Eclipse Day 10

And so we continue with eclipse preparations, now about 10 days to go! Last time we came up with the strategy we will use for the eclipse, tested switching to high speed drive mode and used the intervalometer. We retested focus at 15x and checked a sample of images from the high speed sequence to make sure they were captured and were in focus. We tweaked tracking by figuring out the correction needed between the magnetic pole from the smart phone app and true north since most likely we’re polar aligning during the day.

Today we ran through a timed simulation, beginning with setting up high speed drive mode using the laptop, deploying the shutter for 25 seconds, then switching to single shot mode, setting exposure to 1/2000 and going through a manual sequence of turning the exposure wheel 2 clicks down x 20 times. These are the resulting exposures which would occur during totality:

1/2000, 1/1250, 1/800, 1/500, 1/320, 1/200, 1/125, 1/80, 1/50, 1/30, 1/20, 1/13, 1/8, 1/5, 1/3, 1/2, .8, 1, 2+. 3+

Exposures > 1 sec might capture the Moon’s surface detail.

Picture of set up including Celestron AVX mount, Canon R5 with 500mm telephoto, cardboard box with laptop inside shielded from Sun (kind of- there still is a fare amount of glare in there). Lithium battery is used for power for laptop and mount

After the single shot sequence above, I had to go back to the laptop and change the drive mode back to high speed and reset exposure back 1/4000. Each time you’re done with settings in the utility, you have to be sure to close out of the ultility software and disconnect the camera-laptop usb otherwise the intervalometer will not deploy a high speed shutter burst.

I did 2 runs. The first one, again from high speed shutter at C2 to high speed mode at C3, with the single exposures in between took 4′ 25″. The second one I was able to decrease it to 4′ 8″. The duration of totality is 4′ 25″. This is basically what will save us! This is a fairly long eclipse. So I think we will be good especially with a few more practice runs. The eclipse practice run in the Solar Eclipse Timer app (see last post) uses the 2 minute eclipse from 2017. With my approach I probably would not have been able to get the exiting images at C3, but we will run through that just to hear the announcements that the app plays to you and we can still get a feel for going through the steps as long as we can.

Basically from here on out we will continue to practice, perhaps shaving off a few more seconds. When we arrive at the observing site we can load in the exact longitude and lattitude into the app so it will produce the contact times and be able to run properly.

And finally the weather update….bad 😦 10 day forecasts can be 50/50 though, so we will see.

Thanks for reading!

DrDave

First light for new set-up!

We’re continuing to test the new rig out here in the “desert”. The DRO stepper focuser definitely is working pretty consistently. No problems there. I am noticing out here, while the sky transparency is of course excellent, the seeing is really pretty average thus far. My focusing efforts are generally yielding on average 2-3 arc seconds, which is pretty average. In fact it’s probably no better so far compared to where we were in the Northeast. One issue is collimation which is a bit more difficult with these RC scopes. Right out of the box it looks like it’s around 5-6 arc sec off. Not bad but probably not good enough. I tried playing with the secondary collimation screws but they are really tightened down so I couldn’t budge them. I believe this will have to be addressed before going forward.

At any rate we tested the guiding and did a short 5 minute exposure of M1 (the crab). Results shown here. It’s a raw image with no dark or flat subtraction. Stars are round which is great. Guide error seemed to average around half a pixel. Again this is not significantly different than what we had before with the newtonian. Still using the old ST8XME which is a non-antiblooming camera chip hence a couple of slightly bloomed stars.