View Single Post
Old 04-12-2018, 09:44 AM
ngcles's Avatar
The Observologist

ngcles is offline
Join Date: Dec 2006
Location: Billimari, NSW Central West
Posts: 1,620
A couple of odd spiral galaxies -- NGC 908 & NGC 922.

Hi All,

I have recently been going through my log, reviewing observations I made some time ago with smaller telescopes and editing them up from highly encrypted notes to sensible prose. During that process (that will probably take a year) time I have made a little list of earmarked objects to go back and re-observe with the larger telescope because I saw something in the previous notes or from the POSS photo that made them stand out and be worthy of a re-visit. I re-visited two of them last night with Brontes -- a more ordinary spiral; NGC 922, and the remarkable, peculiar spiral galaxy NGC 922.

Attached see the image of Adam Block of NGC 908. The original is here:

Here are my notes from last night:

x260 19' TF,

NGC 908 Galaxy *
RA: 02h 23m 05.3s Dec: -21 13' 59"
Mag: 10.8 (B) S.B.: 13.1 B-V: +0.65Size: 6.0'x2.6' Class: SA(s)c
P.A.: 75 Inclination: --- R.V.: +1701 Source: RC3 *

x260: This is a large and bright, low-ish S.B quite elongated spiral galaxy in about PA 75. Above it to the N by 4' is a small key-stone type asterism of magnitude 12 & 13 stars. Large oval halo 4.5' x 2' .
The oval end at the WSW end of the galaxy has generally slightly lower S.B than the ENE end . It seems weakly blotchy or curdled over most of the halo and the W end generally has a less distinct edge to it. Overall, it grows weakly in brightness to centre. The E oval end exhibits a curved, weak enhancement just inside the edge of the visible halo that follows the curve around the E extremity. This curved enhancement is just above -- to the N, of a magnitude 14.5 star just inside the halo, slightly S of the major axis. There is a very small, weakly brighter core zone that is only 10-20" diameter containing a faint stellar nucleus.

Then there was the rather odd spiral NGC 922. The attached image is by Hubble NASA/ESA. It shows a mangled asymmetric star-bursting spiral galaxy that is partly ring-form in nature. The real odditiy is that peculiarities like this are usually the result of recent, strong interaction with another galaxy -- but there's nothing apparent nearby to do that -- it seemingly sits alone in space. Here are my notes:

NGC 922 Galaxy *
RA: 02h 25m 04.3s Dec: -24 47' 24"
Mag: 12.5 (B) S.B.: --- B-V: +0.33 Size: 2.0'x1.7' Class: SB(s)cd pec
P.A.: 13Inclination: --- R.V.: +3069 Source: RC3 *

x260: This is a somewhat unusual looking galaxy, found 2' S of a magnitude 13 star. No other stars immediately associated. The outline overall is round, probably about about 1.5-1.75' diameter. The small, faint, spot-type core is offset within the halo by about 10% toward the SE and seems to contain an occasional stellar flash. As to the outer halo. the boundary of the halo from about NE to S is quite hard-edged and drops suddenly to background compared to the NW to SW quadrant that fades much more gently to background. The W side of the halo generally has lower SB than the E -- A bit like a round galaxy with a bite taken out of the W side
Occasionally, you get the impression there is a weakly brighter "bar" within the halo that runs from about geometric centre, through the offset core/nucleus and out into the brighter rim in about PA 90.


Attached Thumbnails
Click for full-size image (n908mishler.jpg)
106.6 KB29 views
Click for full-size image (800px-Hubble_view_of_NGC_922.jpg)
133.8 KB31 views
Reply With Quote