Image of the day

Captured by
Ron Masters

Saturn Dione Tethys 28 August 2021

My Account

New to Astromart?

Register an account...

Need Help?

Posts Made By: Mark Costello III

December 20, 2011 02:15 PM Forum: Religion

Music for Christmas 3

Posted By Mark Costello III

Hi all, this arrangement of "Angels We Have Heard on High" was written about 20 years ago. Here is a choral version of it, similar to how it was done by our choir at the church to which I belonged (1985-1997). The "visual aid" at the beginning reminds me of what I'm thinking about when I'm out there with my 5" achro refractor, particularly at this time of the year.


http://www.youtube.com/watch?v=-926yhq_UGA



Merry Christmas.

December 25, 2011 06:26 AM Forum: Religion

March 27, 2012 02:24 PM Forum: Deep Sky Observing

Shapes of Open Clusters

Posted By Mark Costello III

I was out for about an hour and a half last evening with my 5" achro refractor. The waxing crescent moon had lowered to the point it was hidden by all the trees in my back yard, so I turned my attention to some open clusters: M36 and M37, having observed M35 and nearby NGC 2158 recently. I got to thinking that a lot of these open clusters are fairly irregular in shape and that begged the question: why? Presumably they are true clusters and so linked to each other by gravity. But unlike globulars, they are not spherical (or ellipsoidal) in shape but quite irregular and not even convex (that is to say that to some extent some clusters are "star shaped"). What is the prevailing theory for the reason for their shape and how they got that way?

Thanks in advance for your responses.


April 12, 2012 06:03 AM Forum: Politics

Question for Criminal Lawyers

Posted By Mark Costello III

Yesterday's arrest of George Zimmerman for 2nd Degree Murder in the killing of Trayvon Martin got me to thinking about the different charges involving homicide. I think I know what 1st Degree Murder is, it includes a pre-initial desire to kill the victim, planning the killing as well as killing. But I don't have any real grasp on the differences between it and 2nd Degree Murder, Voluntary Manslaughter, and Involuntary Manslaughter. If criminal lawyers or other who know all the distinctions could respond, I'd appreciate it. Thanks.

November 14, 2012 02:30 PM Forum: Deep Sky Observing

Another Lesson Last Night...

Posted By Mark Costello III

... in the advantages of higher power viewing, that's the lesson I got - again, twice in the same session last night. I was out with my 5"F6.5 achro refractor doing what may be my "farewell for the year" tour of Cygnus (it's going under the trees in my back yard."

The first lesson came while I was looking for NGC 6940. I found an asterism in the area that looked somewhat like a raccoon. The image at 69X was sparsely populated, showing maybe a couple dozen stars or so. But noticing a very soft "glow" in one of the "hind legs" I switched to 118X to take a closer look at it. That was the first lesson. When I did just that, several dozen stars just popped into view all around the leg, many of them concentrated in one of the "joints" (may have been NGC6940 but I'm not sure). A couple dozen more stars also showed up in the second leg. My thought was "who turned on the lights?" The image at 118X was beautiful, like soft Christmas tree lights....

The second lesson came while viewing M29. With just 5" of aperture I just see the outline normally and that's what I was seeing at 118X. When I hiked the power up to 236X, I noticed, or at least thought I noticed a line of dim stars cutting the box in M29 on a ENE-WSW line.

It's interesting when I recalled that the guides I read as I was starting into the hobby as a teen advised us to use low power to pack in the light.... 8O

November 16, 2012 02:06 PM Forum: Off Topic Discussions

Salute

Posted By Mark Costello III

http://gma.yahoo.com/hero-vets-die-saving-wives-texas-parade-crash-084832922--abc-news-topstories.html

Best,

April 18, 2013 10:22 AM Forum: Sports

I Don't Know When Or If....

Posted By Mark Costello III

... I've seen a news article like this. 8O grin

http://www.thepostgame.com/blog/men-action/201304/nfler-leaves-league-medical-school

Way to go, Myron, and all success!

January 31, 2014 06:07 AM Forum: Deep Sky Observing

Last Night's Observation of M34 - Open Cluster Que

Posted By Mark Costello III

Last night (January 30), I was out under the stars for an hour. In keeping with my usual routine of long looks at each object, I spent the entire session looking at M34 and sketching it. The telescope was an ES AR127 (a 5"F6.5 achromatic refractor). To improve my observation skills, I started the sketch of the overall area at 27X (Celestron Ultima 31mm), then a tighter frame of the cluster at 69X (AT 12mm), and finally a good look at the center at 118X (TMB 7mm). I call this the "Bow and Arrow" cluster due to the outline of the center group of stars in M34. With each hike in power, about a dozen or so more stars popped into view. I started a thread on this a couple or so years ago when I reported seeing NGC2158 for the first time in moving up from 103X to 206X while observing M35. I'm not sure that I understand why, but moving up in power has helped seeing more stars, at least in general.

But a couple of the questions I had about M34 or open clusters in general was this: As noted before, the stars in the central region seem to outline a slightly crooked arrow loosely nocked to a bow, hence my nickname of the Bow and Arrow clusters. What I've seen of most open clusters in general is that they take a very irregular shape. My poster child for this statement is the Bee Hive Cluster, M44. More precisely, their shapes are not convex. A shape is convex if a straight line segment between any two points in the shape (including its boundary) lie in the shape (again being on the boundary counts). Rectangles, polygon, ellipses, circles and their three-dimension counterparts (rectangular boxes, ellipsoids, spheres) are convex. Globular clusters, not counting trailers of stars seemingly emanating from its edges, are spherical and ellipsoidal and so are convex. A bow and arrow figure isn't. On the other hand, some open clusters of many (hundreds) of stars begin to take convex shapes, like M11 and each of the double clusters.

So the questions are: (1) The stars in the open clusters are linked by gravity, right? (2) If yes, why are they not spherical or at least convex, or (3) is there a threshold of numbers of stars before they begin to take a convex shapes.

Thanks in advance for your responses.




March 6, 2014 05:47 AM Forum: Equipment Talk

Complementary Telescope for an ES AR127

Posted By Mark Costello III

Hello, everybody. I am the happy owner of an Explore Scientific AR127, a 5"F6.5 achromatic refractor. My only telescope for the last four years, it's kept me hopping for all that time and could for a much longer time. But every so often when I'm observing a galaxy or some other dim deep sky object, or maybe one of the gas giants, I think about the advantages of a second telescope. It'd have a larger objective. Since 5" is my limit for refractors, the companion telescope would work mostly with mirrors. It takes me as little as five minutes to set up my AR127 (it rides an unmotorized Celestron Omni mount). It would be OK for the second telescope to take a little longer to set up, say 15 minutes. That's because I'd bring it out for the longer weekend sessions, it would be my "Saturday Night Special" smile . (The refractor would get weeknight duty and maybe also be out on the weekend as a second telescope.)

Mostly I've been thinking of some kind of Cassegrain reflector, a Schmidt Cassegrain telescope (SCT) or perhaps a Maksutov Cassegrain Telescope (SCT). With their longer focal lengths, I think of an SCT or MCT as a more ideal companion to a refractor as large as 5". Also, a SCT or MCT could ride shotgun with my achro on a two headed alt-az mount. But I've never ruled out a Newtonian. Assuming same quality of make, the Newt should deliver a somewhat superior image due to the smaller size of its secondary mirror assembly (central obstruction or CO). Also, if the Newt was a Dobsonian (Dob), I think I could handle one up to 10" whereas for an SCT, I might be limited more to 9.25" or maybe 8". (I have no problem handling my 35 lb mount and tripod or for that matter moving around my 50 lm rig around for good obserrving vantage points in my yard. I'll not have a Newt on a German equatorial mount.) Finally, there is the difference in cost. I can buy a 10" Dob with built in tracking or an equatorial platform for several hundreds less than a C8HD rig or Meade 8" rig. I'm more likely to be able to afford a Dob than a SCT or MCT rig of the same size.

So my question is: In your opinion, would a 10"F5 Dob be a good companion scope to a refractor like my 5"F6.5 achro?

Thanks in advance for your responses.

June 11, 2014 02:10 PM Forum: Reflectors

Poll for Smaller Dob Owners

Posted By Mark Costello III

Hello, everyone. On a thread in a different astro-website, a gentleman wrote that he did not use a chair when observing with a 12" Dob since he would have to get up and move the chair too frequently to make having a chair beneficial. For those of y'all who have Dobs 12" but in particular for those of y'all with the 8"F6 or 10"F5 (F4.7-5.0) Dobs, do you use a chair and if yes, do you find moving it around during an observing session to be a hassle?

Here's my interest. I'm considering buying a 10" F5 Dob as a complement to my 5"F6.5 achro refractor. I hope to get an equatorial platform for it but in the interest of not overstraining our finances, I'll probably defer the equatorial platform a year and use the time in between to get used to the scope. But I am intending on getting an observing chair if I get the Dob since I figured that I'll need one. Based on my experience with the refractor and earlier times in the hobby when I stood to observe, not using a chair would be for me a show-stopper. I'm much more able to observe, think about what I'm seeing, and write notes and draw it if I'm seated. If I stand, I'm spending too much time fidgeting in an attempt to be comfortable to the point that it's a big distraction on my observing. So if using a chair doesn't work with a Dob, well, it's good to find out now. smile

Thanks in advance for your responses.