Astronomy Archives

DIY Motorized Focuser for FSQ 106ED Telescope

The goal of this project was for the automated focusing system to have great holding torque (80Ncm) for heavy image trains (4-5kg) and very fine steps to accommodate the super tight FSQ106 critical focus zone.

The formula to calculate the critical focus zone on a telescope is :
CFZ = Focal Ratio * Focal Ratio * 2.2
For the FSQ106ED we have : CFZ = 5 * 5 * 2.2 = 55microns
So to be able to have perfect focus achieved we need every step on the motor to be 55microns or less for even better resolution.

The motor used on this build is geared and has a reduction of 250:3 which gives us 4000 steps per revolution.

One full revolution on the focuser coarse knob (where we are coupling our motor) makes the focuser move 29.8mm.
Now we have all the data we can do the maths 😛
(29.8mm * 1000) / 4000 = 7.45 microns per step.

The actual resolution achieved with this build is 7.45 microns per motor step!

Astrophotography – Moon Mosaic Part II

Date : 26/04/2020
Telescope: Vixen VC200L
Camera: ZWO ASI120MM-S

6 part mosaic comprised of 800 frames for each panel.
Stacked on registax and then assembled in Pixinsight.

The Moon today is in a Waxing Crescent Phase. A Waxing Crescent is the first Phase after the New Moon and is a great time to see the features of the moon’s surface. During this phase, the Moon can be seen in the western sky after the sun dips below the horizon at sunset. The moon is close to the sun in the sky and mostly dark except for the right edge of the moon which becomes brighter as the days get closer to the next phase which is the First Quarter with a 50% illumination.

NGC6910 Gamma Cygni and nebulosity

HaRGB version of the beautiful Gamma Cygni and surrounding nebulosity region.

NGC 6910 is a Y-shaped cluster oriented northwest southeast. The two brightest stars are of magnitude 7.NGC 6910 is a small cluster, only 10′ in diameter

The southernmost star is SAO 49563 (or V2118 Cygni), a variable star of spectral type B1.5Ia. Gamma Cygni, not far off the galactic plane is subject to a great deal of interstellar extinction and reddening from interstellar dust. The dust selectively absorbs and scatters blue light (roughly 1/wavelength), so when you look at a star through dust it will appear redder than it really is (basically the same reason the sun is reddened at sunset). The intrinsic B-V color of a B1.5Ia super giant is -0.2. The observed color is 0.83, about the color of a K0 dwarf or a G5 giant, so the star appears yellowish to the eye. Notice the yellow stars in the cluster, caused by interstellar dust, and the bluish-white stars in the vincinity of NGC 6910.

Technical details
Sky-Watcher 80ED Pro Black Diamond
SBIG 8300M
HEQ5 Pro
QHY5
Skywatcher .85x Focal Reducer & Corrector
PixInsight, Main Sequence Software SequenceGeneratorPro
Accessories: Starlight Xpress Starlight Xpress FW 5*2”
Resolution: 1676×1266
Dates: June 13, 2015

Frames:
Baader 7nm Ha 2”: 10×300″ -5C bin 2×2
Baader Blue 2″: 10×120″ -5C bin 2×2
Baader Green 2″: 10×120″ -5C bin 2×2
Baader Red 2″: 10×120″ -5C bin 2×2

Integration: 1.8 hours
Darks: ~50
Flats: ~10
Bias: ~300
Avg. Moon age: 25.75 days
Avg. Moon phase: 15.29%
Bortle Dark-Sky Scale: 2.00
Temperature: 17.50

Annotated version :

M106 Spiral galaxy and neighbors

Messier 106 (also known as NGC 4258) is a spiral galaxy in the constellation Canes Venatici. It was discovered by Pierre Méchain in 1781. M106 is at a distance of about 22 to 25 million light-years away from Earth. It is also a Seyfert II galaxy. Due to x-rays and unusual emission lines detected, it is suspected that part of the galaxy is falling into a supermassive black hole in the center. NGC 4217 is a possible companion galaxy of Messier 106.

Contains: NGC 4346, M 106, NGC 4258, NGC 4248, NGC 4220, NGC 4217

Characteristics
M106 has a water vapor megamaser (the equivalent of a laser operating in microwave instead of visible light and on a galactic scale) that is seen by the 22-GHz line of ortho-H2O that evidences dense and warm molecular gas.
These water vapors give M106 its characteristic purple color. Water masers are useful to observe nuclear accretion disks in active galaxies.
The water masers in M106 enabled the first case of a direct measurement of the distance to a galaxy and thereby providing an independent anchor for the cosmic distance ladder.M106 has a slightly warped, thin, almost edge-on Keplerian disc which is on a subparsec scale.

It is one of the largest and brightest nearby galaxies, similar in size and luminosity to the Andromeda Galaxy.
M106 has also played an important role in calibrating the cosmic distance ladder.
Before, Cepheid variables from other galaxies cannot be used to measure distances since they cover ranges of metallicities different from the Milky Way’s.
M106 contains Cepheid variables similar to both of the metallicities of the Milky Way and other galaxies’ Cepheids.
By measuring the distance of the Cepheids with metallicities similar to our galaxy, astronomers are able to recalibrate the other Cepheids with different metallicities, a key fundamental step in improving the distances to other galaxies in the universe.

Technical details
Sky-Watcher 80ED Pro Black Diamond
SBIG 8300M
HEQ5 Pro
Guiding : QHY5
Skywatcher .85x Focal Reducer & Corrector
Software: PixInsight, Main Sequence Software SequenceGeneratorPro
Accessories: Starlight Xpress Starlight Xpress FW 5*2”
Resolution: 1676×1266

Dates: June 13, 2015

Frames:
Baader Blue 2″: 15×240″ -5C bin 2×2
Baader Green 2″: 15×240″ -5C bin 2×2
Baader Red 2″: 15×240″ -5C bin 2×2

Integration: 3.0 hours
Darks: ~50
Flats: ~10
Bias: ~300
Avg. Moon age: 25.75 days
Avg. Moon phase: 15.29%
Bortle Dark-Sky Scale: 2.00
Temperature: 17.50
RA center: 184.451 degrees
DEC center: 47.451 degrees
Pixel scale: 4.272 arcsec/pixel
Orientation: 176.036 degrees
Field radius: 1.246 degrees

Annotated version :