Working Group Recommendations

1 Attendance

On the side of ESO, the meeting was attended (in part partially) by: S. Arnouts, D. Baade, C. Benoist, J. Bergeron, S. Cristiani, L. da Costa, Y.-S. Kim, E. Pancino, R. Rengelink, A. Renzini, P. Rosati, A. Wicenec, S. Zaggia.
 

2 Summary of Meeting

1. Status of the EIS and Public Survey.

L. da Costa gave an extensive description of the present status of the survey work (see Appendix A with Da Costa's sheet). The WG was impressed by the speed the survey group has carried out the survey and the quality of its products. An issues particularly noted was that sending out the EIS bulk data in response to the 50 request from the community was no really bottleneck. A problem can arise with U-band observations with the WFI, since there are not always sufficient guide stars.

2. Field Selection, IR Observations

Following the publication on the WEB of the Announcement of Opportunities, two proposals were received, one from Jorgensen et al. and the other from Lagache et al.. The Jorgensen proposal did not mention a particular field in which the NTT/SOFI observations should be made (implicitly leaving the choice of the field to the Working Group). Lagache et al. proposed instead the "FIRBACK" field for which deep ISOPHOT data already exist (alpha: 3h11m, delta: -54 degree). Both proposals were considered by the WG to fulfill in general the requirements set by ESO to carry out the IR part of the Public Survey.

The WG noted that the nights allocated to the project in P64 run from January 31 to February 8, as advertised in the Announcement of Opportunities. During those nights the FIRBACK field is visible only during the first two hours, and therefore another field is required to make use of the allocated nights in P64. The WG therefore postponed the discussion of the selection of the team to a decision on the selection of the fields to be covered by the Public Survey, both Optical and Infrared.

On behalf of the Survey Team Stephane Arnouts presented the various options for the three fields (one square deg each), at widely spaced r.a.'s, to be observed in the Public Survey. For the Spring (Chile) field, two options were then extensively discussed:

1. The so-called "Marano Field" that includes the FIRBACK field proposed by Lagache et al., and
2. the so-called AXAF field (alpha: 3h32m, delta: -27degree  which is located at nearly the same r.a..

The WG unanimously agreed that to achieve the goals of the Public Survey any field chosen had to be observed in two bands in the IR (J and K) as well as in five bands in the optical, as stated in the approved proposal. It appeared also very clear that within the nights allocated to the Public Survey only one of the two fields could be covered in both the optical and the IR. A very extensive discussion followed on pros and cons of each of the two options, which are summarized as follows: In favor of the FIRBACK/MARANO field militates the existence of the deep ISOPHOT data; in favor of the AXAF field the existence of the EIS-DEEP public data, of a 7h exposure in the B band with WFI that is also public, and the future availability of the Chandra and XMM data (the X-ray data being subject to a one year proprietary period).

The final decision of the WG was in favor of the AXAF field, on the basis that this field allows to more efficiently combine the basic Public Survey requirement of providing a complete optical and infrared dataset. In addition, the WG noted that the Lagache et al. proposal mentions only the K band observations as essential for the scientific exploitation of the ISOPHOT data, while the WFI optical and IR J band observations are not mentioned among the necessary follow-up of the ISO data. Therefore, choosing the FIRBACK/MARANO field for the optical and infrared observations of the Public Survey would imply abandoning the AXAF field completely, while producing redundant data not strictly required for the scientific needs of the Lagache et al. program. The WG recognizes the outstanding scientific merits of the Lagache et al. program, which is meant to bring to full scientific fruition a major achievement of European space programs. The WG therefore recommends the Lagache et al. team to submit to ESO a regular proposal for observing the FIRBACK/MARANO field in P66.

Finally, the WG formally decides to allocate to the Jorgensen et al. team the duty of conducting the SOFI observations in P64, reduce the data and prepare them for public release.

3. Future of public surveys

The future of public surveys was discussed at lengths and did not yet come to a final conclusion. Issues that were mentioned during the long discussing include:

- Most of the WG strongly support the continuation of public surveys.
- Many important surveys at other observatories are carried out (see Appendix B). To remain competitive, ESO and the WG should see that similar (or better!) surveys are also carried out for the benefit of the ESO community.
- There was a debate on what public kind of surveys should be carried out in the future. Only at the 2.2 and at the VST, or also imaging and spectroscopic surveys at the larger telescopes?
- If there is a public survey at the VST it should be ambitious and very competitive.
- The role of the WG was extensively discussed. Opinions differed. Some felt that the WG was only there to initiate and monitor the present surveys with the NTT and the 2.2 whereas the majority felt that the task of the WG should be much broader and include (i) identifying what surveys of what ever kind are missing at ESO, (ii) take care that such surveys are being carried out, (iii) monitor the progress in carrying out such surveys.
- It was stressed that the competitive science will be delivered by the VLT, and not by public surveys per se. The surveys done and to be carried out should be preparatory work for follow-up observations with the VLT.
- Within any future plan for surveys it is of crucial importance that the role of the survey group at ESO is well defined. It should also have a more stable configuration that it currently has.

4. Membership WG

The membership in the WG should be re-organized. A. Renzini will coordinate the replacement of the members that have left. Suggestions for new members for the WG should be send to Renzini. Special attention should be devoted for having a member from the galactic community.

3 Recommendations:

1. ESO should ask the groups that have requested the bulk survey data for what purpose they needed it and what the results were. Knowing this would be a good tool to help assessing the overall usefulness of the survey projects carried out so far.

2. The upper-limit of the cutouts as can be extracted from the ESO WWW pages should be increased from 7x7arcmin2 to 12x12arcmin2. The reason for this is that an entire arbitrarily oriented FORS field is then always contained within a single extracted images

3. So far the schedule for making the data public was well kept. For future work, the WG recommends to adopt the schedule as proposed by L. da Costa .

4. The time it takes for the WFI data to arrive for reduction within the survey group can sometimes take a full month. Ways should be investigated to shorten this period.

5. The WG recommends to ask for Director's Discretionary time to finish the observations on HDF south at the NTT.

6. The WG recommends to adopt Da Costa proposed strategy for carrying out the approved 2.2 public survey time in terms of fields and filters (see Appendix C).

7. The WG very much welcomes the present discussion with the UK community on building the 4-m survey telescope VISTA on Paranal in a collaborative effort with ESO. It hopes that the present talks will have a positive outcome, since the scientific pay-off can clearly be enormous.

8. The present U-band filter at the WFI does not seem optimal for obtaining samples of candidate z ~ 3 galaxies. It is recommended to use the filter that can be provided by Giavalisco. On the longer time-scale it should be investigated whether a somewhat broader filter would be a more efficient way for pinpointing the z ~ 3 galaxies.

9. Concerning the IR observations at NTT the Working Group passed the following recommendation: 'The Working Group thanks the Joergensen et al. group for the offer to carry out the IR part of the Public Survey in January/Feabruary and it recommends to ESO to accept this offer. The WG recommends that the EIS team at ESO monitors the progress of the observations and data reduction.'

10. For the infra-red NTT survey only data during good seeing which is defined as better than 1.2 should be used in making the final images. If a fields is observed during worse seeing, this field should be re-observed.

11. The WG stresses its earlier recommendations that service observing at 2.2m telescope is urgently needed and ESO is requested to find ways to provide this facility on short time-scales.

12. The WG asks ESO to schedule the 2.2m in an approach as flexible as possible. The possibility of allocated half nights is essential for efficiently finishing the limited number of survey fields.

13. The WG recommends that an astronomer at at least the postdoctoral level located at La Silla should be involved in the survey. He/She could be involved in carrying out the observations and be an essential link between La Silla and the Garching Survey team.

14. The WG welcomes the plan to write a www interface so that the soft ware for searching the sources (Sextractor) can be run remotely on ESO machines. L. da Costa will circulate a draft plan on the details of this interface. Important issues are (1) which parameters should the user have control over and (2) can the user use the coordinates of a catalogue defined at one band to carry out photometry in another band.

15. The schedule for the observations of the public surveys should be well advertised. In this way, proposers for 2.2 time will know during which periods the amount of telescope time available is relatively limited.
 
 

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