[AZ-Observing] NGC 7530 Galaxy Group and Hickson 93
- From: BillFerris@xxxxxxx
- To: az-observing@xxxxxxxxxxxxx
- Date: Tue, 1 Nov 2005 00:06:11 EST
Saturday night, I headed out to Anderson Mesa for some dark sky time.
Despite the heavy dew and fog, I was treated to some fine views of the NGC 7530
galaxy group and Hickson 93. The night was capped with a view of Mars in pretty
good seeing.
NGC 7530: _http://members.aol.com/billferris/n7530.html_
(http://members.aol.com/billferris/n7530.html)
Usually, my observing sessions are structured around a specific program;
Hickson galaxy clusters, Abell planetaries and the like. But sometimes I'll
pick
a patch of sky, open "Uranometria" to the corresponding chart and scan for
anything that catches my eye. This more spontaneous approach led me to track
down a trio of galaxies pictured in southern Pisces.
NGC 7530, NGC 7532 and NGC 7534 are nestled among a slew of galaxies in this
corner of the celestial tapestry. The brightest nearby star is 7.1 magnitude
HD 219200, which shines near the northern edge of the field in my sketch,
which presents a 199X view in my 18-inch Obsession. (See above link.) NGC 7532
is centered. This peculiar-type galaxy has a blue magnitude of about 14.3,
which suggests a visual magnitude of 13.5 or thereabouts. Its 40" diameter
form
is punctuated by a stellar core region. A 10.7 magnitude star simmers 2' to
the south. Twice that distance to the southwest, the delicate foggy glow of
NGC 7530 emerges from the night. This transitional galaxy is similar in size
to
NGC 7532 but obviously fainter. Photometric data available from NED
indicates a blue magnitude of about 14.8. Looking 2' northeast from NGC 7532,
the
delicate circular form of NGC 7534 can be seen. This 14.7(B) magnitude
irregular
galaxy competes with the soft glow of a nearby 14th magnitude GSC star. The
star lies 28" to the south of NGC 7534.
This trio of stellar citadels resides about 175 million light-years from
Earth. Of course, every one of the 19 stars peppering my drawing reside within
the Milky Way.
Hickson 93: _http://members.aol.com/billferris/hickson93.html_
(http://members.aol.com/billferris/hickson93.html)
Five galaxies are gathered in my sketch, which presents a 199X view in my
18-inch Obsession. All five are members of Hickson 93. The largest and
brightest of the quintet is NGC 7550; Hickson 93A. Its 1' diameter form shines
with a
blue magnitude of 13.2, suggesting a mid-12th magnitude intensity at the
peak of visual sensitivity. It's a transitional-type galaxy stationed some 250
million light-years from Earth, which is the same estimated distance to all
but one member of this grouping. A 12th magnitude GSC star shines about 3' to
the south.
NGC 7549 (Hickson 93B) is the somewhat irregular haze visible 5' north of
NGC 7550. This barred spiral displays a pair of long, distended arms in CCD
images. But just the bright inner portion is seen in my 18-inch, this night.
The
barred core covers 60" by 45" area and is arranged roughly northwest to
southeast. A 10th magnitude star simmers 1'.3 to the west. Three arcminutes
west
of NGC 7550 is where the elongated haze known as NGC 7547 (Hickson 93C)
resides. This 14.7(B) magnitude edge-on spiral covers a petite 45" by 30"
patch of
sky along an east-west axis.
Looking 6' to the east-southeast of NGC 7550, the delicate glow of NGC 7558
(Hickson 93E) is teased from the sky. Best seen with averted vision, this 30"
diameter elliptical galaxy has a blue magnitude of nearly 16. This suggests a
visual brightness in the low-15th magnitude range. The radial velocity and
redshift data suggest a distance of more than 440 million light-years for NGC
7558. I wonder what the smallest aperture needed to see this FLS (faint
little stinker) is?
Finally, about 6'.5 northeast of NGC 7550, a tiny 20" diameter smudge of
light emerges. This is PGC 70842 (Hickson 93D) and presumptively NGC 7553,
although that NGC identification is uncertain. This galaxy is just as
challenging
as nearby NGC 7558.
Mars: _http://members.aol.com/billferris/mars102905.html_
(http://members.aol.com/billferris/mars102905.html)
For this, my first extended observation of Mars during the 2005 opposition,
I am treated to a spectacular view of Syrtis Major. The dark continent of
Mars has recently transited the central meridian. Sinus Sabaeus trails as an
outstretched arm toward the following limb. However, Sinus Meridiani is
obscurred by a dust storm. Mare Tyrrhenum extends as a second arm toward the
preceding limb of the red planet. Deltoton Sinus is seen as a thumb jutting
into
Aeria following Syrtis Major.
Hellas is free of clouds. Its oval form is ringed to the south by darker
bands and to the north by Syrtis Major. Mare Hadriaticum, Hellespontus and Mare
Serpentis hold this gigantic impact basin like slender fingers grasping a
bowl. There is the occasional glimpse of a ring-like albedo feature along the
north limb. A check of Leandro Ríos' excellent "Mars Previewer II" application
indicates this may have been Utopia and nearby Protonilus. The entire
following limb is edged in a haze. The south preceding limb also glows white.
Elysium, north of and preceding Hellas, seems brighter when viewed through the
80A
light blue filter. This wasn't the best view of Mars I've ever had but was a
great way to start the 2005 opposition with my one-year old Obsession.
Dark skies rule!
Bill in Flagstaff
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