Thursday, June 25, 2015

Nebraska Star Party Weather

If last year was your first trip to NSP you probably came back wanting to return in 2015 to enjoy even more mild weather. I know I did.

 2014: Uncommonly Cool

This was not a year that people returned with stories of blistering heat or gear-toppling thunderstorms. The first four days were a cool eight or nine degrees below normal, nighttime lows were in the 40s twice, winds were light most of the time and no precipitation fell.  Daytime skies were generally clear to partly cloudy, and no weather (thunderstorms, fog, haze or smoke) was reported. There was an amazingly tiny total of 11 cooling degree days for the period compared to a normal of 50.

Daily summary for Valentine during NSP 2014: 
Date          High Low Departure
July 27 (Sun) 84   50  -8 
July 28 (Mon) 83   49  -9 
July 29 (Tue) 78   54  -9 
July 30 (Wed) 86   49  -8 
July 31 (Thu) 88   52  -5

2015: What to Expect

The average maximum temperature is around 90 and the overnight low (which you'll feel only if you're still up observing or imaging at sunrise) is around 60. Every day has about a one-third chance of a thunderstorm, so of the five days it could be expected that there be one or two with thunder.

Daily Averages for Valentine during NSP 2015:
              Average   Record 
Date          High Low  High Low
July 12 (Sun) 89   60   109  42 
July 13 (Mon) 89   60   107  41 
July 14 (Tue) 89   61   105  44 
July 15 (Wed) 89   61   110  40 
July 16 (Thu) 89   61   113  45 

In other words, last year was an outlier in a good way. You shouldn't expect it to be repeated this year, but no one will complain if it is!

Sunday, June 21, 2015

First Light Image for Gary Honis Modded Canon T2i

Two weeks after getting my camera back from Gary Honis the clouds parted, the moon was out of the sky, and my schedule permitted me to try it out. Finally!

As a target I chose The North American nebula, something I'd imaged before with my ST-8300 in LRGB. The imaging site had light green sky brightness, not nearly as dark as for the CCD image. The telescopes were nearly the same, an AT72 at f/6 vs. my current AT65EDQ at f/6.5. Total exposures were 81 vs 100 m so it's almost a dead heat in terms of expected brightness. Because of the high humidity and the lack of a window heater the CCD was cooled only to about 0C.

Here's the T2i image:

NGC 7000 with Canon T2i and AT65EDQ at Cherry Grove 2015
and here's the ST-8300M image:
NGC 7000 with SBIG ST-8300M and AT72 at Iowa Star Party 2013
The difference is mainly one of brightness and contrast, which is almost certainly a result of my processing. I think the CCD image is a little washed out. I like most aspects of the DSLR image except for the vertical bands that are most apparent on the right portion of the image. These appear to come from the dark frames (I shot only six) and my inexperience processing DSLR images.

Related to those bands, one big change I'm going to make this year is learning how to dither. Based on what I've read it's helpful to let the camera cool after the image is read, and that "lost time" is perfect for dithering.

For this image I powered the camera using the Neewer AC power adapter and controlled the acquisition with the Neewer controller. Both worked perfectly.

Only a little over three weeks remain before the Nebraska Star Party. I've prepped three images for the astrophotography contest, one from Jeffers on the way to the 2014 NSP, one from my first night at NSP, and one from last fall. I need to give my binocular mount a couple more coats of varnish and it will be ready to go.

Wednesday, June 3, 2015

Canon T2i Returns from Gary Honis; Some Accessories for It

My camera is back from Gary Honis, its Baader modification complete. Now stop me if you've heard this before: The imaging weather looks to be bad for the next week or so. *sigh*

So let's talk accessories. Last time I wrote a little about the Neewer shutter control. Now that the camera is back I've been able to give the controller a try. I'm happy to say that it works flawlessly with the T2i.

Three other things I've gotten for the camera work great, too.

The Photive battery charged nicely, but only time will tell how well it serves for astrophotography. I've got three batteries in all (two are original Canons) and my hope is that together they can supply enough power for one full night of imaging.

The Neewer AC power adapter also runs the camera nicely. After the batteries fail I can switch over to an inverter or my Duracell battery with its built in inverter.

An M42/Canon EOS lens adapter also seems solid and lets my ancient Vivitar 28mm f/2.5 fixed-focus lens focus at infinity. I also have a big old 400mm lens that can use the adapter. I'll probably never image with that lens because it's so similar in focal length to my AT65. That and its optical quality is nowhere near that of the little scope.

When the skies finally clear it will be time to test Honin's work. I hope to travel north to a friend's home (with darker sky) and see what it does with the AT65 and IC 1396.