Celestron CPC800 - First Light - Part 2

I have had the opportunity to take my new Celestron scope out a couple of times since my last blog. Once out to my local dark site and another last night in my back yard. The focus of both of these outings was to assess the optics of the scope.

The first task was to determine how well the scope was collminated.  This hast to be done before assessing the quality of the optics. This is pretty easy as you just find a bright star and focus on it. You then adjust the focus inside and then outside and see how the shape of the star changes. It should grow from a point into a perfect circle on both sides of the focus. If the shape is more elliptical and shifts on either side of focus then the scope is not collminated. I pleased to report that Calvin, as my daughter named the scope, is very well collminated.

Assessing the quality of the optics is done by performing a "Star Test."  I am the first to admit that I am not an expert at this technique, but it is pretty simple to perform. Here is a link to a pretty good description of how to perform this test.

Basically all you do is de-focus a star using a fairly high power lens, say 100-200x,  until you can see the diffraction rings appear. You make a mental picture of the rings and then de-focus the star on the other side of the focus. Ideally the ring pattern should be identical. The rings should all be perfect circles and well defined. The brightest rings should appear at the same spot in both the inside and outside of the focus tests. The star test for Calvin went extremely well. There were no signs of any astigmatisms or spherical aberrations.

I spent the remainder of the evening out at the dark site ripping off objects on my H400 list. I was able to log about 30 objects in the two hours I was out there.  Here are some highlights:

Arp 135 - mag 9.6 galaxy in Perseus. At 163x the galaxy appeares oriented in E-W direction, core appears non-stellar


Arp 225- mag 11.0 galaxy in Cam. At 127x it is a very faint smudge, no structure visible. Too low in the northern sky to make out anything to note.

NGC 40 - mag 10.7 planetary nebula in Cep. At 127x the central star appears to be visible. It really tends to pop out more with averted vision.

NGC 1342 - mag 7.2  open cluster in Per. At 127x there are about a dozen brighter stars, 2 dozen fainter ones, not well concentrated.

NGC 1502 - mag 4.1 open cluster in Cam.  At 127x the OC is dominated by a binary in center, it looks like two eyes staring back, 30 fainter stars, loose concentration.

NCG 6803 - mag 9.7 open cluster in Cyg. At 127x the OC forms a cross with 5 brighter stars in a line with fainter stars crossing at a right angle. Almost looks like a miniature Cygnus.

NGC 6885 - mag 5.7 open cluster in Vul. At 78x the OC is dominated by 1 britght star surrounded by 30 fainter stars. Slight mottled look on one side.

NGC 6910 - mag 7.3 open cluster close to the heart of Cygnus. At 127x the OC is dominated by 2 brighter stars, one of which is a nice gold color, about 10 fainter stars strung between the two brighter stars. Fairly well concentrated.

Well, the next blog will be after the new year and I will be taking an assessment of my observing activities of 2011, until then,

Clear skies,
rw

Celestron CPC800 - First Light - Part 1

Last week I wrote about why I chose the Celestron CC800 for my new scope. This week I want to share the first light experience.

The scope arrived via FedEx last Thursday. I worked from home that day so I would be present to accept the rather large boxes and avoid them being abandoned on my front porch. The scope came in two boxes with the Power tank arriving in a third. All appeared in order upon an initial inspection of the condition of the boxes. Celestron used double boxes to ship these scopes in. I am not sure if they have always done this but it sure does make a very secure shipping package.

The set up was quick and easy. I had pre-read the instructions available for download on the Celestron website. The instructions were simple and very clear. The one thing I discovered while setting it up was that it is important that the clutch on the azimuth axes needs to be snugged up a bit when placing the scope on the tripod. This is necessary so that the scope base will turn as the top is rotated to engage with the self locating mechanism.

I was lucky in that the skies Thursday night cooperated and I was able to observe some. For this first light experience I chose not to go to the dark site but to just set it up in my back yard. I did this as I thought if there were issues and I needed some light to help I could always turn on the flood lights. Fortunately this was not necessary.

This first session was really just an opportunity to see how the alignment process worked and not really an observing session. There are several options to chose from in the alignment process. I chose the "Sky Align" method in which you center three bright stars or planets in the eyepiece. The scope's internal computer determines the identities of the objects and calculates its alignment parameters. This takes all of about 5 minutes to do. Once this was performed, I chose an object, Jupiter, and let the scope slew to it and just like magic, Jupiter appeared in the 40 mm eyepiece. Alignment success!

I spent the next hour just getting the hang of the hand controller and slewed to several brighter objects, i.e. M31, M103, and a couple double stars. The observing conditions in the back yard were really not that favorable to determining the optical quality of the scope and so I would just have to be satisfied with check out of the mechanics. I did test the collmination  at one point on a star and I was presently surprised that the scope was still in collmination after being transported and handled.

Well after about an hour I noticed that the corrector plate was starting to dew over quite significantly. So I decided that I would call it a night. The dew shield I ordered has not yet shipped but I am expecting it within another week or so.  Until then, dew is going to be problematic for this scope.

Next week I will tell y'all about the scope's first trip to the dark site I use and how the optics checked out. Until then, Merry Christmas and clear skies.

rw

A New addition to the Family

This week saw a new addition to my family, ......my telescope family that is. After long deliberations and an approval from the family CFO, I placed an order for a Celestron CPC800.

I say, long deliberations because the decision to purchase a new observational instrument is never an easy one for me. For those that know me, they know that I do not like parting with my green backs very easily, and a scope like this requires more than a few green backs. By far this is the most that I have ever laid out for my "hobby."

So how did I arrive at the CPC800 you ask? Well, it has been a long journey, let me tell you about it. As you may know, my main observing instrument for the past year has been a 10" f4.9 reflector on a Dobson mount. This was a step up from my 8" dob reflector that I had used for many years.  The increase in aperture was fantastic and really allowed me to go deeper than I had ever done with the 8". However, along with the extra aperture comes additional weight. I hate to admit it, but the weight issue starts to become more important as one ages and especially when you have to transport and set up the scope at remote sites. My back just ain't as good as it once was, even then it wasn't that great.

The solid tube reflector tube had a weight of about 40 lbs. Anything more than this is really pushing it, especially when handing a precision instrument. It ain't no bag of cement, you know! So weight and portability were high on the list.

The second consideration was the GOTO capability. Now for a long time I have been a strong advocate  of star hopping. You know, using a star chart to "hop" your way from one object to another. Well, ever since fitting my 10" dob with manual degree circles and utilizing a real time planetarium program, I have felt the ever-increasing pull towards the GOTO revolution. I say revolution, but in reality, these computerized GOTO scopes have been available since the 80's, I am just a wee bit behind the times I guess.

GOTO does two things, first it allows the location of faint objects to be like falling off a log once the scope has been properly aligned. Secondly, it keeps the object in the field of view, allowing the possibility of astro-photography at some point down the road.

So, the criteria was a GOTO scope who's components individually weighed not much more than 40 lbs. There were a few candidates, but I settled on the Celestron CPC800. The 8" aperture was driven by the weight consideration as the next size up, the 9.25" weighed in at 64 lbs! The 8 inch was 42 lbs which I thought I could live with.

Reviews of the CPC family on Cloudy Nights forums were generally positive. This is a scope that has been around for a while and Celestron has hopefully had adequate time to work out any bugs in the mechanics and software that drives the scope. I am not one of those that goes out buys the latest and greatest of anything. I prefer to go to school on other's experiences.

The deal closer on the Celestron was finally the sale that the company was running. It was not a huge sale, but it was enough to make me pull the trigger sooner rather than later.

So, there you have it, my reasoning for the new family addition. The subject of my next blog will be the first light impressions of the new family member, until then...clear skies.

rw