Subaru Telescope New Development Group


Subaru Telescope Future Instrumentation
すばる望遠鏡 将来装置計画


Internal Meeting, October 8, 2013

Date / Time: October 8, 2013 13:30 - 15:30 (HST)
Place: Hilo office room 104A+B

Agenda / Presentation Files


Minutes

[ Scope of Decommission Discussions, Timeline ]

* Timescale of decommission? Before TMT is in operation, some 
 instrument would lose its competitiveness. However, if we stop 
 operation of some instruments before TMT's start of operation, 
 we would lose some functions without any alternatives.
  - We should discuss the instrument plan for the entire 2010s, 
   until the TMT starts operations.
  - In the project week we will be asked the decommission plan 
   in 2010s.
  - Subaru users meeting in Jan. 2014 is not the opportunity 
   for the final decision about the entire instrument plan, 
   except for FMOS on which the decision should be made by Jan.
   2014.

* How much of the budget would be reduced in the next 10 years? 
 It is one of the boundary conditions to discuss the instrument 
 plan.
  - If we want to keep some science capability, we should try 
   to maintain the budget scale to achieve that. The reason why 
   we need to consider the decommission is not due to the 
   reduction of the budget, but because the science goals of 
   Subaru Telescope are changing (to large survey type science 
   cases).
  - As a basis of the discussions, we may assume we can keep the 
   budget scale of the current Subaru Telescope for the entire 
   2010s. 
  - We would need to call international partners to maintain 
   the current budget size.


[ Shift to Survey-type Instruments ]

* Shift to survey-type observations means smaller number of 
  instrument exchange?
  - Basically yes.

* Survey instruments - data pipeline plan?
  - For HSC and PFS, building data archive and publishing catalog 
   are important to maximize their science output. HSC team is 
   developing a pipeline for the SSP program. How much we can 
   support general open-use program is TBD. We are discussing 
   with the HSC team and trying to establish a team.
  - For other existing facility instruments, we do not plan to 
   provide reduced data and catalog.
  - For future facility instruments such as PFS and ULTIMATE-
   SUBARU, providing reduced data and catalog processed through 
   the pipeline is one of the goals.

* If we push ourselves into survey-oriented observations, it is 
 somewhat inevitable to reduce variety of Subaru instruments.


[ Priority among Considerations ]

* Is the workload with the current instrument too much? If yes, 
 we need to reduce the workload.
  - Is is difficult to quantify the workload in future.

*  Why is the number of publications with Suprime-Cam keep 
 increasing?
  - It mainly comes from the use of the data archive (SMOKA), 
   probably used by non-Japanese researchers.
  - Note that the approved program with Suprime-Cam is almost 
   flat or is slightly decreasing. The increasing number of 
   annual publications with Suprime-Cam comes mainly from the 
   re-use of past observation data.
  - The number of papers by Suprime-Cam is outstanding, but 
   there should be many aspects to be considered, such as 
   development of new technology, education etc.
  - We will keep Suprime-Cam for the next two years.

- Prime Focus is a unique capability among 8-10m class telescopes 
 (at least until LSST). So wide-field surveys using prime focus 
 instruments make sense.


[ PI-type Instruments, Instrument Development ]

* Can new PI-type instruments substitute or update functions of 
 facility instruments?
  - Most PI-type instruments are designed for some specific science 
   cases.
  - We can not expect high reliability for all of PI-type 
   instruments compared to facility instruments.

* Another thing we should consider is what the science community 
 wants. Building interesting and ambitious instruments based on 
 new technologies are important to keep Subaru competitive and 
 drive development of further future instruments (for TMT and others).
 How much the science community understand and support building 
 such PI-type instruments?
  - The number of PI-type instruments for Subaru is increasing.
  - Recognition of the importance of keeping the instrument 
   development among the entire community is not enough. The 
   support for instrument development by NAOJ HQ has been very 
   limited for years.

* Subaru's role as a test bed for new instruments should be 
  considered in future.

* Important thing is to keep competitiveness of Subaru’s suite of 
 instruments by introducing new instruments.

* Balancing instrumentations for optical and for infrared is 
 important.


[ Time Exchange, Instrument Transfer ]

* Is there a possibility to increase of time exchange?
  - Arimoto: Yes. We will try to increase fraction of time 
   exchange and to stop accepting proposals from non-Japanese 
   researchers.
  - Number of proposals for all Subaru’s instruments are almost 
   identical. If we stop operations of some instruments, twenty 
   percent of time exchange may not be enough to compensate the 
   loss of instruments.

* Functions of some instruments could be substituted by time 
 exchange program.

* Uniqueness of instruments. Currently FMOS has unique 
 capability and UH extensively uses FMOS.

* If we provide survey-type instruments to VLT community, Japanese 
 community would lose some fraction of nights for surveys.
  - Combining Subaru's survey instruments with the instruments in 
   other telescopes which have different capabilities should 
   increase the values of the scientific outcomes.

* We started discussion on the possibility of the transfer of HDS 
 to Gemini.


[ Early Decommission of FMOS ]

* Presentation by Takato-san:

- PFS team is thinking about putting four spectrographs on IR-M3 
 floor by adding new floor. We may be able to reduce some cost 
 if we remove FMOS and put PFS spectrographs on IR-TUE floor. 
 Also, coolant FMOS is using will be enough for PFS. Reducing 
 observatory workload is another point. Maintenance could be 
 easier in IR-TUE floor.
- Have we got the enough science return from FMOS?
- There will be more than three years without prime-focus 
 spectrograph.
- Interval between four spectrographs needs to be shorten to 
 keep the schedule.
- We need to make a decision by Jan. 2014 to keep the PFS schedule.

* Q&A and Discussions:

[PFS Plan]

- Is introducing four spectrographs in one year feasible?
  - Spectrographs will be built in France and in Hawaii only 
   re-assembly and test will be made. It is certainly challenging 
   but is not completely unfeasible.

- Is the first-light of PFS in 2017 really feasible? We need to 
 know the feasibility of the PFS project before we start thinking 
 the FMOS decommission.
  - If we stick to FMOS we may lose PFS due to difficulty in 
   flooring.
  - Originally we planed to keep FMOS until PFS becomes stable. 
   But keeping FMOS along with commissioning of PFS could be 
   difficult for Subaru (infrastructure, workload, budget etc.)

 - Is it possible to start engineering obs. with one spectrograph?
  - It would be possible, but spectrographs will be ready 
   independently from the flooring.
 - How about placing two of four PFS spectrographs on the IR-M3 
  floor and put the other two spectrographs on the IR-TUE floor 
  later?
  - That plan may work, although the commissioning process will 
  become more complicated.

- If the schedule of PFS delays, the project won't be able to 
keep the team, and the project will go into a serious problem.

- Staffing Plan for PFS?: two people to be hired by Subaru from 
 the beginning of the commissioning.
  - More technicians' time would be required to keep PFS 
   spectrographs operational.
  - We need to carefully watch the quality of the instrument to 
   reduce maintenance load.

[Science Cases with FMOS]

- If we carry out FMOS observations rather intensively in S14B 
 and S15A, can we cover significant science cases with FMOS?
  - Some studies combining HSC imaging data and FMOS follow-up 
   spectroscopy would be lost by early decommission of FMOS.
- Galaxy mass-metalicity relation is one of the important 
 science cases for FMOS, and researchers have carried out (or 
 are carrying out now) such programs.
- Star-formation sciences with FMOS could be explored more.


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