Archive for May 24, 2017

Observer’s Challenge: Galaxy M98 in Virgo – May 2017 – Report #99

May 24, 2017

MAY 2017 OBSERVERS CHALLENGE – M-098-1

Image of galaxy M98:  32-inch reflector by Mario Motta from Massachusetts.   

M98

 

“M98 (NGC 4192) is an elongated nearly edge-on type Sb spiral, measuring 8.2′ x 2.0′ and shining at magnitude 11.0.  This galaxy’s surface brightness is rather low, making it a tricky object at high power.  Backyard telescopes show this galaxy as a thin streak of greenish light, slightly curved, showing a faint envelope of gas and a sharp nucleus.”   David J. Eicher – Wisconsin – Editor Astronomy Magazine 

 

“Although M98 has low surface brightness, it can be seen in a 60mm refractor under dark skies.  Through a 105mm scope at around 100x, the galaxy is about 6′ x 2′, elongated N-NW to S-SW.  It contains a brighter, extended patchy core and an off-center, nearly stellar nucleus.”  Sue French –  New York – Deep-Sky Wonders

 

M98 is one of the fainter of the Messier objects and can be especially difficult when observed with a telescope smaller than 4-inches. The surface brightness is very low, and regardless of telescope size, a dark sky is needed to see and fully appreciate the many faint, but fine details this galaxy has to offer.

In a 10-inch reflector, M98 appears fairly bright, elongated, a bright nucleus, with unevenness in the halo, with some mottling noted in the central region. Two brighter sections can be seen in both the NW and SE arms.  The nucleus is off-set toward the SE.  

With a 102 mm refractor, and observing from my moderately light polluted backyard this galaxy appears very faint, elongated and weak without any center brightness. In a 6-inch reflector, the galaxy is slightly enlarged and overall a bit brighter when compared to the refractor.  Roger Ivester – Observer from North Carolina 

 Pencil sketch:

FullSizeRender

Inverted sketch: 

Rogers M-098 Inverted

 

 

By Dr. James Dire –  Observer from Hawaii
M98 is a magnitude 10.1 barred spiral galaxy in the constellation Coma Berenices. The galaxy is located 6 degrees east of the star Denebola. The galaxy is one-half degree west of the 5th magnitude star 6 Comae Berenices. M98 measures 10 x 2.8 arc minutes in size.

M98 is a nearly edge-on galaxy, inclined 74° to our line of sight. The galaxy has tightly wound spiral arms with a chaotic disk and an active nucleus. Distance measurements range from 44 to 66 million light years. It is thought to be a member of the Virgo galaxy cluster. The galaxy may have interacted with M99 750 million years ago which may account for the distortions in its disk.

Pierre Mechain discovered M98 in 1781, confirmed later that year by Charles Messier. Messier added M98, M99 and M100 into his third catalog immediately before publishing this final edition of his famous list. M98 is one of the faintest objects in Messier’s Catalog.

M98 is one of the few galaxies with a blue shift, meaning it is approaching us. This motion may be temporary if M98 is orbiting the Virgo Cluster. It may be at a point in its orbit where it is approaching us. If it is gravitationally bound to the cluster, it will never reach us.

I viewed M98 in a 6-inch refractor. The galaxy definitely was elongated and nearly edge on. No dust lane was visible and the core appeared much brighter then the galaxy’s edges.

My image of M98 was taken with a 10-inch f/6.9 Newtonian with an SBIG ST-2000XCM CCD camera. The exposure was 200 minutes. I would have preferred a much longer exposure to bring out more detail on the edges of the galaxy and may gather more data on it in the future. The brightest star in the image, located near the bottom left edge, is magnitude 11.7. The four star just off the left edge of the galaxy are magnitudes 12.5, 15.2 16.5 and 18.

On the image, note the bright star-forming region on the bottom (south) edge of the disk. The spiral arm edge visible on the top (north) side of the galaxy has bright HII regions with bright star clusters. Even with this small telescope, I was able to capture the distortions on the north edge of the galaxy’s disk. It appears like the galaxy has two disks that are slightly misaligned with each other. This was either caused the interaction with M99 cited above, or two galaxies have merged to create the presently seen M98.  JD 

M98

 

 

Messier 98 is the second faintest object in the entire Messier galaxy only preceded by M91 (only 0.1 magnitudes fainter). With a visual magnitude of 10.1 and a surface brightness of roughly 13.5 it can be a fairly difficult catch under light polluted skies.

Observing in a suburban location, I could barely make out M98 with a 4.5-inch telescope as an elongated galaxy with a brighter core. With a 10-inch dobsonian reflector and high magnification under a dark sky, I could make out some structure from the mottled disk.

I described the object as follows using magnifications between 60 and 343x:

“Elongated in NW-SE direction. Bright core with a nearly stellar nucleus in the middle. Two spiral arm stubs visible, southern one being slightly brighter. Some dark markings near on the NW side of the galaxy but too difficult to sketch properly. With a bit of a stretch the galaxy is 5′ x 2′ in size”.    Jaakko Saloranta – Observer from Finland 

M98 Pencil sketch using a 4.5-inch reflector:   JS 

M98_LVAS

 

 

M98 –  Date of Observation:  4/12/2015 

I first viewed this galaxy on April 2, 1978, using a 3-inch f/10 reflector at 30X. I wrote in my logbook “Very faint, but looms large with averted vision.” On both occasions, M98 was located with the help of an Astro Card.  Glenn Chaple – Observer from Massachusetts 

Pencil sketch with colors inverted.  GC 

Glenns M-098

 

I observed M98 in dark but hazy skies on Cape Cod with a 10-inch reflector at 87x.  It was easily found with a Telrad offset from 6 Com.  It appeared as an oval patch elongated with approximately 1:4 ratio.  The galaxy appeared uniform without internal details.

Joseph Rothchild –  Observer from Massachusetts

 

Time: 5/20/2017 10:30pm EDT; Location: ATMoB Clubhouse
Bortle Scale: 6; NELM: 5; Transparency: Good; Seeing: Average
Telescope: 10-inch f/5 Reflector 

I managed to locate M98 after several minutes of star hopping from Denebola in Leo. This is the first Deep Sky Object that I’ve attempted on my own in a non-goto telescope. It was quite a challenging learning experience. The galaxy did not jump out at me after initially finding the surrounding star pattern, so I doubted myself for a while until I finally spotted it.

I found that my 25mm eyepiece presented the best view at 51x, with a 1.38º FOV.   Using direct vision the core of M98 showed up as a faint glow. Viewing with averted vision, I was able to see a thin elliptical patch aligned with of a chain of three stars to its SE and two stars to its NW.

A bright magnitude 5 star, 6 Comae Berenices, lies 1/2º due east of the galaxy. Chris Elledge – Observer from Massachusetts 

 

M98

Site: Cherry Springs State Park, Coudersport, PA
May 15, 2017
NELM: 6
Seeing: Excellent
Transparency: Excellent

I observed M98 with a Celestron 8SE SCT, and a Meade zoom EP set to 21 mm, for a magnification of 97x.  

This is a delicate and wispy fried egg of a galaxy; at the time I noted, “reminds one of M108; more pronounced west; upward curve East.”

Craig Sandler – Observer from Lexington, Massachusetts 

M98 Galaxy in Coma Berenices 

May 1967 using a 6-inch reflector @ 59x was large, elongated, located 1/2º east of the 5th mag. star, 6 Coma.  

1991 – using a 3-inch reflector @ 39x:  Large, elongated and diffuse.

1992 – With poor transparency ~ 4.0 NELM using a 60 mm refractor @ 21x could not see.
 
1993 – Using 12 x 50 binoculars could not see, however, galaxies M99 and M100 could be glimpsed.  
 
Gus Johnson – Observer from A Delaware  

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