Upload
others
View
10
Download
0
Embed Size (px)
Citation preview
BUILDING A TARDIS MICRO
OBSERVATORY
Duncan Kitchin
OMSI Astrophotography Conference 2011
Overview
� Objectives � The need to minimize setup time
� Analyzing where the time goes
� Solution outline
� Constructing a permanent pier � Components
� Planning
� Construction
� A weather cover � First iteration
� A shed that's bigger on the inside
� Remote electronics box � Requirements - emulating a permanent configuration
� System configuration
� Designing a wiring loom for fast setup
� Optics� Everything in one
� Wrap up � Demonstration (video)
Objectives
� Motivation #1: Setup time
� Multiple trips carrying heavy gear� Set up and roughly align tripod
� Mount, counterweights
� Scope(s)
� Cameras
� Big mass of cables
� Polar alignment� Major time sink – particularly if drift aligning
� Can occupy ½ hour to an hour
� Still might end up with poor alignment (particularly for narrowband imaging)
Objectives
� Motivation #2: Consistency
� Risk of getting something wrong with the setup
� Dismantling/reconstructing setup leaves many
opportunities for screwing something up
� If it’s already dark by the time you notice, the night
could be a write-off
� Changes to electrical configuration can be
problematic
� Something as simple as changing a USB port can
change the system’s behavior
Objectives: Bottom Line
� Setup time
� Start at 60 – 90 minutes
� Target is 5 minutes
� Consistency
� Multiple sources for wasting imaging time
� Make the setup exactly the same every time
The Plan…
� Big item #1: mount setup� Fix this with a permanent pier
� No tripod to set up
� If the mount head stays outside with a cover, can drift align one time and keep it aligned
� Much less to carry outside
� Big item #2: electrical setup� Fix this by putting everything in one box
� A “permanent” electrical setup that moves in one go
� Consistent setup
� Less to carry – one trip
� Big item #3: optical setup� Fix this with a means for storing the whole optical train intact
� Telescope and cameras semi-permanently screwed together
� Stores in a big Pelican case
Constructing a Pier
� Components
� Design
� Planning
� Construction
Components
� Sonotube� They have uses other than making Dobsonian telescopes…
� 12” diameter recommended
� Make some wooden bracing
� Rebar� Large number of 2ft sections, wired together
� Rebar extends all the way up the pier
� 14 x 80lb bags of concrete� Renting a mixer highly recommended
� Be sure to wear a face mask!
� Pier top plate� Many options
� Dan’s Pier Top Plates (http://www.pierplates.com) recommended
� May not be the cheapest option, but very solid and great quality
� Adapters available for many mount types
Design
� Depth of footing will depend on the depth of the
frost line
� Depth to which the ground may freeze
� Must go at least 6” below this point
� Failure to do so will cause “frost heave”
� Washington county frost depth is 12”
� 24 – 36” square hole is adequate for a short 12”
pier
� Height of concrete is about 20” above grade
� Implies approximately a half ton of concrete
Design
20”
12”
24-36”
Planning
� Check for underground obstacles such as utilities
� Mark the extent of the hole with white paint
� Call the utility notification center between 2 and 10
days before digging
� http://www.callbeforeyoudig.org/
� Consider the time of year
� The clay in some parts of Washington County can be
rock hard in the middle of summer
Construction
Construction
Construction
Construction
Construction
Construction
Construction
Construction
Construction
A Weather Cover
� First iteration
� A bag or soft telescope cover
� Adequate solution for short periods
� Watch out for dew
� A more permanent solution
� A shed that’s bigger on the inside
� Trapped mass of air reduces chances of dew
� Space to install a light bulb for warming
The TARDIS Micro-Observatory
The Inspiration
http://doctorwho.bbcamerica.com/
This file is licensed under the Creative Commons Attribution 2.5 Generic license.
© zir.com
Remote Electronics Box
� The remote box contains everything to control
the telescope
� Mount
� Camera
� Autoguider
� Focuser
� All cables
� Several design iterations to yield a satisfactory
result…
Requirements/Motivation
� Keep everything in one place
� Many components & cables needed
� Easy to lose or forget something critical
� Ease of transportation
� Consistency of configuration
� Serial ports – number changes if USB port changes
� USB ports – some cameras don’t like change
� Remote operation
� Operate from a warm home / trailer
� Wireless useful, but not essential
First Configuration
� Network USB hub
� Belkin F5L009
� 5 USB ports
� CAT-5 Ethernet cable
� < $100
� Other models available
� Members at Cloudy Nights forums report success with
Icron Ranger (http://www.icron.com)
� More expensive - > $300 for multi-port version
� WiFi Access Point
� One I had lying around…
First Configuration
WiFi AP USB Hub
USB-Serial
Adapters
Level ShifterPower Strip
First Configuration Assessment
� Keeps everything in one place� All components fit in a box
� Single power cord powers everything on
� Wiring loom with all connectors
� Easy to transport
� Configuration is consistent� Wiring loom ensures specific USB/serial connections
to specific destinations
� Remote operation� Workable, but presents reliability issues over wireless
� Glitch in link performance kills autoguider
Current Configuration
� Similar to first configuration, but instead of USB
hub, there is a “nettop” PC in the box
� Acer AspireRevo AR1600
� Intel Atom 1.6GHz / 1GB DRAM / 160GB HD
� $200 with Windows XP installed
� This model no longer made; current model ~$325
� Operated remotely by VNC installed as a service
� Many different versions available
� This setup uses TightVNC
� Optimized for bandwidth-constrained links
Current Configuration
WiFi AP
Nettop PC
USB-Serial
Adapters
Level ShifterPower Strip
Current Configuration
Current Configuration Assessment
� No more reliability issues
� Capture & guiding is completely self-sufficient
� If the wireless link fails, no problem; just reconnect
and everything is still there
� Note that, because of the setup, this remote PC
is never connected to the Internet
� Doesn’t get automatic updates
� Seems to run strangely quickly for such a low-
powered PC (boots Windows in a few seconds)
Optical Configuration
� Greatly reduced in size
� Off-axis guider is a huge improvement
� Built in OAG in QSI camera
� Many other options
� Weight, complexity & space reduction
� Threaded adapters
� Worth every $ of the 4 x $150 I paid Takahashi…
� Big Pelican case
� Makes it unnecessary to assemble or disassemble the
imaging train in almost all circumstances
Optical Configuration
Optical Configuration
Wrap Up
� Hit all of the big areas that expend time:
� Mount alignment – set up once, alignment is good for
days or weeks
� Much less to carry out – down to 2 trips
� Setup is consistent – much less chance for errors, less
wasted time fixing configuration bugs
� Net: set up in 5 minutes
Demonstration
References
Icron
Remote USB
http://www.icron.com
Dan’s Pier Top
Plates
http://www.pierplates.com
TightVNC http://www.tightvnc.com
Acer
AspireRevo
http://us.acer.com
Utility
notification
http://www.callbeforeyoudig.org/