Tuesday, January 31, 2023

Comet ZTF from Lake Mead NRA, NV

Hiked and photographed Saturday, January 28, 2023. I had hiked out here (the Redstone area) previously, and have also done night photography from near here, as well. But finding some interesting rock formations I found in the daylight was difficult in the dark. You can be just 20 yards away and not see some of these formations. So I when came out here again last month, I dropped some pins (waypoints) with my Alltrails app, then saved the activity, so I could find these places in the dark.

It worked. I got to the parking area about 30 minutees after sunset, walked south, and easily found my first target, the "space alien with eye" formation I called, "Space Alien Arch." That's the first photo, above. Jupiter is the bright object. This is looking to the west, so the skyglow coming from the Las Vegas Valley is pretty obvious.

I then headed north a bit, to my second target. The comet is actually in this shot, as was my intent, but it had no tail, and was so small that it is almost imperceptible at this scale. It's above the two stars at the end of the Little Dipper, about half way up the photo, about 20% in from the right edge

Then I walked back to the parking lot and set up my tracking mount. Set it up dual saddle, with my 80mm f/7 refractor on one side, and my Nikon D3500 with 85mm f/1.8 lens on the other. I alsohad a .8x focal reducer on the refractor, making it effectively a 450mm f/5.6 lens.

My initial shots showed quite a bit of trailing, indicating a poor alignment. So I got behind my mount and adjusted both the altitude and the azimuth to get the main axis more closely aligned with the celestial north pole. Shots after that showed no apparent trailing, at least not at the scale I was shooting and enlarging.

The telescope shots were about 60 seconds at ISO 2000. Nice thin trail visible. Very happy with the result.

I also discovered that my D3500 produces very violet stars, quite different from my D780 (which was attached to my telescope). Not sure if that's due to a setting I made or just the way the sensors are calibrated, or perhaps if one or the other has or doesn't have an IR and/or UV cut filter built in. I definitely like the D780 representation of stars, better.

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