Ground Based Observatories GBO System Design Overview Operational

Ground Based Observatories (GBO) System Design Overview Operational Status Lessons Learned S. E. Harris University of California - Berkeley THEMIS/GBO Review 1 Banff, March 29, 2006

GBO Components All Sky Imager (ASI) Iridium GPS Observatory Support Equipment (OSE) Telesat Dish inside the “Hut” enclosure Variations possible at some sites: Internet AC Power Ground Magnetometer (GMAG) Existing magnetometer “Hut” enclosure not needed Existing Internet connection THEMIS/GBO Review 2 Banff, March 29, 2006

Complete Installation at Mc. Grath THEMIS/GBO Review 3 Banff, March 29, 2006

All Sky Imager (ASI) Main Components • Camera, Starlight Xpress, MX 716 – – – • All Sky Lens – – • Designed for amateur astronomy CCD Format: Interline transfer, 376 x 290 pixels (binned), 8 mm diag. Cooled with TEC for reduced dark current Telecentric design by Keo Consultants Full hemisphere viewing, full resolution obtained 256 x 256 image Environmental Enclosure with Sun Shade THEMIS/GBO Review 4 Banff, March 29, 2006

ASI Unit Test Summary Acceptance Tests: • • • FOV (>170°) Exposure Time (duration at least 1 sec) Spectral Response – Produce detectable response to source radiance < 10 k. R – – – • Spatial Resolution (>250 pixel image diameter) – • Verify point source response Cadence (better than 10 s) – • Goal < 1 k. R Passband 400 – 750 nm 1 sec exposure duration Goal < 3 s Record dark and bias images (room temperature) Pre-Shipment: • • • Focus adjustment and verification Alignment verification (top of image relative to alignment datum) Heater control functional test Sun Shade solenoid functional test (#iterations: 360) Internal mechanical inspection checklist (thm_gbo_116) Final functional test and System Burn-in (duration: several days) THEMIS/GBO Review 5 Banff, March 29, 2006

ASI Responsivity Testing Data report: thm_gbo_118 Recorded on all Imagers: THEMIS/GBO Review 6 • On Axis spectral response • Off Axis spectral response • Dark vs exposure time • Resolution Banff, March 29, 2006

ASI Resolution Testing On-Axis THEMIS/GBO Review 40º Off-Axis 7 80º Off-Axis Banff, March 29, 2006

ASI Enclosure Design Acrylic Dome S. S. Enclosure Heaters Design: Allison Park Group, Inc. THEMIS/GBO Review 8 Banff, March 29, 2006

Sun Shade ASI must survive non-operating exposure to daytime sun • CCD is Sony ICX 249 AL – • Plastic “microlens” on each pixel, transmission reduction w/ exposure to UV All Sky Lens uses Peleng Fisheye f/3. 5 – A/R coating exhibited discoloration after one summer in ATHA Solenoid drive actuates to close shade • Falls open when solenoid power is removed THEMIS/GBO Review 9 Banff, March 29, 2006

ASI Enclosure Performance ASI installed at Ft. Yukon, AK Dome: • • Generally stays clear of snow without intervention Some ice buildup on flange Heating: • • Maintains 60° T using about 50 W avg. heat power Total heating power available is 240 W (60 W in dome) THEMIS/GBO Review 10 Banff, March 29, 2006

Ground Magnetometer GPS Receiver (included at all GBO sites) Antenna and Electronics Integrated into one package NTP compatible (1 msec time accuracy) Fluxgate Magnetometer (sensor shown below) ± 72 Kn. T dynamic range @ 0. 01 n. T Resolution (~23 bits) Offset DAC system for 256 possible ranges per axis 2 Vectors per second data rate Low Power < 4 W USB interface for data retrieval and firmware upload THEMIS/GBO Review 11 Banff, March 29, 2006

GMAG Installation Fluxgate Magnetometer Installed at Athabasca THEMIS/GBO Review 12 Banff, March 29, 2006

OSE Layout (1) Rack Mount Shipping Case (12 U) System Computer GMAG Interface Electronics APS Serial Switch Swappable Hard Drive (2 ea) 28” Iridium modem UPS THEMIS/GBO Review 13 Banff, March 29, 2006

OSE Layout (2) Power Control Unit CR 10 X Datalogger UPS ASI Power Supply CR 10 X Battery THEMIS/GBO Review 14 Banff, March 29, 2006

Power Control Unit (PCU) PCU Features • CR 10 X Datalogger is the environment controller for GBO – – • Provides room temperature environment inside OSE and ASI – – • • Extended temperature range (-55º to +85ºC) Always operating and remotely accessible (via Iridium) Low power consumption (battery can operate it for months) Simple programming and data logging capability Enables use of standard commercial computers, hard drives, etc. Implements graceful shutdown of system in either event of: – Loss of Power – Loss of Temperature (either too high, or too low) CR 10 X is the analog & digital I/O peripheral for System Computer Provides “watchdog” function for System Computer (PC) THEMIS/GBO Review 15 Banff, March 29, 2006

Power Control Unit Interfaces THEMIS/GBO Review 16 Banff, March 29, 2006

OSE Heating / Cooling Devices Solid State Air Conditioner 163 W Capacity Small Space Heaters 175 W, 120 VAC, 2 ea THEMIS/GBO Review 120 VAC Power 17 Banff, March 29, 2006

“Hut” Enclosure “A Box within a Box” Internal Rack Mount Case for Equipment (Doubles as Shipping Case) External Insulated Environmental Enclosure THEMIS/GBO Review 18 Banff, March 29, 2006

Hut Performance No heating in Hut required down to – 40ºC GBO#10, Ft. Smith Cooling required above – 5ºC GBO#10, Ft. Smith THEMIS/GBO Review 19 Banff, March 29, 2006

Instrument Data Flow ASI System Computer GMAG Hot Swap Hard Drive(s) Telesat Modem GPS USB Serial I/O 10/100 Base T Internet THEMIS/GBO Review 20 Banff, March 29, 2006

Status of Operations Number of GBOs Deployed: 11 • • Installation and logistics can be difficult Monitoring and maintaining is harder • Cold • Hot • Power • Inaccessibility • • Internet connection outages Some operational hazards that we’ve survived so far: – e. g. door to the shack stuck open – e. g. stuck thermostat in the shack – generally it’s been reliable, but outages are a fact of life – Ekati and Inuvik RF Interference (More on this later) – data back up is working fine – – system processes can hang up (USB interfaces, NTP daemon) periodically we need to reboot the system • Software issues • Non-responsive custodian THEMIS/GBO Review 21 Banff, March 29, 2006

System Uptime Initial analysis, 8 of 10 stations analyzed • • Based on availability of CR 10 X records logged on site At each station, number of records is averaging 97. 5% – • Of 288 records maximum per day Indicates the systems are up and running normally most of the time THEMIS/GBO Review 22 Banff, March 29, 2006

Learning and Improving System issues are addressed in Problem Reports • • PFRs describe problem and corrective action We track PFRs for each station – – Leaves a paper trail of changes for each site A copy also is attached to site log on ‘wiki’ THEMIS/GBO Review 23 Banff, March 29, 2006

Lessons Learned - Prototype Ice buildup on ASI dome • Added dome heaters Insulation outgassing in ASI • Changed material to foilfaced air pillow THEMIS/GBO Review 24 Banff, March 29, 2006

Lessons Learned (1) Issue PFR Description / Resolution ASI cable length A deployment issue first increased to 60’ settled on 100’ -001 -003 -006 -008 -021 Changed ASI supply to regulated 12 V (60’) Increased sun shade solenoid drive to 24 VAC Changed ASI 12 V supply to meet in-rush current Modify ASI power interface wiring (100’) Increased sun shade solenoid drive to 28 VAC ASI Power Diagram THEMIS/GBO Review 25 Banff, March 29, 2006

Lessons Learned (2) Issue PFR Description / Resolution ASI USB Interface Susceptible to EMI, causes lock up Design is “always on” -005 -018 Add’l power line filtering on Starlight Xpress board Design remote-control USB Disconnect device Enables an easy power reset option Inuvik is skipping exposures to elim. RF interference USB Disconnect Device Prototype Modified USB Board THEMIS/GBO Review 26 Banff, March 29, 2006

Lessons Learned (3) Issue PFR Description / Resolution System monitoring “more is better” -002 -010 Add AC line current monitor Add monitor for PC +5 V Add monitor on ASI power supplies ASI Power Supply Overheating -015 Modify power brick, add heat sink and fan Overheated PC Board Modified Starlight Brick courtesy of Mikko Syrjasuo THEMIS/GBO Review 27 Banff, March 29, 2006

Lessons Learned (4) Issue PFR Description / Resolution Component failures -019 -020 Ekati – USB hard drive failed, PC would not boot Atha – PC power supply failed, blew internal fuse Obsolescence -022 USB Extender device now unavailable, changing all to make them interchangeable ASI Data Interface Diagram THEMIS/GBO Review 28 Banff, March 29, 2006

Open PFRs Issue PFR Description / Resolution Iridium modem config Learning curve -016 APS serial switch auto-configures modem on reset Power reset modem and APS every day Learn all failure modes Recently discovered a situation where modem and APS switch can get into hung state – investigation is ongoing GMAG restart problem -007 Problem associated with GMAG USB interface, does not restart correctly if system reboots when it’s cold Very infrequent occurrence, can be handled by operator intervention THEMIS/GBO Review 29 Banff, March 29, 2006