Harvard-Smithsonian Center for Astrophysics FLWO Ridge Telescopes Periodic Report Issue No. 6, February 2006

The present memo is another report from the F. L. Whipple Observatory. We chronicle FLWO activities and the status and progress of telescopes, instruments and related equipment. The telescopes involved are the 1.5m Tillinghast, the 1.2m, the 1.3m PAIRITEL and the HATs. This belated report covers the period Apr 2005-Feb 2006. All issues of these reports are posted at tdc-www.harvard.edu/flworeport/.

If you have any comments, or for further information on any of the projects below, please contact us.

Telescope projects:

1. The FTS chiller system for the primary mirror has been in operation since Spring 2003. The system maintains the mirror temperatures within about 0.2C of the telescope chamber ambient temperature under observing conditions (see the link to temperatures on the 1.2m web page). During Spring 2005, we found contamination in the glycol lines and a small leak, accompanied by slower temperature slews than in previous seasons. RH replaced the hoses, fittings and glycol. The new hoses are expected to be impervious to degradation by glycol. The system returned to its initial high efficiency in late September 2005. Unfortunately, in Oct 2005 RH found a new significant glycol leak in the chiller where none had been seen before. That required draining the system. RH also found that the glycol pump needed to be rebuilt. The chiller went back in operation in Dec 2005. However, its efficiency was nowhere near its achievable level. RH discovered that the heat exchangers attached to the mirror cell were clogged in an irreversible fashion. RH acquired replacement heat exchangers and replaced the glycol coolant with a flavor friendlier to the Al in the exchangers. The chiller has been operating at high efficiency since early Feb 2006.

2. Remote observing remains popular. Observers who plan to use it should ensure to read the documentation and to contact the staff well before their scheduled runs. It is essential for observers who have never conducted remote observing, who are changing configurations, or who have not used the system in the past year to conduct a dry run of their computer platform before the start of their observations.

3. We continue monitoring the behavior of the new Vaisala relative humidity and temperature measuring system.

4. After the 2005 shutdown, TG installed a new guider similar to the system in use at the 1.5m. He also implemented a new mode to allow use of the guide camera over VNCviewer. WP and TG are implementing remote gain control.

5. WP installed a new fiber optics run from the telescope to the control room, which allows, e.g. for safe sensing of CCD temperatures.

6. The telescope safety brakes remain on the list of backup projects.

7. We are still exploring options for a replacement primary mirror.

Instrument projects:

1. In July, Andy Szentgyorgyi, John Geary and Steve Amato completed work in Cambridge on Keplercam, which replaces Minicam and the older 4shooter. It is a 4Kx4K single-chip 4-amplifier CCD with fast readout, excellent sensitivity and cosmetics, and a long hold time in its dewar. Its temperature is sensed and stored in image headers, thus allowing observers to avoid problems with warm-ups. TG wrote the control software, which was ready for the Keplercam first light in late Jul 2005. It has performed extremely well since then.

2. Stelircam continues to perform fairly well, although the red and blue channels may not be available simultaneously. WP has continued to address (so far) non-lethal failures in the electronics. A major failure may imply the demise of the camera, because many of its components are obsolete and no longer available.

Telescope status and projects:

1. We re-aluminized the primary and secondary mirrors during the Aug 2005 shutdown. We were able to use the "Sunnyside" facility at the U of A again this year. The adhesion and reflectivity of the aluminum were excellent.

2. We monitor the sensitivity of FAST and the telescope optics by observing a small set of standard stars with a 5" slit and the 300gpm grating. Visit www.sao.arizona.edu/help/FLWO/60/fast/fast_updates.html for details. Since the refurbishment of the FAST optics in Sep 2003, the throughput decreased 20% (40%) at red (blue) wavelengths. We attribute that to the degradation of the Al coating of the primary and to contamination of the surface of the FAST corrector optics. The latter were initially sol-gel coated and thus were impossible to clean without losing the coating. After the Aug 2005 shutdown and mirror re-aluminizations, we replaced the corrector with another with hard-coated optics (see below for more on this corrector). These steps along with periodic cleaning of the FAST optics have brought the sensitivity back to the levels in Sep 2003, as desired.

3. On Fri 3 June 2005, the dome control electronics failed during WP's attempt to trace a dome problem. Because of another contemporaneous failure, we had no spares, and as it was a weekend, replacement parts arrived only the following Monday and the telescope was down for 3 nights.

4. In Sep 2005, WP discovered that re-occurring dome problems were mechanical, not electrical. The encoder-measuring wheel would not contact the dome at certain points of rotation. The radial rollers were at the extremes of their adjustment slots. WP loosened, adjusted and tightened some of the rollers, and obtained the correct adjustment procedure from Observadome. WP and RH adjusted the rest of the rollers and the dome was then able to behave correctly.

5. Beginning in Spring 2005, we had infrequent events where the telescope would lock up in RA. There seemed to be no pattern related to position or temperature. The gears were cleaned and re-greased as the finer points of grease became clearer. The manufacturer of the grease pointed out that we had used the wrong kind for many years; WP promptly acquired the correct type. Springs were adjusted to apply more or less pressure between the worm and the wormgear. The lock-ups would disappear, but then reappear. Their frequency started increasing in late 2005. During the night of 16 Jan 2006, the problem came to a head, and the telescope was down for the following 2 nights. The problem was finally pinpointed to the RA drive motor, which had failed. We replaced it with a spare drive and sent out the failed motor for refurbishment. After the replacement, significant oscillations were apparent. During the following week, RH aligned and repaired the flexible RA drive coupling and aligned the worm and the wormgear, which eliminated the oscillations.

6. RH and support worked on the dome, which had been cranky. An insufficient number of the 32 axial rollers were making contact with the base of the dome. After adding shims, about 70% of the rollers make contact most of the time, which is near the design goal.

Instrument status and projects:

1. At the end of the Aug 2004 shutdown, we replaced the sol-gel coated corrector with a hard-coated version (optics were in hand and Warren Brown assembled them). Unfortunately, this corrector produced strangely flared stellar images on the guider. We reverted to the sol-gel coated corrector and returned the other one to WB. The problem was one of sligthly misaligned optics. Warren re-mounted the optics and we swapped correctors again after shutdown in Aug 2005.

2. We received the new FAST3 CCD with its own dewar and electronics in early Jan 2006. TG had the requisite software ready at that time. On Jan 12, we aligned and tested the new CCD on FAST. We discovered that the noise level, e.g. on flats, was too high, and the sensitivity was significantly below expectations. John Geary concurred, and requested that we ship FAST3 back to Cambridge. With Steve Amato, he discovered the cause was an incorrect "signal file" that was easily corrected. They also repaired a faulty temperature sensor. We received FAST3 back at FLWO on Feb 13. We plan to test it again on Mar 7, after the current FAST run, and to bring it into service thereafter if its performance is adequate.

3. The Echelle continued producing useful data, in spite of its age which causes occasional hiccups. As an example, one of these required a repair to a controller that is no longer made. The manufacturer, Oriel (now owned by Newport), claimed they could not repair it. WP repaired it by building a new controller for it.

4. The new high-throughput, fiber-fed TRES (Tillinghast Reflection Echelle Spectrograph) construction is proceeding apace. Andy Szentgyorgyi is working on this project with SAO pre-doc Gabor Furesz. We expect delivery of TRES to FLWO in late Fall 2006.

1. The telescope is continuing nightly operations and is highly productive.

2. WP and RH designed and built an LN2 auto-refill system that includes remote sensing of its status. The system has proven to be quite reliable.

3. A small number of items remain for full automated operations: remote control of the dome fan and power to the telescope drives.

4. Contact Josh Bloom at Berkeley if you have a project that you would like to have added to the queue.

1. Gaspar Bakos, now a Hubble Fellow at CfA, conducted regular observations with his 3 FLWO HATs.

2. GB added 2 new HATs at FLWO, one identical to the previous 3, and a larger one, TopHAT (a 25-cm Baker Cassegrain), for a total of 5 HATs.

3. The program to monitor sky brightness (see Reports No. 2-4) and determine the effect of light pollution continues. We are currently analyzing data from the past 2 years.

4. The FLWO support crew added insulation to the HAT control room in Apr 2005. It is essential to maintain acceptable temperatures now that the number of HAT computers has increased significantly.

1. Please refer to the MMT's own quarterly report.

2. Mike Calkins and Perry Berlind assisted production observations as fiber-Meisters and all-around observers with Hectospec and Hectochelle. They also assisted with Megacam observations. That has meant requesting that observers, especially graduate students, come to FLWO to observe with FAST and the Echelle. We are thankful to the many dedicated observers who have been willing to travel here. But we will continue needing help; please consult the schedules and consider coming to FLWO!

3. Ridge staff continued providing assistance with SAO instrument and computer installation and maintenance, as required. In particular, WH and TG helped with network software and equipment, and RH built doors for the new Hecto dark enclosure.

1. On Jul 7 2005, lightning started a fire on Florida Peak, about 5 miles NE from FLWO. The fire grew to encompass about 23,000 acres when it was 100% contained on July 24. On July 12 we evacuated the mountain following a request from the Forest Service. FLWO was seriously threatened, with the fire pushing to cross over Jack Mountain (between Wrightson and Hopkins) toward the ridge on July 15-17. That put flames within 0.5 miles or so of the ridge, but thanks to the efforts of firefighters, especially the aerial crews that dropped retardant, the fire was held at bay. A good combination of winds and, finally, the start of the monsoon rains on Jul 17 started extinguishing the fire. Additional downpours, typical of the monsoon, led to its full demise by July 24. For additional details, visit http://cfa-www.harvard.edu/cfa/oir/FLWO/FloridaFire. There was no damage to any equipment.

2. We continue to update online documentation as changes occur, often thanks to observers' comments. Please visit often!

3. The issue of network safety remains a high priority. TG continues monitoring the network. He also installed Spamassassin on all Ridge email accounts.

4. Dan Brocious and EF continued working on containing light pollution. In Summer 2005, we participated in meetings in Bisbee, where Cochise County was in the process of adopting a new outdoor lighting code. The county adopted a good code, effective 02 Dec 2005. The final version included input from residents, amateur astronomers and from us, including Grant Williams of the MMT and Liz Alvarez from the U of A. We had a meeting in Jul 2005 with Santa Cruz County staff who would enforce the code in the county. We expect action on the code in 2006!

5. In Apr/May 2005, two bills were narrowly approved by the AZ legislature that could have allowed increases in light pollution, had they not been vetoed by Governor Janet Napolitano. Senate Bill SB1193 would have weakened the ability of municipalities to enforce local ordinances covering billboard and outdoor advertisements (including their lighting). House Bill HB2461 would have allowed flashing LED electronic billboards to be erected "off-premise" and was strongly opposed by neighborhood associations and the astronomical community and industry in Southern Arizona. FLWO joined the astronomical community in AZ in this opposition.