Surveying the Southern Sky with a Robotic Camera

• John E. Gaustad• Swarthmore College

• Wayne Rosing• Las Cumbres

Observatory

SHASSASouthern H-Alpha Sky Survey Atlas

Survey Properties

• Coverage: declination +15 to -90• Image size: 13 x 13 degrees• Image resolution: 0.8 arcminutes• Images to cover the sky: 283• Sensitivity: 2 rayleigh (50X better than POSS)• Purpose:

– study structure of ISM – set limits on free-free contribution to microwave

foreground

We difference line and continuum images:

Equipment

• 50 mm f/1.6 Canon lens

• Spectrasource CCD camera, TE cooled

• 1024x1024 TI chip, 12 micron pixels

• Filters: 3 nm H-, 6 nm dual-band cont.

• Byers German mount

• 10-foot dome from Technical Innovations

• Two PCs, Win95, Visual Basic & IDL

Location: Cerro Tololo (Chile)

Lessons Learned

It Will Take Longer Than You Think

• Dec ’92 DVB “We ought to do a survey.”• ’93-’96 Pilot study• Apr ’96 Pilot study paper published• Jul ’94 First NSF proposal rejected• Jul ’95 JG met WR at Pittsburg AAS• May ’96 Second NSF proposal funded• Nov ’97 First observations at CTIO• Oct ’00 Observations completed• Nov’01 Survey published in PASP

Robotic is Good

• Robots don’t need much space– But the people who set them up do – plan

plenty of space for people to move around while installing and repairing

• Robots don’t get bored

• Robots don’t have to be paid – relatively cheap project

SHASSA Project Cost• Las Cumbres Obs. 40,000• Dudley Observatory 10,000• Fund for Astr. Res. 5,000• AAS 3,000• Keck NE Ast. Cons. 15,000• Swarthmore College 27,000• NSF-9529057 54,000• NSF-9900622 48,000• NASA-JPL 15,000• TOTAL $217,000

• Wisconsin H-Alpha Mapper2 million

• Two-micron All Sky Survey20 million

• Sloan Digital Sky Survey 100 million

• Microwave Anisotropy Probe 180 million

• SHASSA 0.2 million• = 1 deci-wham• = 1 centi-2mass• = 2 milli-sloan• = 1 milli-map

Humans Are Useful

• A truly unattended instrument is costly• Location at an established facility gives

– easy access during setup and testing– logistic support, power, network access, etc.– local staff able to make minor repairs, reboot

computers, etc.– human judgments on weather and safety

(communicated by email to the robot)– camaraderie with other scientists

Perfection is Unattainable

• There is no such thing as an uninterruptible power supply

• Computers do fail:– add cooling fans to power supplies and CPUs– record data redundantly on separate disks

• Learn when to say “this is good enough” – rely on humans for the rest

Keep It Simple

• Use a simple shelter, such as a roll-off roof, not a dome

• Use separate computers for telescope control, camera control, and communications, so these tasks don’t interfere with each other

• Use a computer system compatible with the local network

• Invest in accurate telescope drives, so guiding and focusing is not an issue

Test, Test, Test

• Pre-deploy a trial computer at the remote site for a few months, in order to identify power supply, network reliability, and communications problems

• Integrate and operate the ENTIRE system at home before deploying to a remote site

• Allocate a month or more for initial installation and testing at the remote site

Do a Pilot Study

• Helps to clarify scientific goals

• Identifies technical problems

• If it ends up with publishable results, establishes credibility with funding agencies

Benefits of Amateur-Professional Collaboration

Point of View of Amateur

• Professionals provided– knowledge of scientific goals– credibility with funding agencies, observatory

directors, journal editors– project management– data reduction skills– experience in writing scientific papers

Point of View of Professional

• Amateur provided– high-quality instrumentation– technical expertise– engineering time– enthusiasm, confidence, and dedication

• This meant the project could be done at much lower cost to funding agencies than would otherwise be possible.

Would We Do It Again?

Yes!

But with more realistic expectations of

time and effort involved.

In fact, we are now repeating the survey at

the wavelengths of [SII] and [OIII] lines

http://amundsen.swarthmore.edu/SHASSA