Editing Apparent magnitude

{{Short description|Brightness of a celestial object observed from the Earth}}
{{For|a more detailed discussion of the history of the magnitude system|Magnitude (astronomy)}}
{{Use dmy dates|date=October 2023}}
[[File:65Cyb-LB3-apmag.jpg|thumb|upright=1.4|Asteroid [[65 Cybele]] and two stars in the constellation [[Aquarius (constellation)|Aquarius]], with their magnitudes labeled]]

'''Apparent magnitude''' ('''{{mvar|m}}''') is a measure of the [[Irradiance|brightness]] of a [[star]], [[astronomical object]] or other celestial objects like [[artificial satellite]]s. Its value depends on its intrinsic [[luminosity]], its distance, and any [[extinction (astronomy)|extinction]] of the object's light caused by [[interstellar dust]] along the [[sightline|line of sight]] to the observer.

Unless stated otherwise, the word ''magnitude'' in astronomy usually refers to a celestial object's apparent magnitude. The magnitude scale likely dates to before the ancient [[Ancient Greek astronomy#Astronomy in the Greco-Roman and Late Antique eras|Roman astronomer]] [[Ptolemy|Claudius Ptolemy]], whose [[Star catalogue|star catalog]] popularized the system by listing stars from [[First-magnitude star|1st magnitude]] (brightest) to 6th magnitude (dimmest).<ref>{{cite book |last1=Toomer |first1=G. J. |title=Ptolemy's Almagest |date=1984 |publisher=Springer-Verlag |location=New York |isbn=0-387-91220-7 |page=16 |url=https://archive.org/details/ptolemysalmagest0000ptol/page/16/mode/2up}}</ref> The modern scale was mathematically defined to closely match this historical system by [[Norman Robert Pogson|Norman Pogson]] in 1856.

The scale is reverse [[logarithmic scale|logarithmic]]: the brighter an object is, the lower its [[magnitude (astronomy)|magnitude]] number. A difference of 1.0 in magnitude corresponds to the brightness ratio of <math>\sqrt[5]{100}</math>, or about 2.512. For example, a magnitude 2.0 star is 2.512 times as bright as a magnitude 3.0 star, 6.31 times as magnitude 4.0, and 100 times magnitude 7.0.

The brightest astronomical objects have negative apparent magnitudes: for example, [[Venus]] at −4.2 or [[Sirius]] at −1.46. The faintest stars visible with the [[naked eye]] on the darkest night have apparent magnitudes of about +6.5, though this varies depending on a person's [[Visual acuity|eyesight]] and with [[Horizontal coordinate system|altitude]] and atmospheric conditions.<ref>{{cite journal |last=Curtis |first=Heber Doust |year=1903 |orig-date=1901-03-27 |title=On the Limits of Unaided Vision |journal=[[Lick Observatory|Lick Observatory Bulletin]] |publisher=[[University of California]] |volume=2 |pages=67–69 |bibcode=1903LicOB...2...67C |doi=10.5479/ADS/bib/1903LicOB.2.67C |doi-access= |number=38}}</ref> The apparent magnitudes of known objects range from the Sun at −26.832 to objects in deep [[Hubble Space Telescope]] images of magnitude +31.5.<ref name="AAVSO">{{cite web
|title=Magnitudes: Measuring the Brightness of Stars
|first=Templeton
|last=Matthew
|date=21 October 2011
|publisher=American Association of Variable Stars (AAVSO)
|url=https://www.aavso.org/magnitude
|access-date=19 May 2019
|archive-url=https://web.archive.org/web/20190518084414/https://www.aavso.org/magnitude
|archive-date=18 May 2019
|url-status=live
}}</ref>

The measurement of apparent magnitude is called [[Photometry (astronomy)|photometry]]. Photometric measurements are made in the [[ultraviolet]], [[Visible spectrum|visible]], or [[infrared]] [[Electromagnetic spectrum#Regions|wavelength bands]] using standard [[passband]] filters belonging to [[photometric system]]s such as the [[UBV photometric system|UBV system]] or the [[Strömgren photometric system|Strömgren ''uvbyβ'' system]]. Measurement in the V-band may be referred to as the '''apparent visual magnitude'''.

[[Absolute magnitude]] is a related quantity which measures the [[luminosity]] that a celestial object emits, rather than its apparent brightness when observed, and is expressed on the same reverse logarithmic scale. Absolute magnitude is defined as the apparent magnitude that a star or object would have if it were observed from a distance of {{convert|10|parsec|ly km mi|abbr=off|lk=in}}. Therefore, it is of greater use in [[stellar astrophysics]] since it refers to a property of a star regardless of how close it is to Earth. But in [[observational astronomy]] and popular [[stargazing]], references to "magnitude" are understood to mean apparent magnitude.

[[Amateur astronomy|Amateur astronomers]] commonly express the darkness of the sky in terms of [[limiting magnitude]], i.e. the apparent magnitude of the faintest star they can see with the naked eye. This can be useful as a way of monitoring the spread of [[light pollution]].

Apparent magnitude is technically a measure of [[illuminance]], which can also be measured in photometric units such as [[lux]].<ref>{{cite journal |last1=Crumey |first1=A.|title=Human Contrast Threshold and Astronomical Visibility.|journal=Monthly Notices of the Royal Astronomical Society|date=October 2006|volume=442|issue=3|pages=2600–2619 |doi=10.1093/mnras/stu992 |doi-access=free|arxiv=1405.4209|bibcode=2014MNRAS.442.2600C }}</ref>

== History ==
{{More citations needed section|talk=talk:Apparent magnitude#Main Article Problems|date=May 2019}}
{|class="wikitable" style="float: center; margin-left: 1em; text-align: center;"
! Visible to<br />typical<br />human<br />eye<ref name="SIMBAD-mag6.5"/>
! Apparent<br />magnitude
! Bright-<br />ness<br />relative<br />to [[Vega]]
! Number of stars <br /> (other than the [[Sun]]) <br />brighter than<br />apparent magnitude<ref>{{cite web | url = http://www.nso.edu/PR/answerbook/magnitude.html | archive-url = https://web.archive.org/web/20080206074842/http://www.nso.edu/PR/answerbook/magnitude.html | archive-date = 6 February 2008 | title = Magnitude | publisher = National Solar Observatory—Sacramento Peak | access-date = 23 August 2006}}</ref><br />in the night sky
|-
| rowspan="9" | Yes
|−1.0 || 251% ||1 ([[Sirius]])
|-
|{{0|0}}0.0 || 100% ||5
<small>([[Vega]], [[Canopus]], [[Alpha Centauri]],</small>
<small>[[Arcturus]])</small>
|-
|{{0|0}}1.0 || 40% ||15
|-
|{{0|0}}2.0 || 16% ||48
|-
|{{0|0}}3.0 || 6.3% ||171
|-
|{{0|0}}4.0 || 2.5% ||513
|-
|{{0|0}}5.0 || 1.0% ||{{val|1602}}
|-
|{{0|0}}6.0 || 0.4% ||{{val|4800}}
|-
|{{0|0}}6.5 || 0.25% ||{{val|9100}}<ref>[[Bright Star Catalogue]]</ref>
|-
| rowspan="4" | No
|{{0|0}}7.0 || 0.16% ||{{val|14000}}
|-
|{{0|0}}8.0 || 0.063% ||{{val|42000}}
|-
|{{0|0}}9.0 || 0.025% ||{{val|121000}}
|-
|10.0 || 0.010% ||{{val|340000}}
|}

The scale used to indicate magnitude originates in the [[Hellenistic Greece|Hellenistic]] practice of dividing stars visible to the naked eye into six ''magnitudes''. The [[List of brightest stars|brightest stars]] in the night sky were said to be of [[first magnitude star|first magnitude]] ({{mvar|m}} = 1), whereas the faintest were of sixth magnitude ({{mvar|m}} = 6), which is the limit of [[human]] [[visual perception]] (without the aid of a [[telescope]]). Each grade of magnitude was considered twice the brightness of the following grade (a [[logarithmic scale]]), although that ratio was subjective as no [[photodetector]]s existed. This rather crude scale for the brightness of stars was popularized by [[Ptolemy]] in his ''[[Almagest]]'' and is generally believed to have originated with [[Hipparchus]]. This cannot be proved or disproved because Hipparchus's original star catalogue is lost. The only preserved text by Hipparchus himself (a commentary to Aratus) clearly documents that he did not have a system to describe brightness with numbers: He always uses terms like "big" or "small", "bright" or "faint" or even descriptions such as "visible at full moon".<ref>Hoffmann, S., Hipparchs Himmelsglobus, Springer, Wiesbaden/ New York, 2017</ref>

In 1856, [[Norman Robert Pogson]] formalized the system by defining a first magnitude star as a star that is 100 times as bright as a sixth-magnitude star, thereby establishing the logarithmic scale still in use today. This implies that a star of magnitude {{mvar|m}} is about 2.512 times as bright as a star of magnitude {{math|''m'' + 1}}. This figure, the [[Generalized continued fraction#Example 2|fifth root of 100]], became known as {{vanchor|Pogson's Ratio}}.<ref>{{cite journal |title=Magnitudes of Thirty-six of the Minor Planets for the first day of each month of the year 1857 |author-link=Norman Robert Pogson |first=N. |last=Pogson |journal=[[Monthly Notices of the Royal Astronomical Society|MNRAS]] |volume=17 |page=12 |date=1856 |bibcode=1856MNRAS..17...12P |doi=10.1093/mnras/17.1.12 |doi-access=free }}</ref> The ''1884 Harvard Photometry'' and 1886 ''Potsdamer Durchmusterung'' star catalogs popularized Pogson's ratio, and eventually it became a de facto standard in modern astronomy to describe differences in brightness.<ref>{{Cite book |last=Hearnshaw |first=John B. |title=The measurement of starlight: two centuries of astronomical photometry |date=1996 |publisher=Cambridge Univ. Press |isbn=978-0-521-40393-1 |edition=1. publ |location=Cambridge}}</ref>

Defining and calibrating what magnitude 0.0 means is difficult, and different types of measurements which detect different kinds of light (possibly by using filters) have different zero points. Pogson's original 1856 paper defined magnitude 6.0 to be the faintest star the unaided eye can see,<ref>{{Cite journal |last=Pogson |first=N. |date=1856-11-14 |title=Magnitudes of Thirty-six of the Minor Planets for the First Day of each Month of the Year 1857 |journal=Monthly Notices of the Royal Astronomical Society |language=en |volume=17 |issue=1 |pages=12–15 |doi=10.1093/mnras/17.1.12 |doi-access=free |bibcode=1856MNRAS..17...12P |issn=0035-8711}}</ref> but the true limit for faintest possible visible star varies depending on the atmosphere and how high a star is in the sky. The ''Harvard Photometry'' used an average of 100 stars close to Polaris to define magnitude 5.0.<ref>{{Cite book |last=Hearnshaw |first=J. B. |title=The measurement of starlight: two centuries of astronomical photometry |date=1996 |publisher=Cambridge University Press |isbn=978-0-521-40393-1 |location=Cambridge [England] ; New York, NY, USA}}</ref> Later, the Johnson UVB photometric system defined multiple types of photometric measurements with different filters, where magnitude 0.0 for each filter is defined to be the average of six stars with the same spectral type as Vega. This was done so the [[color index]] of these stars would be 0.<ref>{{Cite journal |last1=Johnson |first1=H. L. |last2=Morgan |first2=W. W. |date=May 1953 |title=Fundamental stellar photometry for standards of spectral type on the revised system of the Yerkes spectral atlas |url=http://adsabs.harvard.edu/doi/10.1086/145697 |journal=The Astrophysical Journal |language=en |volume=117 |pages=313 |doi=10.1086/145697 |bibcode=1953ApJ...117..313J |issn=0004-637X}}</ref> Although this system is often called "Vega normalized", Vega is slightly dimmer than the six-star average used to define magnitude 0.0, meaning Vega's magnitude is normalized to 0.03 by definition.

{|class="wikitable" style="float: right; margin-left: 0.5em; text-align: center;"
|+ Limiting Magnitudes for Visual Observation at High Magnification<ref>{{cite book
 | title=Observing Variable Stars, Novae and Supernovae
 | first1=Gerald | last1=North | first2=Nick | last2=James
 | publisher=Cambridge University Press
 | date=2014 | isbn=978-1-107-63612-5 | page=24
 | url=https://books.google.com/books?id=IzoDBAAAQBAJ&pg=PA24 }}</ref>
|-
!Telescope<br />aperture<br />(mm)
!Limiting<br />Magnitude
|-
| 35
| 11.3
|-
| 60
| 12.3
|-
| 102
| 13.3
|-
| 152
| 14.1
|-
| 203
| 14.7
|-
| 305
| 15.4
|-
| 406
| 15.7
|-
| 508
| 16.4
|}
With the modern magnitude systems, brightness is described using Pogson's ratio. In practice, magnitude numbers rarely go above 30 before stars become too faint to detect. While Vega is close to magnitude 0, there are four brighter stars in the night sky at visible wavelengths (and more at infrared wavelengths) as well as the bright planets Venus, Mars, and Jupiter, and since brighter means smaller magnitude, these must be described by ''negative'' magnitudes. For example, [[Sirius]], the brightest star of the [[celestial sphere]], has a magnitude of −1.4 in the visible. Negative magnitudes for other very bright astronomical objects can be found in the [[#List of apparent magnitudes|table]] below.

Astronomers have developed other photometric zero point systems as alternatives to Vega normalized systems. The most widely used is the [[AB magnitude]] system,<ref>{{cite journal|last1=Oke|first1=J. B.|last2=Gunn|first2=J. E.|title=Secondary standard stars for absolute spectrophotometry|journal=The Astrophysical Journal |date=15 March 1983 |volume=266|pages=713–717|doi=10.1086/160817|bibcode=1983ApJ...266..713O}}</ref> in which photometric zero points are based on a hypothetical reference spectrum having constant [[Spectral flux density|flux per unit frequency interval]], rather than using a stellar spectrum or blackbody curve as the reference. The AB magnitude zero point is defined such that an object's AB and Vega-based magnitudes will be approximately equal in the V filter band. However, the AB magnitude system is defined assuming an idealized detector measuring only one wavelength of light, while real detectors accept energy from a range of wavelengths.

== Measurement ==
{{Main|Photometry (astronomy)}}
Precision measurement of magnitude (photometry) requires calibration of the photographic or (usually) electronic detection apparatus. This generally involves contemporaneous observation, under identical conditions, of standard stars whose magnitude using that spectral filter is accurately known. Moreover, as the amount of light actually received by a telescope is reduced due to transmission through the [[Earth's atmosphere]], the [[airmass]]es of the target and [[calibration stars]] must be taken into account. Typically one would observe a few different stars of known magnitude which are sufficiently similar. Calibrator stars close in the sky to the target are favoured (to avoid large differences in the atmospheric paths). If those stars have somewhat different [[zenith angle]]s ([[Horizontal coordinate system#Definition|altitudes]]) then a correction factor as a function of airmass can be derived and [[Photometry (astronomy)#Calibrations|applied]] to the airmass at the target's position. Such calibration obtains the brightness as would be observed from above the atmosphere, where apparent magnitude is defined.{{cn|date=August 2024}}

The apparent magnitude scale in astronomy reflects the received power of stars and not their amplitude. Newcomers should consider using the relative brightness measure in astrophotography to adjust exposure times between stars. Apparent magnitude also integrates over the entire object, regardless of its focus, and this needs to be taken into account when scaling exposure times for objects with significant apparent size, like the Sun, Moon and planets. For example, directly scaling the exposure time from the Moon to the Sun works because they are approximately the same size in the sky. However, scaling the exposure from the Moon to Saturn would result in an overexposure if the image of Saturn takes up a smaller area on your sensor than the Moon did (at the same magnification, or more generally, f/#).

== Calculations ==
[[File:VISTA Magellanic Cloud Survey view of the Tarantula Nebula.jpg|thumb|upright=1.2|Image of [[30 Doradus]] taken by [[ESO]]'s [[VISTA (telescope)|VISTA]]. This [[nebula]] has a visual magnitude of 8.]]
[[File:Apparent magnitude.svg|thumb|Graph of relative brightness versus magnitude]]

The dimmer an object appears, the higher the numerical value given to its magnitude, with a difference of 5 magnitudes corresponding to a brightness factor of exactly 100. Therefore, the magnitude {{mvar|m}}, in the [[Photometric system|spectral band]] {{mvar|x}}, would be given by
<math display="block">m_{x}= -5 \log_{100} \left(\frac {F_x}{F_{x,0}}\right),</math>
which is more commonly expressed in terms of [[Common logarithm|common (base-10) logarithms]] as
<math display="block">m_{x} = -2.5 \log_{10} \left(\frac {F_x}{F_{x,0}}\right),</math>
where {{mvar|F<sub>x</sub>}} is the observed [[irradiance]] using spectral filter {{mvar|x}}, and {{math|''F''<sub>''x'',0</sub>}} is the reference flux (zero-point) for that [[Photometric system#Filters used|photometric filter]]. Since an increase of 5 magnitudes corresponds to a decrease in brightness by a factor of exactly 100, each magnitude increase implies a decrease in brightness by the factor <math>\sqrt[5]{100} \approx 2.512</math> (Pogson's ratio). Inverting the above formula, a magnitude difference {{math|''m''<sub>1</sub> − ''m''<sub>2</sub> {{=}} Δ''m''}} implies a brightness factor of
<math display="block"> \frac{F_2}{F_1} = 100^\frac{\Delta m}{5} = 10^{0.4 \Delta m} \approx 2.512^{\Delta m}.</math>

=== Example: Sun and Moon ===
''What is the ratio in brightness between the [[Sun]] and the full [[Moon]]?''

The apparent magnitude of the Sun is −26.832<ref name="IAU2015B2"/> (brighter), and the mean magnitude of the [[full moon]] is −12.74<ref name="moon-fact" /> (dimmer).

Difference in magnitude:
<math display="block"> x = m_1 - m_2 = (-12.74) - (-26.832) = 14.09. </math>

Brightness factor:
<math display="block"> v_b = 10^{0.4 x} = 10^{0.4 \times 14.09} \approx 432\,513. </math>

The Sun appears to be approximately {{val|400000}} times as bright as the full Moon.

===Magnitude addition===
Sometimes one might wish to add brightness. For example, [[Photometry (astronomy)|photometry]] on closely separated [[double star]]s may only be able to produce a measurement of their combined light output. To find the combined magnitude of that double star knowing only the magnitudes of the individual components, this can be done by adding the brightness (in linear units) corresponding to each magnitude.<ref>{{cite web | title=Magnitude Arithmetic|url=http://www.caglow.com/info/wtopic/mag-arith | work=Weekly Topic | publisher=Caglow | access-date=30 January 2012 | archive-url=https://web.archive.org/web/20120201203951/http://www.caglow.com/info/wtopic/mag-arith | archive-date=1 February 2012|url-status=live}}</ref>
<math display="block"> 10^{-m_f \times 0.4} = 10^{-m_1 \times 0.4} + 10^{-m_2 \times 0.4}. </math>

Solving for <math>m_f</math> yields
<math display="block"> m_f = -2.5\log_{10} \left(10^{-m_1 \times 0.4} + 10^{-m_2 \times 0.4} \right), </math>
where {{mvar|m<sub>f</sub>}} is the resulting magnitude after adding the brightnesses referred to by {{math|''m''<sub>1</sub>}} and {{math|''m''<sub>2</sub>}}.

===Apparent bolometric magnitude===
While magnitude generally refers to a measurement in a particular filter band corresponding to some range of wavelengths, the apparent or absolute '''bolometric magnitude''' (m<sub>bol</sub>) is a measure of an object's apparent or absolute brightness integrated over all wavelengths of the electromagnetic spectrum (also known as the object's [[irradiance]] or power, respectively). The zero point of the apparent bolometric magnitude scale is based on the definition that an apparent bolometric magnitude of 0 mag is equivalent to a received irradiance of 2.518×10<sup>−8</sup> [[watt]]s per square metre (W·m<sup>−2</sup>).<ref name="IAU2015B2">{{cite journal |author=IAU Inter-Division A-G Working Group on Nominal Units for Stellar & Planetary Astronomy |title=IAU 2015 Resolution B2 on Recommended Zero Points for the Absolute and Apparent Bolometric Magnitude Scales |url=https://www.iau.org/static/resolutions/IAU2015_English.pdf |journal=Resolutions Adopted at the General Assemblies |date=13 August 2015 |arxiv=1510.06262 |bibcode=2015arXiv151006262M |access-date=19 May 2019 |archive-url=https://web.archive.org/web/20160128180606/https://www.iau.org/static/resolutions/IAU2015_English.pdf |archive-date=28 January 2016 |url-status=live }}</ref>

===Absolute magnitude===
{{Main|Absolute magnitude}}
While apparent magnitude is a measure of the brightness of an object as seen by a particular observer, absolute magnitude is a measure of the ''intrinsic'' brightness of an object.  Flux decreases with distance according to an [[inverse-square law]], so the apparent magnitude of a star depends on both its absolute brightness and its distance (and any extinction). For example, a star at one distance will have the same apparent magnitude as a star four times as bright at twice that distance.  In contrast, the intrinsic brightness of an astronomical object, does not depend on the distance of the observer or any [[Extinction (astronomy)|extinction]].<ref>{{Cite web |title=Lecture 4: Page 3, Properties of the Stars |url=https://homepages.uc.edu/~hansonmm/ASTRO/LECTURENOTES/W03/Lec6/Page3.html |access-date=2024-12-05 |website=homepages.uc.edu}}</ref>

The absolute magnitude {{mvar|M}}, of a star or astronomical object is defined as the apparent magnitude it would have as seen from a distance of {{convert|10|pc|ly|lk=out}}. The absolute magnitude of the Sun is 4.83 in the V band (visual), 4.68 in the [[Gaia (spacecraft)|Gaia satellite's]] G band (green) and 5.48 in the B band (blue).<ref name="Bband">{{cite web | title=Some Useful Astronomical Definitions | publisher=Stony Brook Astronomy Program | first=Aaron | last=Evans | url=http://www.astro.sunysb.edu/aevans/PHY523/classnotes523/useful-definitions-pp.pdf | access-date=12 July 2009 | archive-url=https://web.archive.org/web/20110720052227/http://www.astro.sunysb.edu/aevans/PHY523/classnotes523/useful-definitions-pp.pdf | archive-date=20 July 2011 | url-status=live}}</ref><ref name="Gband">{{cite journal | last1=Čotar | first1=Klemen | last2=Zwitter | first2=Tomaž | last3=Traven | first3=Gregor | last4=Kos | first4=Janez | last5=Asplund | first5=Martin | last6=Bland-Hawthorn | first6=Joss | last7=Buder | first7=Sven | last8=D'Orazi | first8=Valentina | last9=De Silva | first9=Gayandhi M | last10=Lin | first10=Jane | last11=Martell | first11=Sarah L | last12=Sharma | first12=Sanjib | last13=Simpson | first13=Jeffrey D | last14=Zucker | first14=Daniel B | last15=Horner | first15=Jonathan | last16=Lewis | first16=Geraint F | last17=Nordlander | first17=Thomas | last18=Ting | first18=Yuan-Sen | last19=Wittenmyer | first19=Rob A |display-authors=2 | title=The GALAH survey: unresolved triple Sun-like stars discovered by the Gaia mission | journal=Monthly Notices of the Royal Astronomical Society | publisher=Oxford University Press (OUP) | volume=487 | issue=2 | date=21 May 2019 | issn=0035-8711 | doi=10.1093/mnras/stz1397 |arxiv=1904.04841  |doi-access=free | pages=2474–2490}}</ref><ref name="Bessell2005">{{cite journal|last1=Bessell|first1=Michael S.|title=Standard Photometric Systems|journal=Annual Review of Astronomy and Astrophysics|volume=43|issue=1|date=September 2005|pages=293–336|issn=0066-4146|doi=10.1146/annurev.astro.41.082801.100251|bibcode=2005ARA&A..43..293B|url=http://www.mso.anu.edu.au/~bessell/araapaper.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.mso.anu.edu.au/~bessell/araapaper.pdf |archive-date=9 October 2022 |url-status=live}}</ref>

In the case of a planet or asteroid, the absolute magnitude {{mvar|H}} rather means the apparent magnitude it would have if it were {{convert|1|AU|km|lk=in}} from both the observer and the Sun, and fully illuminated at maximum opposition (a configuration that is only theoretically achievable, with the observer situated on the surface of the Sun).<ref name="Luciuk">{{Cite web | url = http://www.asterism.org/tutorials/tut35%20Magnitudes.pdf | author = Luciuk, M. | title = Astronomical Magnitudes | page = 8 | access-date = 11 January 2019}}</ref>

== Standard reference values ==
{| class="wikitable floatright" style="text-align:center;"
|+ Standard apparent magnitudes and fluxes for typical bands<ref name="UTmags">{{cite web
 |title=Astronomical Magnitude Systems
 |publisher=Harvard-Smithsonian Center for Astrophysics
 |first=John
 |last=Huchra
 |url=https://www.cfa.harvard.edu/~dfabricant/huchra/ay145/mags.html
 |access-date=18 July 2017
 |archive-url=https://web.archive.org/web/20180721162252/https://www.cfa.harvard.edu/~dfabricant/huchra/ay145/mags.html
 |archive-date=21 July 2018
 |url-status=live
 }}</ref>
|-
! rowspan="2" | Band
! rowspan="2" | {{mvar|λ}}<br />(μm)
! rowspan="2" | {{math|{{sfrac|Δ''λ''|''λ''}}}}<br />([[full width at half maximum|FWHM]])
! colspan="2" | Flux at {{math|''m'' {{=}} 0}}, {{math|''F''<sub>''x'',0</sub>}}

|-
! [[Jansky|Jy]]
! 10<sup>−20</sup>&nbsp;erg/(s·cm<sup>2</sup>·Hz)
|-
| U || 0.36 || 0.15 || 1810 || 1.81
|-
| B || 0.44 || 0.22 || 4260 || 4.26
|-
| V || 0.55 || 0.16 || 3640 || 3.64
|-
| R || 0.64 || 0.23 || 3080 || 3.08
|-
| I || 0.79 || 0.19 || 2550 || 2.55
|-
| J || 1.26 || 0.16 || 1600 || 1.60
|-
| H || 1.60 || 0.23 || 1080 || 1.08
|-
| K || 2.22 || 0.23 || {{0}}670 || 0.67
|-
| L || 3.50 || || ||
|-
| g || 0.52 || 0.14 || 3730 || 3.73
|-
| r || 0.67 || 0.14 || 4490 || 4.49
|-
| i || 0.79 || 0.16 || 4760 || 4.76
|-
| z || 0.91 || 0.13 || 4810 || 4.81
|-
|}

The magnitude scale is a reverse logarithmic scale.  A common misconception is that the logarithmic nature of the scale is because the [[human eye]] itself has a logarithmic response. In Pogson's time this was thought to be true (see [[Weber–Fechner law]]), but it is now believed that the response is a [[power law]] {{xref|(see [[Stevens' power law]])}}.<ref>{{cite journal|title=Misconceptions About Astronomical Magnitudes|author-link=Eric Schulman|first1=E.|last1=Schulman|first2=C. V.|last2=Cox|journal=American Journal of Physics|volume=65|issue=10|page=1003|date=1997|bibcode = 1997AmJPh..65.1003S |doi = 10.1119/1.18714 }}</ref>

Magnitude is complicated by the fact that light is not [[monochromatic]]. The sensitivity of a light detector varies according to the wavelength of the light, and the way it varies depends on the type of light detector. For this reason, it is necessary to specify how the magnitude is measured for the value to be meaningful. For this purpose the [[UBV system]] is widely used, in which the magnitude is measured in three different wavelength bands: U (centred at about 350&nbsp;nm, in the near [[ultraviolet]]), B (about 435&nbsp;nm, in the blue region) and V (about 555&nbsp;nm, in the middle of the human visual range in daylight). The V band was chosen for spectral purposes and gives magnitudes closely corresponding to those seen by the human eye. When an apparent magnitude is discussed without further qualification, the V magnitude is generally understood.<ref>{{Cite web |title=Magnitude {{!}} Brightness, Apparent Magnitude & Absolute Magnitude {{!}} Britannica |url=https://www.britannica.com/science/magnitude-astronomy |access-date=2023-10-19 |website=www.britannica.com |language=en}}</ref>

Because cooler stars, such as [[red giant]]s and [[red dwarf]]s, emit little energy in the blue and UV regions of the spectrum, their power is often under-represented by the UBV scale. Indeed, some [[stellar classification|L and T class]] stars have an estimated magnitude of well over 100, because they emit extremely little visible light, but are strongest in [[infrared]].<ref>{{Cite web |title=Introduction to active galaxies: View as single page |url=https://www.open.edu/openlearn/science-maths-technology/introduction-active-galaxies/content-section-5.4/?printable=1 |access-date=2023-10-19 |website=www.open.edu}}</ref>

Measures of magnitude need cautious treatment and it is extremely important to measure like with like. On early 20th century and older orthochromatic (blue-sensitive) [[photographic film]], the relative brightnesses of the blue [[supergiant]] [[Rigel]] and the red supergiant [[Betelgeuse]] irregular variable star (at maximum) are reversed compared to what human eyes perceive, because this archaic film is more sensitive to blue light than it is to red light. Magnitudes obtained from this method are known as [[photographic magnitude]]s, and are now considered obsolete.<ref>{{Cite journal |title=1910HarCi.160....1P Page 1 |url=https://adsabs.harvard.edu/full/1910HarCi.160....1P |access-date=2023-10-19 |journal=Harvard College Observatory Circular|bibcode=1910HarCi.160....1P |last1=Pickering |first1=Edward C. |date=1910 |volume=160 |page=1 }}</ref>

For objects within the [[Milky Way]] with a given absolute magnitude, 5 is added to the apparent magnitude for every tenfold increase in the distance to the object. For objects at very great distances (far beyond the Milky Way), this relationship must be [[K correction|adjusted for redshifts]] and for [[Non-Euclidean geometry|non-Euclidean]] distance measures due to [[general relativity]].<ref name=umeh>{{cite journal|bibcode=2014CQGra..31t5001U|arxiv=1402.1933|title=Nonlinear relativistic corrections to cosmological distances, redshift and gravitational lensing magnification: II. Derivation|journal=Classical and Quantum Gravity|volume=31|issue=20|page=205001|last1=Umeh|first1=Obinna|last2=Clarkson|first2=Chris|last3=Maartens|first3=Roy|year=2014|doi=10.1088/0264-9381/31/20/205001|s2cid=54527784}}</ref><ref name=hogg>{{cite arXiv|eprint=astro-ph/0210394|title=The K correction|last1=Hogg|first1=David W.|last2=Baldry|first2=Ivan K.|last3=Blanton|first3=Michael R.|last4=Eisenstein|first4=Daniel J.|year=2002}}</ref>

For planets and other Solar System bodies, the apparent magnitude is derived from its [[Phase curve (astronomy)|phase curve]] and the distances to the Sun and observer.<ref>{{Cite journal |title=1967lts..conf..205W Page 205 |url=https://adsabs.harvard.edu/full/1967lts..conf..205W |access-date=2023-10-19 |journal=Late-Type Stars|bibcode=1967lts..conf..205W |last1=Wing |first1=R. F. |date=1967 |page=205 }}</ref>

{{clear}}

==List of apparent magnitudes==
{{more citations needed section|date=September 2019}}
{{See also|List of brightest stars}}

Some of the listed magnitudes are approximate. Telescope sensitivity depends on observing time, optical bandpass, and interfering light from [[Rayleigh scattering|scattering]] and [[airglow]].

{| class="wikitable"
|+Apparent visual magnitudes of celestial objects
! Apparent<br />magnitude<br />(V)
! width="215px" | Object
! Seen from...
!Notes
|-
|−67.57
|[[gamma-ray burst]] [[GRB 080319B]]
|seen from 1&nbsp;[[Astronomical unit|AU]] away
|would be over {{Val|2e16}} (20 quadrillion) times as bright as the Sun when seen from the Earth
|-
|−43.27
|star [[NGC 2403 V14]]
|seen from 1 AU away
|
|-
|−41.82
|star [[NGC 2363-V1]]
|seen from 1 AU away
|
|-
|−41.39
|star [[Cygnus OB2-12]]
|seen from 1 AU away
|
|-
|−40.67
|star [[M33-013406.63]]
|seen from 1 AU away
|
|-
|−40.17
|star [[Eta Carinae|η Carinae]] A
|seen from 1 AU away
|
|-
| −40.07 || star [[Zeta1 Scorpii|Zeta<sup>1</sup> Scorpii]] || seen from 1&nbsp;AU away
|
|-
| −39.66 || star [[R136a1]] || seen from 1&nbsp;AU away
|
|-
|−39.47
|star [[P Cygni]]
|seen from 1 AU away
|
|-
| −38.00 || star [[Rigel]] || seen from 1&nbsp;AU away
|would be seen as a large, very bright bluish disk of 35° apparent diameter
|-
|−37.42
|star [[Betelgeuse]]
|seen from 1&nbsp;AU away
|
|-
| −30.30 || star [[Sirius]] A || seen from 1&nbsp;AU away
|
|-
| −29.30 || star [[Sun]] || seen from [[Mercury (planet)|Mercury]] at [[perihelion]]
|
|-
| −27.40 || star Sun || seen from [[Venus]] at perihelion
|
|-
| −26.83|| star Sun || seen from [[Earth]]<ref name="IAU2015B2"/>
|about 400,000 times as bright as mean full Moon
|-
| −25.60 || star Sun || seen from [[Mars]] at [[aphelion]]
|
|-
| −25 || colspan="3" style="background-color:#EEE;" | ''Minimum brightness that causes the typical eye slight pain to look at''
|-
| −23.00 || star Sun || seen from [[Jupiter]] at aphelion
|
|-
| −21.70 || star Sun || seen from [[Saturn]] at aphelion
|
|-
| −21.00 || star Sun || seen from Earth on an overcast midday
|measuring about 1000 lux
|-
| −20.20 || star Sun || seen from [[Uranus]] at aphelion
|
|-
| −19.30 || star Sun || seen from [[Neptune]]
|
|-
| −19.00 || star Sun || seen from Earth on a very strongly overcast midday
|measuring about 100 lux
|-
| −18.20 || star Sun || seen from [[Pluto]] at aphelion
|
|-
| −17.70 || planet Earth || seen fully illuminated as [[earthlight (astronomy)|earthlight]] from the [[Moon]]<ref name="Agrawal">{{cite journal | last=Agrawal | first=Dulli Chandra | title=Apparent magnitude of earthshine: a simple calculation | journal=European Journal of Physics | publisher=IOP Publishing | volume=37 | issue=3 | date=30 March 2016 | issn=0143-0807 | doi=10.1088/0143-0807/37/3/035601 | page=035601| bibcode=2016EJPh...37c5601A | s2cid=124231299 }}</ref>
|
|-
| −16.70 || star Sun || seen from [[Eris (dwarf planet)|Eris]] at aphelion
|
|-
| −16.00 || star Sun || as [[twilight]] on Earth
|measuring about 10 lux<ref name="Polakis 1997 a712">{{cite web | last=Polakis | first=Tom | title=Radiometry and photometry in astronomy | website=Home page of Paul Schlyter | date=1997-09-10 | url=https://stjarnhimlen.se/comp/radfaq.html#11 | access-date=2024-04-25}}</ref>
|-
| −14.2 || colspan="3" style="background-color:#EEE;" | ''An illumination level of 1 [[lux]]''<ref>{{cite book|url=https://books.google.com/books?id=oTraksy4JYkC&pg=PA4|title=Introduction to Astrophysics: The Stars|first=Jean|last=Dufay|page=3|isbn=978-0-486-60771-9|date=17 October 2012|publisher=Courier Corporation |access-date=28 February 2016|archive-url=https://web.archive.org/web/20170324070545/https://books.google.com/books?id=oTraksy4JYkC&pg=PA4|archive-date=24 March 2017|url-status=live}}</ref><ref name =IM08>{{cite book|first=Ian S.|last=McLean|title=Electronic Imaging in Astronomy: Detectors and Instrumentation|publisher=Springer|date=2008|isbn=978-3-540-76582-0|page=529}}</ref>
|-
| −12.60 || [[full moon]] || seen from Earth at perihelion
|maximum brightness of perigee + perihelion + full Moon (~0.267 lux; mean distance value is −12.74,<ref name="moon-fact" /> though values are about 0.18 magnitude brighter when including the [[Opposition surge|opposition effect]])
|-
| −12.40 || [[Betelgeuse]] (when supernova)|| seen from Earth when it goes supernova<ref>{{Cite journal | doi=10.3847/0004-637X/819/1/7| arxiv=1406.3143| bibcode=2016ApJ...819....7D| title=Evolutionary Tracks for Betelgeuse| year=2017| last1=Dolan| first1=Michelle M.| last2=Mathews| first2=Grant J.| last3=Lam| first3=Doan Duc| last4=Lan| first4=Nguyen Quynh| last5=Herczeg| first5=Gregory J.| last6=Dearborn| first6=David S. P.| journal=The Astrophysical Journal| volume=819| issue=1| page=7| s2cid=37913442| doi-access=free}}</ref>
|
|-
| −11.20 || star Sun || seen from [[90377 Sedna|Sedna]] at aphelion
|
|-
| −10.00 || Comet [[Comet Ikeya–Seki|Ikeya–Seki]] (1965) || seen from Earth
|which was the brightest [[Kreutz Sungrazer]] of modern times<ref name="brightest">{{cite web|url=http://www.icq.eps.harvard.edu/brightest.html|title=Brightest comets seen since 1935|publisher=International Comet Quarterly|access-date=18 December 2011|archive-url=https://web.archive.org/web/20111228014918/http://www.icq.eps.harvard.edu/brightest.html|archive-date=28 December 2011|url-status=live}}</ref>
|-
| −9.50||[[Iridium flare|Iridium (satellite) flare]] || seen from Earth
|maximum brightness
|-
| −9 to −10 || [[Phobos (moon)]]
| seen from Mars
|maximum brightness
|-
| −7.50||[[SN 1006|supernova of 1006]] || seen from Earth
|the brightest stellar event in recorded history (7200 light-years away)<ref name="SN1006" />
|-
| −6.80||[[Alpha Centauri A]] || seen from [[Proxima Centauri b]]
|<ref name="Siegel 2016">{{cite web | last=Siegel | first=Ethan | title=Ten Ways 'Proxima b' Is Different From Earth | website=Forbes | date=6 September 2016 | url=https://www.forbes.com/sites/startswithabang/2016/09/06/ten-ways-proxima-b-is-different-from-earth/ | access-date=19 February 2023}}</ref>
|-
| −6.00||''The total [[integrated magnitude]] of the [[night sky]] (incl. [[airglow]])'' || seen from Earth
|measuring about 0.002 lux
|-
| −6.00||[[SN 1054|Crab Supernova of 1054]] || seen from Earth
|(6500 light-years away)<ref name="SN1054" />
|-
| −5.90||[[International Space Station]] || seen from Earth
|when the ISS is at its [[perigee]] and fully lit by the Sun<ref>{{cite web|url=http://www.heavens-above.com/satinfo.aspx?SatID=25544|title=Heavens-above.com|publisher=Heavens-above|access-date=22 December 2007|archive-url=https://web.archive.org/web/20090705134152/http://heavens-above.com/satinfo.aspx?SatID=25544|archive-date=5 July 2009|url-status=live}}</ref>
|-
| −4.92|| planet Venus || seen from Earth
|maximum brightness<ref name="Mallama_and_Hilton" /> when illuminated as a crescent
|-
| −4.14|| planet Venus || seen from Earth
|mean brightness<ref name="Mallama_and_Hilton" />
|-
| −4 || colspan="3" style="background-color:#EEE;" |''Faintest objects observable during the day with naked eye when Sun is high''. An astronomical object casts human-visible shadows when its apparent magnitude is equal to or lower than −4 <ref>[https://web.archive.org/web/20070627044109/http://www.gsfc.nasa.gov/scienceques2005/20060406.htm NASA Science Question of the Week]. Gsfc.nasa.gov (7 April 2006). Retrieved on 26 April 2013.</ref>
|-
| −3.99|| star [[Epsilon Canis Majoris]] || seen from Earth
|maximum brightness of 4.7&nbsp;million years ago, the historical [[List of brightest stars|brightest star]] of the [[Historical brightest stars|last and next five million years]].<ref name=tomkin>{{cite journal|last=Tomkin|first=Jocelyn|date=April 1998|title=Once and Future Celestial Kings|journal=Sky and Telescope|volume=95|issue=4|pages=59–63|bibcode=1998S&T....95d..59T |url=https://www.thefreelibrary.com/Once+and+future+celestial+kings.-a020468305 }} – based on computations from [[HIPPARCOS]] data. (The calculations exclude stars whose distance or [[proper motion]] is uncertain.) </ref>
|-
| −3.69 || Moon || lit by earthlight, reflecting [[earthshine]] seen from Earth (maximum)<ref name="Agrawal"/>
|
|-
| −2.98|| planet Venus || seen from Earth
|minimum brightness during [[transit of Venus|transits]].
|-
| −2.94|| planet Jupiter || seen from Earth
|maximum brightness<ref name="Mallama_and_Hilton" />
|-
| −2.94|| planet Mars || seen from Earth
|maximum brightness<ref name="Mallama_and_Hilton" />
|-
| −2.5 || colspan="3" style="background-color:#EEE;" |''Faintest objects visible during the day with naked eye when Sun is less than 10° above the horizon''
|-
| −2.50||[[new moon]] || seen from Earth
|minimum brightness
|-
| −2.50 || planet Earth || seen from Mars
| maximum brightness
|-
| −2.48|| planet Mercury || seen from Earth
|maximum brightness at [[superior conjunction]] (unlike Venus, Mercury is at its brightest when on the far side of the Sun, the reason being their different phase curves)<ref name="Mallama_and_Hilton" />
|-
| −2.20|| planet Jupiter || seen from Earth
|mean brightness<ref name="Mallama_and_Hilton" />
|-
| −1.66|| planet Jupiter || seen from Earth
|minimum brightness<ref name="Mallama_and_Hilton" />
|-id=Sirius
| −1.47|| star system Sirius || seen from Earth
|Brightest star except for the Sun at visible wavelengths<ref name="SIMBAD-Sirius" />
|-
| −0.83|| star [[Eta Carinae]] || seen from Earth
|apparent brightness as a [[supernova impostor]] in April 1843
|-
| −0.72|| star [[Canopus (star)|Canopus]] || seen from Earth
|2nd brightest star in night sky<ref name="SIMBAD-Canopus" />
|-
| −0.55|| planet Saturn || seen from Earth
|maximum brightness near opposition and perihelion when the rings are angled toward Earth<ref name="Mallama_and_Hilton" />
|-
| −0.30||[[Halley's Comet#History|Halley's comet]] || seen from Earth
|Expected apparent magnitude at 2061 passage
|-
| −0.27|| star system [[Alpha Centauri]] AB || seen from Earth
|Combined magnitude (3rd brightest star in night sky)
|-
| −0.04|| star [[Arcturus (star)|Arcturus]] || seen from Earth
|4th brightest star to the naked eye<ref name="SIMBAD-Arcturus" />
|-
| −0.01|| star Alpha Centauri A || seen from Earth
|4th brightest ''individual'' star visible telescopically in the night sky
|-
| +0.03|| star [[Vega]] || seen from Earth
|originally chosen as a definition of the zero point<ref name="SIMBAD-Vega" />
|-
| +0.23|| planet Mercury || seen from Earth
|mean brightness<ref name="Mallama_and_Hilton" />
|-
| +0.46|| star Sun || seen from Alpha Centauri
|
|-
| +0.46|| planet Saturn || seen from Earth
|mean brightness<ref name="Mallama_and_Hilton" />
|-
| +0.71|| planet Mars || seen from Earth
|mean brightness<ref name="Mallama_and_Hilton" />
|-
| +0.90|| Moon || seen from Mars
|maximum brightness
|-
| +1.17|| planet Saturn || seen from Earth
|minimum brightness<ref name="Mallama_and_Hilton" />
|-
| +1.33|| star Alpha Centauri B || seen from Earth
|
|-
| +1.86|| planet Mars || seen from Earth
|minimum brightness<ref name="Mallama_and_Hilton" />
|-
| +1.98|| star [[Polaris]] || seen from Earth
|mean brightness<ref>{{Cite journal | last1 = Evans | first1 = N. R. | last2 = Schaefer | first2 = G. H. | last3 = Bond | first3 = H. E. | last4 = Bono | first4 = G. | last5 = Karovska | first5 = M. | last6 = Nelan | first6 = E. | last7 = Sasselov | first7 = D. | last8 = Mason | first8 = B. D. | doi = 10.1088/0004-6256/136/3/1137 | title = Direct Detection of the Close Companion of Polaris with The Hubble Space Telescope | journal = The Astronomical Journal | volume = 136 | issue = 3 | page = 1137 | year = 2008 |arxiv = 0806.4904 |bibcode = 2008AJ....136.1137E | s2cid = 16966094 }}</ref>
|-
| +2.00
|star system [[T Coronae Borealis|T CrB]] (when nova)
|seen from Earth
|Star system that goes nova every 80 years
|-
| +2.40
|[[Halley's Comet]]
|seen from Earth
|About [[Magnitude (astronomy)|Magnitude]] during 1986 [[Apsis|perihelion]]
|-
| +3 || colspan="3" style="background-color:#EEE;" |''Faintest objects visible in an urban neighborhood with naked eye''
|-
| +3.03|| supernova [[SN 1987A]] || seen from Earth
|in the [[Large Magellanic Cloud]] (160,000 light-years away)
|-id=3
| +3.44||[[Andromeda Galaxy]] || seen from Earth
|M31<ref name="SIMBAD-M31" />
|-
| +4 || colspan="3" style="background-color:#EEE;" |''Faintest objects visible in a suburban neighborhood with naked eye''
|-
| +4.00||[[Orion Nebula]] || seen from Earth
|M42
|-
| +4.38|| moon [[Ganymede (moon)|Ganymede]] || seen from Earth
|maximum brightness<ref name="horizons-Ganymede" /> (moon of Jupiter and the largest moon in the Solar System)
|-
| +4.50|| open cluster [[Messier 41|M41]] || seen from Earth
|an open cluster that may have been seen by [[Aristotle]]<ref name="Aristotle">{{cite web|url=http://messier.seds.org/more/m041_ari.html|title=M41 possibly recorded by Aristotle|date=28 July 2006|publisher=SEDS (Students for the Exploration and Development of Space)|access-date=29 November 2009|archive-url=https://web.archive.org/web/20170418184854/http://messier.seds.org/more/m041_ari.html|archive-date=18 April 2017|url-status=live}}</ref>
|-
| +4.50
|[[Sagittarius Dwarf Spheroidal Galaxy]]
|seen from Earth
|-
| +5.20|| asteroid [[4 Vesta|Vesta]] || seen from Earth
|maximum brightness
|-id=Uranus
| +5.38<ref>{{Cite web|url=https://nssdc.gsfc.nasa.gov/planetary/factsheet/uranusfact.html|title=Uranus Fact Sheet|website=nssdc.gsfc.nasa.gov|language=en|access-date=8 November 2018|archive-url=https://web.archive.org/web/20190122221135/https://nssdc.gsfc.nasa.gov/planetary/factsheet/uranusfact.html|archive-date=22 January 2019|url-status=live}}</ref>
| planet [[Uranus]]|| seen from Earth
|maximum brightness<ref name="Mallama_and_Hilton" /> (Uranus comes to perihelion in 2050)
|-
| +5.68|| planet Uranus || seen from Earth
|mean brightness<ref name="Mallama_and_Hilton" />
|-
| +5.72|| spiral galaxy [[Triangulum Galaxy|M33]] || seen from Earth
|which is used as a test for [[naked eye]] seeing under dark skies<ref name="SIMBAD-M33">{{cite web|url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=M33|title=SIMBAD-M33|publisher=SIMBAD Astronomical Database|access-date=28 November 2009|archive-url=https://web.archive.org/web/20140913102508/http://simbad.u-strasbg.fr/simbad/sim-id?Ident=M33|archive-date=13 September 2014|url-status=live}}</ref><ref name="M33">{{cite web|url=http://www.astropix.com/HTML/A_FALL/M33.HTM|title=M33 (Triangulum Galaxy)|last=Lodriguss|first=Jerry|date=1993|access-date=27 November 2009|archive-url=https://web.archive.org/web/20100115043351/http://astropix.com/HTML/A_FALL/M33.HTM|archive-date=15 January 2010|url-status=live}} (Shows bolometric magnitude not visual magnitude.)</ref>
|-
| +5.80 ||[[gamma-ray burst]] [[GRB 080319B]] || seen from Earth
|Peak visual magnitude (the "Clarke Event") seen on Earth on 19 March 2008 from a distance of 7.5&nbsp;billion light-years.
|-
| +6.03|| planet Uranus || seen from Earth
|minimum brightness<ref name="Mallama_and_Hilton" />
|-
| +6.49|| asteroid [[2 Pallas|Pallas]] || seen from Earth
|maximum brightness
|-
| +6.5 || colspan="3" style="background-color:#EEE;" |''Approximate limit of [[star]]s observed by a '''mean''' naked eye observer under very good conditions. There are about 9,500 stars visible to mag 6.5.<ref name="SIMBAD-mag6.5"/>''
|-
| +6.50|| global cluster [[Messier 2|M2]] || seen from Earth
|mean naked-eye target
|-
| +6.64|| dwarf planet [[Ceres (dwarf planet)|Ceres]] || seen from Earth
|maximum brightness
|-
| +6.75|| asteroid [[7 Iris|Iris]] || seen from Earth
|maximum brightness
|-id=extremegalaxy
| +6.90|| spiral galaxy [[Messier 81|M81]] || seen from Earth
|This is an extreme naked-eye target that pushes human eyesight and the Bortle scale to the limit<ref name="SEDS">{{cite web|url=http://messier.seds.org/m/m081.html|title=Messier 81|date=2 September 2007|publisher=SEDS (Students for the Exploration and Development of Space)|access-date=28 November 2009|archive-url=https://web.archive.org/web/20170714113244/http://messier.seds.org/m/m081.html|archive-date=14 July 2017|url-status=live}}</ref>
|-
| +7.25|| planet Mercury || seen from Earth
|minimum brightness<ref name="Mallama_and_Hilton" />
|-
| +7.67<ref>{{Cite web|url=https://nssdc.gsfc.nasa.gov/planetary/factsheet/neptunefact.html|title=Neptune Fact Sheet|website=nssdc.gsfc.nasa.gov|language=en|access-date=8 November 2018|archive-url=https://web.archive.org/web/20190110222952/https://nssdc.gsfc.nasa.gov/planetary/factsheet/neptunefact.html|archive-date=10 January 2019|url-status=live}}</ref>|| planet Neptune || seen from Earth
|maximum brightness<ref name="Mallama_and_Hilton" /> (Neptune comes to perihelion in 2042)
|-
| +7.78|| planet Neptune || seen from Earth
|mean brightness<ref name="Mallama_and_Hilton" />
|-
| +8|| colspan="3" style="background-color:#EEE;" |''Extreme naked-eye limit, Class 1 on [[Bortle scale]], the darkest skies available on Earth.<ref name="Bortle">{{cite web |date=February 2001 |title=The Bortle Dark-Sky Scale |publisher=Sky & Telescope |author=John E. Bortle |url=https://skyandtelescope.org/astronomy-resources/light-pollution-and-astronomy-the-bortle-dark-sky-scale/ |access-date=18 November 2009 |archive-url=https://web.archive.org/web/20090323232806/http://www.skyandtelescope.com/resources/darksky/3304011.html |archive-date=23 March 2009 |url-status=live }}</ref>''
|-
| +8.00|| planet Neptune || seen from Earth
|minimum brightness<ref name="Mallama_and_Hilton" />
|-id=extremestar
| +8.10|| moon [[Titan (moon)|Titan]] || seen from Earth
|maximum brightness; largest moon of Saturn;<ref name="horizons-Titan" /><ref name="arval" /> mean opposition magnitude 8.4<ref name="jpl-sat" />
|-
| +8.29
|star [[UY Scuti]]
|seen from Earth
|Maximum brightness; one of largest known stars by radius
|-
| +8.94|| asteroid [[10 Hygiea]] || seen from Earth
|maximum brightness<ref name="AstDys-Hygiea" />
|-
| +9.30|| spiral galaxy [[Messier 63|M63]] || seen from Earth
|-
| +9.5|| colspan="3" style="background-color:#EEE;" |''Faintest objects visible using common 10×50 [[binoculars]] under typical conditions<ref name="binoculars"/>''
|-
| +10|| [[Apollo 8]] [[Apollo command and service module|CSM]] in orbit around the Moon || seen from Earth
|calculated (Liemohn)<ref name="Physics and Astronomy">{{cite web | title=Tracking the Apollo Flights | website=Static Web Pages for Physics and Astronomy | date=1968-12-21 | url=https://pages.astronomy.ua.edu/keel/space/apollo.html | access-date=2024-03-20}}</ref>
|-
| +10
|star system [[T Coronae Borealis|T CrB]](average)
|seen from Earth
|Star system that goes nova every 80 years
|-
| +10.20|| moon [[Iapetus (moon)|Iapetus]] || seen from Earth
|maximum brightness,<ref name="arval" /> brightest when west of Saturn and takes 40 days to switch sides
|-
| +11.05
|star [[Proxima Centauri]]
|seen from Earth
|closest star (other than the Sun)
|-
| +11.8
|moon [[Phobos (moon)|Phobos]]
|seen from Earth
|Maximum brightness; brighter moon of Mars
|-
| +12.23
|star [[R136a1]]
|seen from Earth
|Most luminous and massive star known<ref>{{Cite news|url=https://www.space.com/41313-most-massive-star.html|title=What Is the Most Massive Star?|work=Space.com|access-date=5 November 2018|archive-url=https://web.archive.org/web/20190111150305/https://www.space.com/41313-most-massive-star.html|archive-date=11 January 2019|url-status=live}}</ref>
|-
| +12.89
|moon [[Deimos (moon)|Deimos]]
|seen from Earth
|Maximum brightness
|-
| +12.91||[[quasar]] [[3C 273]] || seen from Earth
|brightest ([[luminosity distance]] of 2.4&nbsp;billion [[light-year]]s)
|-
| +13.42|| moon [[Triton (moon)|Triton]] || seen from Earth
|Maximum brightness<ref name="jpl-sat" />
|-id=Pluto
| +13.65|| dwarf planet [[Pluto#Observation|Pluto]] || seen from Earth
|maximum brightness,<ref name="pluto" /> 725 times fainter than magnitude 6.5 naked eye skies
|-
| +13.9
|moon [[Titania (moon)|Titania]]
|seen from Earth
|Maximum brightness; brightest moon of Uranus
|-
| +14.1
|star [[WR 102]]
|seen from Earth
|Hottest known star
|-
| +15.4 ||[[Centaur (minor planet)|centaur]] [[2060 Chiron|Chiron]] || seen from Earth
|maximum brightness<ref name="AstDys-Chiron" />
|-
| +15.55|| moon [[Charon (moon)|Charon]] || seen from Earth
|maximum brightness (the largest moon of Pluto)
|-
| +16.8 || dwarf planet [[Makemake]] || seen from Earth
|Current [[Opposition (astronomy and astrology)|opposition]] brightness<ref name="AstDys-Makemake" />
|-id=17
| +17.27|| dwarf planet [[Haumea]] || seen from Earth
|Current opposition brightness<ref name="AstDys-Haumea" />
|-
| +18.7 || dwarf planet [[Eris (dwarf planet)|Eris]] || seen from Earth
|Current opposition brightness

|-id=19
| +19.5 || colspan="3" style="background-color:#EEE;" |''Faintest objects observable with the [[Catalina Sky Survey]] 0.7-meter telescope using a 30-second exposure''<ref>{{Cite web |url=https://catalina.lpl.arizona.edu/about/facilities |title=Catalina Sky Survey (CSS) Facilities |access-date=3 November 2019 |archive-url=https://web.archive.org/web/20191103212019/https://catalina.lpl.arizona.edu/about/facilities |archive-date=3 November 2019 |url-status=live }}</ref> and also the approximate [[limiting magnitude]] of [[Asteroid Terrestrial-impact Last Alert System]] (ATLAS)
|-
| +20.7 || moon [[Callirrhoe (moon)|Callirrhoe]] || seen from Earth
|(small ≈8&nbsp;km satellite of Jupiter)<ref name="jpl-sat" />
|-
| +22 || colspan="3" style="background-color:#EEE;" |''Faintest objects observable in visible light with a 600&nbsp;mm (24″) [[Ritchey-Chrétien telescope]] with 30 minutes of stacked images (6 subframes at 5 minutes each) using a [[Charge-coupled device|CCD detector]]<ref name="24inch">{{cite web|date=5 October 2009|title=17 New Asteroids Found by LightBuckets|publisher=LightBuckets|author=Steve Cullen (sgcullen)|url=http://www.lightbuckets.com/news/37/17-new-asteroids-found-by-lightbuckets/|archive-url=https://web.archive.org/web/20100131051349/http://www.lightbuckets.com/news/37/17-new-asteroids-found-by-lightbuckets/|archive-date=31 January 2010|access-date=15 November 2009}}</ref>''
|-
| +22.8
|[[Luhman 16]]
|seen from Earth
|Closest [[brown dwarf]]s (Luhman 16A=23.25, Luhman 16B=24.07)<ref name="Boffin et al. 2014" />
|-
| +22.91|| moon [[Hydra (moon)|Hydra]] || seen from Earth
|maximum brightness of Pluto's moon
|-
| +23.38|| moon [[Nix (moon)|Nix]] || seen from Earth
|maximum brightness of Pluto's moon
|-id=24
| +24 || colspan="3" style="background-color:#EEE;" |''Faintest objects observable with the [[Pan-STARRS]] 1.8-meter telescope using a 60-second exposure''<ref>{{cite web| url = https://panstarrs.ifa.hawaii.edu/pswww/?page_id=34| title = Pan-STARRS limiting magnitude| access-date = 12 August 2019| archive-date = 24 November 2020| archive-url = https://web.archive.org/web/20201124152242/https://panstarrs.ifa.hawaii.edu/pswww/?page_id=34}}</ref> This is currently the limiting magnitude of automated allsky [[astronomical survey]]s.
|-id=25
| +25.0 || moon [[Fenrir (moon)|Fenrir]] || seen from Earth
|(small ≈4&nbsp;km satellite of Saturn)<ref name="sheppard-saturn" /> and about 25 million times fainter than what can be seen with the naked eye.
|-
| +25.3 || Trans-Neptunian object {{mpl|2018 AG|37}} || seen from Earth
|Furthest known observable object in the Solar System about {{convert|132|AU|e9km|abbr=unit|lk=off}} from the Sun
|-id=26
| +26.2 || Trans-Neptunian object {{mpl|2015 TH|367}} || seen from Earth
|200&nbsp;km sized object about {{convert|90|AU|e9km|abbr=unit|lk=off}} from the Sun and about 75 million times fainter than what can be seen with the naked eye.
|-id=27
| +27.7 || colspan="3" style="background-color:#EEE;" |''Faintest objects observable with a single 8-meter class ground-based telescope such as the [[Subaru Telescope]] in a 10-hour image<ref>[http://www.skyandtelescope.com/astronomy-resources/astronomy-questions-answers/what-is-the-faintest-object-imaged-by-ground-based-telescopes/ What is the faintest object imaged by ground-based telescopes?] {{Webarchive|url=https://web.archive.org/web/20160202021559/http://www.skyandtelescope.com/astronomy-resources/astronomy-questions-answers/what-is-the-faintest-object-imaged-by-ground-based-telescopes/ |date=2 February 2016 }}, by: The Editors of Sky Telescope, 24 July 2006</ref>''
|-id=28
| +28.2 ||[[Halley's Comet]] || seen from Earth (2003)
|in 2003 when it was {{Convert|28|AU|e9km|abbr=unit|lk=off}} from the Sun, imaged using 3 of 4 synchronised individual scopes in the [[European Southern Observatory|ESO]]'s [[Very Large Telescope]] array using a total exposure time of about 9 hours<ref name="ESO2003">{{cite web |date=1 September 2003 |title=New Image of Comet Halley in the Cold |url=https://www.eso.org/public/news/eso0328/ |archive-url=https://web.archive.org/web/20250313011405/https://www.eso.org/public/news/eso0328/ |archive-date=13 March 2025 |access-date=29 April 2025 |publisher=[[ESO]]}}</ref>
|-
| +28.4 || asteroid {{mpl|2003 BH|91}} || seen from Earth orbit
|observed magnitude of ≈15-kilometer [[Kuiper belt]] object seen by the [[Hubble Space Telescope]] (HST) in 2003, dimmest known directly observed asteroid.
|-id=29
| +29.4 || [[JADES-GS-z13-0]] || seen from Earth || Discovered by the [[James Webb Space Telescope]]. One of the furthest objects discovered.<ref name="Robertson2022">{{Cite journal|display-authors = etal |first1 = B. E. |last1 = Robertson |title = Identification and properties of intense star-forming galaxies at redshifts z > 10 |journal = Nature Astronomy |year = 2023 |volume = 7 |issue = 5 |pages = 611–621 |doi = 10.1038/s41550-023-01921-1 |arxiv = 2212.04480|bibcode = 2023NatAs...7..611R |s2cid = 257968812 }}</ref> Approximately a billion times fainter than can be observed with the naked eye.
|-
|-id=31
| +31.5 || colspan="3" style="background-color:#EEE;" |''Faintest objects observable in visible light with [[Hubble Space Telescope]] via the [[EXtreme Deep Field]] with ≈23 days of exposure time collected over 10 years<ref>{{cite journal |last1=Illingworth |first1=G. D. |last2=Magee |first2=D. |last3=Oesch |first3=P. A. |last4=Bouwens |first4=R. J. |last5=Labbé |first5=I. |last6=Stiavelli |first6=M. |last7=van Dokkum |first7=P. G. |last8=Franx |first8=M. |last9=Trenti |first9=M. |last10=Carollo |first10=C. M. |last11=Gonzalez |first11=V. |title=The HST eXtreme Deep Field XDF: Combining all ACS and WFC3/IR Data on the HUDF Region into the Deepest Field Ever|journal=The Astrophysical Journal Supplement Series |date=21 October 2013 |volume=209 |issue=1 |page=6 |arxiv=1305.1931 |bibcode=2013ApJS..209....6I |doi=10.1088/0067-0049/209/1/6|s2cid=55052332 }}</ref>''
|-
| +35 || unnamed asteroid || seen from Earth orbit
|expected magnitude of dimmest known asteroid, a 950-meter Kuiper belt object discovered (by the HST) [[Occultation|passing in front of a star]] in 2009.<ref name="hstoccultation">{{cite news |url=https://www.nasa.gov/mission_pages/hubble/science/hst_img_kuiper-smallest.html |title=Hubble Finds Smallest Kuiper Belt Object Ever Seen |work=[[NASA]] |access-date=16 March 2018 |language=en |archive-url=https://web.archive.org/web/20170609103407/https://www.nasa.gov/mission_pages/hubble/science/hst_img_kuiper-smallest.html |archive-date=9 June 2017 |url-status=live}}</ref>
|-
| +35 || star [[LBV 1806−20]] || seen from Earth
|a luminous blue variable star, expected magnitude at visible wavelengths due to [[interstellar extinction]]
|}

==See also==
* [[Angular diameter]]
* [[Distance modulus]]
* [[List of nearest bright stars]]
* [[List of nearest stars]]
* [[Luminosity]]
* [[Surface brightness]]

==References==
{{Reflist|refs=

<ref name="moon-fact">{{cite web |last=Williams |first=David R. |title=Moon Fact Sheet |publisher=[[NASA]] (National Space Science Data Center) |url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html |date=2 February 2010 |access-date=9 April 2010| archive-url= https://web.archive.org/web/20100323165650/http://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html| archive-date= 23 March 2010 | url-status= live}}</ref>

<ref name="pluto">{{cite web |last=Williams |first=David R. |title=Pluto Fact Sheet |work=National Space Science Data Center |publisher=NASA |date=7 September 2006 |url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/plutofact.html | access-date=26 June 2010| archive-url= https://web.archive.org/web/20100701180605/http://nssdc.gsfc.nasa.gov/planetary/factsheet/plutofact.html| archive-date= 1 July 2010 | url-status= live}}</ref>

<ref name=arval>{{cite web|title=Classic Satellites of the Solar System|url=http://www.oarval.org/ClasSaten.htm|publisher=Observatorio ARVAL|access-date=25 June 2010|archive-url=https://web.archive.org/web/20100731193653/http://www.oarval.org/ClasSaten.htm|archive-date=31 July 2010}}</ref>

<ref name=jpl-sat>{{cite web |title=Planetary Satellite Physical Parameters |publisher=[[JPL]] (Solar System Dynamics) |url=http://ssd.jpl.nasa.gov/?sat_phys_par |date=3 April 2009 |access-date=25 July 2009| archive-url= https://web.archive.org/web/20090723024226/http://ssd.jpl.nasa.gov/?sat_phys_par| archive-date= 23 July 2009 | url-status= live}}</ref>

<ref name=sheppard-saturn>{{cite web |title=Saturn's Known Satellites |publisher=Carnegie Institution (Department of Terrestrial Magnetism) |first=Scott S. |last=Sheppard |author-link=Scott S. Sheppard |url=http://www.dtm.ciw.edu/users/sheppard/satellites/satsatdata.html |access-date=28 June 2010 |archive-url=https://web.archive.org/web/20110515215254/http://www.dtm.ciw.edu/users/sheppard/satellites/satsatdata.html |archive-date=15 May 2011 |url-status=live }}</ref>

<ref name=horizons-Ganymede>{{cite web |title=Horizon Online Ephemeris System for Ganymede (Major Body 503) |publisher=California Institute of Technology, Jet Propulsion Laboratory |author=Yeomans |author2=Chamberlin |url=http://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=mb&sstr=503 |access-date=14 April 2010 |archive-url=https://web.archive.org/web/20140202122141/http://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=mb&sstr=503 |archive-date=2 February 2014 |url-status=live }} (4.38 on 1951-Oct-03)</ref>

<ref name=horizons-Titan>{{cite web |title=Horizon Online Ephemeris System for Titan (Major Body 606) |publisher=California Institute of Technology, Jet Propulsion Laboratory |author=Yeomans |author2=Chamberlin |url=http://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=mb&sstr=606 |access-date=28 June 2010 |archive-url=https://web.archive.org/web/20121113022855/http://home.surewest.net/kheider/astro/titan-maxmag.txt |archive-date=13 November 2012 |url-status=live }} [http://home.surewest.net/kheider/astro/titan-maxmag.txt (8.10 on 2003-Dec-30)] {{Webarchive|url=https://web.archive.org/web/20121113022855/http://home.surewest.net/kheider/astro/titan-maxmag.txt |date=13 November 2012 }}</ref>

<ref name=AstDys-Hygiea>{{cite web |title=AstDys (10) Hygiea Ephemerides |publisher=Department of Mathematics, University of Pisa, Italy |url=http://hamilton.dm.unipi.it/astdys/index.php?pc=1.1.3.1&n=10&oc=500&y0=2095&m0=6&d0=27&h0=00&mi0=00&y1=2095&m1=6&d1=28&h1=00&mi1=00&ti=1.0&tiu=days |access-date=26 June 2010 |archive-url=https://web.archive.org/web/20140512215451/http://hamilton.dm.unipi.it/astdys/index.php?pc=1.1.3.1&n=10&oc=500&y0=2095&m0=6&d0=27&h0=00&mi0=00&y1=2095&m1=6&d1=28&h1=00&mi1=00&ti=1.0&tiu=days |archive-date=12 May 2014 |url-status=live }}</ref>

<ref name=AstDys-Chiron>{{cite web |title=AstDys (2060) Chiron Ephemerides |publisher=Department of Mathematics, University of Pisa, Italy |url=https://newton.spacedys.com/astdys/index.php?pc=1.1.3.1&n=2060&oc=500&y0=2097&m0=4&d0=3&h0=00&mi0=00&y1=2097&m1=4&d1=3&h1=00&mi1=00&ti=1.0&tiu=days |access-date=26 June 2010 |archive-url=https://web.archive.org/web/20110629201115/http://hamilton.dm.unipi.it/astdys/index.php?pc=1.1.3.1&n=2060&oc=500&y0=2097&m0=4&d0=3&h0=00&mi0=00&y1=2097&m1=4&d1=3&h1=00&mi1=00&ti=1.0&tiu=days |archive-date=29 June 2011 |url-status=live }}</ref>

<ref name=AstDys-Makemake>{{cite web |title=AstDys (136472) Makemake Ephemerides |publisher=Department of Mathematics, University of Pisa, Italy |url=https://newton.spacedys.com/astdys/index.php?pc=1.1.3.1&n=136472&oc=500&y0=2010&m0=3&d0=17&h0=00&mi0=00&y1=2010&m1=3&d1=17&h1=00&mi1=00&ti=1.0&tiu=days |access-date=26 June 2010 |archive-url=https://web.archive.org/web/20110629200626/http://hamilton.dm.unipi.it/astdys/index.php?pc=1.1.3.1&n=136472&oc=500&y0=2010&m0=3&d0=17&h0=00&mi0=00&y1=2010&m1=3&d1=17&h1=00&mi1=00&ti=1.0&tiu=days |archive-date=29 June 2011 |url-status=live }}</ref>

<ref name=AstDys-Haumea>{{cite web |title=AstDys (136108) Haumea Ephemerides |publisher=Department of Mathematics, University of Pisa, Italy |url=https://newton.spacedys.com/astdys/index.php?pc=1.1.3.1&n=136108&oc=500&y0=2010&m0=4&d0=6&h0=00&mi0=00&y1=2010&m1=4&d1=6&h1=00&mi1=00&ti=1.0&tiu=days |access-date=26 June 2010 |archive-url=https://web.archive.org/web/20110629200847/http://hamilton.dm.unipi.it/astdys/index.php?pc=1.1.3.1&n=136108&oc=500&y0=2010&m0=4&d0=6&h0=00&mi0=00&y1=2010&m1=4&d1=6&h1=00&mi1=00&ti=1.0&tiu=days |archive-date=29 June 2011 |url-status=live }}</ref>

<ref name="SIMBAD-Sirius">{{cite web |title=Sirius |publisher=SIMBAD Astronomical Database |url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Sirius |access-date=26 June 2010 |archive-url=https://web.archive.org/web/20140111192351/http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Sirius |archive-date=11 January 2014 |url-status=live }}</ref>

<ref name="SIMBAD-Canopus">{{cite web |title=Canopus |publisher=SIMBAD Astronomical Database |url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Canopus |access-date=26 June 2010 |archive-url=https://web.archive.org/web/20140714165140/http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Canopus |archive-date=14 July 2014 |url-status=live }}</ref>

<ref name="SIMBAD-Vega">{{cite web |title=Vega |publisher=SIMBAD Astronomical Database |url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Vega |access-date=14 April 2010 |archive-url=https://web.archive.org/web/20150707221325/http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Vega |archive-date=7 July 2015 |url-status=live }}</ref>

<ref name="SIMBAD-Arcturus">{{cite web |title=Arcturus |publisher=SIMBAD Astronomical Database |url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Arcturus |access-date=26 June 2010 |archive-url=https://web.archive.org/web/20140114050352/http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Arcturus |archive-date=14 January 2014 |url-status=live }}</ref>

<ref name="SIMBAD-mag6.5">{{cite web |title=Vmag<6.5 |publisher=SIMBAD Astronomical Database |url=http://simbad.u-strasbg.fr/simbad/sim-sam?Criteria=Vmag%3C6.5 |access-date=25 June 2010 |archive-url=https://web.archive.org/web/20150222212314/http://simbad.u-strasbg.fr/simbad/sim-sam?Criteria=Vmag%3C6.5 |archive-date=22 February 2015 |url-status=live }}</ref>

<ref name="SIMBAD-M31">{{cite web |title=SIMBAD-M31 |publisher=SIMBAD Astronomical Database |url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=M31 |access-date=29 November 2009 |archive-url=https://web.archive.org/web/20140519223154/http://simbad.u-strasbg.fr/simbad/sim-id?Ident=M31 |archive-date=19 May 2014 |url-status=live }}</ref>

<ref name="SN1006">{{cite journal |last1=Winkler |first1=P. Frank |title=The SN 1006 Remnant: Optical Proper Motions, Deep Imaging, Distance, and Brightness at Maximum |journal=[[The Astrophysical Journal]] |date=2003 |volume=585 |issue=1 |pages=324–335 |doi=10.1086/345985 |last2=Gupta |first2=Gaurav |last3=Long |first3=Knox S. |bibcode=2003ApJ...585..324W|arxiv = astro-ph/0208415 |s2cid=1626564 }}</ref>

<ref name=SN1054>{{cite web |url=http://messier.seds.org/more/m001_sn.html |title=Supernova 1054 – Creation of the Crab Nebula |website=SEDS |access-date=29 July 2014 |archive-url=https://web.archive.org/web/20140528074855/http://messier.seds.org/more/m001_sn.html |archive-date=28 May 2014 |url-status=live }}</ref>

<ref name="binoculars">{{cite web |date=2004 |title=Limiting Magnitude in Binoculars |publisher=Cloudy Nights |first=Ed |last=Zarenski |url=http://www.cloudynights.com/documents/limiting.pdf |access-date=6 May 2011 |archive-url=https://web.archive.org/web/20110721072103/http://www.cloudynights.com/documents/limiting.pdf |archive-date=21 July 2011 |url-status=live }}</ref>

<ref Name="Mallama_and_Hilton">{{cite journal |author=Mallama, A. |author2=Hilton, J.L. |title=Computing Apparent Planetary Magnitudes for The Astronomical Almanac |journal=Astronomy and Computing |volume=25 | pages=10–24 |date=2018 |doi=10.1016/j.ascom.2018.08.002 |arxiv=1808.01973 |bibcode=2018A&C....25...10M|s2cid=69912809 }}</ref>

<ref Name="Boffin et al. 2014">{{cite journal |author=Boffin, H.M.J. |author2=Pourbaix, D. |title=Possible astrometric discovery of a substellar companion to the closest binary brown dwarf system WISE J104915.57–531906.1 |journal=Astronomy and Astrophysics |volume=561 | page=5 |date=2014 |doi=10.1051/0004-6361/201322975 |arxiv=1312.1303 |bibcode=2014A&A...561L...4B|s2cid=33043358 }}</ref>

}}<!-- END: refs= -->

== External links ==
* {{cite web|url=http://www.icq.eps.harvard.edu/MagScale.html |title=The astronomical magnitude scale |website=International Comet Quarterly}}

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[[Category:Observational astronomy]]
[[Category:Logarithmic scales of measurement]]