Two "Nearby" Dark Sky Sites, Maybe--and More as I Find Them

Minneapolis and St. Paul create a substantial amount of light pollution. Even at a distance of about 50 miles their combined light dome will show up clearly in long exposures. Where can one go to find really dark skies for all-night imaging?

Existing Minnesota Astronomical Society (MAS) sites are either not very dark or are distant: Cherry Grove Observatory (about an hour away, between light green and dark yellow sky as used by Light Pollution Atlas 2006), Eagle Lake Observatory (3/4 hour, light yellow), J. J. Casby Observatory (half hour, light orange), Long Lake Conservation Center (2 3/4 hours, light blue), and Crex Meadows (not an official MAS site, 2 hours, light blue).

These are either too bright (Cherry Grove, Eagle Lake, Belwin), too far (LLCC) or lacking in any accommodations (Crex). LLCC use is limited to specific weekends, eliminating the ability to take advantage of weeknight clear sky opportunities.

I spent some time doing an initial survey of what's available in the 2 to 3 hour driving range. I've looked at Lake Shetek state park previously; it's very nice, good horizons, electricity, green zone dark, and no reservations are needed during off-peak times (i.e., Labor Day through October). This park is busy at other times, though, and reservations are needed. Given the fickle weather around here, reservations are a good way of throwing one's money away. Here's what I mean:

State Park camping reservations work like this in Minnesota in 2015: A standard drive-in rustic campsite (no electric) is $15 to $19 per night.

Let's take an example of a two-night imaging trip: Getting the reservation is at least $38.50 (this assumes a $15 nightly fee and includes the $8.50 online reservation fee (use the phone instead and it's a $10 fee). Cancelling four days in advance will get you only $20 back (The $38.50 less the reservation fee less a $10 cancellation charge. You're out $18.50. Cancel later than that--which is more likely going to be the case given the quality of cloud cover forecasts--and you only get $3.50 back because the first night's charge of $15 is forfeited. You're out $35.

Another difficulty with state parks in general is their tendency to put campgrounds in wooded areas (Lake Shetek is a wonderful exception). There are a number of parks under dark skies, but if you put your gear up next to your tent (as I do) it's going to be under trees.

The good thing about State parks is that after labor day they tend to empty out and  it's often possible to obtain camp sites without going through the reservation system. Lake Shetek would be great for this in September and October.

Parks that don't require reservations such as those administered by counties are easier to use. Generally they don't have much in the way of facilities, but if you're used to primitive camping at star parties that's perfectly fine. Are there any dark-sky parks that look like candidates within a few hours drive from the Cities?

Yes, and they're surprisingly dark.

Cottonwood county's South Dutch Charley (also spelled Charlie) County Park is little more than a wooded lot, but it sits under light blue zone sky that's 2.5 hours drive away. Google Earth images suggest that it may have some places to camp that allow a southern view. At $10 a night you don't get much beyond a shelter and pit toilet, but when one can carry one's own power that's no problem. SDC is in familiar territory sitting only 16 miles west of Jeffers Petroglyphs.

Location of South Dutch Charley Park

Renville county's Vicksburg County Park (aka County Park No. 2) is a little larger and is 2.1 hours away. $12 a night for camping, its sky is on the line between light blue and dark green. Because this park sits next to the Minnesota River it will probably have plenty of mosquitoes during summer, but spring and fall visits may be pleasant.

Skalbekken County Park (aka Renville County Park No. 1, 2.2 hours away) is farther up the river and under dark green skies. It's farther from Redwood Falls than Vicksburg is, reducing its light dome to the SE. On the other hand, the dome from Granite Falls to the NW will be substantially brighter.

Locations of Skalbekken and Vicksburg County Parks

Here's how these two areas are located relative to the Twin Cities:

Yes, one has to drive this far to find blue zone sky.

I'll visit all of these sites in June and July to see if they are suitable for imaging trips.

ADDED:

Another dark sky camping location is in Iowa, 6.5 miles WSW of Rice in Mitchell County. It has light blue zone sky and is about 2 1/4 hours from my location. $10 camping with electrical hookups available. Worth checking out, probably on the return trip from this year's Eastern Iowa Star Party (assuming I'm able to attend).

Here's a map of the proposed sites showing the Atlas 2006 sky brightness. I've include my location and some other fairly dark sites mentioned in this post.

I looked at Wisconsin and NW of the Twin Cities, but couldn't find anyplace worth mentioning. The nice dark blue area south of LLCC seems to be mostly forests, but it contains one possible site: Snake River County Park. Aerial pictures of the camping area suggest it's forested, but it is worth a look on my next trip to LLCC (probably next summer).

ADDED 5/27: Another camping area only an hour and a half from home is Clear Lake Park in Sibley county. It's in a light green zone and about 11 miles north of New Ulm so there's going to be a substantial light dome to deal with. Camping is free (you need to get permission from the county Sheriff's office) and it looks like there may be considerable open space in which to set up.

ADD 5/58: Let's add a few more possibilities. Lake Hanska County Park is a light green zone park a little under two hours away. Blue zone camping can be found at Garvin County Park 7 miles WNW of Tracy. More blue zone at Oraas Park South of Clarkfield. All of these have inexpensive tent camping.

Maybe it's time to summarize these in a table:

SITE	ZONE	DRIVE	FEE	LOC	Elec	H2O	NOTE
Clear Lake	L Green	1:31	?	10 NNW New Ulm	N	Y	1
Garvin	L Blue	2:51	$10	7 WNW Tracy	Y	Y	2
Lake Hanska	L Green	1:53	$10	9 NW Madelia
Oraas	L Blue	2:38	$5	7 S Clarkfield 16 SW Granite Falls	Y	Y
Pioneeer	L Blue	2:19	$10	6 WSW Riceville	Y	Y
Skalbekken	D Green	2:17	?	8 SE Granite Falls	N?	N?	3
South Dutch	L Blue	2:33	$10	4 NE Westbrook	?	Y	4
Vicksburg	L Blue	2:06	?	10 NW Redwood Falls	?	?	3

NOTES
(1) Probable substantial light dome to south; must contact Sheriff’s office to OK stay
(2) Almost all campsites have electricity (extra $5)
(3) Very forested; no direct link at present from county web site.
(4) Open through end of October (most are open only until October 15)

At this point I'm most inclined to opt for South Dutch Charley and Garvin. Garvin in particular is attractive because of it having electricity, and aerial views suggest some campsites have passable horizons.  

Sadly I couldn't find any dark blue zones within reasonable driving distance unless one goes into South Dakota or north into the forests of Minnesota. There are a few light gray zones near the SD border, but as you might expect they're devoid of campgrounds.

Five LBNs in one image

Last night everything worked correctly and I managed to image the cluster of LBNs in Serpens that includes LBN 8, 10, 11, 19, and 1122.

Here's the image:

These are NOT very bright. Only 1122 rises to the level of LBN brightness 4; 11 is brightness 5, and 8, 10, and 19 are all brightness 6. Which is to say that these are really quite dim. Despite 170m of luminance shot at f/4 aggressive stretching is needed to pick out the nebulae. Regardless of that, I consider these good enough to satisfy the Astronomical League.

These five lift my count to 92. Where will the final eight come from?

The remaining objects [and their brightnesses] within reach are clustered.

Cluster 1 Sh 2-12 [4], Sh 2-13 [?], and NGC 6357 [?]. These three fit into a 200mm lens field. Image during July.

Cluster 1: Sh 2-12, Sh 2-13, and NGC 6357 (Lobster)

Cluster 2 LBN 20 [4] and LBN 22 [5]. The AT65's field is perfect for this pair. Image during June or July.

Cluster 2: LBN 20 and LBN 22

(Cluster 3) LBN 70 [6], IC 4701 [4], and LBN 52 [2] fit into a 135mm lens field. LBN 70 is huge; it encloses the Eagle Nebula and LBN 68. July or August.

Cluster 3: LBN 70, IC 4701, and LBN 52

(Cluster 4) IC4812 [?] and NGC 6729 [?]. This pair also fits nicely into the AT65 FOV, although the TV-102 might be better. July.

Cluster 4: IC 4812 and NGC 6729

The four clusters contain ten objects, putting me two over the required 100. There are a couple of very dim objects that remain for August and September in the event that these fail, and if those fail it's back to winter imaging!

Another Star Party Cloud-Out; Camera update

Today is the Saturday of the Two Rivers Spring Star Party and I'm posting this blog when I should be enjoying dark skies. The sad fact is that the entire run of the party has been filled with of clouds and rain and I've bailed out rather than sit in a tent for the remainder of the party.

AMENDED: The IR Satellite loop suggests that Saturday night is starting out clear. It won't stay that way, though; by midnight or 1 A.M. clouds will cover from the west. It still wouldn't have been a suitable night for my imaging.

A tale of woe: My last several parties are the Iowa Star Party (two out of two nights unsuitable), The Northern Nights Star Fest (three out of four cloudy/rainy nights) and now the TRSSP (three out of three cloudy/rainy nights). That gives me a whopping one night out of nine that I could see the stars.

The next star party is the Nebraska Star Party in July. Maybe I should ask them to pay me to stay away.

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The T2i arrived sooner than expected! It's amazingly clean--it looks almost brand new, and more importantly looks to be 100% functional. I've communicated with Gary Honis about the modification, and he's got a slot open at the end of May. Maybe I'll have the modded camera back in time for the NSP? It could ride my CG-5 mount and do wide-field imaging while I'm using the CCD for other objects.

A New Camera

Last time I mentioned that I was considering purchasing a DSLR for imaging and had narrowed the field of candidate models to a short list.

The winner is the Canon T2i. I was able to pick one up on eBay for $183. (Here's hoping that it arrives in good shape and performs as well as the seller says it will.)

Here's how the T2i compares with the other candidates:

The 40D (introduced in 2007) has a sturdier build valued by professionals but lacks the video capability of the T2i that can be used for solar system imaging. The 40D is considerably larger and is 10.3 oz. heavier than the T2i; after imaging with the ST-8300M+FW8 tandem I'll appreciate the difference in weight and bulk. The T2i's pixel size is much smaller (4.3 vs. 5.7 m) making it a better match for my AT65 and TV-102. It's reported that the T2i's sensitivity is 2 f-stops better than the 40D.

The XSi (2008) is one model more recent than my XTi and has a large number of owners doing astrophotograpy. I suspect this is because it was the first consumer-class Canon camera with LiveView and USB one-cable operation. The XSi lacks video, and the T2i is said to be 3 f-stops more sensitive.

The T3i (2011) has slighter less noise than the T2i (2010), but it lost the crop mode video capability that helps with solar system imaging. The T3i adds the tilt-out display that's useful when the camera is used without a laptop but this feature is of little value to me. It also costs more to purchase being a year newer.

The T2i has a better display screen for focusing than either of the earlier models.

Assuming that the purchased camera checks out okay I'll be sending it off to Gary Honis for his Baader modification.

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Two Rivers Spring Star Party Update--- It begins in three days and the weather forecast for the party is terrible: Every night mostly cloudy with a 40-50% chance of rain. Ugh.

A More Diverse Imaging Capability

It's been cloudy, or clear with a waxing moon. So I've been working on small projects and considering a purchase.

The parallelogram binocular holder

 is coming along. This week completed all the work needed to completely assemble it. Amazingly it actually worked, providing the 11x80 binoculars with smooth freedom of motion. This morning I stained the pieces and tonight (or whenever the rain ends) I'll give it a nice coat or two of spar polyurethane.  No one is going to mistake it for the handiwork of a skilled wood worker, but it will work. And in the dark of night when it's used no one will notice the rough corners.

Remounting the Finder and Autoguider on my C925

The finder shoe on Celestron's C925 sits a little off-axis, making it more convenient to use. The small stock finder is so lightweight that the torque it produces is negligible. But the torque can become substantial when I configure the scope for imaging. For imaging I use a "Y" shaped mount that carries both a 9x50 finder and Orion MiniGuider. These throw the scope quite a bit off balance around the declination axis.

One solution would be to add a counterweight on the scope's opposite side, but it could be messy trying to figure out how much weight should go where.

A better solution was made possible by a dovetail bar installed on the scope by its previous owner. The bar extends from front to back and is made of stout ADM manufacture; it works great as a sort of handle for lifting the scope.

It was short work to drill a couple of holes in the bar, tap threads into them, and fasten a spare Vixen-style finder shoe I happened to have. This shoe has a flat base and fits perfectly onto the bar. Now the finder/guider tandem sits exactly opposite the scope's base and the torque should be gone.

Now the purchase: Adding Imaging Flexibility

I'm seriously considering adding a DSLR for imaging. This isn't intended as a replacement for my ST-8300M, which gives me the ability to do narrowband imaging from my back yard.

Perhaps this is a case of gear envy brought on by lousy weather. Maybe it's just me getting a little tired of having to shoot flat frames for every channel when I do LRGB. Maybe it's just an itch caused by some unexpected funds coming from the closing of my software business. In any event, I've been investigating used DSLRs.

Let's start with a price point of $600 maximum for a modded camera body. Preferred would something under $400. Under $300 would be great! And because I'm somewhat invested in Canon lenses, I'll consider only a Canon body.

Models being considered are the 40D, XSi, 50D, T1i, T2i and T3i. I've seen and handled the 40D; it's a nice camera, better built to resist the elements than the XSi is. The 50D is said to be a step up from the 40D; of the three Tn cameras the T2 stands out because of its crop mode video capability which makes it suitable for solar system imaging.

Two Rivers Spring Star Party: Image Planning

Sometimes planning seems like an exercise in futility, but it can be helpful when preparing to image far from home.

My first 2015 star party trip is to the Two Rivers Spring Star Party at the May new moon. This is located a little north of Barry, IL on a private farm. There's no power except for recharging batteries, so I'll be running from my big batteries all three nights.

What's to image? There's a cluster of five ALBN objects to go after. Fitting neatly into a 135mm field are LBNs 8, 10, 11, 19, and 1122. All are emission nebulae. 1122 is a brightness four, 11 a five, and the rest sixes. This is an all-night group, complete with a meridian flip around 2 A.M. if the four hours from 10 to 2 aren't adequate. This should make a nice LRGB image!

LBN 10 is located at the red "X" NE of LBN 8and is about the same size as LBN 1122

Assuming there's a second clear night, I'll go after something not possible from Minnesota. LBN 1091 transits at 12:49 at an altitude of almost 16 degrees. This has an LBN brightness of 6, so it's going to be difficult if not impossible.

The rest of the ALBN objects I have to do are better imaged later in the summer. If there's a third night of clear sky I'll do a pretty picture. Maybe an LRGB of the Antares area at 135mm. What're the chances of that?

M51

I changed my imaging plans (as I often do) and imaged M5 instead of M82. I'd have more time on target that way. As it ended up, I had 105m unbinned L, and 40m binned 2x2 of R, G, and B. These were about the longest I wanted to go with the C925 operating at f/10.

I'm still having issues with the image--the sensor plane is not perpendicular to the optical axis. Possibly this happened at the coupling, or potentially much worse is an issue with the secondary mirror. Coma-like stars aside the big issue was the sky brightness. Once again the limiting magnitude was awful, something like 3.5.

Another ongoing issue is the poor showing of blue and the color balance in general.(Note the pink star at left and the blue-green one to the right.) I'm going to be a bit of a purist and suggest that many imagers oversaturate M51 to make the arms a vibrant blue. Something between what they do and what you see above would be more to my taste.

This weekend I hope to return to ALBN imaging, but as the day has progressed the weather forecast has deteriorated. If it clouds out I'll have a chance to clean my optics and work on my binocular holder. Almost time to send in my registration for the Two Rivers Spring Star Party!