Three major milestones were passed since the last Newsletter: Phoenix (without a detector) visited Kitt Peak on 1 April and was mounted on the 2.1-m telescope. Installation, including drilling a new set of bolt holes in the back of the 2.1-m telescope, went without problems. Stars were acquired on 1 April using the internal dichroic and a CCD guider. An important test was to look for any interference where the instrument could physically run into the telescope. Measurements had indicated that the yoke area could be a problem. It turns out that Phoenix clears the yoke, but there is interference at declinations greater than +75 with various attachments to the yoke. By removing a tie rod support bracket and the (currently unused) coud tube full sky access would be possible. However, given the small amount of sky north of +75, the northern declination limit will be declared to be +75 on the 2.1-m unless this limit impacts user science.
Following the trip to Kitt Peak, Phoenix was cooled down for the first time. The performance exceeded our optimistic projections. The instrument reached a stable temperature of 50 K in three days. Phoenix is cooled only by dual compressed helium refrigerators, and we had expected that cooling could take as long as five days. The temperature goal was less than 70 K, at which point the thermal radiation contribution to the dark current becomes negligible. The Phoenix mechanical designer, Randy Cuberly, and mechanical engineer, Tim Ellis, are to be commended for an exceptional job in designing the thermal insulation and radiation shielding. We are able to warm the instrument to room temperature in two days using resistive heaters. Without the use of heaters, the instrument is so well insulated that it would take weeks to warm. While the cryogenic systems all work better than planned, note that as with COB and SQIID, it will be impossible to open Phoenix without a long lead time and advanced planning.
The third milestone was the completion of electronics to run the array.
The warm electronics boxes were fully checked out and a ROIC (bare read
out) installed in an Aladdin array mount and operated cold in Phoenix
using wildfire. The read noise of the ROIC was 37 e
warm and 32 e
cold. Before the ROIC can be replaced with an engineering grade Aladdin
array, the detector temperature must be controlled to a few hundredths
of a degree. This work is currently underway.
As announced in the previous Newsletter, a special scheduling process will occur for the fall 1996 semester Phoenix proposals. Several blocks of 2.1-m time are being set aside for Phoenix late in the 1996 schedule. The Phoenix proposal deadline for these blocks will be announced on the Web site (http://www.noao.edu/kpno/phoenix/phoenix.html). In addition, interested users should send e-mail to hinkle@noao.edu. Progress reports are being sent periodically to users who have sent email to hinkle. Unless major problems are encountered, the operating specs for Phoenix will be announced in late June. You will be notified of the proposal deadline at that time. We realize that many people have travel plans in June and July so adequate time to prepare proposals will be allowed.
Ken Hinkle