Glossary of terms used on this site.
Click one of the letters above to advance the page to terms beginning with that letter.


0.4 meter telescope search for term

A heavily modified and redesigned Meade 40cm telescope with an LCOGT mount, electronics, and instruments. At least 24 of these will be installed at up to eight sites around the world. Two 0.4 meter telescopes are housed in the LCOGT-designed Aqawan enclosure.


1.0 meter enclosure search for term

An integrated enclosure system for the LCOGT 1.0 meter telescope, designed and built by LCOGT and incorporating a modified 19-foot dome from Ash-Dome. Includes all dome functions and equipment, distinct from the telescope and instruments.

1.0 meter telescope search for term

LCOGT’s primary science telescope. Eighteen of these are planned for up to eight sites around the Earth, each one remotely and robotically controlled. Instrumentation on the telescopes supports high-resolution science images, medium-resolution spectroscopy, and lucky imaging.


2.0 meter telescope search for term

LCOGT acquired two 2.0 meter telescopes in 2007, the Faulkes Telescope North (FTN) sited at Haleakala, Hawaii and the Faulkes Telescope South (FTS) sited at Siding Spring Observatory in Australia. Used by scientists throughout the world, linked into RoboNet, and also used for educational purposes.


absolute magnitude search for term

The apparent magnitude an object would have if it were located at a distance of 10 parsecs. This is a measure of the intrinsic brightness of a celestial object.

adaptive scheduler search for term

Part of the LCOGT observatory scheduling software. This centralized LCOGT software program produces a daily observing plan from the monthly planner program and sends it to the various LCOGT sites. The plan extends several days to accommodate for network outages, and provides alternative observations to allow for changing conditions.

apparent magnitude search for term

The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth. The brighter the object appears, the lower the value of its magnitude.

Aqawan search for term

A clamshell-style enclosure designed by LCOGT that houses two 0.4 meter (40cm) LCOGT telescopes or other instrumentation, as needed.

ARI search for term

Astrophysics Research Institute of Liverpool John Moores University (LJMU). Owners and operators of the Liverpool Telescope (LT) and the original Telescope Management Centre (TMC) for the Faulkes Telescopes before operations were taken over by LCOGT in 2007.

Ash-Dome search for term

Manufacturers of the dome used for the LCOGT 1.0 meter telescopes. Several modifications are made including replacing the azimuth motors and adding a dome control panel. The 1.0 meter enclosure walls are designed and constructed by LCOGT.

astrometric agent search for term

A software function responsible for acquiring target and guide objects in the night sky, typically based on one or more standard star catalogs, then calibrated using optical evidence. At LCOGT, this is a component of the Java Telescope Control System (jTCS) that will be common across the 40cm, 1.0 meter and 2.0 meter LCOGT telescope mounts.

astronomical unit search for term

The average distance between the Earth and the Sun. Approximately 1.496 × 10^8 km or 93 million miles.


binning search for term

An imaging term, this is the process of combining charge from adjacent pixels in a CCD during readout. Performed prior to digitization in the on-chip circuitry of the CCD by specialized control of the serial and parallel registers. Binning improves signal-to-noise ratio and increases frame rate, but at the expense of reduced spatial resolution. In spectroscopic CCD systems, the dispersed slit images lie along the CCD columns (perpendicular to the serial register) and the resulting images are then binned along the columns. Binning thus provides marked increases in the signal-to-noise ratio without loss of spectral resolution.

Boltwood cloud sensor search for term

A device to estimate the level of cloud cover by comparing the temperature of the sky to the ambient ground-level temperature. The device makes other environmental measurements as well. Used by LCOGT at observatory nodes.

BOS search for term

See Byrne Observatory.

BPL search for term

LCOGT names observatory nodes by the nearest airport code. BPL is a pseudo-airport code meaning Back Parking Lot, referring to telescopes and enclosures and other components at LCOGT headquarters in Santa Barbara.

Byrne Observatory search for term

An LCOGT observatory node housing an 0.8 meter (32") LCOGT telescope. Located in the Santa Ynez mountains on the University of California, Santa Barbara Sedgwick Preserve, the observatory is named in memory of Laurie Nelle Byrne who served as a docent at the reserve, and in honor of the Byrne family. Sometimes referred to as SQA, the Santa Ynez airport code. The node is used for testing, photometry, and public outreach.


CCD search for term

See charge-coupled device.

celestial sphere search for term

This is a very large imaginary sphere around the Earth with the longitude and latitude lines from the Earth projected onto it.

Cerro Tololo Inter-American Observatory search for term

Observatory and host organization at Cerro Tololo, Chile where LCOGT is installing an Observatory node.

charge-coupled device search for term

A device that captures and then moves electrical charge to an area where the charge can be converted to a digital value. Achieved by shifting the signals between capacitive bins within the device one at a time. Each CCD is optimized for specific characteristics including spectral range, quantum efficiency, read noise, etc. Highly sensitive to thermal changes, CCDs are maintained at very stable, low temperatures.

clam-shell enclosure search for term

A telescope enclosure with two symmetrical shutters or roof segments that open like a clam’s shell. LCOGT designed the clam-shell style Aqawan enclosure to house LCOGT 0.4 meter telescopes and other instruments.

COJ search for term

LCOGT names observatory nodes by the nearest airport code. COJ is the Coonabarabran airport code, the airport closest to the LCOGT Siding Spring, Australia observatory node.

commissioning search for term

The process used to enable and verify a device or enclosure for astronomical use. Commissioning occurs in two stages at LCOGT: on-sky commissioning is a complete process that prepares the device for use at LCOGT headquarters; on-site commissioning revalidates the device after disassembly, shipping, and installation on-site.

Coordinated Universal Time search for term

Roughly the same as GMT, UT, ZT, military time. All astronomical observations use this time rather than the local time.

CPT search for term

LCOGT names observatory nodes by the nearest airport code. CPT Is the Capetown airport code, the airport closest to the LCOGT SAAO Sutherland, South Africa observatory node.

CTIO search for term

See Cerro Tololo Inter-American Observatory.


dark current search for term

Dark current describes the rate of generation of thermal electrons at a given CCD temperature. Cooling the CCD reduces dark current dramatically. Many scientific-grade CCDs employ multi-pinned-phase (MPP) technology to further reduce dark current.

dark noise search for term

Arises from the statistical variation of thermally generated electrons within the silicon layers comprising a CCD. Dark noise, which also follows a Poisson relationship, is the square root of the number of thermal electrons generated within a given exposure.

data cubes search for term

A three- (or higher) dimensional array of values, commonly used to describe a time series of image data. Used in LCOGT image captures from the lucky imaging and high speed photometry (LIHPS) cameras to deliver a series of images.

declination search for term

Declination is similar to latitude and is measured in degrees, arcminutes and arcseconds, north or south of the celestial equator in the celestial sphere. Positive values correspond to positions north of the equator, negative values refer to positions south of the equator.


ecliptic search for term

The apparent annual path of the Sun on the celestial sphere.

EE80 search for term

80% Encircled Energy, expressed in arcsec or mm; this is a measure of the concentration of energy in an optical image. If a single star is brought to its sharpest focus by a lens giving the smallest image possible with that given lens (called a point spread function or PSF), calculation of the encircled energy of the resulting image gives the distribution of energy in that PSF. LCOGT’s criteria for encircled energy for its optics is 80% of the energy is encircled.

electron multiplying charge-coupled device search for term

Used as the imaging chip in LCOGT’s lucky imaging and high-speed photometry (LIHSP) cameras, these are characterized by high sensitivity and extremely low read noise. EMCCDs are image sensors that detect single photon events without an image intensifier, achieved through the unique electron-multiplying structure built into the chip.

EMCCD search for term

See electron multiplying charge-coupled device.

exoplanet search for term

An extrasolar planet, or exoplanet, is a planet outside the Solar System. LCOGT astronomers have located over 40 exoplanets to date.


Faulkes Telescope North search for term

LCOGT's 2.0 meter robotic telescope sited at Haleakala Observatory, Maui, Hawaii. Built by Telescope Technologies Limited (TTL), FTN saw first light in August 2003. LCOGT acquired the telescope in 2005 and began operating it in 2007. The telescope is housed in a clam-shell enclosure, and its original specification was identical to the Liverpool Telescope (LT).

Faulkes Telescope South search for term

LCOGT's 2.0 meter robotic telescope sited at Siding Spring Observatory, New South Wales, Australia. Built by Telescope Technologies Limited (TTL), FTS saw first light in July 2004. It was acquired by LCOGT in 2005, operated by LCOGT since 2007. The telescope is housed in a clam-shell enclosure, and its original specification was identical to the Liverpool Telescope (LT).

flexible image transport system search for term

A customizable digital format used to store, transmit, and manipulate scientific and other images. LCOGT captures images using a FITS format.

FLOYDS search for term

See folded low-order white-pupil double-dispersed spectrograph.

focal length search for term

The distance from the lens to the focal point.

focal point search for term

The point at which a lens or mirror forms an image of a distant point of light.

folded low-order white-pupil double-dispersed spectrograph search for term

LCOGT-designed low resolution spectrograph designed for use on the 2.0 meter telescopes (FTN and FTS) covering 350 — 1100 nm at 1.2 nm spectral bandwidth. Also called FLOYDS from Folded Low Order whYte-pupil Double-dispersed Spectrograph.

frame transfer mode search for term

CCD image capture mode without a shutter in order to speed the readout process. Only half of the CCD image area is exposed to light, the other half is masked and is used to temporarily store the image from the exposed half. Once the image in the form of electrical charge is shifted to the masked or storage area, the image area of the CCD starts collecting the next frame while the storage area digitizes and reads out the stored charge. LCOGT uses frame transfer CCDs on all primary science instruments to speed image processing.

FTN search for term

See Faulkes Telescope North.

FTS search for term

See Faulkes Telescope South.

full width at half maximum search for term

An expression of a gaussian profile. A standard mathematical term for an expression of the extent of a function, given by the difference between the two extreme values of the independent variable at which the dependent variable is equal to half of its maximum value.

full-frame mode search for term

A method of operating a CCD with a shutter to control exposure. The entire CCD is exposed and subsequently masked (by the shutter). While masked, readout occurs. Due to the time required to read data, and to execute the shutter, the percentage of time available for exposures is more limited than in frame transfer mode.

FWHM search for term

See full width at half maximum.


high-speed photometry search for term

Method of systematic monitoring of large regions of the sky with high temporal resolution used to detect and investigate short stochastic optical flares from a number of variable astrophysical objects (GRBs, SNe, flare stars, CVs, X-Ray binaries) of unknown localizations as well as near-earth objects (NEOs), both natural and artificial.

homing search for term

The act of an axis or mechanism determining its position prior to normal operations. There are variety of ways of doing this. Some systems move to a reference mark (e.g. the end of travel in one direction) and then creep back off to determine a repeatable physical position. More sophisticated systems may be able to home in any position by briefly traversing across a short series of encoded reference marks, from which the physical position may be determined.


IAC search for term

See Instituto Astrofisico de Canarias.

IfA search for term

See Institute for Astronomy.

Institute for Astronomy search for term

Organization founded at the University of Hawaii (UH) in 1967 to manage Haleakala and Mauna Kea Observatories, and to carry out its own program of fundamental research into stars, planets and galaxies.

Instituto Astrofisico de Canarias search for term

International Spanish research center with observatories in La Palma and Tenerife, Canary Islands, constituting the European Northern Observatory (ENO). The host organization for the LCOGT Canary Islands observatory node.


Java Telescope Control System search for term

Designed by LCOGT, this set of software programs combines an astrometric agent and a sequencing agent to handle commands and control, and includes all agents related to telescope control; for instance a mount agent and optical tube assembly agent.

jTCS search for term

See Java Telescope Control System.


light curve search for term

Graph of light intensity of a celestial object or region, as a function of time, usually in a particular frequency interval or band. Can be periodic, as in the case of eclipsing binaries, cepheid variables and other periodic variables, or aperiodic, as for a nova, a cataclysmic variable star, a supernova or a microlensing event. The light curve, together with other observations, can yield considerable information about the physical process that produces it or constrain the physical theories about it.

light-year search for term

The distance that light travels in a vacuum in one year. Approximately 9.5 × 10^12 km or 63,240 AU.

LIHSP search for term

See lucky imaging and high-speed photometry cameras.

Liverpool Telescope search for term

A 2.0 meter robotic telescope sited at the Observatorio del Roque de los Muchachos (ORM) on the island of La Palma, Canary Islands, owned and operated by Liverpool John Moores University (LJMU). Manufactured by TTL, it saw first light in July 2003. Its original specification is identical to the two Faulkes Telescopes. The telescope is housed in a clam-shell enclosure, and was entered into the Guinness World Records as the largest robotic telescope in the world (which may still be true).

LJMU search for term

Liverpool John Moores University, owners of TTL before it was acquired by LCO in 2005, who are the owners of the Liverpool Telescope (LT) and whose Astrophysics Research Institute (ARI) operate the LT, and previously operated FTN and FTS.

LPL search for term

LCOGT names observatory nodes (and office locations) by the nearest airport code. This is the Liverpool airport code, the airport closest to the LCOGT Birkenhead, UK office.

LSC search for term

LCOGT names observatory nodes by the nearest airport code. This is the La Florida airport code in La Serena, Chile, the airport closest to the LCOGT Cerro Tololo, Chile site.

LT search for term

See Liverpool Telescope.

lucky imaging search for term

Technique for delivering near-diffraction-limited imaging on ground-based telescopes. This corrects for the atmospheric turbulence which normally limits the resolution of ground-based observations by combining multiple fast exposures which freeze the motion caused by the turbulence. For papers and a bibliographic history see the Institute of Astronomy, University of Cambridge, Lucky Imaging Web Site

lucky imaging and high-speed photometry cameras search for term

Single photon sensitivity CCDs combined with high Quantum Efficiency (QE) at multi-MHz rapid readout speeds, with ultra-low noise performance. LCOGT is implementing the Andor Luca R or the Andor Luca S for this purpose.


magnification search for term

The factor by which the apparent angular size of an object is increased when viewed through a telescope.

medium resolution echelle spectrograph search for term

An echelle spectrograph uses two diffraction gratings (echelles), rotated 90 degrees with respect to each other and placed close to one another. An entrance point rather than a slit is used and a 2nd CCD-chip records the spectrum. LCOGT’s fiber-fed MRES covers 390-860 nm, and will be installed for use on up to two 1.0 meter telescopes at each observatory node.

microlensing search for term

An astronomical phenomenon due to the gravitational lens effect, that when one celestial object is sufficiently aligned with another, can be used to capture information ranging from the mass of a planet to the mass of a star, regardless of the light they emit.

monthly planner search for term

Part of the LCOGT observatory scheduling software. This centralized LCOGT software program picks up the seasonal observing budget from the seasonal planner and produces a monthly observing schedule. The adaptive scheduler picks up this monthly plan and breaks it down into into site-specific daily plans.

MRES search for term

See medium resolution echelle spectrograph.


Observatorio del Roque de los Muchachos search for term

Observatory site located on the island of La Palma, Canary Islands, where the Liverpool Telescope (LT) is located along with other research-class telescopes.

observatory node search for term

An LCOGT observatory node is the physical area leased to LCOGT for the construction and operation of enclosures and devices at a given site, as well as the functionality available at that site. LCOGT plans up to eight nearly identical nodes with additional supporting sites such as BPL in Santa Barbara and Byrne Observatory in Santa Ynez, California.

OGG search for term

LCOGT names observatory nodes by the nearest airport code. This its the Maui, Hawaii airport code, the airport closest to the LCOGT Haleakala Hawaii observatory node.

ORM search for term

See Observatorio del Roque de los Muchachos.


parsec search for term

The distance at which 1 AU subtends and angle of 1 arcsec. Approximately 3.26 light years.

photometry search for term

Science of the measurement of light, in terms of its perceived brightness to the human eye.

photon noise search for term

Inherent natural variation of incident photon flux. Photoelectrons collected by a CCD exhibit a Poisson distribution and have a square root relationship between signal and noise.

precession search for term

A phenomenon caused by small changes in the Earth’s rotation over time, which cause the right ascension and declination of other celestial objects to change slowly.


QE search for term

See quantum efficiency.

quantum efficiency search for term

The percentage of photons hitting a photoreactive surface (such as a CCD) that will produce an electron–hole pair. It is an accurate measurement of the device's electrical sensitivity to light.


readout noise search for term

Uncertainty introduced during the process of quantifying the electronic signal on a CCD. The major component of readout noise arises from the on-chip preamplifier.

refractive index search for term

The ratio of the speed of light in a vacuum to the speed of light in the medium.

right ascension search for term

Right Ascension, abbreviated R.A., is a measure of distance on the celestial sphere measured eastward along the celestial equator. It is similar to longitude and is measured in hours, minutes and seconds.

Robonet search for term

Prototype global network of large (2.0 meter) robotic telescopes with observing time on the Liverpool Telescope (LT) for specific projects, plus additional time on the Faulkes Telescopes North (FTN) and South (FTS).


SAAO search for term

See South African Astronomical Observatory.

SBA search for term

LCOGT names observatory nodes by the nearest airport code. This is the Santa Barbara, California code, the airport closest to the LCOGT, Inc. headquarters in Goleta, California.

SBIG search for term

Acronym for Santa Barbara Instrument Group, makers of CCD cameras. LCOGT uses these cameras primarily as autoguiders.

SDSS search for term

See Sloan Digital Sky Survey.

seasonal planner search for term

Part of the LCOGT observatory scheduling software. This centralized LCOGT software program gathers all approved observing proposals and produces a long-range observing budget for the full LCOGT network. The monthly planner picks this up and created a monthly observing plan. This in turn is picked up by the adaptive scheduler which breaks the plan down into a site-specific daily schedule. This is passed to individual site agents which execute the observations as conditions allow.

SEMS search for term

See site environment monitoring station.

sidereal day search for term

23 hours, 56 minutes, 4.1 seconds, the amount of time it takes the Earth to rotate 360 degrees. This is approximately 4 minutes shorter than a solar day.

Siding Spring Observatory search for term

Observatory in Australia, the host organization for the eastern Australia LCOGT observatory node. Managed by the Research School of Astronomy and Astrophysics (RSAA) of the Australia National University (ANU).

signal-to-noise ratio search for term

For CCDs, the relative magnitude of a signal compared to the uncertainty in that signal on a per-pixel basis. Specifically, it is the ratio of the measured signal to the overall measured noise (frame-to-frame) at that pixel. Components of signal-to-noise (SNR) include photon noise, read noise, and dark noise.

site agent search for term

Part of the LCOGT observatory scheduling software. This local LCOGT software program accepts a daily observing plan from the centralized adaptive scheduler and does its best to execute the plan. The site agent reports back status and success or failure.

site environment monitoring station search for term

A standardized LCOGT-installed weather station at each observatory node.

site services building search for term

A 20-foot shipping container that contains the LCOGT on-site network and computing servers, a Universal Power Supply (UPS), an air conditioning unit, and a medium resolution (MRES) spectrograph that will be fiber-fed from two of the 1.0 meter telescopes on-site.

site storage container search for term

A double-sized shipping container that will contain a subset of parts and tools for maintenance and repair tasks on-site.

slewing search for term

The motion of an axis or mechanism where it is moving in response to a series of tracking commands.

Sloan Digital Sky Survey search for term

An astronomical program capturing deep, multi-color images covering more than a quarter of the sky and creating 3-dimensional maps containing more than 930,000 galaxies and more than 120,000 quasars using a dedicated 2.5-meter telescope at Apache Point Observatory, New Mexico.

South African Astronomical Observatory search for term

Observatory site at Sutherland near Capetown, South Africa and host organization for the South Africa LCOGT observatory node.

spectrograph search for term

An instrument that separates an incoming wave into a frequency spectrum. LCOGT designed and will install a low resolution spectrograph called the Folded Low Order whYte-pupil Double-dispersed Spectrograph (FLOYDS) and a medium resolution model called the Medium Resolution Echelle Spectrograph (MRES).

SQA search for term

LCOGT names observatory nodes by the nearest airport code. This is the Santa Ynez, California airport code, the airport closest to the LCOGT Sedgwick observatory node.

SSB search for term

See Site Services Building.

SSC search for term

See site storage container.

SSO search for term

See Siding Spring Observatory.


TAC search for term

See Time Allocation Committee.

Target of Opportunity search for term

Unexpected astronomical events of extraordinary scientific interest for which observations on a short time scale are justified. LCOGT is set up to respond to these within the iterative observation scheduling programs.

TEC search for term

See thermoelectric-cooled.

Teide Observatory search for term

Teide Observatory, Canary Islands, Spain, host site for the Canary Islands LCOGT observatory node. Also called TFN.

telemetry agent search for term

A software module that receives and writes telemetry submissions from telescopes, instruments, and other processes and converts the data into commands that can be reported and read by other agents. For example, weather telemetry data is used by the site agent to determine whether specific observations are possible.

Telescope Management Centre search for term

Organization at Liverpool John Moores University set up to provide management for operations of the Faulkes and Liverpool telescopes. Part of the Astrophysics Research Institute (ARI), LCOGT assumed operations of the Faulkes Telescopes from the ARI TMC in late 2007. TMC continues to manage the Liverpool Telescope.

Telescope Technologies Limited search for term

Based in Birkenhead, UK, TTL built five 2.0 meter -class telescopes worldwide: the 2.0 meter Liverpool Telescope (La Palma, Canary Islands), the 2.0 meter Faulkes Telescope North (Maui, Haleakala, Hawaii), the 2.0 meter Faulkes Telescope South (New South Wales, Siding Spring, Australia), the 2.0 meter IUCAA Telescope (Pune, India) and the 2.4 meter Yunnan Telescope (Lijiang, China). TTL was originally owned by Liverpool John Moores University (LJMU); acquired by LCOGT in 2005.

TFN search for term

LCOGT names observatory nodes by the nearest airport code. This is the Tenerife North airport code on the Canary Islands, the airport closest to the LCOGT observatory node at the Teide Observatory, Canary Islands, Spain.

thermoelectric-cooled search for term

A solid-state heat pump cooling method used by LCOGT to cool the Luca R and Luca S lucky imaging camera EMCCDs. Using a Peltier device, the thermoelectric heat pump moves heat from one side of the device to the other side against the temperature gradient (from cold to hot), using electrical energy.

Time Allocation Committee search for term

At LCOGT, a scientific committee that meets twice yearly to review and approve observing program proposals for LCOGT.

TTL search for term

See Telescope Technologies Limited.


UBVRI search for term

Filter designations on the Johnson/Kron/Cousins/Bessell/Landolt system for ultra-violet, blue, visual, red, infrared.

ugriz search for term

Filter designations on the Sloan SDSS system for ultra-violet, green, red, infrared, "zing".

UTC search for term

See Coordinated Universal Time.


Yunnan Telescope search for term

The Yunnan 2.4 meter telescope, built by TTL, is owned and operated by the Yunnan Astronomical Observatory (YAO) and is located at the Gao Meigu Observatory outside Lijiang, China. It saw first light in November 2006 and is similar to the Faulkes Telescopes but with a larger primary mirror making it wider. Uses a Nasmyth focal station and de-rotator, and is sited in a rotating dome.