A)  INTRODUCTION


In the latest years, the increment and efficiency of the large surveys of Near Earth Objects are facilitating the discovery of a greater number of fainter NEO asteroids. The traditional follow-up task made by many observatories with medium aperture telescopes is resulting more and more difficult and, in many cases, is getting impossible or with a less quality astrometry, due to the poor signal produced in the image which not permit the accurate astrometric reduction that such objects require.

We are in front of a paradox in which many of the new discoveries of NEOs cannot be confirmed neither carry out the correct follow-up the next days by great part of the observatories dedicated to such tasks, and frustrating, therefore the improve in the equipment in many of those observatories with medium size telescopes is, in general, costly and not easy to finance.

The present project was born by the observation team of the observatory of Mallorca in arranging of some telescopes of greater aperture to continue with the NEO follow-up work that traditionally has come carrying out the latest years. For that, after a first experimental phase along 3 years, in which 3 Schmidt cameras of 40-cm for asteroid and NEO follow-up were already built, practically only with their own means, the construction of 3 new telescopes of  61-cm were initiated, with some very characteristic premises, that would turn out the project interesting and attractive also for other observatories with medium apertures and limited economic resources.
Those main goals were:

ECONOMICAL TOTAL COST
COMPACT-REDUCED SIZE
AUTOMATED OBSERVATION
LOW WEIGHT TUBULAR STRUCTURE
OPTIMIZED FOCAL RELATIONS

Our prior experience in the construction of the other mountings, and particularly the lastest 40-cm. Schmidt cameras, allows us to confront this new project, with renewed ideas and clear conclusions such as:

a) The construction of the optical and mountings for the new 61-cm telescopes, is an enterprise that can be mostly undertaken with the optical, technical, mechanical, electronic and data processing resources of the team and the collaborators of the observatory.

b) The size of the CCD chip, have left of being the main economic impediment. We see no longer the need to employ so short focal ratios to compensate its reduced surface, what produces not only a high arcsec/pixel ratio, but does not permit to reach the theoretical limit magnitudes, because of low contrast.

c) We have not obtained good results in trials with altazimuth and german mountings. For simplify and optimize the automation we choose this time forks mountings

d) A known free electronic-software, already developed and well experienced with some adaptations, seems been valid and sufficient for the control of the new forks, avoiding thus also the investment of time and money in a new development.

e) The short tubes allow us to build simple, economical, light and reduced forks without flexions neither excessive inertia moments, they could be set up in domes or shelters of reduced size and without the foundation prepared to bear large weights. That determinant one condition obliges us to a compact optical design, more complex, but that we consider most feasible by the members of the observatory.

f) Considering the complexity of the compact optical design, and keeping in mind that the primary mirrors are built for members of the observatory team, a Klevtsov type design was finally choosed, where the spheric primary mirror avoids most of the work complexity. A double corrector should be the only element built by a specialized company alien to the observatory.

g) Although in our places, the designs with frontal plate corrector (Schmidt, Schmidt-Cassegrain), are good options for the protection of the optical elements from the environment, their price is high and their production is complex, and was ruled out. Although the Klevtsov design is an "open tube", we have tested with success the fine sheets of turbo-film to compensate the deterioration of the aluminized surfaces with the time.

B) DEVELOPMENT AND TECHNICAL DETAILS

In April of 2001, once the telescopes were designed and their optical configurations were determined, and having studied the prices, the construction in parallel of the 3 telescopes Klevtsov destined to the observatories
620-Observatorio Astronůmico de Mallorca, 946-Ametlla de Mar and 165-Piera was initiated. (The stations of Ametlla de Mar and Piera, are part of the Observatorio de Mallorca team). Their serial construction permits a greater reduction of prices by unit.

Currently (latest December, 2002) the project is on the following phase:

OPTICALS:

Primary Mirrors:

The 3 glass blanks of Black Vitrified Ceramic type (BVC glass) were imported from Canada (ASM Products, P.O. Box 1092, St-Basile, Quebec, Canada L3N-1M5 (
asmprod@videotron.ca). The opticals have been spherized to f/2.3 by Joan Guarro, member of the team of the Observatory of Mallorca. They are already concluded.

Correctors:

Klevtsov Corrector: composed by a double crystal BK7 of 18-cm of diameter. The corrector has been designed for those primary mirrors and to obtain a f/4.0 resultant focal lenght. The design and analisis of the optical has been performed by Mr. Gerardo Avila, of the Optical Instruments Group of the European Southern Observatory. (Karl_Schwarzschild-st. 2 85748 Garching, Munchen, Germany) VALMECA S.A.R.L. (Serge Deconihout), Lantelme 04700 PUIMICHEL (France) taked charge of the construction of the 3 correctors. They are already concluded.
MECHANICS:

Base and fork of tubular structure of solded iron, roll-bears and crowns, all of that already built by TALLERES MECANICOS A. FORT (
Ametlla de Mar-Spain) (regular collaborator at the observatory of Ametlla de Mar). The optical tube of aluminum tubular structure.
ELECTRONICS:

The telescope is pointed for an adaptation of the Mel Bartels Project, by means of steppers. (http://www.bbastrodesigns.com/cot/cot.html) A simple and economical electronic control design. Although that hardware was thought up at first by Bartels to automate small mountings, we have verified their optimum performance with big mountings, by changing some details, voltages, motors and reductors.

The electronic devices are concluded, and the steppers, the reductors, and the tracking mechanisms, as well as control computers are all of them already available.
SOFTWARE:

A program specifically developed by the observatory team (PANYC) controls both the forks and the CCD cameras by means of an
ASCOM platform and LX200 commands. The program permits to be operated on inatended way both for survey and follow up. The control software has been tested extensively in other diverse telescopes
A new PANYC asp version allows a full internet control by the members of the observatory of Mallorca
CCDs:

The Observatory of Mallorca, has acquired 3 CCD FLI - Finger Lakes Cameras (
http://www.fli-cam.com/) with detectors SITe 1024x1024 back-iluminated 24 x 24 microns. For each one of the telescopes.
An external system of cooling its being on practice.
C) EXPECTATIONS:

1) We trust to be able to have the sufficient resources to have fully operating the 3 telescopes before the end of 2002. Its exclusive dedication will be in the field of the follow-up and survey of asteroids (with priority on the confirmation (NEOCP), the follow-up of virtual impactors catalogued by
NEOdys and Sentry, and the recovery of NEOs, to the limit of detectability, that we estimate on mag 20.5 while we maintain the present CCD cameras, trusting with all it to increase the number, quality and utility of our future observations.

2) Constructive plans and images of the 3 telescopes, assembly phases will be exposed in a permanent way in the web site of the
Observatory of Mallorca, with the intention of stimulating and to offer ideas to other observatories with medium size telescopes, to renew their instrumental, by means of a simple construction and by a reasonable economic cost.
D) LATEST NEWS:
mall.jpg (24189 bytes)
Ametlla, Dec 7, 2002 Piera, Dec 24, 2002 Mallorca, Jan 4, 2003
E) SOME REFERENCES: