Urban Observing Report—the Go To Experience

My motto is “there’s always something to look at,” and this is equally true for the urban observer, for whom the Moon is not just another source of sky glow, but a object of interest itself. There’s not much deep-sky observing to be had, but lunar, planetary, and stellar observing from the city is lots of fun. It’s certainly better than nothing!

I set up tonight about 9:30, as it takes a few minutes to move my 12” Skywatcher dob from the shed to a spot in the yard, connect the cables, and follow the setup procedure. From time to time, the GPS fix takes a long time—not sure what is up with that! But I finally achieved it.

[One property of the SynScan alt-azimuth software that is often overlooked is that if you start the scope up pointing north and level, and if the location is correct (which it should be if you haven’t moved it since the last time), then the telescope will TRACK pretty well, even if the GoTo is not spot on. This is true because, to follow an object of fixed RA and Dec, the signals to advance the altitude and azimuth of the telescope are only a function of its current altitude and azimuth and the latitude. So you can easily observe and track an object by manually moving the telescope to centre it, once you have started up in the manner mentioned.

To do more, you need to have a precise date and time and you must orient the telescope to at least 2 stars. I also find that correcting the GoTo pointing at each object continually improves the GoTo accuracy.]

My backyard view is severely constrained, so I tend not to plan my sessions much. I find out what is not blocked any houses and trees and observe those things. I started with Jupiter and his moons, before he dropped into the trees. The seeing was pretty good last night, and much detail was observed in the cloud bands. [I forgot to say that I also take care to align the finder to the telescope every session, and before that I check the optical alignment—both of these can become misaligned with the collapsible dobs.]

I looked at a couple of double stars in the SynScan list, but those objects are woefully under-represented, as are variable stars. Time to break out the SkyFi gizmo that plugs in to the hand controller (which I then hang up) and to whip out my iPhone (on low brightness, set to the Sky Safari app w/ red night screen). Since I figured this out before, it only takes seconds for my iPhone to be in charge! Now I have access to all the objects in Sky Safari!

Now I’m looking with gas. It is really, really hard to star-hop in the urban environment! A zero-power finder is next to useless, as you can’t see much to point at. You need at least a quality 50-mm finder (which I have) to see the stars to hop to, but it is still frustrating that there are so few stars to see naked-eye. The SynScan/SkyFi/SkySafari option really works: you choose a sector of the sky that you can see, then you look on the Sky Safari chart to see what you can observe. I turn on labelling for double stars, and I see a forest of numbers representing star separations. I touch one and look at its info. Looks good? Hit the Go To button.  whirr whirr  There it is, nice! Now adjust the centring and hit “align” to revise the pointing accuracy. I sound several minutes moving around the many cool double stars in Bootes.

By then the Moon had cleared the side of the house, and I was able to spend a good half hour exploring the terminator, almost at the limb, with some severely fore-shortened craters: Bailey, Grimaldi, Riccioli…

I wanted to observe some carbon stars, but SkySafari does not have such a designation, so I had to go inside an consult—wait for it—the Observer’s Handbook, p. 295. It was easy enough to find a few to add to an observing list in SkySafari by their star name:  SS Vir, R CrB, U Hya—the latter was behind trees! SS Vir was found with GoTo: it turned out to be a beautiful ruby red, mag. 7. I recall observing R CrB years ago in binoculars, and watched it fade in a infrequent dimming event. I looked in my 12” last night and could see nothing!

I went inside for a break, and decided I could not wait for Saturn to clear the house, so I went back and moved the telescope without turning it off. Then I quickly re-aligned the scope and observed Saturn: disk, rings, Cassini division. I thought I saw 5 moons, but one turned out to be a star.

I packed it in about 12:30 am, a bit cold, a bit tired, but a lot satisfied.

Author: 
DChapman