intermittent tiny nucleus

6-13-2004, 12:17 am EDT - 10-inch f/6 Newtonian.  Seeing:  Poor.  Transparency:  Poor.  Indian Meadows.  Light polluted - 70X:  Nice, bright, oval galaxy elongated 3:2 northwest-southeast.  North end passes between a mag. 11 star (north side) and a mag. 12 star (south side and a little more distant), all along the longest side of a bright triangle of mag. 8, 9, and 10 stars. - 170X:  4' long and one-third as wide.  Faint halo.  Much brighter, large, oval interior with a small, slightly brighter core area.

Gus Johnson: LVAS Friend from Maryland.  NOTE: On April 19, 1979, Gus Johnson, visually discovered Supernova 1979C in spiral galaxy M100.  NASA announced on November 15, 2010, there was evidence of a black hole as a result of this supernova explosion.

Using a 5-inch f/5.7 reflector at 60X presented a Saturn-like shape with two stars nearby.  Photos showed a third star that looked just a bit dimmer than the second star, with the two dimmer stars being on opposite sides of the galaxy.  The small size of the galaxy was seen better with 60X than with 30X.  9-17-1982.

On a mag. 5.5 night, the galaxy was very dim in a 12 X 50 finder, and was better seen in my 2.4-inch refractor at 21X, which also showed nearby NGC 5907.  5-20-1992.

M102 second card:

Not viewed in about 19 years, but was found (with some difficulty) on 6/29/11 using an 8-inch f/6 at 60X, then 133X.  It was about a mag. 5.5 night for unaided eyes.  Stars had some halo.  I was surprised that I apparently saw it in a 12.5 X 50 mm finder 19 years ago and NGC 5907 which seemed very dim to him.  M102 was in a fair-sized triangle that fit the field even at 133X.  The previously-seen two stars were easy, but the third may have been glimpsed at 133X with averted vision.