EVIDENCE OF ASTEROID SATELLITES FROM 30 YEARS

OF OBSERVATION

PAUL D. MALEY¹, D.W. DUNHAM², D. HERALD³

¹UNITED SPACE ALLIANCE & INTERNATIONAL OCCULTATION TIMING ASSOCIATION (IOTA), HOUSTON, TX; ²IOTA, GREENBELT

MD; ³IOTA, CANBERRA AUSTRALIA

FIRST BINARY WORKSHOPSTEAMBOAT SPRINGS CO.

JULY 21-23, 2007

HISTORY OF SATELLITE DETECTION

• 1977 (6) HEBE OCCULTATION STARTED THE PROCESS

• >1029 PRIMARY OCCULTATIONS OBSERVED (as of December 2006)

• 42 SUSPECTED SATELLITE EVENTS

• 9 HIGH PRIORITY CANDIDATES

CONSTRAINTS

• IN SITU OBSERVATIONS

• CHASING SHADOWS

• TECHNOLOGY: SMALL TELESCOPES; COTS EQUIPMENT

• VISUAL OR VIDEO

• OBSERVATIONS ARE UNREPEATABLE

• RESOLUTION LIMITED TO HUMAN EYE OR VIDEO FRAME RATE

• NO FUNDING

(6) HEBE & γ CETI

NUMBER OF ASTEROID OCCULTATIONS OBSERVED 1961-2006

0

50

100

150

200

250

1950 1960 1970 1980 1990 2000 2010

YEAR

NUM

BER

NUMBER OF ASTEROID OCCULTATIONS WHERE POSSIBLE SATELLITES WERE REPORTED

01234567

1970 1975 1980 1985 1990 1995 2000 2005 2010

YEAR

NUM

BER

OCCULTATION CANDIDATE DEPENDENCIES

• Limiting magnitude +12.5• star and asteroid magnitudes• depth of magnitude drop during occultation• duration of occultation• path reliability• proximity of observation zone to twilight• elevation of target star above the horizon• whether available instrumentation is expected to be sensitive

enough to collect the data• angular separation from the moon• phase of the moon• overall weather in the region of proposed observation• possible hazards in observation zone including political,

civil, military

METHODS OF DETECTION

• VISUAL

• PHOTOELECTRIC

• VIDEO (STANDARD VIDEO RATE)

• DRIFT SCAN

IOTA STRATEGIES

• USE OF INTERNET

-COMMUNICATION AND COORDINATION

-DISTRIBUTION OF PREDICTIONS/CHARTS/SOFTWARE TOOLS

-LOCATING SAFE SITES

-LATEST WEATHER DATA

• USE OF MOBILE STATIONS

• PREPOINTED REMOTE STATIONS

SATELLITE DETECTION STRATEGIES

• UTILIZE VOLUNTEER OBSERVERS, KNOWN OBSERVATORIES

• MULTIPLE OBSERVERS, CLOSE SPACING

• ALTERNATION OF VIDEO & VISUAL OBSERVERS

• TWO VIDEO STATIONS 1KM APART

PREPLANNED SITE LAYOUT

ISSUES OF CREDIBILITY

• SINGLE SITE OBSERVATION

• REACTION TIME

• HARDWARE PROBLEMS

• ATMOSPHERIC SCINTILLATION

• CLOUD PASSAGE

• WRONG STAR TARGETED

• LOW ELEVATION

• INTERPRETATION OF DATA

SINGLE CHORD

ONE POLE

FRAGMENTED COVERAGE

NEAR COMPLETE MAP

TRANSATLANTIC

TRANSPACIFIC

COMPLETE SITE COVERAGE

HIGHEST RESOLUTION

FINE MAPPING

SATELLITE ANALOG: (11072) HIRAOKA

CASE STUDY 1– (532)HERCULINA (1978 June 7)

Pro: Simultaneous Photoelectric & visual observationsCon: Low star elevation (3 degrees) at Anderson Mesa

CASE STUDY 2– (216)KLEOPATRA (1980 Oct 10)Pro: 2 observations 2000 ft apart; color change reported like for main event

Con: Both observations were visual

CASE STUDY 3– (71)NIOBE (2005 Feb 10)Pro: 16-inch telescope used for secondary event; star 8th mag.

Con: Visual (but accurately timed with WWV)

CASE STUDY 4– (98)IANTHE (2004 May 16)Pro: Video

Con: Event was 0.2 seconds long

REJECTION (2004 Jun 24)

OPPORTUNITIES for STUDY

• VESTA OCCULTATION JAN 07 (CHILE) + 1991 OBSERVATIONS + HST IMAGES3D MODEL

• CHECKS ON POSITIONS OF KNOWN SATELLITES USING MOBILE IOTA OBSERVERS

CHALLENGES - 1• AGING EXPERIENCED OBSERVER CADRE• LACK OF FUNDING PREVENTS EXPANSION

OF EFFORTS• SIFT THROUGH THE FACTS TO ISOLATE

THE TRUTH• LIMITED TO EARTHBOUND OBSERVATION• NEA’S HAVE POOR ASTROMETRY• EDUCATING NEW OBSERVERS

CHALLENGES - 2

SAGAN DANGERFIELD GALILEO

PROMISE FOR THE FUTURE

•MIGRATION AWAY FROM VISUAL OBSERVATION

•ESTABLISH VIDEO AS A STANDARD

•ADOPT SOFTWARE VIDEO REDUCTION TOOLS

•ADOPT STANDARD METHODOLOGY:

-OBSERVATION WINDOW

-MULTIPLE FIELD STARS

-AUTOMATED OBSERVATION STATIONS

•IMPROVE NEA ASTROMETRY

PROMISE -2•DEMONSTRATIONS IN OTHER COUNTRIES

•ESTABLISH FUNDING SOURCES

-CLAY CENTER MOBILE OBSERVATORY DEVELOPMENT

•DEVELOP BETTER STRATEGIES FOR INTERCEPTION

•EXPAND OBSERVER CORPS THROUGH PUBLICATION

•BETTER PREDICTIONS FROM TMO AND FASTT

•INTERACTIVE GOOGLE MAPS FOR SITE DETERMINATION

•NEW SOFTWARE FOR OBSERVER COORDINATION

•DEVELOP WAYS TO USE ROBOTIC OBSERVATORIES

•COLLABORATION WITH PROFESSIONAL COMMUNITY (E.G. BERTHIER—KNOWN MINOR SATELLITES, SICARDY—PLUTO)

•EXPANSION OF ONE OBSERVER ESTABLISHING MULTIPLE UNTENDED STATIONS

CONCLUSIONEVIDENCE SHOWS:

• DETECTION OF A KNOWN SATELLITE HAS BEEN PROVEN

• NO SATELLITES HAVE BEEN CONFIRMED VIA METHODS DESCRIBED

SATELLITE SIGNIFICANCE:

• ORION MISSION TO A NEA

BACKUP SLIDES

CASE STUDY 5– (2)PALLAS (1978 May 29)Pro: Photoelectric; secondary event reached level of primary event

Con: 0.1 second duration

CASE STUDY 6– (146)LUCINA (1982 Apr 18)Pro: Image intensified video; bottom level expected for Lucina alone

Con: No other field stars

CASE STUDY 7 – (18)MELPOMENE (1978 Dec 11)Pro: Photoelectric obs of primary/secondary

Photoelectric Record at Monticello, UT; tracking errors, frozen drive

Photoelectric recording at Flower & Cook Obs., Ambler, PA

CASE STUDY8 = (772)TANETE (2004 Apr 18)Con: Visual, seen 2 minutes before primary