Opus Observes: If I Haven't Seen It, It's New to Me

10:45 p.m. Tuesday 24 March 2009 PDT (2009-03-25-0545 UT)

I've been meaning to get out for a couple of nights, but this one was
the first one where it wasn't too windy out and my allergies weren't
acting up. By the time I got set up, M42 was already only a degree or
so from setting over the roofline of our house (the backyard patio where
I set up is east of the house), but I still decided to point it that way
to have a look. As I expected, there was too much turbulence from the
latent heat over the roof to have a chance at resolving E or F, but the
Orion Nebula is always worth a good look. Even with the turbulence the
nebula itself is still full of interesting detail at 50x.

From there it was over to M51, the Whirlpool Nebula, the first galaxy to
show a spiral nature (observed by Rosse in the late 1840s). This was
the first time I'd ever tried to observe the Whirlpool this early in the
year; normally, by the time I give this a try, it's either overhead or
beginning to set in the northwest. This time it was still medium high
in the east. I had an unusual amount of trouble finding it, which might
have had something to do with it being suspended in the light dome over
L.A. Normally, I'm able to find the right spot in the finder, but this
time, I had to star-hop from 24 Canum Venaticorum in the eyepiece. Even
at 50x this was something of a chore, though not an entirely unenjoyable
one. Even when I had it definitely in the field of view, it was not an
easy detection. There was no question of finding its partner (NGC 3195)
in the mix. So perhaps the light pollution did have something to do
with it.

After that came my first new target of the night, NGC 3242, the
so-called Ghost of Jupiter. Except that I didn't think it was new; I
was sure that I had seen it before. But a quick text search of my
observation logs doesn't show a reference to either NGC 3242 or the
Ghost. Again, this was a bit tricky to find in the light-polluted sky.
I'd estimate the limiting magnitude to be maybe as much as a
half-magnitude lower than in previous sessions, and Alphard (alpha
Hydrae) was the only star easily visible to the unaided eye in that
general area. I used that as a starting point and was able to star-hop
in the finder most of the way. Once there, though, it was easy to see.
At 50x, it took a second or two for me to cotton on to its non-stellar
nature. I switched the 24 mm Panoptic out for a 6 mm Radian with a
narrowband filter. The seeing was not tremendously good (perhaps a
couple of arcseconds of blur), but the Ghost is a bit fuzzy to begin
with, so perhaps it didn't matter so much. It was clearly elongated
somewhat along a northwest-to-southeast axis, with three or four knots
of light arranged along this major axis, bent slightly to the southern
edge, almost as if we were seeing an equatorial string of lights along
this Ghostly Jupiter, seen from high above a temperate latitude.

After that, I didn't expect much from Saturn, given the seeing, and so I
managed not to be too disappointed. No real cloud structure could be
seen, aside from some subtle banding. The rings are almost edge-on now,
of course, except that their inner edge, first in the crepe ring and
then in the empty space inside that, could be seen as a dimming in the
overall profile of the rings. I observed Saturn at 130x, the 6 mm
Radian with the f/6.3 focal reducer. I figured that would help with any
troubles I was having navigating the light-polluted skies.

My real reason for going to Saturn was as a setting-off point for my
last target (and second new one) of the night: a double star just over
the constellational boundary, 40 Sextantis. I tried first at 32x (the
24 mm Panoptic), and then at 130x, but I could not split it either way.
So I tried something I've done in the past, which is to slip in the
8-24 mm Vixen zoom, because sometimes details can only be seen within a
relatively narrow band of magnification. I started at 16 mm and worked
my way down toward 8 mm. Only as I got down toward the 8 mm to 10 mm
range (about 100-130x) did the split become relatively straightforward
to discern, although whether it was because of that particular power or
a momentary improvement in seeing wasn't clear. At any rate, I
estimated the position angle at 20 degrees (the actual figure according
to Ridpath and Tirion is 13 degrees). The separation is supposed to be
2.3 arcseconds but it seemed tighter than that to me.

--
Brian Tung
The Astronomy Corner moved to http://www.astronomycorner.net/
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On Mar 25, 11:22*pm, (Brian Tung) wrote:
10:45 p.m. Tuesday 24 March 2009 PDT (2009-03-25-0545 UT)

I've been meaning to get out for a couple of nights, but this one was
the first one where it wasn't too windy out and my allergies weren't
acting up. *By the time I got set up, M42 was already only a degree or
so from setting over the roofline of our house (the backyard patio where
I set up is east of the house), but I still decided to point it that way
to have a look. *As I expected, there was too much turbulence from the
latent heat over the roof to have a chance at resolving E or F, but the
Orion Nebula is always worth a good look. *Even with the turbulence the
nebula itself is still full of interesting detail at 50x.

From there it was over to M51, the Whirlpool Nebula, the first galaxy to
show a spiral nature (observed by Rosse in the late 1840s). *This was
the first time I'd ever tried to observe the Whirlpool this early in the
year; normally, by the time I give this a try, it's either overhead or
beginning to set in the northwest. *This time it was still medium high
in the east. *I had an unusual amount of trouble finding it, which might
have had something to do with it being suspended in the light dome over
L.A. *Normally, I'm able to find the right spot in the finder, but this
time, I had to star-hop from 24 Canum Venaticorum in the eyepiece. *Even
at 50x this was something of a chore, though not an entirely unenjoyable
one. *Even when I had it definitely in the field of view, it was not an
easy detection. *There was no question of finding its partner (NGC 3195)
in the mix. *So perhaps the light pollution did have something to do
with it.

After that came my first new target of the night, NGC 3242, the
so-called Ghost of Jupiter. *Except that I didn't think it was new; I
was sure that I had seen it before. *But a quick text search of my
observation logs doesn't show a reference to either NGC 3242 or the
Ghost. *Again, this was a bit tricky to find in the light-polluted sky.
I'd estimate the limiting magnitude to be maybe as much as a
half-magnitude lower than in previous sessions, and Alphard (alpha
Hydrae) was the only star easily visible to the unaided eye in that
general area. *I used that as a starting point and was able to star-hop
in the finder most of the way. *Once there, though, it was easy to see.
At 50x, it took a second or two for me to cotton on to its non-stellar
nature. *I switched the 24 mm Panoptic out for a 6 mm Radian with a
narrowband filter. *The seeing was not tremendously good (perhaps a
couple of arcseconds of blur), but the Ghost is a bit fuzzy to begin
with, so perhaps it didn't matter so much. *It was clearly elongated
somewhat along a northwest-to-southeast axis, with three or four knots
of light arranged along this major axis, bent slightly to the southern
edge, almost as if we were seeing an equatorial string of lights along
this Ghostly Jupiter, seen from high above a temperate latitude.

After that, I didn't expect much from Saturn, given the seeing, and so I
managed not to be too disappointed. *No real cloud structure could be
seen, aside from some subtle banding. *The rings are almost edge-on now,
of course, except that their inner edge, first in the crepe ring and
then in the empty space inside that, could be seen as a dimming in the
overall profile of the rings. *I observed Saturn at 130x, the 6 mm
Radian with the f/6.3 focal reducer. *I figured that would help with any
troubles I was having navigating the light-polluted skies.

My real reason for going to Saturn was as a setting-off point for my
last target (and second new one) of the night: a double star just over
the constellational boundary, 40 Sextantis. *I tried first at 32x (the
24 mm Panoptic), and then at 130x, but I could not split it either way.
So I tried something I've done in the past, which is to slip in the
8-24 mm Vixen zoom, because sometimes details can only be seen within a
relatively narrow band of magnification. *I started at 16 mm and worked
my way down toward 8 mm. *Only as I got down toward the 8 mm to 10 mm
range (about 100-130x) did the split become relatively straightforward
to discern, although whether it was because of that particular power or
a momentary improvement in seeing wasn't clear. *At any rate, I
estimated the position angle at 20 degrees (the actual figure according
to Ridpath and Tirion is 13 degrees). *The separation is supposed to be
2.3 arcseconds but it seemed tighter than that to me.

--
Brian Tung
The Astronomy Corner moved tohttp://www.astronomycorner.net/
*Unofficial C5+ *Home Page athttp://www.astronomycorner.net/c5plus/
*The PleiadAtlas Home Page athttp://www.astronomycorner.net/pleiadatlas/
*My Own Personal FAQ (SAA) athttp://www.astronomycorner.net/reference/faq.html

Brian: Nice report... I am guessing that Opus is your C-5?? As far
as 40 Sextans goes, this is the data from Skytools which uses the WDS
catalog and computes orbits if necessary:

AB: 6.61+7.91 mag, STF1476, ADS 7936, B=HIP 52913
PA 16° Sep 2.40" (1997) :

I would say your 20 degrees is pretty darn close. I will have to give
40 Sexans a try tonight.

One of my favorites which is not so far away is Alula Australis in
Ursa Major. It's a bit tighter than 40 Sexans but a quite a bit
brighter:

AB: 4.39+4.9 mag, STF1523, ADS 8119, B=HR 4374
Definitive Orbit: P=59.9 yr, a=2.54"
PA 217° Sep 1.61" (2009.2) (Sky Tools again)

I was giving it a go the other night in my 4 inch F/7 refractor but I
was only getting elongation. It's pretty easy to find, it's the last
star of Ursa Major on the leg that reaches out to Leo, it has a nearby
mag 3.5 star Alula Borealis and mag 3.4 or brighter Chort and Zosma in
Leo point right at it.

Jon

What type/ size of scope is "Opus"?

Thanks,
Seth

"Brian Tung" wrote in message
...
10:45 p.m. Tuesday 24 March 2009 PDT (2009-03-25-0545 UT)

I've been meaning to get out for a couple of nights, but this one was
the first one where it wasn't too windy out and my allergies weren't
acting up..........................

----------------snip---------------------------------.

Brian Tung wrote:
10:45 p.m. Tuesday 24 March 2009 PDT (2009-03-25-0545 UT)

I've been meaning to get out for a couple of nights, but this one was
the first one where it wasn't too windy out and my allergies weren't
acting up. By the time I got set up, M42 was already only a degree or
so from setting over the roofline of our house (the backyard patio where
I set up is east of the house), but I still decided to point it that way
to have a look. As I expected, there was too much turbulence from the
latent heat over the roof to have a chance at resolving E or F, but the
Orion Nebula is always worth a good look. Even with the turbulence the
nebula itself is still full of interesting detail at 50x.

Hi, Brian, and thanks for the fine observing report! This reminds of
earlier this year when, after seeing M42 and the adjoining clusters
many times in 15x70 binoculars, I got a look with my Dob at 40x. Here it's
humorous that from indoors, I like you face an architectural constraint:
instead of a roofline, the top of my window. With the binoculars,
getting close to the window and viewing a while after M42 has transited
so that it's at a lower altitude helps; with the Dob, as was possible
earlier this year, viewing well before it transits.

However, you're a far more keen and systematic observer than I am: I need
to find out what E and F are -- ah, Google reveals that they're close
doubles in the Trapezium. Maybe the advantage of my naivete is that
I'm not much aware of seeing issues; but, as you say, it's possible
to enjoy the view while being ready to make those more exacting
observations when conditions permit.

With many thanks,

Margo

Thanks Brian, Jon, and Margo. I've really gotta get some starlight one
of these nights...
Marty

Jon Isaacs wrote:
Brian: Nice report... I am guessing that Opus is your C-5?

Seth Waterston wrote:
What type/ size of scope is "Opus"?

I really need to remember to identify the scope. Yes, Opus is a
Celestron
C5+, a 5-inch SCT. Pretty good optics for a mass-produced scope. We
used to have some active tussles over the big CO of the C5+. Ahh, the
good ol' days.

--
Brian Tung
The Astronomy Corner moved to http://www.astronomycorner.net/
Unofficial C5+ Home Page at http://www.astronomycorner.net/c5plus/
The PleiadAtlas Home Page at http://www.astronomycorner.net/pleiadatlas/
My Own Personal FAQ (SAA) at http://www.astronomycorner.net/reference/faq.html

Margo Schulter wrote:
However, you're a far more keen and systematic observer than I am: I need
to find out what E and F are -- ah, Google reveals that they're close
doubles in the Trapezium. Maybe the advantage of my naivete is that
I'm not much aware of seeing issues; but, as you say, it's possible
to enjoy the view while being ready to make those more exacting
observations when conditions permit.

Thanks for the kind words, Margo. E and F are dim companions to A and
C in the Trapezium, respectively. I have a page on the stars he

http://www.astronomycorner.net/notes/trapezium.html

F is actually somewhat brighter than E, but considerably harder to
see,
usually, because it's so close to C, the brightest star in the
Trapezium.
The reason why turbulence is more important than transparency or
darkness is that there's already substantial background light from the
nebula itself. Any substantial turbulence will smear the light of E
and F
until it blends in with the nebula (which as I'm sure you've noticed
is not
exactly uniform to begin with). And forget G and HH, which are 16th
magnitude or so. (E and F are about the 11th magnitude. Brian Skiff
had precise figures for them a while back, I'll see if I can hunt them
down.)

Thanks for the kind words, Margo. E and F are dim companions to A and
C in the Trapezium, respectively. I have a page on the stars he

http://www.astronomycorner.net/notes/trapezium.html

F is actually somewhat brighter than E, but considerably harder to
see,
usually, because it's so close to C, the brightest star in the
Trapezium.
The reason why turbulence is more important than transparency or
darkness is that there's already substantial background light from the
nebula itself. Any substantial turbulence will smear the light of E
and F
until it blends in with the nebula (which as I'm sure you've noticed
is not
exactly uniform to begin with). And forget G and HH, which are 16th
magnitude or so. (E and F are about the 11th magnitude. Brian Skiff
had precise figures for them a while back, I'll see if I can hunt them
down.)

I just viewed both E and F last weekend in our 10" f/6 dob as well as our
club's new 14" f/4.7 dob. With decent seeing, these were easy targets.
However, in our 6" f/8 the E star is relatively easy but the F star is much
more difficult (surprise, surprise) and I recall only seeing it twice with
this scope, both times around sunrise. When the seeing is excellent, the F
star is easy and it seems as if you should never have trouble seeing it.
However, this is not so and when the seeing is mediocre then it is difficult
for the reasons you state. BTW, our club used to have a C5, and the one time
I observed with it I recall being impressed with the quality of the optics
and views.

Dennis