[Prev][Next][Index][Thread][Search][Objects]
(IAAC) Obj: NGC 4631, NGC 4656 - Inst: TV-102 (102mm f/8.6 APO refractor)
----
Observation Poster: Ron B[ee] <ronby@cox.net>
Observer: Ron B[ee]
Your skills: Intermediate (some years)
Date/time of observation: 03/12/02 12:00am PST
Location of site: 117h 9m W (Lat 32h 43m N, Elev 2000 ft.)
Site classification: Exurban
Sky darkness: 5.0 <Limiting magnitude>
Seeing: 5 <1-10 Seeing Scale (10 best)>
Moon presence: None - moon not in sky
Instrument: TV-102 (102mm f/8.6 APO refractor)
Magnification: 22x, 44x, 73x, 110x
Filter(s):
Object(s): NGC 4631, NGC 4656
Category: External galaxy.
Class:
Constellation: CVn
Data: mag 9.6, 10.6 size 15.5' x 2.7', 15.0' x 2.9'
Position: RA : DEC :
Description:
Having unchained the Markarian chain of small tiny galaxies, the
TV-102 Light Cup entered the "Land of the Giants" (giant galaxies
I mean) on Sunday night under unsteady, twinkling stars, some breeze,
some LP from west, lots of LP from south and scattered high clouds
earlier.
After giving a good hoppidy chase, the Light Cup easily harpooned
The Whale Galaxy with the 40mm Pentax XL (22x), a bright big galactic
"mammal". Its designation is mag 9.6 NGC 4631 edged on galaxy. Its
unidentical twin brother, mag 10.6 NGC 4656, was submerged and
couldn't be seen however. When NGC 4656 surfaced at 44x, the 20mm
TV Plossl "harpoon" nailed it too and is a lot dimmer than NGC 4631,
which is bright with this EP. The Whale forms a slightly bending
line with the following 5 stars: GSC 2531:2068, a dim mag 12.1 GSC
2531:1739, GSC 2531:1669, GSC 2531:1915, and GSC 2531:979. (Also a
mag 12.8 star GSC 2531:260 was noted.) Do you know why it's called
the "Whale Galaxy"? Well, staring at NGC 4631 and its surroundings
under quality time gave me an impression that a very long bulging
whale was swimming in the ocean of space followed by a group of tiny
star fishes. Or perhaps, it is the whale swimming and secreting its
stool ;-) of these 5 stars, given its tilt angle. Which view do you
see (guess which is my favorite rationale for the name ;-)?
NGC 4656 is brighter at 73x (12mm TV Radian) than at 44x and is still
in the same FOV as NGC 4631. It's brighter in the central region
than the outer edge, no core seen. The Whale now takes up 1/3 of
FOV, no core seen. Two star inside the galaxy can now be viewed, one
near the edge of the galaxy and one lodged inside, both close to the
central portion. NGC 4656 turned into an extremely dim elongated
smudge at 110x (8mm Radian) while NGC 4631 is only slightly dimmer.
The two stars in the galaxy are much easier to see now but one star
noticeably outside but touching an off-ntered portion of the galaxy.
These two stars were confirmed by this beautiful picture on SEDS (see
link below). Immediately, I got a mental image of Jonah lighting
up a torche inside the belly of the whale ;-).
The "arm" toward the group of mentioned 5 stars is noticeably dimmer
than the arm on the opposite side. Here's beautiful sketch (through
a 10-in Newt) I found on the web that *amazingly* looks very much
like what I saw at 73x.
http://www.jwebdale.btinternet.co.uk/ngc4656.htm
http://www.seds.org/messier/xtra/ngc/n4631.html
By looking at the photo (to confirm the two stars), I just learned
that both sketch and photo can help to look for other details. So
the next night under a mag 5.4 sky with less light pollution, I tried to
see if the Light Cup could detect mottling. Alas, they were no where
to be seen. But I did get a strong "impression" that perhaps under a
real dark sky, it may be poosible. So "Moby Dick" got a away this
time and Captain "Light Cup" is now obsessed with a rematch under a
more favorable condition ;-).
--
Optional related URLs:
** This observing log automatically submitted via the Web from:
http://www.visualdeepsky.org/enter-log.html
To stop receiving all 'netastrocatalog' lists, use the Web forms at:
http://www.visualdeepsky.org/subscribe.html