The Calar Alto Time Allocation Committee - how it works

The CAHA TAC consists of 7 members. Two of them are international, which are jointly nominated by CSIC and MPG, two of them are Spanish and are nominated by CSIC and two of them are German and are nominated by the MPG. In addition, the CAHA director is ex officio a member of the TAC. One substitute is nominated for the Spanish and one for the German community by CSIC and MPG, respectively. In assigning the committee members, great care is taken to ensure a broad range in expertise. Each member is appointed for a period of 2 years; a term of at most four years is possible. The length of the appointment is certainly a good compromise between the need for continuity in the process and a healthy rotation within the communities. The current composition of the CAHA TAC can be found here , the statutes of the CAHA TAC here .

Once the proposal deadline is over, an overview of the proposals submitted is made and two referees are assigned to each proposal. Great care is taken to avoid conflicts of interest. If possible, the proposals are assigned to experts in the particular field. However, given the limited number of TAC members (compared to HST- and ESO-TACs), it is clear that this is not always possible. The two referees evaluate the proposal, assign a preliminary grade to it and give comments both of which are circulated among the entire TAC before the TAC meeting. It is expected that each TAC member reads all proposals.
In the meeting the first referee summarizes the scientific content of the proposal and gives his opinion, followed by the opinion of the second referee. A discussion on that proposals follows. In the end, the two referees give their grades, which are averaged for the preliminary ranking. It should be emphasized here that conflicted members are asked to leave the room or to refrain from the discussion.
Once the proposals for an individual telescope are discussed, the number of nights available for each partner is defined. This is normally taken as 50% of the number of nights available in total after subtracting the nights allocated for Directors Discretionary Time (DDT), technical time, guaranteed time (currently up to 1/3 of the total time for Germany and Spain), and international time. In an important change to the previous situation, where only a few, exceptionally good international applications were scheduled, the Calar Alto observatory is now open for applications from foreign countries. Thus, international proposals are evaluated and recommended the same way as regular proposals from Germany and Spain. Once the nights available for Germany and Spain are settled the final ranking is made. Some of the proposals, in general the highest ranked ones, may be assigned Service A status, which means that in addition to the time requested the same amount of time is reserved in a so called Service A buffer. This ensures that weather or technical losses for the scientifically best proposals can be compensated, and that these programmes get a quasi-guaranteed complete data set. However, this does not mean that twice the amount of time must be used for the programme. If a programme with Service A status can be fully carried out during its originally requested time, the time in the buffer is used either for other Service A programmes, for DDT or technical time, or for additional observing programmes which are drawn from the ranked list. Although it is at present still possible that observers whose programme is scheduled in Service A are welcome to carry out their programme during the fixed allocation observing block themselves, the observatory makes an effort to move towards flexible scheduling for all Service A programmes.

By tradition, defining the cutoff is a delicate exercise. Therefore, the proposals around the cutoff are sometimes rediscussed and regraded in order to establish the final ranking. This ranking is than used by the managing director of the CAHA to create the observing schedule. It is clear that the TAC can not define a sharp cutoff. Depending on the pressure on individual months, dark time or instruments, some of the proposals above the cutoff can not be implemented, while others below the cutoff can be scheduled. This schedule has then to be approved by the directors of CSIC and MPIA. It is their right, to override the recommendations of the TAC due to various circumstances.
After the meeting, the two referees for each proposal are asked to modify their comments which are sent to the applicants, if necessary. The directors of CSIC and MPIA specifically asked the TAC to provide  comments as detailed as possible. Any feedback to the applicants, if they ask for details of the evaluation process has to be channeled through the chair (currently J. Heidt) of the TAC.

The last TAC meeting was held from April, 27-29 2004 in Granada. About 75 proposals for the 3.5m telescope and about 45 proposals for the 2.2m telescope had to be discussed for the autumn semester 2004. Thus, the oversubscription was relatively high at the 3.5m telescope (factor ~3.1) and modest at the 2.2m telescope (factor ~1.4). Remarkably, the oversubscription was almost identical for both the Spanish and German time at either telescope. In the end, for the 3.5m telescope 19 proposals (9 Spanish, 8 German, 2 International) and for the 2.2m telescope 29 proposals (15 Spanish, 10 German, 4 International) could be implemented. Guaranteed programmes are not counted here. The amount of nights allocated to Spanish and German programmes was almost identical at the 3.5m telescope, while Spain got a bit more than 50% at the 2.2m telescope. The TAC was particularly impressed by the high quality of the proposals submitted. It is clear, that the selection of the very best ones was really a demanding task!
In order to lower the pressure at the 3.5m telescope and to make the 2.2m telescope more attractive, CAHA considers to implement new instruments at the 2.2m telescope. One option could be a near-infrared  wide field imager which would match Omega2000 at the 3.5m. Observations in the Ks band could then be carried out at the 2.2m telescope with similar efficiencies than with Omega2000. Alternatively, an instrument allowing multi-object spectroscopy on a wide field for survey work could be an option. The 1.23m telescope is currently in idle status. If a group would come up with a long-term project for the 1.23m telescope, there should be a possibility to implement this. Please contact T. Henning or R. Gredel for details.

This year's Calar Alto Colloquium was held for the first time in Granada on April, 27th. About 20 talks were presented showing the broad range of disciplines in astrophysics investigated with the Calar Alto telescopes and new instrumentation or upgrades thereof coming up. Unfortunately, only about 50 (mostly Spanish) participants attended the meeting. I would like to point out here that the Calar Alto Colloquium is not only an excellent tool to present projects in front of a large community and to exercise some lobbying for the TAC, but also a very good opportunity to discuss with collegues observing strategies, share ideas, eventually start new projects and finally have an update about latest instrumentational changes/upgrades. It is always held before the TAC spring meeting. The next Calar Alto Colloquium will be held in spring 2005 in Heidelberg. The dates are not yet fixed, but the announcement will be circulated in due time. The TAC hopes that a large number of people from both, Spain and Germany will attend and present their projects. The TAC may also consider to ask some groups specifically to give an overview about their projects conducted with Calar Alto telescopes.

It is obvious that a substantial fraction of the applicants is somewhat frustrated since their proposal did not make it. This does not necessarily mean that their science is poor. In many cases, tiny issues make the difference between a successful and an unsuccessful proposal. A good introduction on how to write a successful proposal can be found here , opinions from TAC-members here . Although the links given above refer to HST-proposals, their content is mostly valid for Calar Alto proposals as well. I will not summarize here what can be found in the links above, but here is a list of the most important points:

• Be as concrete as possible, but use your space
• Select your sample carefully
• Add always figures if possible, they can improve a proposal quite a lot
• Don't cheat, exhausting time requests will be identified and make a bad impression
• Don't cite your own work only. This gives a bad reputation!
• If you resubmit, take into account the comments by the TAC. The memory of the TAC is exiting! If you resubmit your proposal without taking into account the comments by the TAC, the TAC itself is frustrated. Everybody in the TAC spends a considerable amount of time to referee proposals. Ignoring ones work is never a good idea!
• Publish your data timely. And please, acknowledge in a footnote the use of the Calar Alto as it has to be done for all the other major observatories. Details can be found here (item Publications) . Remember, that Germany and Spain spend a considerable amount of money for Calar Alto. Its the only way to demonstrate the need for Calar Alto!
• Finally, everybody makes mistakes. Even the TAC!