Some astronomical images taken from my backyard observatory:

The link to the images Some okay, some require a better night.

I'm active with astronomy and imaging since 1997.  Since 1996, I moved four times for my work. In 2009, I settled in the northern part of the Netherlands. The skies are reasonably dark here, sufficient to do some CCD astronomy with modern cameras.The SQM value in my garden is about 20.4. Imaging is done from my observatory shed in the garden.

 astronomical obervatory                   

The seeing from this sub urban location is reasonable. The only problem is the rare clear nights. At good conditions on images taken near the zenith, the stars are about 3 to 4 arc seconds wide. 

Currently I use four telescopes:

Telescopes in useTypeSpecificationRemarks
TS APO65Q Imaging star also sold under other brands such as SharpstarAPO65QFlat Field APO,  refractor astrograph 65mm opening, focal length 420 mm, F/6,5Since December 2013. This is a wonderful powerful small
 refractor astrograph. It has flat and coma free focal area
and image scale makes in less sensitive to the seeing and
 guiding errors. Stars are tiny points.
 Ideal for wide field.

APO, 3 lens element objective and build in flattener lens
Dual speed 2" rack and pinion focuser
Diameter of  the corrected field: 44mm.
TS APO100Q Imaging star also know as SVQ100, Sharpstar 100Q ED APO
 astrograph and Tecnosky 100Q.  type test report
APO100QFlat Field APO,  refractor astrograph 100mm opening, focal length 580 mm, F/5,8Since September 2014. A "photo machine". The bigger
 brother of the APO65Q.

APO, 3 lens element objective and build in flattener lens
Dual speed 3" rack and pinion focuser
Diameter of  the corrected field: 49mm
GSRC6, a 6" Ritchey-Chrétien made by GSO and also sold as AT6RCGSRC6 Ritchey-Chrétien - dual hyperbolic mirror 152 mm opening, focal length 1370 mm, F/9Since april 2014 Workhorse for the longer focal length images.
Rather slow, high focal ratio.

Secondary mirror holder obstruction 25% by area
BK7 glass, metal tube,
Grayford focuser
LX200 classic by Meade:LX200 Schmidt Cassegrain 200 mm opening, focal length 1250 mm, F/6,3  Since mid 200. I also have a classic 8 inch classic LX200,
native F/6,3 (mid 2000)  The venerable LX200 F/6,3 is
withouta good correction lens no longer suitable for the
modern large CCD chips. Closer to the  image corners it
 becomes worse due to the optical imperfections either from
coma or quality of the reducer I use. Used currently for visual

Secondary mirror holder obstruction 18.6% by area

The mount used in the HEQ5pro parallatic since april 2014.  

Field of view some CCD calculations and eyepc projection can be calculated with this Excel  spreadsheet 

For guiding an old cute Celestron 90mm f/5.6 Maksutov (500 mm focal length)  white spotting scope is used. The optics are pretty raw and not very good, but due to the relative large 90 mm opening, the attached QHY5 mono guide camera finds always a guide star. It is mounted with a clamp to the vixen dovetail. It accepts 1.25 inch and the mirror doesn't shift after some settling time. In November 2014 I bought a CLS light pollution filter. Here some CLS filter test results

Cameras in use
Active pixels
Sensor size
Pixel size Field of view with APO100Q telescope Field of view with APO65Q Field of view with GSO 6" RC Remarks
QHY5 mono guiding camera. CMOS
Mitron MT9M001, QE 56 % max.
1280 x 1024 6.7 mm x 5.3 mm 5.2µm x 5.2 µm
(2,1 arc sec for 500 mm)
(46' x 37')
- - - In use since 2011

The QHY5 has a large monochrome chip and makes guiding easy
QHY8 cooled OSC (color) camera
Sony CCD, ICX453AQ
3040 x 2016 28.4 mm diagonal, 23.4 mm width, 15.6 mm height 7.8µm x 7.8µm square 2.8 arc sec/pixel     (93' x 141') 3.8 arc sec/pixel     (126 x 190') 1.2 arc sec /pixel       (40 x 60') In use since 2011

Color method: RGB BAYER film on CCD, The QHY8 is a cooled one shot color (OSC) camera with a low noise Sony chip. No darks are not required.In December 2013 it was discovered that the QHY8 was suffering from severe tilt. This is now fixed using rubber strips / rubber support.
ASI1600MM-Cool,  cooled mono imaging camera. ASI1600MM-Cool Panasonic CMOS,  MN34230ALJ  4656 x 3520 21.9 mm diagonal, 17.6mm width x 13.3mm height   3.8 µm x 3.8 µm 2.6 arc sec bin_x_2
(79' x 105')

1.3 arc sec bin_x_1
3.8 arc sec bin_x_2
(110' x 145' )

1.9 arc sec bin_x_1

1.2 arc sec bin_x_2
(34' x 44' )

0.6 arc sec bin_x_1

In use since 2016.

Cooled mono camera, cold CMOS.

In 2017 the focuser was  motorised  to cope with the focus drift due to temperature changes.

For sun images, a home made filter based on Baader solar film is used:
   Sun filter

For flat fields I use a photo frame with an EL panel EL panel on top of the telescope  previously I used a light box. 

APO65Q images:

Below some images showing the potential of the APO65Q. Initally the LX200 was used a platform  but now the HEQ5. Better images will come if the weather allows. Sometimes images where made during the moon was shining resulting in more background noise.

M101 M13 M51

The link to the rest of the images Some okay, some require a better night.

APO100Q images:

Below some images showing the potential of the 100Q:

M31 by 100Q NGC7000

I'm using use a 34 cm long dovetail so that I can mount the guiding scope at the front. It requires some distance rings between the brackets and dovetail otherwise it will touch the dew cap. Adapted 1/4 inch screws not too long are required.

The 100Q is pretty new. There are three reviews available on the web: 1 and translated 2, 3

The link to the rest of the images Some okay, some require a better night.

As an experiment I tried the focal reducer CCDT67 in combination with the APO100Q without succes. Stars at the corners become lines like the image is slighly rotated around the center.

GSO Ritchey-Chrétien images:

The GSO RC6 was tested at the optical test bench of H. Dekker. The optics where fine at the centre after good collimation. Ronchi test showed nice lines and the artificial stars showed a nice diffraction pattern. First astro images however where not successful. After many experiments with the low cost Orion/Skywatcher flattener at different distances, I achieved good results at 72 mm chip-flattener distance (designed for refractors at 55mm). At shorter distance the stars at the corners of the 23x15mm CCD chip become a little elongated like comets. According the literature they should be oval due to astigmatism and curvature. A 1/4mm focus adjustment gave the best focus in the corners but still not a perfect star indicating the amount of curvature . So with a flattener the telescope is performing as desired. Imaging using a focal reducer CCDT67 as recommend by some was not successful even at only 0.8 reduction. It is not possible to use it combined with the flattener since the flattener is too long. Without the the flattener the curvature doesn't go away.

 Here my description how to collimate the RC.

Here the first image at 72 mm distance:

M56 with flattener at 72 mm

- The link to the rest of the images 

Two studies I did:

- Counting stars and an empirical formula for estimating the number of stars in an area:

The brightness (SQM) value of the twilight sky

Last update 2017


The weather forecast and actual satellite image: