On Dec 16, 1997, Jim Kern and I made a number of simple tests with the equipment at the RIT Observatory. Throughout the early evening, the weather was clear, but thin clouds started to cover the sky around 8:30 PM as we were leaving. We used no filter for any observations.
First, we connected the Astrovid camera to the back of the 16-inch telescope and focused on Saturn. We looked at the images up in the warm Astronomy House. Jim fiddled with the keyboard of the Autoscope computer, and discovered that it acts (somewhat) like the manual paddle down in the dome. We were able to move the telescope by small amounts in each direction. It may be necessary to switch the A/B box from its normal setting in order to cause the keyboard to be interpreted as the paddle. Jim found that he could move the focus motor in one direction only; for some reason, the logical key to move the motor back didn't work. However, it is possible to use the "Focus Menu" to move the focus by some set number of steps in both directions. Thus, one can manage to find a good focus setting, albeit awkardly.
It looks like we can control the telescope completely from the Astronomy House! Great news. However, it will be hard to place a target onto the tiny area of the video camera, or the CCD camera (each about 4 arcminutes on a side). Perhaps we will be able to hook the _old_ video camera onto the 3-inch Maksutov telescope, mount it on the 16-inch, and use it as a video finder.
We ran a video cable up through the conduit in the
control-room closet, so that it went upstairs into
the "TASS room".
I turned on the computer up there, connected the
Snappy frame-grabber to it, and loaded the Snappy
software.
We were able to view the video feed on that computer
in real-time, and snap a few pictures.
These are examples of the mode with lowest resolution,
so we hope that we can take somewhat better pictures
in the future.
We were able to see three moons of Saturn on the video display, after turning the gain and exposure time all the way up: Titan (V = 8.3), Rhea (V = 9.9) and -- very faintly -- Dione (V = 10.6).
We then replaced the video camera with the Meade CCD camera. The flip-mirror box onto which we attached the Meade barely fit into the 2-inch diameter hole in the center of the telescope's mounting plate. Jim had to wiggle it and push pretty hard to get it to slide into place.
We took several sets of images of Saturn, each in
batches of 4 images. We selected the best 1 of
each set, and discarded all the others (most of
which showed some amount of shimmer, either due
to the air or the drive).
Here are closeups of Saturn from the best ones.
The first image has an exposure time of 90 msec, and
a few pixels near the center of the disk are saturated;
the others have exposure times of 75 msec.
You can click on any image to get a full-size FITS version.
When you look hard at any one image, you can see several moons:
Dione is the fainter object, directly to the right of the rings,
and Rhea is the brighter object to Dione's upper right.
Titan is outside the field of view, further to the right.
We then tried to take pictures of some known field in order to figure out the plate scale. I suggested we try the area just north of Capella, since that was easy to find. However, it turns out that Capella is so bright that there are very few catalogued stars within a few arcminutes of it. Ooops -- my fault. We couldn't determine the plate scale with our pictures. However, we did discover one very important thing: when the telescope points to the Northeast, the red "safety" light inside the dome can illuminate the Meade CCD camera! Compare these two pictures of the same field just north of Capella. The exposure time for both was 5 seconds.
This one was taken with the dome light on;
the scale ranges from pixel values of 12,800 (black)
to 14,800 (white).
Just a moment later, after turning off the red light,
we took this image:
here, the color scale ranges from pixel values
of 5400 (black) to 5600 (white).
The FWHM is about 7.5 pixels.
