Thoughts from Starlight Cascade

After the great “Brockville” fireball of 2020dec07, 19:30EST, we checked allsky1pi as well to see if it recorded the event that allsky2 (UWO) captured.

It did not.

Hmm… wonder why not?

After days of troubleshooting we came across an interesting anomaly.

The allsky1pi camera performs autoexposure from early dusk through dark and into early dawn. Looking at Sunday’s data, we had approx 540 images at 161MB, and during the dark cycle these maxed out at 60 seconds.

Interestingly enough, the config file for the software lists exposures and maxexposures at 90 seconds. hmmm.. looking more carefully at each image, they are in fact timestamped 90 seconds apart, not 60.

hmmm.

It seems that the camera is exposing up to a max of 60 seconds and then waiting for 30 seconds to fulfill the configuration file’s 90 sec entry.

Checking the camera stats, it says it can do up to 1000seconds. So.. a possible problem explained but not fixed.

https://astronomy-imaging-camera.com/product/asi120mc-color

We changed the configuration to 60seconds for exposure and maxexposure and reviewing the last two nights, it seems to be working. Timestamps are now only 60 seconds apart for 60 sec exposures and there are approx 820 images now at 270MB.

So the most likely answer as to why allsky1 did NOT capture the event.. it happened in the30 second deadtime between exposures.

OK.. that is now fixed! no more missing time!

Still have to figure out what is responsible for limiting it to only 60 seconds? The camera hardware itself in some way? The autoexposure has some limiting factor configured somewhere else? Gremlins?

Mars on the cold evening of Saturday Nov 14th. It was already -6C but clear and relatively stable air. To get around the postprocessing overexposure of the last few nights, these were underexposed on purpose, down to about the 70% level on firecapture histogram.

The BAA Mars Mapper has South up but otherwise is helpful in identifying surface features.

Only two 5 minute imaging runs were completed that evening. This is the animated .gif of the two together. This is with a x2 barlow and as you can see, the absolute pixel size of Mars is small and getting smaller. We have heard of other imagers using up to x5 barlows (with a subsequent 25 times less light than no barlow at all), so that means you need a bigger telescope. That means I still need a bigger telescope.
Syrtis Minor is approaching the centre with Hellas towards the bottom left and Syrtis Major on the far left.

Mars on Wednesday evening during the weekly social chat videoconference. Now that we are on Standard Time, it is a little easier to get outside and image in the evening.
This is the BAA Mars Mapper simulation (their south is up, my south is down). It can be found here:
https://britastro.org/node/23843
I only wish they would add the ability to flip it to reflect my personal optics.

Sinus Meridiani is central with Chryse on the upper left moving to the right. The south polar cap is not really all that visible, and the bright spot on the lower right is the Hellas Basin.

I just noticed that the image of the telescope setup is old and incorrect. The 90 deg diagonal was removed some time ago. I will have to find a newer image to reflect reality!

Tracking continues to be so-so on the Meade LXD55 mount. Manual guiding corrections are needed every 30-60 seconds or so.
The new firecapture beta 2 is working well. I still do a 30 second no autoalign and then a 30 second autoalign, followed by 180 second runs with autoalign, then a 120 second wait, giving a cycle of 5 minutes from one imaging run to the next.

Lastly the animation of 9 imaging runs.

A good clear night, the first in a long time, albeit a little cold.
Mars is now up high fairly early on in the evening, so we went out and imaged Mars from 20:45 to 21:12 EDT. The almost full moon was up and fairly close to Mars, so it would not have been a great night in any event.
All of the images were overexposed, even though I progressed down from 13ms to 11ms. It wasn’t enough.
There was a lot of skyglow from the Moon and so far I am attributing it to that.
Transparency was poor, seeing was average.
Mars was 39 degrees altitude, an apparent diameter of 20.23 arcseconds, Magnitude -2.2
The animation does show surface detail moving, so I am a happy camper.. the session worked.
The partial dew shield I am using is a cardboard file folder cut on a diagonal. It doesn’t work well however as the equatorial mount can turn the telescope itself upside down and then the dew shield does not work at all.
TODO action item for today, build another one that is more fully symmetrical.
Also, whilst imaging the almost full moon, I noticed a lot of hard dust spots on the images. Turning the camera, the spots did not move, therefore they are on the camera portion of the optical system, not the barlow or the telescope itself.
TODO action item for today, clean the camera.. again.

Lastly the animation of 8 observing runs, ranging from 30 seconds to 240 seconds.

We went inside as the temperature had plummeted to -8C and we are not nearly acclimatized to that amount of cold quite yet.

The next week looks much warmer and I am looking forward to getting out again as Mars rises even higher.

Mars Wednesday evening. It was unexpectedly somewhat clear, at least in the direction of Mars, last night. A lot of cloud all around, affecting other imagers to some degree.
This was a run of 8, approx 180seconds each, shorter for the initial run as usual.

Identifying features: I used to use the Sky and Telescope Mars Previewer, but it is finicky to time zone settings and often confusing. Since then I have started to use the

British Astronomical Association Mars Mapper. One issue I have with it, it does not seem to allow a north-south switch. I image with north up, it shows south up. I also looked at Stellarium, but do not believe it shows correct surface features for the time.

S&T Mars Previewer

Stellarium

BAA Mars Mapper

The southern pole ice cap shows a little. The lighter colour of the northern hemisphere is the Tharsus region, with Olympus Mons (not really showing detail). The darker southern hemisphere contains features such as Solis Lacus but again you can’t really identify in these low resolution images.
Of these three, the BAA is the only one to overlay names, which is very handy when you are first getting used to the topography.

Since then I have also started to use the Sky&Tel Mars Previewer again, this time setting it to UTC time. It seems to work better and I will go back to using it to compare what I image to what is supposed to be reality.

Lastly, the 8 images animated together:

Shadow transits of Moons of Jupiter on Jupiter are relatively common.
Double shadow transits are somewhat less common.
Seen here is the moon Io off to the right with two shadows, one from Callisto and the other from Io, also off to the right. The Great Red Spot appears only in the first few image runs, then goes around the edge.

The double transits and the Great Red Spot were to begin at 17:25 EDT but it was still daylight. The telescope pointing could not find Jupiter, not until 18:27 when Jupiter was visible to the naked eye and the Telrad finder helped aim the scope.
Images were taken every five minutes until the end of the event at 19:25 EDT. So instead of 2 hours, only 1 hour of images were captured.

Images runs were 180 seconds each and processed with PIPP, Autostakkert! and Registax for wavelets.
An animated .gif of the entire event is below: