Format of the Zodiacal Observation History Files

[Adapted from the Explanatory Supplement]

All three verions of the ZOHF are organized into 572 files each. There is one SOP per file starting with SOP 29, i.e., File 1 corresponds to SOP 29, and File 572 to SOP 600. Within a file, each 80-byte logical record contains the timing, pointing and infrared data a for a single eight-second (0.5-seconds in the case of the 2' Resolution ZOHF) average (Table 1). Each logical record is identified with an OBS, but OBSs are not otherwise separated from one another within a SOP file. SOPs for which no survey data exist contain one dummy record which has a valid SOP number but zeroes in all other fields.

                  Table 1.  Format of the ZOHF

Start	Name	Description			Units		Format
Byte
1	NSOP	SOP number					I3
4	NOBS	OBS number					I3
7	NUTCS	Time UTCS - elapsed from	1E-2 sec	I10
		0 hours UT, 1 Jan 1981
17	INCL	Inclination			degrees		F6.2
23	ELONG	Solar Elongation		degrees		F6.2
29	BETA	Ecliptic Latitude		degrees		F6.2
35	LAMBDA	Ecliptic Longitude		degrees		F6.2
41	I(nu1)	12 micron Brightness Density	Jy sr-1		E10.4
51	I(nu2)	25 micron Brightness Density	Jy sr-1		E10.4
61	I(nu3)	60 micron Brightness Density	Jy sr-1		E10.4
71	I(nu4)	100 micron Brightness Density	Jy sr-1		E10.4

Solar Elongation: ELONG

Elongation is the angle between the line of sight and the Sun. Inclination is the angle between the ecliptic plane and the plane containing the Earth, Sun, and observation direction (i.e., the azimuth angle about the Earth-Sun axis). Elongation was fixed in each OBS, and inclination increased at a constant rate. These angles are related to geocentric ecliptic coordinates by the following expressions:

cos(ELONG) = cos(BETA) x cos(LAMBDA - LAMBDA(Sun))
sin(INCL) = sin(BETA)/sin(ELONG),

where LAMBDA(Sun) is the ecliptic longitude of the Sun.

Brightness Densities: I(nu1), I(nu2), I(nu3), I(nu4)

Conversion from in-band brightness to brightness density assumes a source with an energy distribution which is flat in flux per unit octave as explained in Section VI.C of the Explanatory Supplement.

Missing SOPs (dummy data record with zeros in all fields):

053, 054, 055, 056, 058, 200, 258, 259, 260, 261, 262, 263, 264, 442, 594, 595, 596, 597, 598

Within a file, each logical record contains the timing, pointing and infrared data for a half-second (~2') average, plus the infrared intensities for the subsequent half-second sample.

Format of the Zodiacal Observation History Files

ZOHF information

ADF/IRAS page