iPhone Saturn, “Camera Method” Polar Alignment
I didn't do any observing Friday, 29 April, and Saturday, 30 April, even though it was clear. We drove up to the Verde Canyon, near Sedona, Arizona, early Saturday morning (a four hour drive) and took a four hour ride on the Verde Canyon Railroad. I have posted 37 of my nearly 200 photos and videos online.
I had hoped to do some observing Sunday night, 1 May, but there was some wind, some clouds, and I was tired from the trip. So, I decided to skip it. I did open the observatory on Monday, 2 May, at 1835 MST, 77°F. The sky was clear and it was generally calm. At 1843 MST, I went to Sirius to focus, then viewed Saturn in the 26mm eyepiece. It was very nice in the 15mm eyepiece even though the sun would not set for another 20 minutes. The planet and ring system were clearly visible, although at low contrast with the bright background sky. I took the above photo of Saturn at 1919 MST (a few minutes after sunset) with the iPhone 4, afocal 15mm eyepiece + 2X Barlow Lens, moon filter, some digital zoom. The iPhone was mounted using the MX-1 adapter from Magnilux. The photo above is full-frame (and is a single frame, not a stacked image). The only editing was to darken the sky background.
I then viewed Saturn with the 15mm + 2X Barlow Lens (267X). The view was lovely as the seeing was excellent. Two moons were currently visible against the still bright background. At 1946 MST, two more moons were now visible (making for Titan, Rhea, Tethys, and Dione). I tried for Enceladus but it was not seen. I then began waiting for twilight to end for the main purpose of this session. I wanted to re-do the wedge polar alignment. I have previously done a “Drift Method” alignment using an illuminated reticle eyepiece. This time I wanted to try the “Camera Method”, using the D7000 DSLR to assist in the wedge polar alignment. At 1954 MST, I set up for doing the camera alignment by attaching the D7000 at prime focus + visual back. I powered off the telescope, powered it on, skipped the AutoStar alignment, set the Targets to “Astronomical”, moved the telescope to DEC 0° and pointed it South. At 2020 MST, I began the alignment. My South image showed that the wedge azimuth was good, needing no adjustment:
The image is slightly out-of-focus but shows essentially no drift during the slewing (see the “Camera Method” link for details on what the images show). I then moved the telescope to point to the West (still at DEC 0°). Here is where the challenges began. The first West image showed some drift, meaning that the wedge latitude was slightly off:
I adjusted the latitude on the wedge and took another image. It showed a small change, so I made another adjustment. This time the “V” got wider instead of closer. So I reversed the direction of the adjustment. No change. I went back and forth several times trying to find the right latitude setting. The best I got was this image:
I went back to the South, DEC 0°, and took another image, with this result:
There was now a slight azimuth error. I was out of time for this session (due to an early morning commitment). I gave up on doing this camera alignment. I think the Drift Method with a reticle eyepiece is better (for me, at least) since it gives more immediate feedback on what is happening as you make the adjustments.
I removed the camera and did a normal AutoStar One Star alignment. GOTO Saturn was good. On the next session, I will re-do the wedge polar alignment using the “Drift Method” alignment with an illuminated reticle eyepiece.
Closed the observatory at 2155 MST, 60°F.
Tuesday, May 3, 2011