duncan kitchin omsi astrophotography conference 2011

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

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


WiFi AP

Nettop PC

USB-Serial

Adapters

Level ShifterPower Strip

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

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/

duncan kitchin omsi astrophotography conference 2011

Documents