Occultation Set-up

Astronomical Society of the Palm

Beaches

Terrence R. Redding, Ph.D.

What is an Occultation?• http://weblore.com/richard/images/Supercompressed_AnimationWizard2.gif

Occultations of Stars by Asteroids

• Difficult to predict; 1st seen in Sweden in 1958

• Techniques developed by IOTA to improve astrometric techniques

• Observations through GPS and video to determine the sizes, shapes, satellites, and accurate positions of the asteroids

• Accurate orbits allow mass determinations from measuring perturbations of the orbits

• Very close double stars and stellar angular diameters resolved

• Geometry shown in next figure

• More distant objects (Trojans, Centaurs, TNO’s) harder to predict but more valuable

Setup – Use what you have – get what

you need!

• Telescope – wide field

• Record – video best – tape - notes

• Timing is everything – the more precise the

better

• Plan – what – when – where – what to expect

• Preparation – days of planning only to miss

the event by seconds

• Weather – update forecast

Simple Camera for Slow Bright

Occultations

Canon PowerShot

Canon EOS Rebel T1i

Canon T1i Image

Common Occultation Camcorder

First Occultation Setup

Setup Trimmed Down

Bare minimum for precision• Telescope

– Widest field possible

• Camera

– 30 fps

– Low lux .001 or better common

• Camcorder

– DVI with AVI on digital tape

– Canon ZR series most popular

– ZR 80 – 95 record on camera

• GPS

– IOTA-VTI available

– Camcorder can be time-

stamped early to support

multi-station deployment

• Photometry

– LiMovie and Tangra

Redding South Observatory

RSO 70mm Occultation Scope

First Success

Richard Nugent Video Setup

Scotty’s Migration

10th Mag Stars Mighty Mini

How are Occultation Observations

Done?• Video – becoming the most common

• Visual – essential for confirmation

• Steps:– 1. Locate the target star and track it during the 5 minute window surrounding

the occultation.

– 2. Tune in your shortwave radio to either 5, 10 or 15 Mhz (this is radio station W W V out of Ft. Collins, Colorado)

– 3. Start your recorder at least 3 minutes prior to the predicted time of the occultation and make sure it can be heard in the recorder.

– 4. When you see the target star dim/vanish, yell "D" , and when you see the target star reappear, yell "R" into the recorder. Continue to record and watch the target star for a possible second occultation (by an asteroid moon) for 2-3 more minutes.

– 5. Note your location by estimating the distance and direction from the nearest intersection. Draw a diagram if needed of your location. Use this information to get your latitude and longitude map or Google Earth

What Does an Occultation Look Like

• View the YouTube Video of Recent occultation

with satellite discovery – Conard

• http://www.youtube.com/watch?v=kMEEvdo

RIS0

• No confirmation of satellite

• Confirmation needed before naming rights

granted

• There are never enough observers

Occult Watcher Main Screen

Guide 8 Charts

Guide 8 Finder Chart

Guide 8 Charts

Initial Distribution of Stations

OW Map Site Selection

Three Mobile Observation Sites

Complete Deployment Plan

Planning Complete?

Precisely Pointed Automatic

Astronomical Station to

Record the eclipse of the star

TYC 1884-01329-1 by the asteroid (621) Werdandi at

10:26 EDT this evening

If you have any questions or concerns, call my cell phone,

561-351-1520, I’m nearby

Terry Redding,

International Occultation Timing Assoc.

Please do not disturb -

Conducting an Occultation

Observation

• Plan in detail

• Plan early and expect to revise plan

• Map observation sites

• Inspect sites and revise as needed

• Charge batteries and pretest all equipment

• Reverse load to support deployment

• Prepoint, reverse order to turn recorders on

• Retrieve sites

Reporting an Occultation Observation

• Visually inspect tapes

• Transfer to disk selected video

• Virtual Dub

• Analyze in Tangra

– Be sure to have target star

– Guide star

– Comparison Star

• File one report per observation site.

References

• http://www.lunar-

occultations.com/iota/iotandx.htm

• http://www.poyntsource.com/New/index.htm

• http://scottysmightymini.com/

• http://www.palmbeachastro.org/TerrysPage.h

tm

• http://weblore.com/richard/AsteroidPage.htm