Venus, Saturn and Jupiter

Both telescopes were running and waiting for polar alignment when I went in for dinner. Even though I got a brief nap in, I was so tired that I almost didn’t go out.

But I did. The Sun had just set so I had a little while before I could polar align. I noticed that Venus was accessible from the Meade, and wouldn’t be for long, so I shot it in IR and UV instead of collimating the Meade. I was happy enough with the Meade’s collimation that I could live with it for another night. The seeing that close to the horizon was horrible. I’m not expecting much from the image. I was surprised to see how close to “1st Quarter” phase that Venus is already.

Interestingly, I had perturbed the G11’s polar alignment while attempting to collimate earlier in the day, but I reset it using my phone compass and inclinometer. I figured that I had gotten it pretty close based on the Venus’ low drift rate, and I found that it was within ½ degree when I checked it later in the polar alignment scope.

After finishing with Venus and waiting for it to get dark enough to polar align, I brought up the TV/ASI6200. I am out of practice with that camera and it was not happy with me. I struggled with it but finally got it going. By then it was dark enough to polar align, and I wanted to be prepared to catch Saturn when it cleared the trees so I went back to the Meade. I never got back to this scope. I finished with Saturn and Jupiter by 2230, and was so tired that I gave it up for the night.

All in all, Saturn and Jupiter went well. The seeing kinda came and went. I assessed it at 3-4 (Poor) on the Pickering Scale – first time that I actually used that. At one point I noted that while capturing the red channel that Jupiter almost completely whited out.

For Saturn, I captured 4 or 5 RGB runs, which I hope to individually stack and derotate in WinJUPOS. I captured 6 iRGB runs to individually stack and derotate in WinJUPOS. The GRS was well positioned on Jupiter, and at the end of the Jupiter run, I did an RGB run on a tiny ROI around Io.

I stacked the Io frames last night, and while not great, the result is interesting. The bad seeing was certainly and issue. I set the histogram at about 80 percent so that its upward jumps would not exceed 100 percent. It was jumping between 65 percent and 95 percent, I suspect because of the tiny target and the bad seeing.

I estimated that Io would present as about 9 or 10 pixels in diameter on my sensor given my optics. I used 3x drizzle when I stacked which yielded a disk of about 25 px. The colors are not great, and I am not able to see any surface detail, but given that I set the histogram down in the 80 percent range, I am pretty confident that the disk that I am seeing is real, and that only the dimmer halo around it are caused by seeing distortions. I want to try this again, but under better seeing, and I want to research which of the moons is more likely to reveal surface details.

So, what didn’t go so well. I had hoped to use FireCapture’s autoalign and autoguide. I couldn’t get it to work on Venus, so I elected to manually guide on Saturn and Jupiter. My final polar alignment must have been pretty good, because I only needed to nudge about once a minute to keep the target in a fairly tight ROI. Autoguding will make my life much easier, so I hope to read on this today and work on it tonight.

I was able to work out how to do flat frames yesterday, and completely eliminate dust in an image that I knew was there. The hard part was to capture the flat frames in the same ROI as the target was captured. The harder part, which I didn’t think through too well, is that the dew shield has to come off and the telescope has to be pointed at (or close to) zenith so that I can lay a light panel on it. Doing this between Saturn and Jupiter is just too much. I expect that I would loose 20-30 minutes between targets. I’ve gotta think on this. Flats do hide dust. I’ll show you today and we can talk about noise management approaches.

As a result of my flats exercise, I knew where the dust was on my sensor, and I decided to live with it since I could flat frame it out. OBTW, I did manage to find clean spots that I used to place targets for imaging. I had taken apart my planetary imaging set up so that I could replace the luminance filter with UV for shooting Venus. I took it apart again to but L filter back in for shooting Saturn and Jupiter. This took more time that I would have liked, but the real killer was that I now have so much more dust on the sensor. I can’t live with the dust and the time sink.

I have been thinking about ZWO’s 8 x 1.25” wheel for a while, but now the decision’s been made and I am going to buy it. You can have my 5 x 1.25” wheel if you want it. You’ll just need to buy whatever filters you want, but at least an LRGB set. I find IR helpful but not critical on lunar, Mars and Jupiter. I used it on Venus, but do not yet know how that turned out.

I have gotten ambitious and set up two scopes a couple of times, but have NEVER used the second scope. I don’t think that I will do that again. I will continue to concentrate on improving my planetary techniques while Jupiter and Saturn are around and at least for a few more weeks, and then jump fully back into DSO with the TV after that.

All in all an enjoyable evening, even though I was quite tired. I came at 2230, and was in bed by 0015. It was quite chilly, and I noted that it was 57 degrees when I came in. Be sure to bring something warm enough.

Other than processing, the only things on my to-do list is to clean filters, see what else that I can learn about guiding in FC, and take down the TV. Prep for tonight is priority, the data that I collected last night can wait for the next cloudy day, which will be here soon enough.

Venus - 2021-09-03 0010 UTC
Jupiter - 2021-09-03 0306 UTC

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