SMOKA Okayama Photographic Plate Archive Search

Overview

Using SMOKA Okayama Photographic Plate Archive Search, you can search Digitized plate data of Okayama 188cm telescope by Plate ID, Plate Size, a position (specified by R.A. and Dec (J2000) and Radius), DATE-OBS (observation date), Filter, Object Name, and Emulsion. This page provides the detailed information on input/output format of search/result page.

Please click the links below for specific information for Okayama Photographic Plate archive.

The Catalogue of Dry Plates with Newton Focus of the188-cm Reflector

Scanning Equipment and Software

Scanner: EPSON GT-X980 flatbed scanner
Software: EPSON SCAN (transparency scanning mode)

Scanning Methodology

Photographic plates placed directly on scanner glass surface
Orientation: Glass side down, emulsion side up

Known Issues

Image Distortion

Greater distortion occurs in the sub-scanning direction (line CCD movement) compared to the main scanning direction (line CCD array direction) due to flatbed scanner characteristics.

Focus Alignment

The focal plane is not aligned with the emulsion surface. The GT-X980's transparency scanning mode expects samples to be positioned 2.5mm above the glass surface, while photographic plate glass thickness is approximately 1mm, resulting in focus discrepancy.

Newton Rings

Optical interference patterns (Newton rings) are visible in many images due to the gap between the plate glass surface and scanner glass surface.

Image Processing Variability

Dynamic range and gamma values vary across images, making it impossible to determine actual plate transmission rates or photographic density values.

Data Format Specifications

Saved as 8-bit depth (lower 8 bits only) despite 16-bit specification
Information loss in bright star centers

Search Form Information

Input field format

Plate ID

The Plate ID is a combination of the plate size, 4 digit sequential number, and a branch number represented by an alphabet letter (A, B, C).

Plate Size

The classification of plate size is as follows:

    NL: 164 mm x 164 mm (60 arcmin x 60 arcmin)
    NS: 82 mm x 107 mm (31 arcmin x 46 arcmin)

R.A. and Dec

The equatorial coordinates of the celestial region where you want to search.
A number of formats are accepted for the R.A. and Dec. Here are some examples:

            R.A.            Dec
        12h34m56.7s     -76d54m32.1s
        12h 34m 56.7s   -76d 54m 32.1s
        12h34m56s       -65d43m21s
        12h 34m 56s     -65d 43m 21s
        12h34.5m         54d32.1m
        12h 34m         +54d 32m
        12.5h            54.3d
        12h             +54d

        12h34m56.7      -76d54m32.1
        12h 34m 56.7    -76d 54m 32.1
        12h34m56        -65d43m21
        12h 34m 56      -65d 43m 21
        12h34.5          54d32.1
        12h 34.5         54d 32.1
        12h34           +54d32
        12h 34          +54d 32

        12:34:56.7      -76:54:32.1
        12:34:56         65:43:21
        12:34.5         +54:32.1

The string is interpreted as decimal degrees unless it includes a delimiter, 'h' or ':'.

       123.4             54.3
       123              -54

Spacing is not important. You can delimit the hours/degrees, minutes, and seconds with h/d, m, or colons(:). Without the delimiters, the value is interpreted as decimal degrees.

Radius

How far around the search position you would like to search, in arcminutes.
This field is ignored, when range operator is not used in R.A. or Dec field.

DATE-OBS (Observation Date)

The date of the observation in Universal Time (UT). The date can have any of the following formats:

      1975-04-25     (yyyy-mm-dd)

You can use a range operator; for example,

   expression                    search range
2000-12-15..2000-12-31      2000-12-15 0hUT <= (obs date/time) < 2000-12-31 24hUT
>=2001-01-01                2001-01-01 0hUT <= (obs date/time)
>2001-01-01                 2001-01-02 0hUT <= (obs date/time)
<=1998-06-30                                   (obs date/time) < 1998-06-30 24hUT
<1998-06-30                                    (obs date/time) < 1998-06-30  0hUT

If no range operator is used, the search range is as follows:

2000-12-15                  2000-12-15 0hUT <= (obs date/time) < 2000-12-15 24hUT

Filter: You can search for plates that use a specific filter .
Select NULL to search for plates without any filter.
None (the state where nothing is selected) indicates no filter is specified.