SAO 24929 (7 Camelopardalis)

While I was looking for galaxy UGC3217 on the 2003-01-25 imaging session (which I didn't find), I took this overexposed image of SAO 24929. Nothing interesting to see here, but the only result of that session.

Galaxy NGC3631

Another binning test.

2003-01-18: 4 minute 2x2 binned exposure (4x60s). Camera cooled to -29°C.

Galaxy NGC 891

On my third imaging session I have been experimenting with binning. This image was made with 2x2 binning. Because the ST-7XE main CCD doesn't have many pixels to begin with, then resulting image is rather small. However, the sensitivity for each pixel is increased fourfold, and the well depth twofold. For LRGB imaging and photometry this will certainly have its uses. In this case, with normal binning I would only have reached the depth of this image after 42 minutes, instead of the 10.5 minutes used here.

2003-01-18: 630s 2x2 binned exposure (21x30s). Camera cooled to -30°C.

Mirach (β Andromeda)

I found this overexposed image of Mirach between my images of the 2003-01-18 imaging session. Nothing interesting to see here, except for the faint star at 11h relative to and close by Mirach, which is the magnitude 14.2 GSC 2286:693. After all, this is only a one second exposure.

Galaxy M63

2003-01-18: 150s exposure (5x30s). Camera cooled to -30°C.

Globular Cluster M3 (NGC5272)

2003-01-18: 150s exposure (15x10s). Camera cooled to -30°C.

Galaxy M81

While experimenting with automatic tracking and stacking, I took this image of galaxy M81. The polar alignment of the telescope was poor, hence the common part of all sub-images was relatively small. So I ended up with a galaxy not even fitting in the final image.

Anyway, the spiral arms and dust in this galaxy are obvious.

30x30s exposures combined (total 15 minutes). Camera cooled to -25°C.

Planetary Nebula M76 (NGC 650) in Perseus

For the second imaging night with the ST-7XE, I mounted the telescope in Polar Mode. This is the first time I used the tracking CCD of the camera for automatic guiding of the telescope and I experimented with automatic tracking and stacking. The striping in this final image is the result of poor polar alignment and the sub-exposures being too short.

In this image of M76, commonly known as the Little Dumbbell Nebula, the bright expanding elliptical ring seen almost edge-on is quite obvious. The dim "wings" along the axis perpendicular to this ring are visible as well, although barely in this image. Both of these structures are expanding.

20x15s exposures combined (total 5 minutes). Camera cooled to -25°C.

Galaxy M82

That same night I pointed the telescope towards the irregular Galaxy M82 (NGC 3034), in Ursa Major (Big Dipper). Its visual brightness is magnitude 8.4 and apparent dimension 11.2' x 4.3' (Uranometria 2000 2nd ed.).

For this object I enabled the telescope tracking and used a focal reducer. With the ALT-AZ mounted telescope, the longest exposure I can take in this area of the sky at this focal length (about f/6.9), without the effects of field rotation causing the stars to streak too much, is about 30 seconds. This single unguided 60 second automatically dark subtracted image is the best result of this night. The camera was cooled to -25°C.

The amorphous galaxy M82 contains a starbursting nucleus. Images in the light of ionized Hydrogen and Sulfur show vast filaments of ionized gas streaming away from the galaxy. In the image below, this ionized gas is not visible, but dark dust lanes and patches in the central part of M82 are. The central dark dust lane can be observed visually as well with the same telescope. The stars in this image are all part of our own galaxy. Their distances are up to a few hundred light years. M82 itself lies far beyond the borders of our galaxy, at a distance of about 12 million light years.

One minute exposure. Camera cooled to -25°C.

Polaris (North Star)

This is the first image of an astronomical object I ever took with my ST-7XE camera. Last night, I mounted the telescope in ALT-AZ mode, attached the camera, pointed the telescope to Polaris, roughly focused it, and shot this 10 second exposed image. The camera was cooled to -10°C.

As this was just a simple camera check, even the telescope tracking was completely turned off.
Polaris itself is completely overexposed in this image, and the raw image contains blooming streaks above and below the star, proving that this camera indeed has a NABG sensor. You see, Astronomics initially sent me an ABG version, which I returned immediately after discovering this using a pin-hole test.

I manually cleaned the blooming streaks (some artifacts are still visible), and used non-linear histogram stretching to improve the visibility of the companion.

Polaris is a binary star at a distance of 431 light years, consisting of a bright magnitude 2 supergiant and a much dimmer magnitude 9 main sequence star, separated by about 18 arcsecs. Even though this 7 magnitude difference makes it a bit harder, I found on 2005-03-25 that I could easily resolve the binary with my 80mm refractor at a magnification of 31x.

From the original (bloomed) image, I determined that the apparent distance between the two components is 26.7 pixels. Attaching the camera directly to the focuser therefore results in a system with a focal ratio close to f/11.

The same night, I also took my first image of galaxy M82.