Posts Made By: Roland Christen

I'm posting this for those who have experienced some tracking issues where the guide star seemed to jump in RA or Dec by several pixels during a normal run. I experienced this last night after a 4 hour imaging session where tracking was on the order of 1/4 pixel. Traced it down to the camera cable rubbing on the pier strut. Just touching the cable actually sent the guide star back and forth by several pixels in both RA and Dec.

It turns out that while the mount is slowly advancing in RA the cable was slowly dragging across the pier strut in a stick-slip mode. This was enough to move the guide star by as much as 5 pixels. Since the mount is always moving in RA, this is the direction that the cable is being pulled and this is why the guide star moves primarily in RA.

In the attached screen shot you can see the first RA guide star anomaly marked by a red 1 arrow. The second one occurred about 5 minutes later (red 2 arrow). When I saw that I went to the mount and gently touched the heavy power cable coming from the STL11K camera. The guide star jumped around 5 pixels as marked by the green 3 arrows. Even though the camera, focuser and scope were properly tightened down, still a loose cable dragging will cause the guide star to jump around by several arc seconds.

So, the advice I have for imagers is to not hang the cable down. Rather tie it securely to the mount Dec axis before looping it down to the ground. Either that or run it inside the mount, but again secure it to the scope body so that it cannot tug at all on the camera body.

Not exactly deep sky imaging, but for those who love a deep crystal clear sky, the IDA has announced the first International Dark Sky Sanctuary in the Chilean Andes:
In the Chilean Andes:

http://darksky.org/chilean-astronomical-site-becomes-worlds-first-international-dark-sky-sanctuary/

I was fortunate to spend a week at this site last year doing some maintenance work on University of Chile telescopes. A fabulous place for deep sky observing. It has now been designated as the first international dark sky sanctuary. The views from the 8000 ft. elevation are breathtaking with sub-arc second seeing on the majority of nights. Nearby towns in the valley are growing at a rapid rate and light pollution does threaten this area unfortunately.

Uncadeepsky

The Milky Way in Cygnus from the Propeller nebula to the Tulip Nebula. Crescent nebula in the middle, Sadr nebula near center bottom. This image is reduced to about 16% of its full resolution size (I also posted a larger version in the gallery section).

Image taken with 130EDX refractor at F4.7 with the Quad TCC. Camera STL11K, Filter Astrodon 5nm H-alpha. Mount AP Mach1 mounting. Exposure between 1.5 and 3 hours per frame.

Rolando

Since my observatory is now embedded in severe light pollution, I have taken to imaging in narrowband. here is an image of Andromeda Galaxy in H-alpha. It shows a nice ring of hydrogen "flowers" around the periphery of the galaxy. 10 x 15 minute exposure with 130EDX refractor at F4.5

Rolando

A quickie image on a night of mediocre seeing with the nearly full Moon up. Nevertheless, was able to get a workable image while testing a mount and astrograph. 6 x 5 minute LRGB exposures, QSI 683 camera.

Rolando

Why not pass on it and let the next person in line have a go? You obviously don't want it.

Rolando

Anyone know what has happened to the Customer Gallery?

Rolando

Taken with 16" astrograph over the last 3 nights, 24x10 minute exposures, crop from center of STL11k frame. May do color later.

Rolando

The rising Moon last night flooded the hazy sky with light, making deep sky imaging impossible. So instead I took a single image in H-a light, 1/10 sec exposure. And then closed up the observatory.

Rolando

Finally a clear night to shoot this very colorful galaxy. I had very limited time to shoot Luminance and RGB. Only 3 x 5 minute exposures of each color and 10 x 10 minute Luminance. No time for flats or darks in the RGBs unfortunately. Imaged with AP 305F3.8 Riccardi-Honders, QSI 683WSG camera. If skies co-operate I will take more RGBs to get a better noise-free image. Even though it looks like I took H-alpha for the red, there is not any H-a added to this image.

Rolando