24 Feb 2018

After a star tracking project I got hooked on astronomy. This post wraps up my first attempt photographing the Moon.

Astrophotography can get extremely expensive. I’m a rookie therefore I tried to keep everything affordable. My 300$rig: The Raspberry Pi 3 connected to the camera An "extra" universal T-Adapter The rig assembled and ready ## First Image 31. January 2018, the Blue Moon and a clear sky made a perfect opportunity for a first test. I pointed the equatorial mount towards the celestial north pole and adjusted the motor to account for the Earth’s rotation. After I attached the “extra” universal T-Adapter the telescope was ready. Then I adjusted the focal point using raspistill’s preview over Wi-Fi 1. A Blue Moon has nothing to do with the color After a bit of fiddling with the parameters I decided to set shutter speed to 10 seconds and leave everything else untouched. This was definitely not a smart move. Fine-tuning recording parameters is important. Moreover, automatic tuning of parameters will ruin your long running recording series! But for this first project the goal was to accumulate know-how. The perfect shot is out of my reach, yet. $ raspistill \
--stats \
--mode 3 \
--encoding bmp \
--quality 100 \
--timestamp \
--output 'moon%d.bmp' \
--shutter 10000 \
--timeout 0 \
--nopreview


I choose to use BMP encoding for the images. Simply because I thought a bitmap is the closest I can get to a RAW image. This assumption is false. The BMP file format is is much more complex than I assumed2. Next time i will try extracting the RAW data from the JPEG as described in the awesome Picamera documentation. Between 2018-01-31T22:07:53+00:00 and 2018-02-01T00:07:37+00:00 I then finally started recording.

moon1517436473.bmp: The first image

Well, the images are generally too red and blurry. I tried to correct this during post-processing.

## Post-processing

First I manually removed distorted and extremely blurry images. Leaving me with 139, worth 3.2 GiB of data. hugin 34 then assembled the panorama below. Again, everything on default parameters with a 20° field of view.

Assembling the Moon in hugin

The unprocessed panorama

The result is still red and blurry. This is why I then applied the following transformations in gimp:

1. Desaturate
• Average strategy
• Brightness: -60
• Contrast: 60
3. Despeckle
• Recursive
• Black level: -1
• White level: 256
4. Sharpen
• Sharpness: 50

The processed image

## Final Thoughts

Compared to the imagery on wikimedia mine is a child’s drawing. But it’s mine! I am happy with the result because I was able to identify a lot of things to improve and test:

• Write a program which finds automatically the best recording parameters
• Find a procedure for motor calibration