[sac-forum] Re: Call for Observations
- From: <saguaroastro@xxxxxxx>
- To: sac-forum@xxxxxxxxxxxxx
- Date: Thu, 23 Oct 2008 14:04:35 -0700
AJ,
Very interesting Change of pace. Looks like I'
ll be able to get out this weekend to the antennas and the wx prospects look
good as well. this will certainly shorten the planning time.
Rick
---- AJ Crayon <acrayon@xxxxxxx> wrote:
> Here are 3 months worth of the observations lists. There is still time for
> Lacerta so if you have some spare observing time why not give this a try.
> The December list has already appeared in the newsletter but the new one is
> for January 2009 and covers the Trumpler Class of classifying open clusters.
>
> I'll not be observing this weekend but don't let that stop you. Get out and
> give these objects a try regardless of your telescope size and then, of
> course, send me the observations for inclusion into the newsletter.
>
> So far we haven't done anything in the constellation of Lacerta.
> Surprisingly it contains open clusters and galaxies, which is what waits us
> for this session. Starting from the western part, near Cygnus, is NGC7209, a
> bright open cluster that is in both the 110 Best NGC and Herschel 400 lists.
> It has about 25 stars from 9th mag. Do you see it as scattered or
> compressed? About 5° south is the barred spiral NGC7223. What about the bar
> and spiral arms? Can you see them? Moving towards the northern part of the
> constellation is the open cluster IC1422 and its 25 or so stars. The second
> galaxy, NGC7265, is same magnitude as NGC7223 but is larger and has a lower
> surface brightness. NGC7296 is on the Herschel 400 list is small and has 20
> stars, so it may not be that easy to find. The last selection is the
> elliptical galaxy NGC7426. Beware it is just to the east of SAO72851, a
> double star, whose primary is mag 5.7.
>
>
> Our constellation, for December, is Piscis Austrinus meaning Southern Fish.
> There are numerous galaxies in this constellation that should be within reach
> of 8" telescopes. So, let us hope the weather favors us for this unexpected
> trip below the celestial equator. Starting from the western end is the
> asterism titled Air Balloon and found at R.A. 21h 30.0m Dec -25° 30'. It is
> about 45' in diameter, contains a nice collection of 7th and 8th mag stars
> and is described as a closed loop of stars. What does it look like to you?
> Now on to the galaxies and we start with NGC7135 that is mag 11.7, less than
> 3' and just southeast of 3 stars with mag 9.5, 10.3 and 11 that form a nice
> right triangle. Now we move on to a galaxy group containing 4 or 5 galaxies.
> The first is the spiral NGC7172, almost 12th mag, elongated and sporting an
> equatorial dust band. Can you spot it? The other galaxies are located just
> 7' due south and consist of NGC7173/74/76. They are located between 2 stars
> of 9th and 10th mag in a north of northeast position. NGC7173 is the
> northern most, is 12th mag and somewhat elongated in a southeast position.
> NGC7174 is a little larger, somewhat elongated in an easterly position and at
> mag 13.3 is the faintest of the group. The last is NGC7176 only very
> slightly elongated with an uncertain position angle. Also involved in this
> triple grouping is the mag 11.9 galaxy LEDA198475 located between NGC7173 and
> NGC7174. This grouping of galaxies is also known as Hickson 90. Moving on
> to the others, we continue with 11th mag NGC7314. This galaxy is quite
> elongated, not doubt because we are seeing the bar of this barred galaxy.
> Now mosey on to the spindle shaped IC5269, a rather small, elongated galaxy
> of mag 12.2. Next is the nearly edge-on NGC7361 at mag 12.3. Can you
> detect a little brighter middle? Last we have the very elongated IC5271 at
> mag 11.6. What do you see in the middle?
>
>
>
> For January we will do something a little different, like do a study of
> Trumpler classification for open clusters. Briefly there are 3 codes used to
> describe a cluster. They are concentration, magnitude range and richness.
> The first, concentration, indicates how the cluster stands out from the Milky
> Way background and used 4 Roman Numerals. Their descriptions are
>
> I Detached, strong concentration towards the center,
>
> II Detached, weak concentration towards the center,
>
> III Detached, no concentration towards the center,
>
> IV Not well detached from surrounding star field.
>
> There are 3 number for magnitude range; 1 for small or ±2 magnitudes, to 3
> for wide range. One of 3 letters are used for richness they are p for poor,
> under 50 stars; m for medium with 50 to 100 stars and r for rich having over
> 100 stars. For this session we will have all concentration classes as they
> seem to be the description causing the most difficulty. To this end we will
> not stay in one constellation as in the past, but will meander around fall
> constellations. If you are interested in learning more about this
> classification methodology see Touring the Trumpler Classes by Richard
> Harshaw, which can be found on the SAC web site. To better understand the
> classification pan around the cluster to see how the detached description
> relates to each. While at it note the magnitude range and count, or
> estimate, the number of stars. Now on to the clusters, in descending
> concentration order. M 37 in Auriga is I 2r. IC 361 in Camelopardalis is II
> 1 r. NGC1512 in Perseus is II 1 m. NGC7789 in Cassiopeia is II 2 r. Back
> into Perseus for III 1 r is NGC1245. Finally, again in Cassiopeia is NGC 225
> an III 1 p cluster. Now, having done this study, perhaps we should consider
> doing during the summer. Let me know your thoughts and preferences.
>
> worth
>
> AJ Crayon
> Phoenix, AZ
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