Appendix A — PC-ASTROM The Input File

This appendix gives a more formal and complete specification of the input file than is given in the main text, and concludes with a more comprehensive example.

INPUT FILE:

SEQUENCE

‘/’

SEQUENCE

‘/’

. . .

SEQUENCE

‘END’

Blank records are ignored. Any record may end in a comment, which begins with an asterisk. Where records contain numbers these are free-format, decoded by the slaDbjin and slaDfltin routines in SLALIB, separated by spaces or a single comma. Lowercase and uppercase can be freely mixed. Any number of sequences is permitted.

SEQUENCE:

RESULTS EQUINOX RECORD, optional

TELESCOPE TYPE RECORD, optional

PLATE DATA RECORD

OBSERVATION DATA, 0-3 records

REFERENCE STARS, 2-3 per star for 2-1000 stars

UNKNOWN STARS, 1-2 per star for any number of stars

OBSERVATION DATA:

TIME RECORD

OBSERVATORY RECORD

METEOROLOGICAL RECORD

(Any order; any selection; repeats harmless.)

REFERENCE STAR:

COLOR RECORD (optional; repeats harmless)

REFERENCE STAR RA,DEC RECORD

REFERENCE STAR X,Y RECORD

A color record applies to all subsequent stars, both reference and unknown.

UNKNOWN STAR:

COLOR RECORD (optional; repeats harmless)

and/or:

UNKNOWN STAR X,Y RECORD

or:

UNKNOWN STAR RA,DEC RECORD

RESULTS EQUINOX RECORD:

EQUINOX

In the absence of this record, J2000.0 is used.

TELESCOPE TYPE RECORD:

[APPROX] PROJECTION

In the absence of this record, ‘SCHM’ is assumed.

PLATE DATA RECORD:

[APPROX] RA DEC EQUINOX [EPOCH]

The position specified is that of the plate center. The epoch is optional only if the information is supplied later in a time record (see next item).

TIME RECORD:

Either:

‘T...’ UT

or:

‘T...’ ST

The first of these forms allows the epoch to be omitted from the plate data record.

OBSERVATORY RECORD:

Either:

‘O...’ STATION

or:

‘O...’ [LONGITUDE] LATITUDE [HEIGHT]

The longitude may be omitted only if the sidereal time has been or will be specified via a time record. The height defaults to an estimate based on the air pressure.

METEOROLOGICAL RECORD:

‘M...’TEMPERATURE [PRESSURE]

The temperature defaults to 278 degrees K. The pressure defaults to an estimate based on the height.

COLOR RECORD:

‘C...’

WAVELENGTH

A wavelength, once specified, applies to all stars from then on. The starting default is 500 nm.

REFERENCE STAR RA,DEC RECORD:

Either:

RA DEC PMR PMD EQUINOX [EPOCH] [PARALLAX] [NAME]

or:

RA DEC EQUINOX EPOCH [NAME]

The second format implies inertially zero proper motion.

REFERENCE STAR X,Y RECORD:

X Y

UNKNOWN STAR X,Y RECORD:

X Y [NAME]

UNKNOWN STAR RA,DEC RECORD:

RA DEC EQUINOX [NAME]

EQUINOX:

The epoch of the equator and equinox of a mean [ fi; Æ ] coordinate system. A Besselian epoch implies the pre IAU 1976 system (as used in the FK4 catalog) and a Julian epoch implies the post IAU 1976 system (as used in the FK5 catalog).

APPROX:

‘~’ (tilde)

At the start of the telescope type and plate data records, this specifies that the radial distortion and plate center, respectively, are to be fitted.

PROJECTION:

‘ASTR...’= astrograph

‘SCHM...’= Schmidt (default)

‘AAT2...’= AAT prime focus doublet

‘AAT3...’= AAT prime focus triplet

‘AAT8...’= AAT f=8 with vacuum plateholder

‘JKT8...’= JKT f=8 Harmer-Wynne

‘GENE...’ DISTORTION = generalized pincushion/barrel distortion

DISTORTION:

A number, the parameter q in the pincushion/barrel distortion expression r' = (1+q | r | ^2 ) r , where r' is the radial vector to the star image from the intersection of the optical axis and the plate, and r is the same vector but assuming tangent-plane geometry. The vectors are in units of one focal length.

EPOCH:

A Besselian or Julian epoch: a single number resembling years AD, optionally preceded by ‘B’ (for Besselian) or ‘J’(for Julian). In the absence of a prefix, epochs before 1984.0 are assumed to be in the Besselian timescale, and epochs from 1984.0 onwards are assumed to be in the Julian timescale.

RA DEC:

A mean [a,d] expressed as six numbers: hours, minutes, seconds, degrees, arc minutes, arc seconds. The seconds and arc seconds can be given to any reasonable precision; the others must be integers. All the numbers except the degrees must be positive; southern d is indicated by minus degrees (even if zero).

UT:

The UT epoch of observation expressed as six numbers: years AD, month, day, hours, minutes. All but the minutes must be integers. The year, month and day must form a valid date in the Gregorian calendar.

ST:

The local (apparent) sidereal time of observation expressed as two numbers: hours,

minutes. The hours must be an integer.

STATION:

A character string specifying one of the observatories supported by the slaObs routine

in SLALIB.

LONGITUDE:

The east longitude, expressed as two numbers: degrees (which must be an integer) and arcminutes. West longitudes may be indicated either by minus degrees (even if zero) or by east longitude > 180 degrees.

LATITUDE:

The (geodetic) latitude, expressed as two numbers: degrees (which must be an integer) and arcminutes. South latitude is indicated by minus degrees (even if zero).

HEIGHT:

A single number, the height above sea level in metres.

TEMPERATURE:

A single number, the ambient temperature in degrees K.

PRESSURE:

A single number, the pressure in mB.

WAVELENGTH:

A single number, the effective wavelength in nm.

PMR PMD:

Two numbers, the proper motions in seconds and arcseconds per year respectively.

PARALLAX:

A single number, the annual parallax in arcseconds.

NAME:

The name field, which is always optional, is simply the first 10 characters of the comment, excluding the ‘*’ and any leading spaces.

X Y:

Two numbers, the Cartesian coordinates on the plate; the units of x and y should preferably be the same and in the mm to m range (e.g. mm), and the zero points should not be too far from the region of measurement. The example input file which appears on the next page includes two sequences. The

first is for a typical run using measurements from a Schmidt plate, while the second is for precise reduction, in observed place, of AAT f=8 measurements, including automatic determination of the radial distortion and plate center. For brevity, neither sequence includes as many reference stars as would normally be advisable.

B1950 * Results in FK4

SCHM * Schmidt geometry

19 04 00.0 -65 00 00 B1950.0 1974.5 * Plate center, and epoch

18 56 39.426 -63 25 13.23 -0.0002 -0.036 B1950.0 * Ref 1

44.791 85.643

19 11 53.909 -63 17 57.57 0.0058 -0.044 1950.0 * Ref 2

-46.266 92.337

19 01 13.606 -63 49 14.84 0.0020 -0.026 1950.0 * Ref 3

17.246 64.945

19 08 29.088 -63 57 42.79 0.0016 0.018 1950.0 * Ref 4

-25.314 57.456

19 02 10.088 -63 29 16.73 0.0012 -0.019 1950.0 * Ref 5

11.890 82.766

-5.103 58.868 * Candidate

19 09 46.2 -63 51 27 J2000.0 * Radio pos

/ * End of first sequence

* AAT plate 2266 (f/8 RC) NGC 3114

~ AAT8 * To be fitted

~ 10 01 00.0 -59 53 01 B1950 * To be fitted

Time 1984 01 20 16 00

Obs AAT

Met 288 899

Color 450 * Default color for reference stars

10 01 21.203 -59 52 14.05 B1950 J1984.1

9.0353 18.4211 *130

10 00 16.401 -59 52 52.16 B1950 J1984.1

1.7304 17.9282 *70

10 00 18.516 -59 53 10.20 B1950 J1984.1

1.9669 17.6566 *73

10 00 19.620 -59 49 01.62 B1950 J1984.1

2.1223 21.3760 *74

10 00 20.525 -59 52 01.09 B1950 J1984.1

2.2025 18.6888 *75

10 00 21.416 -59 51 30.27 B1950 J1984.1

2.3067 19.1501 *76

10 00 22.896 -59 53 49.60 B1950 J1984.1

2.4544 17.0626 *80

10 01 26.159 -59 50 38.50 B1950 J1984.1

9.6143 19.8435 *134

10 01 28.328 -59 51 16.86 B1950 J1984.1

9.8509 19.2653 *138

10 01 54.446 -59 54 39.28 B1950 J1984.1

12.7495 16.1963 *156

10 01 54.523 -59 50 01.72 B1950 J1984.1

12.8193 20.3493 *157

10 01 57.438 -59 51 26.29 B1950 J1984.1

13.1292 19.0793 *161

10 00 12.385 -60 08 08.51 B1950 J1984.1

1.1637 4.2188 *65

C 500

5.8265 12.7252 *104 red

C 400

5.8265 12.7252 *104 blue

END

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Appendix A — PC-ASTROM The Input File

WAVELENGTH

NAME: