Units

Listed below are Units of Measurement, supported by TMT observatory framework and are available as Enumerated values. Units are optionally attached to Parameter Keys.

Default Units for Keys

The default unit for UTCTimeKey and TAITimeKey (in Scala and Java both) is utc & tai respectively. For all the remaining keys, default unit is NoUnits.

SI Units

Name	Abbreviation	Description
angstrom	Angstrom	unit of length (10^-10 m)
alpha	alpha	fine structure constant
ampere	A	unit of electrical current
arcmin	arcmin	arc minute; angular measurement
arcsec	arcsec	arc second: angular measurement
bar	bar	unit of pressure
candela	candela	unit of luminous intensity
day	d	day - 24 hours
degree	deg	degree: agular measurement 1/360 of full rotation
degC	degC	degree celsius
degF	degF	Fahrenheit
elvolt	eV	electron volt
gauss	gauss	unit of measurement of magnetic induction
gram	g	unit of mass or weight
hertz	Hz	SI unit of frequency
henry	henry	unit of electrical inductance
hour	h	unit of time
joule	J	SI unit of energy
kelvin	K	base unit of temperature
kilogram	kg	base unit of mass in SI
kilometer	km	unit of length equal to 1,000 metres
liter	l	metric unit of volume
lm	lm	unit of luminous flux, or amount of light,
lsun	Lsun	solar luminosity
lx	lx	SI derived unit of illuminance measuring luminous flux per unit area
meter	m	meter: base unit of length in SI
mas	mas	milli arc second: angular measurement
me	me	electron mass - mass of a stationary electron
meter	m	unit of length
microarcsec	µas	micro arc second; angular measurement
millimeter	mm	unit of length equal to 0.001 metre
millisecond	ms	milliseconds
micron	µm	micron: alias for micrometer
micrometer	µm	micrometer
minute	min	minute is a unit of time
MJD	MJD	Modified Julian Date
mol	mol	mole: Unit of amount of substance
month	month	unit of time
mmyy	mmyy	Month/Year
mu0	mu0	magnetic constant
muB	muB	moment of electrons is bohr magneton
nanometer	nm	nanometers
newton	N	SI unit of force
ohm	ohm	unit of electric resistance
pascal	Pa	SI unit of pressure
pi	pi	pi is the ratio of the circumference of a circle to its diameter
pc	pc	unit for expressing distances to stars and galaxies,
ppm	ppm	part per million
radian	rad	radian: angular measurement of the ratio between the length of an arc and its radius
second	s	second: base unit of time in SI
sday	sday	sidereal day is the time of one rotation of the Earth
steradian	sr	steradian: unit of solid angle in SI
volt	V	Volt: electric potential or electromotive force
watt	W	Watt: power
Wb	Wb	Weber: SI derived unit of magnetic flux
week	wk	week: 7 days
year	yr	year

CGS Units

Name	Abbreviation	Description
coulomb	C	coulomb: electric charge
centimeter	cm	centimeter
D	D	Debye(dipole) - electric dipole moments of molecules
dyn	dyn	CGS unit of force
erg	erg	CGS unit of energy

Astrophysical Units

Name	Abbreviation	Description
au	AU	astronomical unit: approximately the mean Earth-Sun distance
a0	a0	bohr radius
c	c	speed of light
cKayser	cKayser	unit of wavenumber equal to reciprocal of a centimeter
crab	crab	unit for measurement of the intensity of Astrophysical X-ray sources
damas	damas	degree minute arcsecond
e	e	electron charge
earth	earth	earth unit
F	F	Farad: SI derived unit of electrical capacitance
G	G	Gravitation Constant gives the constant of proportionality
geoMass	geoMass	Earth Mass
hm	hm	hour minute
hms	hms	hour minute seconds
hhmmss	HH:MM:SS	hour minutes seconds(sexagesimal time)
jansky	Jy	Jansky: spectral flux density
jd	jd	Julian Day at an instant is Julian day number plus the fraction of a day since the preceding noon in Universal Time
jovMass	jovMass	Jupiter Mass
lightyear	lyr	light year
mag	mag	stellar magnitude
mjup	mjup	Jupiter mass
mp	mp	proton mass
minsec	m:s	minute second
msun	msun	solar mass
photon	photon	photon
rgeo	Rgeo	Earth radius
rjup	Rjup	Jupiter radius
rsun	Rsun	solar radius
rydberg	Rydberg	ionization energy of hydrogen in its ground state (~13.6 eV)
seimens	seimens	derived unit of electric conductance
tesla	tesla	unit of magnetic induction
u	u	atomic mass unit

Imperial Units

Name	Abbreviation	Description
barn	barn	unit of area for cross section of scattering (10^28 m^2)
cal	cal	thermochemical calorie: pre-SI metric unit of energy
foot	ft	international foot
inch	inch	international inch
pound	lb	international avoirdupois pound
mile	mi	international mile
ounce	oz	international avoirdupois ounce
yard	yd	international yard

Datetime units

Name	Abbreviation	Description
tai	tai	TAI Time unit
utc	utc	UTC Time unit
date	date	date
datetime	datetime	datetime

Others - Engineering

Name	Abbreviation	Description
NoUnits	none	scalar - no units specified
bit	bit	bit
encoder	enc	encoder counts
count	ct	counts as for an encoder or detector
mmhg	mmHg	millimetre of mercury
percent	percent	percentage
pix	pix	pixel

Usage Examples

Scala

copysource// declare keyname
val s1: String = "encoder"

// making 3 keys
val k1: Key[Boolean] = KeyType.BooleanKey.make(s1)
val k2: Key[Short]   = KeyType.ShortKey.make("RandomKeyName")
val k3: Key[String]  = KeyType.StringKey.make(s1)

// storing a single value, default unit is NoUnits
val bParam: Parameter[Boolean] = k1.set(true)
val bDefaultUnitSet: Boolean   = bParam.units === Units.NoUnits // true

// default unit for UTCTimeKey
val utcParam: Parameter[UTCTime] = KeyType.UTCTimeKey.make("now").set(UTCTime.now())
// default unit for TAITimeKey
val taiParam: Parameter[TAITime] = KeyType.TAITimeKey.make("now").set(TAITime.now())

// storing multiple values
val paramOfShorts: Parameter[Short] = k2.set(1, 2, 3, 4)

// values to store
val weekDays: Array[String] = Array("Sunday", "Monday", "Tuesday")

// default units via set
val paramWithUnits1: Parameter[String] = k3.setAll(weekDays)
// associating units via withUnits
val paramWithUnits2: Parameter[String] = k3.setAll(weekDays) withUnits Units.day
// change existing unit
val paramWithUnits3: Parameter[Short] = paramOfShorts.withUnits(Units.meter)

Java

copysource//declare keyname
String s1 = "encoder";

//making 3 keys
Key<Boolean> k1 = JKeyType.BooleanKey().make(s1);
Key<Short> k2 = JKeyType.ShortKey().make("RandomKeyName", JUnits.NoUnits);
Key<String> k3 = JKeyType.StringKey().make(s1, JUnits.NoUnits);

//storing a single value, default unit is NoUnits()
Parameter<Boolean> bParam = k1.set(true);
boolean bDefaultUnitSet = bParam.units() == JUnits.NoUnits; //true

//default unit for UTCTimeKey
Parameter<UTCTime> utcParam = JKeyType
        .UTCTimeKey()
        .make("now")
        .set(UTCTime.now());

//default unit for TAITimeKey
Parameter<TAITime> taiParam = JKeyType
        .TAITimeKey()
        .make("now")
        .set(TAITime.now());


//storing multiple values
Parameter<Short> paramOfShorts = k2.set(
        (short) 1,
        (short) 2,
        (short) 3,
        (short) 4
);

//values to store
String[] weekDays = {"Sunday", "Monday", "Tuesday"};

//defaults units via set
Parameter<String> paramWithUnits1 = k3.setAll(weekDays);
//associating units via withUnits
Parameter<String> paramWithUnits2 = k3.setAll(weekDays).withUnits(JUnits.day);
//change existing unit
Parameter<Short> paramWithUnits3 = paramOfShorts.withUnits(JUnits.meter);

Source Code for Examples

• Scala Example
• Java Example