Special Projects
  • Project Pluto - or "Back to the roots" by Dr. L. Schmadel, Dipl.-Ing. W. Paech und Dipl.-Ing. F. Hofmann

This site describes the attempt to take an image of the dwarf planet Pluto with modern photographic technology and a 2-inch telescope.

Back to Special Projects
Images - SUN
Images - MOON
Images - DEEPSKY

July 11-13, 2015 - Project Pluto

A few years ago, probably at the time when the Pluto probe New Horizons was launched, Dr. Schmadel from the Astronomical Data Center Heidelberg and Dipl.-Ing. Paech sat with a beer together. Somehow the idea arised whether it is possible to take an image of Pluto with a classic 2-inch telescope and modern photographic technology or whether a larger telescope is necessary.

The idea disappeared over the years out of the heads, but arised again with the planning of the Namibia stay from Paech in 2015. In these days the New Horizons probe should also reach its destination. So the project Pluto was revived and a two-inch telescope was needed. All of the following images can be enlarged by clicking on it.
The objective should have a better quality than the cheap Chinese products. And it should have precisely an aperture of 2 inch.

Zeiss Jena sold the traditional 50/540 mm lens for decades. Therefore contact with Baader Planetarium was established because they once offered the complete range of Zeiss amateur products.
Mr. Thomas Baader was very interested in the project and searched and found a Zeiss Jena objective FH 50/540 mm "deep in the Baader Planetarium cellar" and made it available for the project. The 50/540 mm was traditionally sold as C-lens, but there were some lenses designed as Fraunhofer lenses, i.e. the FH 50/540 mm. The focal ratio is f / 10.8.

This small telescope was built in the cellar by Paech. The focuser comes from the "leftovers box" and is not very good. A tipping of the tube was minimized by a very tight installation of the rack into the flange. The three pictures above show (from left to right) the Zeiss lens, the sketch of the tube and the finished "Pluto telescope" before painting. The large telescope in the background is a 125 mm refractor under construction.

The finished telescope was roughly tested for its imaging quality and focal position in Germany by Paech. Afterwards it was wrapped in a padded poster roll and went off in a normal case to Namibia.

In Namibia it was mounted on a transportable Celestron CGEM-DX. In parallel, a Pentax 105, which served as guiding telescope. A Canon EOS 60 D was used for taking the images.

In the night from 10.7. to 11.7. some test images were taken for checking the imaging quality and the limiting magnitude.
The two images to the right show Eta Carinae (NGC 3372) and "Herschel's jewel box" (NGC 4755, the brightening the lower image comes from the star Beta Crucis). The exposure was 5 x 120 seconds at 640 ASA (NGC 3372) and 5 x 60 seconds (NGC 4755). The night temperature was about 15 degrees celsius (it was spring in Namibia).

Apart from the expected blue halos (mitigated in image processing) and elongated stars in the corners shows the lens a decent figure.
Pluto was at that time in the constellation Sagittarius, near the stars Xi 1 and Xi 2 with a brightness of 14.3 mag. Compared to the discoverer - Claude Tombaught - we have the advantage of knowing the exact position of Pluto from a planetarium program. The left image shows a gif animation between GUIDE 9.0 (by the company Project Pluto - Nomen est omen :-)) and a telescopic image (11.07.2015, 640 ASA, 300 seconds). In the right image Pluto is marked.

Both images can be enlarged by clicking on it.
Unfortunately Pluto was very close to a 14.86 mag star in the first image and we had some tracking errors in the 5 images. On 12 and 13 July the images were taken again, also for verifying the proper motion.
The animation on the left side shows the movement of Pluto from the 12th and 13 of July.
This link shows an animation of the movement between July 11 and 12.

The image to the left shows the entire field with the marked Pluto position on July 12, 2015. The orientation of all images is: north up, east left.

Click here for a large image
Conclusion: There are 5 good images (800 ASA, t = 300 seconds) in Canon raw format from the night between July 12 and 13. The images here are single images in jpg format. The image quality shown here is expected to improve with the addition of the raw images. But already, the single images (limiting magnitude about 16 mag.) show Pluto clear and obvious. It can be said: project Pluto successfully completed. It does not always have the 20 inch model, also with small telescopes you can get great results.

Many thanks to Mr. Thomas Baader and the Staff of Onjala Lodge in Namibia for supporting the "Project Pluto"

Sun Moon Solar System DeepSky Widefield Miscellaneous Spec. Projects

All Images and all Content are © by Franz Hofmann + Wolfgang Paech