1. FourStar Status Eric Persson (OCIW) Presented By

2. May 20, 2007FourStar Status2 Instrument Overview Vacuum Vessel Electronics Rack Dewars Focal Plane Mechanisms Camera Module Window 200K Radiation Shield Conical Adapter 77K Radiation Shield

3. May 20, 2007FourStar Status3 CDR & Post CDR Response Many useful recommendations from the CDR panel. –Load ring modifications –Camera module support –Gear materials and coatings –Heaters for warmup –Cold clamps All CDR action items have been addressed at this time. CDR recommendations have resulted in a multitude of design simplifications and modifications.

4. May 20, 2007FourStar Status4 Recent Milestones 1.Contract signed for construction of vacuum vessel 2.Detectors finished and ready for delivery

5. May 20, 2007FourStar Status5 Detectors Had the choice of the best 4 out of 5. Done. The 4 Science-grade detectors are now in hand. –Best specs: QE: J 0.79 H 0.90 Ks 0.97 stddev(QE): J 0.014 H 0.014 Ks 0.01 readnoise: 18 e- rms (CDS) dark: 0.0005 e-/sec full “well”: 150,000 e- crosstalk: 6.1% (total) in 8 surrounding pixels bad & hot pixel count: 0.01% (mostly dead) –Testing caveats: 1.QE at K cannot be real 2.readnoise of other devices not as low

6. May 20, 2007FourStar Status6 Ongoing Work at Carnegie 1.Lifetime testing of mechanisms at 77K, 2.Developing array test dewar for testing ASICs and engineering grade array when electronics arrive, and 3.Building focal plane mechanisms.

7. May 20, 2007FourStar Status7 Ongoing Work at IDG/JHU Orders are being released for cart hardware. Parts are being fabricated for the electronics racks and the various chassis. Drawings sets for remaining thermal and opto- mechanical hardware being prepared for release.

8. May 20, 2007FourStar Status8 Schedule

9. May 20, 2007FourStar Status9 Narrow Band Filters They will work in the fast beam at the price of a 25% reduction in flux for a clean profile. There are 7 free positions. 1.We ask the SAC members to poll their institutions in order to propose filters and to find funding for them soon. They should be ordered by September 1, 2007. The relevant parameters are (only) central operating wavelength and bandwidth. 2.The team will work with the SAC to choose the set of <= 7 filters that can be accommodated in the 2 filter wheels. FourStar will not be paying for the filters.

10. May 20, 2007FourStar Status10 Narrow Band Filters (concl’d) 3.The team will design and specify the filters. There are several additional parameters that must be designed in, viz., substrate thickness for parfocality, blocking, and extra wavelength shift in the fast beam. 4. Carnegie will then order the filters and invoice the proposers’ institutions with an extra charge for design. Typical costs are likely to be ~ $10K per filter. 5. Once the instrument has been closed up in preparation for its commissioning run, it will not be reopened solely for the purpose of inserting a new or replacement filter (because of risk).