Digitization and Archivingof the

Palomar-Leiden Survey of Faint Minor Planets

and the

Three Palomar-Leiden Trojan Surveys

L. D. Schmadel1, G. Burkhardt1, R. M. Stoss1, W. Paech2

1Astronomisches Rechen-Institut, Heidelberg, Germany2Institut für Erdmessung, Hannover, Germany

Numbers…

- 1.2-m f/2.5 Oschin Schmidt on Palomar Mountain

- Kodak Glass Plates, 35.6cm x 35.6cm, 1mm thickness

- Field of View: 6.5° x 6.5°

- Limiting magnitude: ~ 20mag

Palomar-Leiden Survey (PLS)

- Statistical studies of asteroid population (Extension to MDS [1950-52, lim. mag. 16])

- 18° x 12° region centered on vernal equinox 3x2 fields

- 130 plates

- 1960 Sept. 24, 25, 26, 27, 28, 29, and Oct. 17, 22, 24, 25, 26

- Exposure times of 10min to 40min

- Guided on mean asteroid motion!

Total of ~ 2400 discoveries

1561 numbered (MPC, 2006 Apr. 16)

1960

- Statistical studies of Jupiter-Trojan population

- 12° x 12° region 2x2 fields centered on L5

- 54 plates

- 1971 Mar. 24, 25, 26, 27, and Apr. 02, 16, and Mai 13, 14, 16

- Exposure times of 12min

- Guided on mean Jupiter-Trojan motion!

Total of ~ 750 discoveries

429 numbered (MPC, 2006 Apr. 16)

1971

First Palomar-Leiden Trojan Survey (T1S)

- Statistical studies of Jupiter-Trojan population

- 12° x 12° region 2x2 fields centered on L4

- 76 plates

- 1973 Sept. 19, 20, 24, 25, 29, 30, and Oct. 04, 05

- Exposure times of 12min

- Guided on mean Jupiter-Trojan motion!

Total of ~ 1400 discoveries

1008 numbered (MPC, 2006 Apr. 16)

1973

Second Palomar-Leiden Trojan Survey (T2S)

- Statistical studies of Jupiter-Trojan population at L5

- 6° x 30° region 1x5 fields centered on L5

- 68 plates

- 1977 Oct. 07, 11, 12, 16, 17, 21, 22

- Exposure times of 9min to 13min

- Guided on mean Jupiter-Trojan motion!

Total of ~ 1500 discoveries

855 numbered (MPC, 2006 Apr. 16)

1977

Third Palomar-Leiden Trojan Survey (T3S)

The authors of

THE PALOMAR-LEIDEN SURVEYOF FAINT MINOR PLANETS

Astron. Astrophys. Suppl., 2, 339-448 (1970)

Tom Gehrels (b.1925)

Paul Herget (b.1908, †1981)

Ingrid van Houten-Groeneveld (b.1921)Cornelis Johannes van Houten (b.1920, †2002)

Palomar Observatory

1.2-m Schmidt

MPC in Cincinnati

(1947-1978)

Leiden Observatory

MPC in Cambridge

(1978- )

A problem and a solution…

- Total of ~ 340 plates

- Each one 35.6cm x 35.6cm in size (14“ x 14“)

- Largest affordable Scanner (DINA3: 29,7cm x 42,0cm): ~ 12“ x 17“

Problem!

Solution…

- Two Scans per plate

- 1800dpi 0.95“/pixel

- Each Scan = 0.8 GB

- Total of 0.5 TB

N

*

S

E W

Epson

10000XL

• A3 flatbed color image scanner• Epson MatrixCCDTM line sensor• Read area 12.2"x 17.2" (310mm x 437

mm)• 87,840 pixels/line (2400 dpi optical

resolution)• Scanning speed 5.3 msec/line (grayscale)• Grayscale depth 16-bit/pixel, Dmax 3.8• AutoFocus system (CCD and lens unit)

FEM analysis of plate bending

Project stages

• Phase 1 - Plate shipping from Leiden to Hannover• Phase 2 - Photographic documentation• Phase 3 - Cleaning• Phase 4 - Scanning

• Phase 5 - Software development• Phase 6 - Scanner analysis• Phase 7 - Archive generation• Phase 8 - Plate shipping from Hannover to Heidelberg

• Phase 9 - Scientific data mining tasks + Archive Online

Palomar Schmidt plate label at the NE corner(emulsion side: plate number, date, center coordinates)

P-L plate detail as seen from the glass side

Documentation: image processing

Wobbling (Scan direction horizontal)

Wobbling (Scan direction vertical)

25 x 17 crosses out of 116 x 116 matrix

Clean cross and contaminated cross

Wobbler… , 1µm positional, 0.1 pixel accuracy

Fourieranalysis in direction of Scanning (local distortions)

Global distortions

Dir

ecti

on o

f sc

ann

ing

Solver

10min exposure 40min exposure

GetField

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