Skywatcher 15075

Novelty: I tought myself the use of IRIS. Some images clearly show that I did not substract a dark-rame (yes, I would know how to do it... I was just lazy enough not bothering).

Coma is clearly visible on some of the images; this is due to the focal reducer, needed to get the webcam into the focal plane of the system. The focal reducer I used is one that threads onto the filter-threads of 1,25” eyepiece filter threads. The further distant the focal reducer is to the CCD, the more reduction is resulting, and also, the more aberrations are introduced. For some of the images below the focal reducer was placed as the first element of the imaging optical train, preceding the IR/UV-cut filter and the specialty filter used.

M42

106 frames w/ different exposure lengths (CLS filter)

M45

33 frames (CLS filter)

Horse Head Nebula (B 33 & IC 434)

Full color, as it came out of IRIS (UHC filter)
99 frames of 30s exposures, 0.5 focal reducer

Red channel of above data set, the emission nebula IC434 mainly
radiates (Hydrogen α), thus blue and green simply adding noise only.
Alignment was far from perfect, you might notice the (subtracted)
hot-pixel creeping below the “horse's nose”.

Flame Nebula (NGC 2024)

Full color, “full brightness”, zeta ori barely shows the second component at
the upper left side.

Full color, contrast, gamma and brightness set to optimize on the nebula with still
keeping zeta ori visible in both components.

Red channel image, NGC 2024 is a Hα emitting bright nebulus.
See the hot-pixel strolling into the flame?

M15

M15 globular cluster, f=750mm

M11

M11 open cluster, focal reducer, f=400mm

The Telescope

SkyWatcher SK15075 (on H EQ-5) arranged for visual observations.
The tripod is a little low for comfortable observations; one is kneeling
on the ground, trying to align the eye's visual axis with the optical axis
of the eyepiece.

Last modified February 9^th 2005.