[sac-forum] Re: Call for Observations
- From: "Richard Harshaw" <rharshaw2@xxxxxxx>
- To: <sac-forum@xxxxxxxxxxxxx>
- Date: Sat, 25 Jul 2009 11:01:53 -0700
Enjoy!
Richard Harshaw
Cave Creek, AZ
President, The Saguaro Astronomy Club (2009)
From: sac-forum-bounce@xxxxxxxxxxxxx [mailto:sac-forum-bounce@xxxxxxxxxxxxx]
On Behalf Of AJ Crayon
Sent: Saturday, July 25, 2009 8:51 AM
To: SAC Forum
Subject: [sac-forum] Call for Observations
Here's an update on where we are for observations. Let's stay with the
current set as published in the last newsletter. We will be a bit behind
but that shouldn't make a difference. If you get a chance to observe, do so
(need I say more?). So far I have observations from Rick Rotramel and Dan
Gruber.
Finally, for your reading and observing enjoyment, is the content of last
newsletter. Note the prior observations have a strike through.
So, with the above introduction here are the next two month?s worth of
observations. For June we begin with the E1 M105 in Leo then E7 NGC3384 aka
NGC3371 in Leo both in same field of view but ignore NGC3373. For spirals
start with the Sa NGC4429 in Virgo then the Sb NGC2985 in Ursa Major and
finally the Sc M99 in Coma Berenices. For July begin with the E1 M84 and E3
M86 both in Leo and in same field of view next is E4 M49 in Virgo. For the
barred spirals begin with the SBa NGC3227 in Leo then SBb M95 in VirgoLeo
and SBc NGC4535 in Virgo. Now which do you prefer, elliptical, spiral or
barred spiral galaxies? Personally I prefer spiral or barred spirals.
There are a plethora of others, which also includes irregulars and dwarf
along with the many subdivisions. For more study see
<http://en.wikipedia.org/wiki/Galaxy_morphological_classification>
http://en.wikipedia.org/wiki/Galaxy_morphological_classification that covers
lots more. See also Luginbuhl and Skiff, Observing Handbook and Catalog of
Deep-Sky Objects; Kepple and Sanner, The Night Sky Observer's Guide and
Steinicke and Jakeil Galaxies and How to Observe Them.
There seems to be more time for another pass at Ophiuchus. This time we
will concentrate on globular clusters of varying magnitudes and
concentrations. Starting out one of the brighter ones is NGC6235, you
should be able to resolve some of the 14th to 16th mag stars ? count them!
Take extra care in locating the next 3 because there are 3 others within 5°.
First of the 3 is NGC6293 and is a little brighter than the first one but
about twice as big. Moving on to NGC6304, towards the southeast, check to
see if the brighter middle is noticeable. To the northeast is NGC6355 with
its gradually brighter middle. These 3 form an equilateral triangle about
3° on a side and are part of the Herschel 400 list. Moving on to a
challenge is IC 1257 a small, faint globular cluster. It was identified as
a distant globular cluster in 1996. Perhaps even more of a challenge is HP
1, which I also will call small and faint. As an aid to finding the
globular its location is 17 31.1 -29 59. The HP is for Haute Provence, a
French Observatory. The final globular is located almost between beta and
gamma Ophiuchi. It is NGC6426, another Herschel 400 entry. Can you detect
the elongation described in the NGC description?
AJ Crayon
Phoenix, AZ
Call for Observations
August, 2009
Richard Harshaw
Unless otherwise noted, all observations made from a suburban site.
"Hubble Tuning Fork"
M84
---
8-inch SCT at 104x. Bright and round, but without details. The axis runs
SE-NW.
M86 is 20 min SE and is the brighter of the two.
14x70 Binos. Small and moderately bright.
M84 was been discovered and cataloged by Charles Messier on March 18, 1781 when
he also cataloged 7 more nebulous objects in the same celestial region, all of
them member galaxies of the Virgo Cluster.
From its appearance, it was classified as an E1 elliptical, which is also in
accordance that it is only populated by old yellowish stars. However, there is
now some evidence that this may actually be a face-on lenticular galaxy.
As a peculiar (but perhaps no way unique) feature, M84 contains a central
machine which ejects two small but conspicuous jets, which can be seen in the
radio light. This object was also the target of a 1997 investigation of M84 by
the Hubble Space Telescope, shortly after its second service mission (STS-82);
it was found that the nucleus of M84 contains a massive central object of 300
million solar masses, concentrated in less than 26 light years from the
galaxy's center.
[http://www.seds.org/messier/m/m084.html, Mar. 23, 2006]
M86
---
8-inch SCT at 104x. It looks large and bright, with fuzzy edges. It runs
SE-NW.
14x70 Binos. Very difficult.
M86 wasdiscovered and cataloged by Charles Messier on March 18, 1781 when he
also cataloged 7 more nebulous objects in the same region of the sky, all
member galaxies of the Virgo Cluster.
This bright giant galaxy is either an elliptical of type E3 or a lenticular
galaxy of type S0_1(3); modern classifications apparently tend more to the
lenticular classification. It has a conspicuous system of faint globular
clusters. However, this system of globulars is far less populated than that of
its giant neighbor to the SE, M87.
M86 is the galaxy which has the fastest approaching velocity, and thus the
highest blue shift, of all Messier galaxies (and thus all Messier objects): It
is approaching us! Holmberg (1964) has therefore speculated that it should be a
close foreground galaxy and not a Virgo cluster member. This speculation has
been referred to, and occasionally been adopted, by several sources, including
George R. Kepple's and Glen W. Sanner's Observer's Guide.
But the Virgo cluster membership of M86 is also suggested by its more or less
obvious interaction with the intergalactic gaseous matter in the Virgo cluster,
which was reported from X-ray observations, discovered by Forman et.al. (1979).
Moreover, M86 does not hold the record: Another Virgo cluster member, IC 3258,
approaches us at 517 km/sec.
Additional evidence for M86's Virgo Cluster membership may be derived from deep
images of this galaxy which show slight disturbing of its faint outskirts,
probably caused by gravitational interaction with its neighbors.
The outskirts of M84 and M86 seem to overlap; the angular distance between
their centers of about 16.5 arc min corresponds to a projected distance of only
roughly 300,000 light years. This, however, is probably a perspective effect,
as otherwise their outliers would be even much more distorted; there is
probably some radial distance, or distance difference from us, between these
two galaxies; it is not known which one is a bit closer to, and which a bit
farther away from us.
On M86's fast motion through the intergalactic medium of the Virgo Cluster (the
"Intra-Cluster Matter", ICM), the galaxy's interstellar matter collides at high
velocity with this material, and is probably "ram-pressure stripped" from the
galaxy (Rangarajan et.al. 1995). On this occasion, the matter is heated. Dust
within this matter, previously held within colder gas clouds, is probably
destroyed when the matter heats during the collision. Analysis of the ram
pressure indicates that, in addition to its peculiar radial velocity with
respect to the Virgo Cluster, M86 may have a tangential velocity component of
about 500 km/sec in southward direction.
[http://www.seds.org/messier/m/m086.html, Mar. 23, 2006]
M49
---
8-inch SCT at 37x. It resembles an oblate globular cluster, with a bright
center. It is even and shows no details at any magnification. The axis runs
SE-NW. A 12 mag star lies 2 min W of the center.
14x70 Binos. Small but moderately bright.
It was discovered by Messier on February 19, 1771.
It is 50,000 light years in diameter and is one of the most massive ellipticals
known (at 5 times the Milky Way's mass). It contains very few blue giants.
Virgo Cluster member.
Elliptical galaxy M49 was the first member of the Virgo cluster of galaxies
discovered, by Charles Messier who cataloged it on February 19, 1771. It is
also the second galaxy discovered beyond the Local Group after Lacaille's
discovery of M83.
M49 is one of the brightest Virgo Cluster member galaxies with its mag 8.5,
which corresponds to an absolute magnitude of approximately 22.8, regarding its
distance of about 65 million light years. It is one of the giant elliptical
galaxies in this great cluster (besides M60 and M87), and is of type E4 in
Hubble's classification scheme. Its extension of 9 x 7.5 arc minutes
corresponds to an ellipsoid with a projected major axis of nearly 160,000 light
years (we don't know the real extension along the line of sight toward us, of
course, as we don't know the spatial orientation of the real ellipsoid axes),
so it is actually a big ellipsoid. Older estimates have suggested a mass which
might be bigger than that of the nearby giant M87, but now it is assumed that
M87 is much denser. With its integrated spectral class G7 and color index
+0.76, it is yellower than most galaxies in the Virgo cluster. Longer exposures
show a system of globular clusters, which however is much less crowded than
that of M87 and more comparable to that of M60. According to W.E. Harris' list,
this galaxy has a system of 6300 +/- 1900 globulars. Halton Arp has included
M49 as No. 134 in his Catalogue of Peculiar Galaxies as an "Elliptical with
Nearby Fragments".
[http://www.seds.org/messier/m/m049.html, Mar. 23, 2006]
NGC 3227
--------
8-inch SCT at 83x. Oblong (NW-SE) with a bright center. NGC 3226 lies just N.
This galaxy is a Seyfert, and is known to emit X-rays and radio waves. It is
interacting with NGC 3226, a dwarf elliptical.
M95
---
8-inch SCT at 83x. Very bright nucleus, it is mottled at high power. The axis
runs NNE-SSW.
M96 is also in the field (it lies E).
14x70 Binos. Very, very faint and small splash. Extremely difficult.
Long exposures show a Theta shape.
The galaxy belongs to M96 Subgroup of the Leo I Cloud. The Leo I Cloud
includes the M65-M66 Subgroup. The M96 Subgroup's brightest members are M95,
M96, M105, NGC 3377 and NGC 3384. It is a compact group.
Pierre Méchain discovered M95, together with M96, March 20, 1781. Consequently,
Charles Messier included it in his catalog on March 24, 1781.
M95 is a barred spiral of type SBb, or SB(r)ab according to de Vaucouleurs'
classification, with nearly circular arms. Alan Sandage, in the Hubble Atlas of
Galaxies, calls it a "typical ringed galaxy". Its overall appearance is quite
similar to M91 except that M95 has more pronounced spiral structure.
Barred spiral galaxy M95 was one of the galaxies in the key project of the
Hubble Space Telescope for the determination of the Hubble constant: the HST
was employed to look for Cepheid variables and thereby determine this galaxy's
distance. A preliminary result has been obtained and published in 1996-97 by
the HST H0 Key Project Team (paper VII, 1997). Their result, corrected for the
semi-recent adjustment of the Cepheid brightness zero point by ESA's Hipparcos
astronometric satellite, is a distance of 35.5+-3.1 million light years. This
is in semi-good agreement with the value of about 41 million light years (after
correction for Hipparcos results) which had been obtained earlier by Nial R.
Tanvir for its neighbor M96, and implies a distance of all the galaxies in the
Leo I group of about 38 million light years.
[Source: http://www.seds.org/messier/m/m095.html, Mar. 10, 2006]
NGC 4535
--------
8-inch SCT at 65x. Extremely faint, with a N-S axis. The nucleus is faint but
starlike. A 13 mag star lies on the N end.
Virgo Cluster member.
Astronomers studied luminous Cepheid variables in this galaxy and estimate its
distance to be 52 +/- 3 million light years away.
Very sharp, very small, extremely bright nucleus or star.
"Which do you prefer, elliptical, spiral or barred spiral galaxies?"
Ellipticals are easier to see, especially at immense distances, but like
globulars, they tend to start looking like each other! Spirals show much more
personality and detail, so I lean towards spirals. Barred spirals are also
enjoyable, but most of them are too distant for their bars to show well in
small telescopes.
OPHIUCHUS
=========
NGC 6235
--------
8-inch SCT at 83x. Faint and grainy. It takes high power well, though, and
is bracketed by two faint stars.
11-inch SCT1 at 98x. Small, grainy object in a very rich field. It is
centered in a faint triangle of 11 mag stars. It appears to be brighter on the
W side. Class 5.
William Herschel found it in 1986.
Some astronomers think this may really be a large and dense open cluster.
The brightest stars are 14.0 mag and the horizontal branch is 16.7 mag.
Interstellar absorption here runs about 1.1 mag.
NGC 6293
--------
8-inch SCT at 104x. Unresolved, but brighter towards the core. It has an E-W
axis. There is a blue star near the E edge.
The stem of B59, the Pipe Nebula, lies just S.
There is a neat tiny triangle of stars just off the SE edge.
William Herschel found it on May 24, 1784.
The brightest stars are 14.3 mag and the horizontal branch is 16.5 mag.
Absorption amounts to 1.3 mag here.
NGC 6304
--------
8-inch SCT at 104x. Faint, unresolved and round. Use high power. It is
surrounded by brighter stars.
William Herschel found this cluster on August 30,1786.
The brightest stars are 14.2 mag and the horizontal branch is 16.2 mag.
Absorption here runs a hefty 3.9 mag.
NGC 6355
--------
8-inch SCT at 83x. Indistinct and compact, near two fairly bright stars (9
mag, 10 mag).
William Herschel found this cluster on May 24, 1784.
The horizontal branch is 17.2 mag.
IC 1257
-------
8-inch SCT at 83x. That's it?
It was first reported by Spitaler in 1890 (who found it with a 27" scope in
Vienna). Shapley listed it as an open cluster in his 1930 monograph, but
Collinder did not include it in his 1931 monograph (Trumpler did not list it
either). Hogg listed it as an open cluster in 1958, as did Lynga in 1987.
Cederblad listed it as a nebula (!) in 1946. But the CMD shows it is
definitely a globular.
The brightest stars are about 19 mag. It is 23 light years in diameter. It
lies 58,400 light years from the galaxy's center and behind a rather heavy (but
uniform) sheet of foreground reddening.
HP 1
----
11-inch SCT1 at The Antennas Site, 233x.
Very small and faint, it birghtens quickly to a stellar center (or a star is
superimposed). Several dim stars encirlce it. Glittery background.
NGC 6426
--------
8-inch SCT at 104x. Faint and round; high power helps a little.
11-inch SCT1 at 193x. Very small ball, not resolved; rather uniform in
appearance.
The horizontal branch is 18.0 magnitude.
It is reddened 1.7 magnitudes..
Discovered by William Herschel on June 3, 1786.
Other related posts:
