Application for Observing Time
at the Calar Alto Telescopes

- General Information -

Applications for observing time at the 2.2- and 3.5-m telescopes for Spring semester 2020
(January 1 through June 30)

Spanish Open Time at the CAHA 2.2- and 3.5-m telescopes
The Principal Investigator (PI) of the proposal must be affiliated with a Spanish Institution at the time of submission (see exceptions below).
Co-investigators (CoIs) from all countries are welcome to participate along with the Spanish PI.
  • Earliest date for submission is September 6, 2019.


  • October 9, 2019 23:59:59 CEST

PIs coming from other European countries are kindly asked to apply via NorthStar/Opticon. In 2020A semester (deadline to apply is over), up to 10 nights were available on the 3.5-m telescope and 10 nights also on the 2.2 m. Travel funds are available for accepted OPTICON proposals. Please also note the possible different deadlines!
Proposals of PIs from non-European countries may be granted with observing time only if they are extremely well rated by the TAC. International teams can also buy observing time (see below).

News and remarks
  • 3.5-m and 2.2-m telescopes
    As an ICTS (Spanish Singular Scientific Facility), Calar Alto offers a minimum of 20% of the available observing time. Due to the new status of the observatory, the number of available observing nights for the Spanish community is larger since 2019. For this reason, Calar Alto encourages Spanish PIs to send their proposals and take advantage of the new situation.

    Calar Alto also offers the option to buy observing time at the 3.5-m and 2.2-m telescopes. A separate operation agreement between CAHA A.I.E. and the respective user institution shall be signed. But a proposal must be submitted, and it will be evaluated by the TAC. Only the highly ranked pay-per-night proposals will be accepted. For further information, please contact CAHA director (director at

  • 1.23-m telescope
    There is no definite deadline for this telescope. For any use of the 1.23-m telescope, a separate operation agreement between CAHA A.I.E. and the respective user institution shall be previously signed. Please contact CAHA director (director at

    CARMENES is available for Open Time programs in 2020 Spring semester. We remind the main science case of the CARMENES Guaranteed Time Observations (GTOC): the detection by the radial velocity method, follow-up and characterization of planets around M dwarfs. The agreement between CAHA and the CARMENES consortium protects this science case.
    PIs of CARMENES open time proposals which might overlap with this science case are encouraged to contact the CARMENES consortium for collaboration. In all other cases, arguments explaining why the science case does not overlap should be provided in the "Astrophysical Context" subsection (8a) of the proposal.

  • CAFE
    After the upgrade (high-reflectivity grating plus temperature-controlled room) and commissioning of the spectrograph, an improved CAFE is available for the Spring 2020 semester, reaching a radial velocity accuracy below 10 m/s.
    A new pipeline developed by Jorge Lillo-Box is available to reduce CAFE data (including the automatic extraction of radial velocities for FGKM stars). The pipeline works with data from the current or previous semesters. A paper about the pipeline will be published soon. Please contact Jorge (jlillo at for further information.

    The wide-field infrared camera is being upgrated. The former mosaic of four HAWAII-2RG with poor cosmetic quality is being replaced by a new, single HAWAII-4RG detector. The integration of the large, monolithic detector is about to start, and commissioning is expected to take place in March-April 2020.
    PANIC is thus offered on a shared-risk basis at the end of the Spring semester (May-June), for a maximum of 5 nights on the 2.2 m. The idea is that interested teams propose early-science projects to demonstrate the potential of the new HAWAI-4RG (field of view ca. 27'x27') monolithic detector by performing novel studies in the near-infrared.

  • PlanetCam
    The two-channel (0.38-1.7 microns) lucky-imaging camera ( 2016PASP..128c5002M) is fully operational at Calar Alto and can be mounted on the 1.23- and 2.2-m telescopes. Although the use of the camera corresponds to its owner (the Group of Planetary Sciences GPC of UPV/EHU), in its visiting instrument mode at Calar Alto Observatoriy, the use of PlanetCam (PASP 128,5002) can be requested for any other program through a collaboration with the GPC.
    Potential applicants please contact Prof. Agustín Sánchez-Lavega (agustin.sanchez at

  • TWIN and MOSCA
    These two instruments are not offered this Spring 2020 semester.

  • Visitor, Service A and Service B programs:
    CAHA will approve programs in visitor and service mode.
    Visitor mode proposals are encouraged and will have higher priority to be scheduled. CAHA favors in particular the education of young researchers who have no or little previous hands-on experience on a professional telescope. Visitor mode runs including PhD (or young postdocs) will be considered very positively by the TAC.
    We kindly remind the PIs asking for visitor mode proposal that they must send observers for the allocated nights, although they might differ from the ones indicated in the proposals. In case visitors are planning to go up to the observatory only for part of the allocated nights, "Partly service mode" may be asked.
    Service programs will be executed as A (priority) and B (backup) as follows:

    1. Service A: Only for highly ranked proposals. The observations will be done in queue mode (exceptions see below) and buffer time is allocated to ensure that the obtained data set is complete.
    2. Service B: These programs are scheduled as backup, when all Service A programs (including those for guaranteed time) have got their data or they cannot be executed. This implies that time for these programs is allocated generally towards the end of the semester and only proposals whose objects have the appropriate RA can be considered, or when medium weather conditions are acceptable.
    3. Visitor mode: The observations will be performed by the visiting astronomer in a fixed period. Limited buffer time will be reserved. If the requested observing conditions are demanding (good seeing, photometric, etc.), a back-up program should be included. It should be also discussed and approved by the TAC.

    We also ask the PI (or any CoI) of any servide mode proposal to send detailed instructions at least one week in advance before the first planned observation. Last day changes in the setup may not be accepted/feasible, except if justified by the outcome of the previous observing night.
    This will allow us to secure the scheduling and setup of the instruments on the 2.2- and 3.5-m telescopes well in advance, while leaving time to iterate if needed with the PI. Changes to this rule will be only accepted under exceptional circumstances (e.g. sudden illness).

  • Rules for Open Time service observations
    Programs in service mode are generally performed during service blocks. Although tentative observing slots are assigned for each program, the observations will be performed in a kind of queue mode. This gives the observatory more flexibility to react on changing observing conditions, so that the programs will benefit from higher efficiency.

    Please note: at the 2.2-m telescope, due to the cadence requirements of the Black Hole project in progress, the observations of approved Open Time programs will be carried out in blocks of no more than three nights in a row. Visitor mode time slots may exceptionnaly be extended to a maximum of 4 nights.

    In contrast to other instruments, whose configuration can be changed quickly between one program and another, PMAS needs more time for setup changes. This implies that the configuration cannot be changed during the night and thus a queue scheduling is difficult, if not impossible. For this reason (and only for this instrument), the rules for observations in service mode are changed in the sense that:

    • "Service mode" means "delegated service", i.e CAHA staff will carry out the observations, but on specific dates, usually without compensation for weather losses.
    • The TAC will favor programs requesting whole nights. Programs requesting few hours for several nights will usually not be approved. They should propose a secondary program (in the back-up section) for the rest of the night, which has to be approved by the TAC, and being above the cut-off.
    • If the requested observing conditions are demanding (very good seeing, photometric night, etc), a back-up program should be included, just as in the case of the "Visitor Mode" programs.

    Proposals requesting fractions of nights can be accepted in visitor mode, although they should be exceptional and very well justified, and should receive a high grade by the TAC.

  • Available instruments for Spring 2020

    3.5-m telescope

    2.2-m telescope

    1.23-m telescope

    Visiting instruments

      Calar Alto offers the option of installing your own instrument at the observatory telescopes. Please contact CAHA director (director at well in advance, to consider the feasibility.

  • Proprietary period for observing data
    All observing data from Open Time Programs will be made public by the Virtual Observatory (VO) in Madrid, after a proprietary period of one year after the end of the observations.

  • Report the published articles
    Calar Alto Observatory kindly asks you to inform us (info at of any publication that makes use of data collected at our facilities. The most appealing publications may be worth a press release, so please contact us in advance about any breakthrough result based on CAHA data to study its possible public diffusion.

    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 Andalusian Universities and the Instituto de Astrofísica de Andalucía (CSIC)."

If you would like to get an email reminder in the future to inform you about the start of the next proposal round, send an email to notice"at" with the subject line "CfP subscribe". In the same way you can unsubscribe from this list with the subject line "CfP unsubscribe".

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Last updated: 3 September, 2019