One Channel; Dozens of Bites

Another camping trip to Lac qui Parle State Park is over and it was a partial success. Let's start with the good news first: I got the blue channel data I needed:

Blue Channel of IFN

This is based on 1.72 hours of total exposure. Blue is usually the weakest channel in terms of signal and to me this looks decent. I'll try to get about the same exposure time for green and red. The strongest blue signal seems to be in the area just below Polaris; this may make that area whitest, which would be in agreement with what I've seen in other images.

[ Compare this to the luminance channel image in the previous post. Blue looks much less contrasty, right? Consider that the blue channel has only 1/3 (or so) of  the luminance signal, and that the above is based on 69 subs compared to the luminance's 177 subs; you can roughly figure this has an equivalent exposure of only 1/8 of the luminance. It didn't get lifted nearly as far above the background, so less contrast. ]

See the copyright notice? That's because my little blog is now getting scraped two or three times every day. Probably not because it's worth scraping, but simply because it exists. I can't really do much of anything that's effective to stop it without adding a CAPTCHA-like layer that would force everyone to choose which squares are motorcycles, or traffic signals, or whatever bots can't easily distinguish. I don't like those things, so I won't subject others to them.

Now the unfortunate part of the trip. The first night's imaging ended prematurely when somehow PHD2 became convinced it was using my imaging camera as the guide camera. This wreaked havoc with things: I started getting repeated timeouts, and a couple of the frames suffered from strange excursions probably caused by calibration mismatch due to different focal lengths. I shut down the sequence and tried troubleshooting, but it was simply not happy. It was already 1:30 A.M. so I decided to give up and get it worked out the next day. Here's what the misguided guider was doing on two of the frames:

Excursions along one of the guider axes.

This was clearly along one of the guider's axes. The guiding display of corrections looked like a strong square wave. 

The next day was unpleasantly warm (almost 90 F and dead calm). I redid PHD's hardware profile and collected the new dark/bad pixel frames it demanded. Things seemed to work; there was a steady stream of images. It also needed a new calibration, something I could only do once it was dark. As dusk fell the mosquitoes attacked in force. My Coleman shelter worked reasonably well to protect me, but all this reconfiguring was making me repeatedly get in and out of the protected area, each time allowing dozens of hungry mosquitoes in. Neither the usually effective Ultrathon or DEET products kept them off me. It was not fun.

There were thunderstorms already west of me in South Dakota, the last satellite images showed high blowoff from them headed directly my way. The forecast was for rain and possibly severe weather around 5 A.M., meaning I'd have to break down everything and pack it away before turning in. 

Between all that and how the bites on my arms and hands were welting up I decided to pack it in and  get a good night's sleep. As it turned out there was rain but the severe stuff went elsewhere. I was glad to have bailed on the night. 

I don't think I'll be making any more mid-summer trips to the park, it's just too buggy for this imager. What a change it was from the previous month's visit!

I'll only have some of the July new moon to see about collecting the red and green frames as my wife is having her second knee replacement done on the day of the new moon. I'll probably just wait for the Northern Nights Star Fest at the end of August, as that should be cooler, darker, and will have longer nights. Or, if that's completely clouded out the Iowa Star Party in October or any clear, dark nights I can get out to Eagle Lake.

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Tariff Watch: The Rokinon lens remains in stock at B&H at $449. This price is 22% above the February pre-tariff price, which is very close to the current tariff of 26% with South Korea.

Back From the 2019 Nebraska Star Party

I was at the 2019 Nebraska Star Party for Sunday through Thursday nights and it could have gone better.

It's been a wet year in Nebraska and that means the usual mosquito herd is larger than normal. The first night, Sunday, there was only a modest breeze that faded around sunset; the herd emerged and immediately zeroed in on me. My bug spray was unable to hold them off and I was forced to retreat to a screened enclosure after obtaining only a polar alignment. No imaging.

Monday night had a partly cloudy hour, but Tuesday through Thursday Nights were all cloudy with episodes of rain. So for me NSP 2019 was a bust. At best I would have gotten one solid night had I been able to endure the biting.

I have a feeling that as the trend of increasing rainfall continues (thank you, global warming) this will be the case more and more often. That means it's time to adapt.

My thought is that if I can work from a screened enclosure I can manage even on those really buggy nights. This means I need an enclosure and a way to control my imaging rig from a distance of maybe 20 feet or so.

At present I control everything using a single USB cable from laptop to imaging rig. According to standards this limits me to about 16 feet between laptop and rig. Subtracting 6 feet for drops to and from the ground and I'm left with about 10 horizontal feet of separation, so I need to extend my USB. This can be done using powered USB repeaters, but that would mean added connections and power lines. the simpler way is to use an Ethernet extender like this:

This passes USB between two boxes via up to 60m of Cat5 or Cat6 Ethernet cable, with only the box on the rig requiring external power. Some serendipity: The required power is 12V DC and uses the same connector I'm already using with my USB hub on the rig. And the on-rig box acts as a powered four-port USB hub. The only drawback is that this is strictly USB 2, so if I add a USB 3 device I'm in trouble. This is available on Amazon for under US$60.

Focusing is not pleasant when you're being bitten, so a motorized focuser is needed. Unfortunately the only motorized focusers for an AT-65EDQ cost close to $1000 when all is said and done. This is a very nice little scope, but I'm not sure I want to spend that kind of money on it. A much less pricey option is a JMI Motofocus, but they have stopped making them for the AT65 and I could find no vendor who has one in stock.

Luckily some years ago I was given an Orion version of the Motofocus. It wasn't designed for the AT-65, but it was close. All I needed to do was add a small piece of aluminum sheet to it and buy a couple of longer bolts.  I made a nice long phone cord so that it can be used over a much greater distance than the coiled handset cord it came with.

The piece of aluminum (silver rectangle in the above image) is epoxied to the Orion-provided mounting bracket to extend it the required distance. The longer screws and small stacks of washers provide the needed offset to keep things square and allow the larger focus knob to rotate freely. Note that there is no clutch on this so while the motor is attached there is no manual focusing. If you need manual, just undo the two outermost screws on the bracket and replace the motor with the AT65's fine focus knob.

The last operation is one I can't really do much about: polar aligning. This will still require standing at the scope and adjusting azimuth and altitude by hand. Nothing is perfect :)


The final adaptation is a freestanding screened area that's large enough for setting up a small table and chair. I went with this one from Coleman:

This is available from multiple vendors for a wide range of prices. The footprint is a spacious 10'x10', so I'll even have room for a little lie-down while imaging. Despite this being floorless, it gets good comments about keeping the bugs out. We shall see. One thing, though--don't imagine that this is adequate as a sun or rain shelter. I purchased mine from Kohls.

So I'm now set for the mosquitoes. Unfortunately there's nothing I can do about clouds and rain, but that's always been the case.