FreeLists / az-observing / [AZ-Observing] NGC 7530 Galaxy Group and Hickson 93

[BillFerris@xxxxxxx]

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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