KING 70cm Telescope

• Location

Name	MPIA, Heidelberg
Latitude	N 49º 23' 44"
Longitude	E 08º 43' 25"
Altitude	560 m

• Mechanical Characteristics

Mounting	German Equatorial mount (49º 23m)	​link
Structure
Right ascension axis
Declination axis

• Optical Characteristics

Aperture	70 cm
F#	8
Focal distance	5600 mm
Plate scale	27 μm/arcsec (37 arcsec/mm)
Field of View (without coma)	11.7 arcmin = 18.95 mm (without corrector)
Field of View (maximum usable)	20 arcmin = 32.4 mm
Configuration
Focal station	Cassegrain
Focus mechanism	Secondary mirror
Focus range

• Other Characteristics

	GROB = fast	~ 90 deg/min
Speeds	MITTEL = medium	~ 30 deg/min
	FEIN = slow	~ 1 deg/min
Pointing accuracy without correction	10-20 arcmin
Pointing accuracy with correction	< 1 arcmin
Tracking	15 arcsec/sec
Unguided observations	up to 180 s

• Documentation
  • Operations manual This document contains the instructions of how to operate the Telescope, the dome, and the CCD. We encourage you to use it.
  • ./Maintenace?: xxx, xxx

KING 70cm Telescope Documentation

This telescope, built under the directorship of the MPIA's founding director, Prof. Elsässer, was completely designed and manufactured by the in-house Mechanical Design and Construction Group (Mr. Belleman) in the early 1980's. The electronic drive was also constructed by members of the institute.

A bit of history (according to Ulrich Grözinger's excellent memory): Design and construction at MPIA, start of project ~1981 (as filler project). A very similar copy was build. The copy was originally planned for the ​Gamsberg in Namibia, partially owned by MPIA, but eventually given away to an association of amateur astronomers. KING was erected in the Eastern dome of the Elsässer lab in May 1986, first light in June 1986, first presentation to the public at the open-house day in July 1986.

The telescope was initially used for testing and improving astronomical instruments built for the Observatory on Calar Alto (Almería, Spain). The telescope was maintained to be in an operational mode at all the times, though more attention was given to purely mechanical rather than astronomical function. As time went by, the instrumentation being designed and built for Calar Alto became heavier, and therefore no longer possible to mount these large instruments on the 70 cm telescope. Since then, the 70 cm telescope was mainly used to demonstrate the behavior and work of a professional telescope to visiting groups of for small observational programs of members of the institute.

In 2014 a CCD and its control electronics were installed. This upgrade from the more than 20 years old system provided the telescope with an operational CCD with hopefully at least another 20 years to go. This CCD is currently in operation. During 2020 the old computer (from 2014) was renovated and the CCD control software migrated to the new computer.

Although the telescope remains operable, it sees less and less use as time goes by.

Furthermore:

Spiegel wurden von Fa. Kaufmann in Crailsheim beschafft.
Sockel ist mit Sand gefüllt (ca. 1.5t), Frontring ist ausgeschäumt
Bleigewichte (zum Auswuchten) am MPIA gegossen, Auswuchtgewichte f. Stundenachse
(Gegengewicht) können durch elektr. Taster am Pult verschoben werden.
Die Auflösung der Inkremental-Positionsencoder beträgt rechnerisch 50 marcsec. 

-----Translation by DeepL----
Mirrors were purchased from Kaufmann in Crailsheim.
Base is filled with sand (approx. 1.5t), front ring is foamed.
Lead weights (for balancing) cast at MPIA, balancing weights for hourly axis
(counterweight) can be moved by electric push-buttons on the console.
The resolution of the incremental position encoders is 50 marcsec.

We uploaded the scanned original documentation including all schematics. For detailed construction drawings please consult the archive of the MPIA construction department ​link. Downloads:

• MPIA_70cm_Teleskop design A few drawings to start with giving the size scale of the hardware.
• Overview drawing from scanned documentation (PDF, 2.1MB) Includes schematic drawings of control desk, main electric installation and motor drive principle.
• The scanned electronics schematics (PDF, 22.5MB) Let's hope you will never need it.
• Scanned cabling plans (PDF, 3.7MB) Let's sincerely hope you will never ever need it.
• Various encoder datasheets (PDF, 7.1MB)
• ​Diploma thesis of Felix Hormuth lists some technical details of KING, the Lucky Imaging experiment AstraLux?, and a pointing model of the telescope, reducing the 10' uncalibrated pointing accuracy down to ~1'.

• Mirror re-coating, Felix Hormuth's notes:

Last time performed: 2004.

Foreseen to be re-coated periodically: Recommended for Spring 2013 (did not happen).

Lief damals schon über das e-Procurement, sollte also im Einkauf noch einen Paper Trail geben.

Bei Bedarf in LS Hamburg anfragen, wer gerade der Ansprechpartner für's Bedampfen ist, dann mit demjenigen 
einen Termin finden und den Preis erfragen, dann über unsere Verwaltung den Transport organisieren.

Damals war dort Arnis Levits (alevits@hs.uni-hamburg.de) der Kontakt, Bedampfung hatte 1300.- netto gekostet.

Unser Primär- und Sekundärspiegel haben damals gleichzeitig reingepaßt, das macht die Sache günstig. 
Jetzt haben beide aber auch eine SiO2-Schicht oben drauf, können also schonend gereinigt werden, ohne daß man gleich das Alu ablöst.

Nach dem Wiedereinbau hab' ich nur mal intra-/extrafokale Pupillenbilder gemacht. Die sahen gut aus.
Die Spiegelhalterungen sind schon recht praezise, daher haben wir damals auf irgendwelche Neujustierungen verzichtet.
Kenne auch keine weitere Dokumentation.

-----Translation by DeepL----
At that time, this was already done via e-procurement, so there should still be a paper trail in purchasing.

If necessary, ask LS Hamburg who the contact person for steaming is, then find an appointment with them and ask for the price, then organize transport via our administration.

At that time Arnis Levits (alevits@hs.uni-hamburg.de) was the contact, steaming cost 1300.- net.

Our primary and secondary mirrors fitted in at the same time, making it cheap. 

But now both have a SiO2 layer on top, so they can be cleaned gently without detaching the aluminum.

After re-installation, I only took intra-/extrafocal pupil pictures. They looked good.

The mirror mounts are quite precise, so we did not do any readjustments.
I don't know of any other documentation.

Upgrade plans (in the future)

• Pointing model of the telescope shall be recalibrated with images with uniform distribution on the sky. A minimum of ~ 40-65 images are needed. If you want to volunteer for this task, please contact Conchi Cardenas.
• Automatic defocus (change for each filter. Some runs shall be perform for each filter and epoch. If you want to volunteer for this task, please contact André Boné (bone@…).
• Tracking issue (gets stuck, or jumps once in a while). Investigate this issue is needed too. If you want to volunteer for this task, please contact André Boné (bone@…).
• Maintenance plan for camera and telescope.
• Have a webcam (on TRAC) from inside the dome, and maybe link other cams from outside
  • since it runs 24/7, the webcam should NOT emit any light (no LEDs etc), and ideally it sends via WLAN, so we only need a power plug
• Primary mirror re-coating after evaluation.

Ticket administration

https://svn.mpia.de/trac/gulli/king/report

Pictures of the construction and mounting of the telescope