A guide for visiting astronomers on Calar Alto

In this guide you will find useful information for your stay at Centro Astronómico Hispano en Andalucía (CAHA) on Calar Alto. Part of this information may also be of interest for remote observers. If it is your first time on the mountain, please read this introduction carefully 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

The Calar Alto staff wants to provide you with adequate support to make your stay as pleasant and productive as possible. In order to do this, it is important for us to get detailed information about: Please send us this complete information at least 2 weeks in advance using the form Arrival and Needs of Guest Observers (please fill in one form per observer/run).

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 (+34 950 632 500) or by email.

What you find at Calar Alto

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

Things you should prepare

Prices (VAT included)

Room (without breakfast) as of January 1st, 2024 50.00 €Meals 16€
Taxi LEI airport - Calar Alto80.00 €
Almería - Calar Alto70.00 €
Almería - Airport14.00 €
Waiting time10.00 € / hour
Gergal (train station) - Calar Alto 47.50 €

Breakfast is served by vending machines (bread, fruits and yogurts are available for free).



Upon arrival at the "Hotel" (ring the bell or call from the phone inside the white box), each 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 a couple of forms needing the VA signature. 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 incl. TV and leisure rooms, and dormitories.

Additional astronomer's lodging (apartments) lie in a separate complex near the hotel (see map).


All meals are prepared by an external catering service from a nearby village (Las Menas de Serón). Lunch or/and dinners have to be ordered in a sheet displayed in the hotel cafeteria (the first day meals can be specified in the arrival form). Make sure that you have placed your orders in advance by checking on the sheet 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:

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

If you have special requirements for food (e.g. allergies) or lodging please inform us in advance in the arrival form and check again with the administrative staff upon arrival.

Telephone, fax, photocopies

Internal calls: internal telephone lists are next to all phones. Simply lift the receiver and dial the 3-digit desired number.

Outgoing calls: outgoing calls may be made from the phones in the observing rooms. To place a national call, first dial '0' and the desired number. For an international call, add '00' after the initial '0', the international country code (e.g. '49' for Germany), followed by the number. Please favour using your mobile phone (Wifi signal is good in most places of the hotel and in the lab) for long distance, private calls.

You may receive calls via the Spanish lines at the following number:

where xxx is the Calar Alto extension.

Cell phones: thanks to an antenna located close to the 3.5 m, there is a good cell phone network between the observatory buildings (not so much inside the domes!) for all operators based on the Movistar network.

Telefax (still used for some specific official documents): 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. Do not forget that the administration staff is not on duty during the weekend.

On site transportation

One car has been assigned to each telescope:

       Telescope     Car number

         3.5m:        13  (after 14:00 (LT), if needed, all the day)
         2.2m:         2  (after 14:00 (LT), if needed, all the day)
Drive safely (and fasten your seatbelt), being especially aware of ice on the road in winter and remaining always within the observatory area. Pedestrians, pets, cattle and wild animals may cross (or walk on...) the road anytime, day and night. When driving at night, favour parking lights + hazard lights under clear conditions; when foggy, please switch on the fog lights.

At the hotel entrance you will find, during the summer season, an assortment of bicycles which are at your disposal.


Old technical books and journals may be read at the library, located in the laboratory building. Books may be taken out (e.g. to your room) during the visiting period. When borrowing a book, never forget to leave an 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 in our Call for Proposals.

Publications must contain a footnote as follows:

"Based on observations collected at the Centro Astronómico Hispano en Andalucía (CAHA) at Calar Alto, operated jointly by the Junta de Andalucía and the Instituto de Astrofísica de Andalucía (CSIC)"


Before leaving Calar Alto, please do not forget to:

Observing instructions


The Calar Alto staff 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 is expected to participate in the run preparation and in the actual observations.

Astronomical support

Upon arrival at Calar Alto, the VA should contact by mail/by phone the coordinator (day shift) astronomer on duty who will provide her/him with support at the beginning of the observation run. This astronomer coordinator is responsible for instructing the VA in the use of the instrumentation and for deciding when the VA is qualified to use the instrument. (S)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 (TA) is scheduled each for the 3.5 m and the 2.2 m telescope. As professional observers, they do not only perform mere operating tasks, but may also observe actively on behalf of the VA. The technical astronomer is also responsible of the safety of the telescopes and instruments at night. The working time of the TAs begins at sunset and finishes strictly at sunrise.

Telescope or instrument 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 TA who may help in fixing it or in making a preliminary diagnosis and in contacting a technician. In the uncommon case of simultaneous technical issues on various telescopes, these will be solved on the best effort basis, giving priority to the largest telescope/urgency of the malfunction.

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 sufficient knowledge about it!

Technical personnel

The technicians and engineers 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 on duty is on call until midnight (local) including on most week-ends and holidays. The VA should not directly request the technical personnel to perform any task not previously brought to the attention of the TA.

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: The TAs being responsible for the safety of the telescope and the equipment, they may decide to close the dome or to keep it closed even if the conditions seem decent to observe. Their decision is final and shall be followed immediately.

Astronomical data

All the data obtained are stored on the instrument computer disk. Moreover they are copied to the private archive of each PI (Prime Investigator, who is not necessarily the VA) and also to an anonymous ftp server if needed (e.g. to share data on-the-fly with CoIs), from where they can be retrieved. Ask the staff for details.


Find here a some information about the IT dept. The CAHA engineers will do their best to solve any computer-related issue during your stay.

Calar Alto, February 2024