by Ron Bhanukitsiri
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 last 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 ;-).
Have anyone seen the mottling inside the Whale? If so, which aperture (and what's the LM) could you see it with?