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.

Smoke and the June New Moon; A Couple of Things Fixed (maybe)

This week would be a prime time for heading out to Lac qui Parle state park for some dark sky imaging. But there's some serious smoke action ruining that plan. Here's what the smoke looks like from space.

The location of Lac qui Parle State Park is given by the red dot

Fortunately for the health of people in the Dakotas and western Minnesota it's all far above the ground and the air we breathe. 

This is a blue light satellite image from late in the day of 12 June. Both Dakotas are under multiple smoke decks; you can see the layering across western Minnesota where each layer casts a shadow onto the layer beneath it. The eastern edge of the smoke is slowly pushing eastward. 

 I can't say I'm confident this will clear out during the coming new moon weekend of 16-18 June. Western Canada continues to burn.

It's already complicated trying to forecast clouds and adding smoke makes it all the more difficult. Clear or cloudy? Transparent or murky? The decision to travel an hour or more to a dark sky location has become an exercise in nowcasting.

In some ways this is much the same as a cloud deck. It may not be opaque, but the extinction is formidable. In the image below of north central south dakota you can see contrails at flight level casting shadows onto the smoke!

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Two issues may have been resolved last night. The glitchy behavior of my QHY5LII guide camera was absent with the USB cable connected to a USB3 port, and I got a beautiful PHD2 calibration after I turned off the mount's PEC. This has not been a problem in the past, so I wonder if the PEC file become corrupt while it sat unused this winter. It's going to stay off until I have a chance to retrain the mount.

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I've also learned how to use NINA to acquire images for mosaics, and have set up a file to perform a six-panel mosaic of the Veil Nebula. The first two panels will complete the East Veil.

Opening Night, 2023 (M44 & NGC 6823)

Basically, my first attempt at using a state park failed. Not because of the park. It was the weather, of course. And smoke. There's not much advantage to imaging from a dark sky site when the transparency is severely reduced by a layer of heavy smoke. The camping reservations for the May new moon were canceled and I'll try again in June. 

Last night the smoke relented and even though it was a first quarter moon I got some imaging done from the club's Eagle Lake observatory site. There was time for only two targets, M44 and NGC 6823. As expected there were some rough spots, but I think some things were learned, too.

NINA

Nina  had one glitch and one nice feature I was using for the first time.

I could not get NINA's advanced sequencer to accept multiple targets; Trying to add M76 to M44 resulted in two entries for M44. I'm fairly sure I had forgotten some necessary step as this had worked before.

The NINA manual rotator worked wonderfully and let me get the images properly framed by hand. It took only a few adjustments to get within the "good enough" orientation range.

PHD2

I initially had the scope slew due south to the celestial equator for calibration. Under normal circumstances during calibration you'll see PHD nudge the mount first in one direction and then back to the starting point, then do the same along a line perpendicular to the first direction. While doing the second line it wandered a bit before doing as expected. PHD let me know it wasn't happy; at the conclusion of calibration it announced that the calibration was suspect. The mount had been polar aligned, balanced, and so far as I could see no cables were dragging, so it's a mystery to explore next time. 

Evidently the guiding calibration was good enough, as it kept the stars round in most frames.

Periodically guiding would go badly off in both RA and Dec, producing bad stars. I suspect cable snagging, but maybe it's related to the calibration issue? Either way, it's going to be something to look out for next time.

Guide Camera

I started the evening using a QHY5L-II-M guide camera, a finicky little device. Last night it frequently stopped so I swapped it out for my ancient Starshoot Autoguider. The SSAG is not terribly sensitive, but it works!

Past experience with the 5L, powered by the USB connection, suggests it's picky about the input voltage. Last night I connected through one of the convenient USB2 ports on my ASI 2600. Next time it's going to straight to a USB3 port on my Pegasus Powerbox. Maybe that will clean up its act?

Mount balancing

Confession time: While I do always try to balance the mount, I don't generally practice "east heavy" imbalance. That's going to change after last night. Initially with "near-perfect balance" tracking was only so-so. Restarting with the mount rebalanced to be east heavy significantly improved tracking, just as everyone says. If only I would pay attention

Now the images... These are preliminary processing results: neither makes use of deconvolution or sharpening. Both images were acquired the night of first quarter moon, with only about 25 degrees between the moon and M44.

M44

 

M44 is one of those objects that in my opinion is best imaged by a system that gives the stars diffraction spikes. The spikes can provide a sense of separation between the cluster and the field stars that simulates the visual impression this big cluster has in a wide-field scope. I know there's software that can add spikes, but that kind of "artistic" modding is not something I want to do.

[ Details: ASI 2600 mono ccd, Takahashi FSQ-106 @ f/5, 11x60s for each channel of RGB. Image resized to about 20% of full scale. If you look along the lower edge left of center you'll see my master flats from 2022 are obsolete.]

This result suggests that an RGB imaging scheme of 12x60s for each channel may be adequate for quick imaging of bright open clusters, and that 60s exposures are short enough to preserve star color. 

Next is NGC 6823:

 

NGC 6823 (and NGC 6820 if you know where to look)

NGC 6823 is a combination open cluster and bright nebula. The cluster is 7 arcminutes in diameter (about 1/10th the size of M44) so this is a test of what some of the smaller clusters in the Astronomical League's Open Open Cluster list may look like if I use the same camera and optics to image the list.

Can you tell 6823 is in Vulpecula? Look at all the stars, and how those stars are driven to red near-extinction by their light scattering through light years of interstellar gas and dust. 

[There is some confusion around 6823 and 6820, with 6820 often referred to as the emission nebula around 6823 (see The Night Sky Observer's Guide Volume 2, for example). This doesn't agree with the definition of 6820 being a reflection nebula. If you look a plate solve of the 6823 area, you'll see 6820 is centered around a small blue nebula well offset from the cluster of stars within 6823. This is also where SIMBAD puts it. You can barely see it in my much-reduced image as a tiny smudge just outside the upper left quadrant of the emission nebula. My color calibration doesn't get 6820's color correct.]

[ Details: ASI 2600 mono ccd, Takahashi FSQ-106 @ f/5, 21x60s blue + 20x60s green + 19x60s red. Image resized to about 40% of full scale.]

Those light frame counts tell you that I lost 12 frames out of 72. That's 1 frame in 6 and clearly is not adequate.

And what's next? Waiting for a clear night. What I'd like to see is how a full moon affects open cluster imaging. And when it's new moon time again, the boring spring sky will be at least partially replaced by the sky of summer.

Revised Startup for APT/Stellarium/PHD2 et al.

I've updated all the software I use for image acquisition: APT, PHD2, Stellarium, and ASCOM. 

All the updating went without problems, so Yay!

However, my old way of starting all these in order of APT first, then Stellarium, and finally PHD2 seems to not work well any more. What seems to happen is that APT and Stellarium can't work through ASCOM correctly, and APT sometimes launches an instance of PHD2 out of impatience?

Some experimenting was needed, and the result is that the order of starting now goes like this:

1. Power the mount and allow time for it to boot. My Gemini 2 takes a couple of seconds, most others are probably faster
   
2. Power up everything else and insure it's all running and has made its USB connections.
   
3. Start Stellarium and let it connect to the mount (if all is good it should correctly show the direction in which scope is pointing)
4. Start PHD2 and connect it to the guide camera and mount
5. Start APT and connect it to the camera
6. Start the camera cooling via APT
7. Connect APT to the mount
8. At this point use PoleMaster to do a polar align using the ASCOM hand control, finishing with the scope in its park position (counterweight-down and approximately targeting the NCP)
9. Re-aim the scope far away from the NCP and train PHD2. You can delay this step until after you have pointed the scope at your target.
   
10. Sync the mount using APT's Point Craft (I use ASTAP for plate solving---it's amazingly fast and almost never fails to solve!
    
11. Use either Stellarium or APT's Go-To to acquire your imaging target. Do whatever composing you want.
    
12. Start PHD2 guiding or let APT handle things. 
13. Make sure your focus is perfect and start your exposure plan

Basically: power up, start the helper apps, start APT, start camera cooling, do polar align, sync the mount, acquire target, train PHD2, start imaging. If you're using autofocus, insert its setup where appropriate.

Worth noting is that the use of Stellarium (or any planetarium program) is entirely optional. APT provides extensive object lists and has similar Go-To and Sync features---everything you need to image.