It has been nearly eight months since I have documented any observing. It isn't that there hasn't been any observing in all that time although there has probably been precious little. But blogging is a habit, a commitment, and I just haven't been into it. Maybe that will change.
A good while ago I got a deal on a 6" Newtonian reflector that another former AAA member had in his closet. He purchased it from another AAA member, sans mount, who was moving away. It is a 6" f4 mirror mounted in a Sonotube with a 2" helical focused. Soon after I got it I met Peter at Pier 84, where AAA was holding a public observing session, and we used it to observe the moon cradling it in our laps. The views looked pretty good as near as we could tell.
I had previously done some research on scopes at Adorama and was on the verge of buying a Macksutov-Cassigrain when I got this scope. So I went back to Adorama to see how I could mount it. I was thinking either the big brother to the Bogen 410 geared head on a heavy duty photography tripod or a German equatorial mount and tripod. The EQ mount would have been the easier option since I could have bought mounting rings, but I am more used to an Alt/Az mount with a geared head. My primary concern in all this scope stuff was portability. Knowing this one of the Adorama sails people told me about a cut in CA who builds a collapsible Dobsonian mount called the 1St Base. I contacted the guy and after a lot of questions andbuying eyepieces and a unit finder to find the balance point of the scope we agreed on the specifications for my custom mount. Due to business travel and poor weather in CA it took a good while to get the mount finished and it only arrived here around the middle of next month.
FedEx did their normal gravity assist unload (push it out the back of the truck until it falls to the ground) and the box was broken open. They day they were supposed to deliver it they wouldn't because I supposedly wasn't available to accept it or my business was closed. Three days later it finally was delivered and I had to personally sign for it even though it was valued for delivery without a signature. I imagine that they figured they had probably damaged it and wanted me to sign for it to absolve them of responsibility. I say that in hindsight because I was so happy to have gotten it that I never thought of checking for concealed damage before signing for it. Once I got it upstairs and dug it out of a cubic yard or so of styrofoam squiggles I found that they had dropped it on it's head and mashed the wood on some of the edges and, more importantly, pulled half of the screw heads through their holes in one of the 30" piano hinges. The mounting rings, which were shipped in a separate and intact box, have a lip or flange of thin wood that is supposed to keep them in place in the rocker box which was also broken in several places. I talked to the maker about the best way to effect repairs and have already reinstalled the hinge. I also bought some hardware that I am going to install to take the place of the lip which I have further broken even when I was being careful with it.
Peter and I went up to TPO for the "Super Moon" a couple of weeks ago (we were underwhelmed) and that was my first real observing session with the scope and the first chance I have had to try out the mount. I have a couple of pictures of the scope from that night that I will have to upload one of these days.
I got a folding hand truck from Home Depot and attached a Staples milk crate to it to transport the scope. The rocker box with attached ground board goes into the milk crate and is bubbie tied to the handle then the OTA with attached rings is slipped in in front of it. It isn't too bad pulling it but I know about it he next day. It doesn't take me any longer to get to TotL than when I was just carrying binoculars in a backpack. If there were uncrossed buses that went from here up CPW or it wasn't such an ordeal getting large packages into the electric sewer I would use public transportation more. When we quit observing we are catching the last bus of the night which is empty so having the big cart is no big deal, but that bus only gets me half way home.
The views of the Moon looked sharp but appeared to me to lack contrast. That might just be that it has been so long since I have seen the full Moon that I don't remember what it looks like. I was observing Palus Somni, my favorite Lunar feature, and found a crater, Lyell, that neither Peter nor Iave noticed before. I also looked at Saturn a little and with the 18mm Kellner (34x) it was very crisp and I think I could just make out some black between the rings and the planet at their widest extent. The views with other eyepieces were't anywhere near as good. Certainly they are not what I am used to seeing in Peter't TP-10 or in his refractor.
Last Sunday it looked like it was going to be clear early but a bit windy and cloud up as the night progressed and Peter was going to be busy so I ran down to Pier 84 which is a lot closer than TotL. I looked at The Pleiades, M45, and found that all of my stars had two comet tails just like back in my Coulter CT-100 days. I guess bouncing the scope from pothole to pothole moved the mirror. I saw nebulosity in M42, the Great Orion Nebula, but not a lot of it. The views of Saturn weren't anything to write home about. It was very windy on the pier and I only stayed there for an hour. There was no one else there during that time.
Tonight NOAA was saying better than 35% clouds all night and building late but CSC was showing it clear except for a brief period after sunset. CSC pegged it. I went up to TotL alone arriving at 2045 and stayed until 2400. Right after I got setup and was observing M45 one large clump of stratocumulus moved in and was gone within 15 minutes then there was some light haze but no more clouds.
I started out on M42. I am getting reasonably proficient getting the scope pointed with the 18mm lens by just sighting over where the rings clamshell joins. Even with the 18mm Kellner (34x) I was able to make out all four stars of the Trapezium. I tried the 15mm (41x) Plossl but the nebulosity wasn't as obvious at that magnification.
This is the start of Global Astronomy Month and the focus tonight through tomorrow night is on Saturn so that is where I spent most of my time after he rose over the trees. I had several people stop to take a look. I found that views were good with my 18mm Kellner (34x) and 9mm (68x) Plossl and acceptable with the 6mm (101x) Plossl. I had trouble focusing the 4mm (152x) Plossl. I gave the 9mm a try with the 2x Barlow (136x) to try and get an idea if the problem was with the eyepiece or if the scope just can't use that much magnification and found that it was just as hard to focus when I could figure out here the exit pupil was. I also tried a yellow filter on the 6mm to see if it would help to define the ring structure, surface banding or polar caps to no avail. I think I saw space between the rings and the planet at their farthest extent. I saw Titan (m8.4) and eventually Rhea (m9.3).
I performed a drift test on the 9mm (AFoV .77° or 46.2 arcminutes) and came up with a TFoV of 34.59 arcminutes. I performed the test using Saturn which was at Dec -2.98° at the time.
| Transit Time |
|---|
| 2 minutes 19.95 seconds |
| 2 minutes 19.88 seconds |
| 2 minutes 19.13 seconds |
I averaged the readings and plugged them into the formula
TFoV (arcseconds) = seconds * (0.250845 * Cos Dec)
Along the way home I noticed that the rings had started to twist in the milk crate. When I got home I found that they had rotated 45° from where they started out. Perhaps that is where they want to be and where I should place them. The golf towline that was between the rings and the mount had fallen to the bottom of the crate so there was wood to wood contact that has probably caused more cosmetic damage. The lip on the bearing wheel has sustained more damage but I am writing that off as cosmetic at this point and need to install my brass hardware to take over their frnction. And the OTA has slipped out of the rings and was sitting on the bottom of the crate. I need to get some thick foam down there and maybe more bungles to stabilize the rings.
Another habit I have gotten out of is making field notes. It isn't terribly important when I am only observing a couple of objects but when I start looking at more objects I will want to be filling in my observing tables and that will require field notes.
