Una guía para astrónomos visitantes en Calar Alto

In this guide you will find some useful information for your stay on Calar Alto. If you stay here the first time, please read carefully this introduction in order to get acquainted with the basic rules of the observatory.

In the following you find information about:

(the little green arrow brings you back to the index)

Preparing your Stay

Inform Calar Alto in Advance

Calar Alto staff wants to provide you with an adequate support. In order to do this it is important for us to get detailed information about:

  • Who will observe
  • Dates of arrival and departure
  • Details about the required instrumentation

Please send us this information at least 2 weeks in advance using the form Arrival and Needs of Guest Observers

Calar Alto returns a receipt (maybe with a delay of 4-5 days). In case you don't receive anything please contact us by phone or email.

What you find on Calar Alto

Here you find briefly, what you may expect during your stay:

  • A Library with all most important periodicals, catalogues and handbooks
  • The Palomar Sky Survey
  • The digitized sky survey on CD-Rom
  • Computers (UNIX) for data reduction
  • Observing clothes, only to be worn in the telescope buildings.
  • A car during nighttime (see On Site Transportation)
  • A torch
  • A phone for long distance calls in the hotel
  • A library of belletristic literature
  • Radio and CD players in the hotel lobby, as well as in the observer's rooms of the telescopes with a limited number of disks (donations are welcome).
  • Spanish and german TV, billard and table tennis

Things You should prepare

  • Prepare euros or credit card to pay the bill for hotel, meals, taxi etc. Foreign currencies cannot be accepted.
  • Bring warm clothes. In spite of its latitude the temperatures on Calar Alto rarely exceed 20 degrees in summer and can reach -10 degrees in winter. From November to April you should reckon with snow.

Prices (VAT included)

Room (without breakfast) 45,00 €

Taxi Airport - Calar Alto 80,00 €
Almería - Calar Alto 70,00 €
Almería - Airport 14,00 €
Waiting time 10,00 € / hour
Meals 16.00 €


Breakfast is served by vending machines.



Upon arrival at the "Hotel", the Visiting Astronomer (VA) picks up an envelope at the entrance containing the apartment key, a torch, an electronic card for the cafeteria as well as an information sheet which tells him, who will be his supporting staff member. The VA may also check out an alarm clock from the administration office, to be returned before leaving Calar Alto.

The hotel contains the administration office, the cafeteria, lounges, TV-room, dormitories, mailboxes and an outgoing telephone.

The astronomer's apartments are in a separate complex near the hotel (see map).


All meals are prepared to order in the hotel cafeteria. Make sure that you have placed your orders in advance by checking in on the list provided.

The latest ordering time for lunch, served at 13:00 hours, is 11:00 hours. The latest ordering time for dinner is 15:00 hours.
Dinner (local)time varies according to the season:

  • From last Sunday of October to last Saturday March : 17:00
  • From April to October : 18:30

Breakfast may be taken at any time (self service). Hot and cold drinks are also available via self service.

If you require sandwiches or extra dishes for night lunch, order them in the cafeteria before 15:00 hours. Prices can be taken from the list.

Telephone, Fax, Photocopies

Internal Calls: internal telephone lists are next to all phones. Simply lift the receiver and dial the desired number.

Outgoing Calls: outgoing calls may be made from the phone box in the hotel lobby. To place a call, push the white button, wait for the outside line tone (continuous tone) and then dial the desired number. For an international call dial '00', the international country code (eg. '49' for Germany), followed by the number. Please record all telephone calls in the book provided, including the number of units displayed by the counter; they will be charged to the VA's personal account.

You may receive calls via the spanish lines (telefonica) at the following number:

  • +34 950 632 xxx

where xxx is the Calar Alto extension.

Telefax: Outgoing faxes should be handed to the secretary during office hours (8:00 - 18:00 hours). Incoming faxes may be received via the secretary's (+34-950-632504) or via the public fax: +34-950-632506. This fax device is located in the laboratory building, room no. 006.

Photocopies: the photocopier is located in the entrance area of the laboratory building.

Travel Reservations

Travel reservations, confirmations, or changes may be made through the administration staff. Due to the distance of the observatory from Almeria, it is wise to make your departure plans well in advance. This will help our administration staff to get everything ready prior to your departure. Don't forget that the administration staff is not in during the weekend.

On Site Transportation

One car has been assigned to each telescope:

       Telescope     Car No. 

         3.5m:         13  (after 14:00 h, if needed, all the day)
         2.2m:          2  (after 14:00 h, if needed, all the day)

Drive carefully, be especially aware of ice on the road in winter and keep always within the observatory area. During nighttime use only parking lights.

The keys should always be left in the car.

At the hotel entrance you will find an assortment of bicycles which are at your disposal (in summer).


Books and periodicals may be read at the library, located in the laboratory building. Books may be taken out during the visiting period. When borrowing a book, never forget to leave adequate notice. All publications must be returned to their former places before you leave.


The bibliographic data of any publications based on observations at Calar Alto are to be communicated to CAHA as described on our web page


Publications must contain a footnote as follows:

'Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC)'


Before leaving Calar Alto please do not forget to:

  • Fill out a 'Closing Report', giving a brief report on the observing run including comments, critics and suggestions. Please use the electronic form: http://www.caha.es/CAHA/FORMS/closing_report.html
  • Clean your computer account.
  • Return any books to the library.
  • Please keep order in the dome and in the control room. Return everything to its proper place and remove the remains of your snacks.
  • Cancel any bills at the secretary's office. Please note that you have to pay your bill for accommodation, meals, private telephone calls etc. before you leave the observatory. Payment can be made in euros, by credit card or Eurocheque. Foreign currencies cannot be accepted.
  • Return keys, torch and magnetic card to the secretary or throw it into the box provided in the hotel entrance.

Observing Instructions


The personnel of Calar Alto will provide adequate support and help to visiting astronomers while they carry out their planned observations. Because of limitations in the size of the staff, however, a successful observing campaign requires the cooperation and participation of the VA to an extent greater than may be the case at other observatories. These instructions have been written in order to avoid any misunderstanding with regard to the nature of the support that the VA may ask or expect to receive and the extent to which the VA ist expected to participate in the actual observations, their preparation, or processing.

Astronomical Support

Upon arrival at Calar Alto, the VA finds in his envelope an information sheet with the name of the person, who supports him at the beginning of his observation run. This person is responsible for instructing the VA in the use of the instrumentation and for deciding when the VA is qualified to use the instruments. He is the primary contact between the VA and all other technical personnel of Calar Alto. The VA, accordingly, should not directly approach a technician to perform any task that falls outside regular duties, as specified below.

Technical Astronomers (TA)

Generally one technical astronomer is scheduled each for the 3.5m and the 2.2m telescope. They do not only perform mere operating tasks, but may also observe actively on behalf of the VA. The working time of the TAs begins at sunset and finishs at sunrise.

Telescope or Instruments Failure

In case of a malfunction or failure in an instrument or telescope - suspected or real - the VA should first communicate the trouble to the NA who may be of help in fixing it or making a preliminary diagnosis and in contacting a technician. Under no circumstances should the VA attempt to carry out readjustments or repairs, no matter how simple they may appear. Any malfunction should be entered in the night report and described with as much detail as possible. Malfunctions can only be fixed by the technical staff if there is knowledge about it!

Technical Personnel

The technicians responsible for the maintenance of telescopes and instruments are generally organized in a manner, that technical help is available every day of the week. A technician is on call until 3 a.m. (local). The VA should not directly request the technical personnel to perform any tasks not previously brought to the attention of the NA.

Technical support for your own specialized equipment can be given only if arrangements have been made well in advance of your arrival. Even when such arrangements exist, keep in mind that the major portion of their daily activity is directed to the immediate needs of observatory operations, so the effectiveness of any assistance will depend upon how careful the advance planning was. Avoid making requests at the last minute.

Weather Conditions

For the protection of the telescopes and their equipment no observing activity shall be undertaken and the domes shall be maintained closed under the following conditions:

  • Excessive Wind: Domes shall be closed when the wind gust velocity as measured in the free air exceeds:
    • 18 m/s at the 1.23 m and the Schmidt telescope;
    • 21 m/s at the 2.20 m telescope, and
    • 24 m/s and the 3.5 m telescope.
    After closing the dome for a wind gust alert, a waiting time of 15 min is established as a security margin. The dome may be re-opened only after such time interval with wind gust below the limit.
  • Excessive Humidity: Domes shall be closed when the external humidity exceeds 98 %. The domes shall be closed whenever the difference between the coldest part of the telescope and the dew point is below 2 degrees. In extreme cases, for instance during rapidly varying humidity at high levels or during rapid increases of the dew point towards the outside air temperature, the technical astronomer may decide to close the dome earlier.
    Domes can be reopened when the humidity has dropped below 95%. In cases of ice build up and water condensation, the technical astronomers may decide that the dome stays closed even if the humidity falls below 95%.
  • Excessive Frost: The domes shall be closed whenever the outside temperature is below -15º C.
  • Ice or Snow on the Dome: No dome shall be opened when there is ice or snow on them.
  • Excessive airborne Dust: No domes shall be opened if excessive dust is present in the air. This condition is indicated when the surrounding mountains are hidden frow view.

The technical astronomers are responsible for the safety of the telescope and the equipment and may decide to close the dome or to keep the dome closed even if the conditions seem good. Their decision is final and shall be followed immediately.

Astronomical Data

All obtained data are stored on the disk of the instrument computer. Moreover they are copied to the archive and to the ftp server, from where they can be retrieved. Ask the staff for details.


Find here a quick information for visiting astronomers.