Sky this Week

There is a possibility for us in Colorado this month to break some thin crescent observing records that Peter mentioned in his blog last January. Inspired by that prospect (or maybe temporary insanity), I got up about 4:30 am this morning, packed up the notebook, binoculars, and camera and headed off to a parking area east of Louisville’s Monarch High School to see if I could spot the waning crescent. I started scanning the horizon at 5:40 with 10×50 binoculars but wasn’t able to see it until 6:03 am, only 20 minutes before sunrise. Only a thin patch was visible, maybe 10 arc minutes long. At first I thought it was just a small jet contrail as contrast between it and the background was better than expected. Also the azimuth was to the south (right) of sunrise point. I had figured earlier it would be to the north (left). A quick check with sky chart software confirmed that the position was correct and I’d been searching mostly in the wrong direction earlier.

I changed my position so that the limb of a distant tree was just below the crescent to see if I could see it without the binoculars. I was able to see a small light point that matched with the binocular position. I switched between binoculars view and no binoculars several times to check. I was only able to spot the faint patch only twice out of 5 or so tries though, so it was at the muddy edge of visibility.

I also shot a number of images of the horizon with a Canon Xti but used too wide an angle. I suspect high magnification is needed to increase contrast between the bright twilight and the scarcely brighter thin crescent. Sky was mostly clear, no wind, temperature was 47° F, transparency excellent, turbulence fair or better.

Unfortunately, weather is turning rainy for a few days here, so the prospects for seeing the new crescent Tuesday evening and breaking the crescent moon bracket interval aren’t looking good.

Update April 17

The skies cleared late in the afternoon, so I packed up the cameras, scopes, and other equipment and set up at a trail head on Davidson Mesa just off nearby McCaslin Blvd. Unfortunately there was a band of clouds over the mountains to the west which was in exactly the wrong place. It was clear to the south, north, and overhead. Maybe next year..

Last evening 14 of us in the Boulder, Longmont, and Fort Collins astronomy clubs met at Crow Valley Campground north of Briggsdale, CO for a very enjoyable night under dark skies. Conditions were very good — one of those evening we all hope for but only rarely experience. Excellent transparency, a cloudless sky, no wind, and even fairly warm temperatures for this time of year. Temperatures were in high 40s and 50s early in the evening so most of us were in light jackets until 9 or 10. Turbulence was only fair, about 5/10 most of the evening. It got a bit frosty around 4 am with temperatures in the low 20s. In Colorado you soon learn to bring your cold weather gear along year round, so it wasn’t a problem for most.

I spent most of the evening checking off spring objects in Ursa Major and Canes Venatici. I held off imaging until just before 4 so I could catch Jupiter’s red spot and comet Lovejoy. I tried for 96P Machholz as well, but it was behind the trees to the east.

I managed to get in some practice shooting the crescent moon at dawn in preparation for tomorrow morning and Tuesday evening this week. The shot above was not the best. I had better composition in some earlier shots which I lost due to an incorrect setting in my focusing software — it deleted all but the last image taken. In early shots the moon was lower and the wind mill wasn’t against the tree in the background. Darn… It makes a fairly nice desktop wall paper though, despite the obvious flaws. Here is a 1280×1024 version.

A group of us from astronomy clubs in Boulder, Longmont, and Fort Collins met this weekend at Crow Valley Campground just north of Briggsdale, CO in the Pawnee National Grasslands. Due to snow and cloudy weather it was the first night since last October we were able to enjoy some truly dark skies.

It was a fabulous night! The sky was clear all night, turbulence was 6/10, no wind, the transparency was excellent, and humidity was low. We were in shirt sleeves until about 8pm (temperature in high 50s) and we didn’t have to put on much winter gear until the temperature dipped to freezing around 1 am.

I succombed to Messier madness for the first time. I cheated and used the Nexstar 11 “goto” to locate most of them. Except for M74 and M55 all 109 objects were trivial to locate. The scope performed flawlessly and put most objects within the middle 1/3 of a 30 arc-min field. Only a few were off a half a field — and it did it all night long without even a resync. I’ve recently had problems with “goto” accuracy. A few days ago I located a loose connector going to the altitude sensor micro-switch .

While waiting for some Messier objects to rise in the early morning, we had time to visit some favorites like the Veil nebula, blue snow ball, blinking planetary, NGC 4565, ghost of Jupiter, and many others. Saturn was excellent and even Jupiter was looking good in the steady air despite being low in Sagitarius.

I didn’t try for the 110th object, M30. We had a tough time locating globular M55 shortly after 6. M30 wasn’t due to rise for another 20 minutes. I’ve read that M30 is extremely difficult, and maybe impossible to locate unless the date and everything are just right if you are north of 35 degrees latitutde.

Only downside was that I had planned on doing a couple comets and the Pluto occulation with the Stellacam2. Unfortunately, the driver for the video card I use crashed the notebook and removed all the other video drivers in the process. The video card is going to be reassigned to the trash shortly.

Last evening I met up with some members of the local astronomy clubs in Boulder, Longmont, and Fort Collins, Coloarado at Crow Valley Campground near Briggsdale. It was quite cold, around 3 °F, no wind, clear sky, turbulence 7/10, and fantastic transparency. Unfortunately, I forgot my counterweight, dew shield, and dew heater. Lucky for me Dan was there and let me use his catalytic heater to clear off the corrector plate so I was able to do some imaging. It was pretty frustrating though as the clutches would slip now and then from the unbalanced load.

Compare this to one I took on Jan 29 — excellent transparency makes a difference!