Palomar Observatory

File:Palomar Mountain Observatory 3c 1948 issue U.S. stamp.jpg

Astronomer George Ellery Hale, whose vision created Palomar Observatory, built the world's largest telescope four times in succession.{{Cite web|url=https://www.britannica.com/biography/George-Ellery-Hale|title=George Ellery Hale {{!}} American astronomer|website=Encyclopedia Britannica|language=en|access-date=2020-03-20}} He published a 1928 article proposing what was to become the 200-inch Palomar reflector; it was an invitation to the American public to learn about how large telescopes could help answer questions relating to the fundamental nature of the universe. Hale followed this article with a letter to the International Education Board (later absorbed into the General Education Board) of the Rockefeller Foundation dated April 16, 1928, in which he requested funding for this project. In his letter, Hale stated:

"No method of advancing science is so productive as the development of new and more powerful instruments and methods of research. A larger telescope would not only furnish the necessary gain in light space-penetration and photographic resolving power, but permit the application of ideas and devices derived chiefly from the recent fundamental advances in physics and chemistry."

{{Main|Hale Telescope}}

The 200-inch telescope is named after astronomer and telescope builder George Ellery Hale. It was built by Caltech with a $6 million grant from the Rockefeller Foundation, using a Pyrex blank manufactured by Corning Glass Works under the direction of George McCauley. Dr. J.A. Anderson was the initial project manager, assigned in the early 1930s.{{cite magazine|magazine=Popular Mechanics|author=Hearst Magazines|title=Super Camera of the Skies|url=https://books.google.com/books?id=TtcDAAAAMBAJ&pg=PA52|date=April 1942|publisher=Hearst Magazines|page=52}} The telescope (the largest in the world at that time) saw first light January 26, 1949, targeting NGC 2261.[http://365daysofastronomy.org/2009/01/26/january-26-60th-anniversary-of-hale-telescope-first-light/ "60th Anniversary of Hale Telescope,"] 365 Days of Astronomy (podcast). January 26, 2009. The American astronomer Edwin Powell Hubble was the first astronomer to use the telescope.

The 200-inch telescope was the largest telescope in the world from 1949 until 1975, when the Russian BTA-6 telescope saw first light. Astronomers using the Hale Telescope have discovered quasars (a subset of what was to become known as Active Galactic Nuclei) at cosmological distances. They have studied the chemistry of stellar populations, leading to an understanding of the stellar nucleosynthesis as to origin of elements in the universe in their observed abundances, and have discovered thousands of asteroids. A one-tenth-scale engineering model of the telescope at Corning Community College in Corning, New York, home of the Corning Glass Works (now Corning Incorporated), was used to discover at least one minor planet, 34419 Corning.{{JPL|34419|†}}

File:Palomar Observatory Dome - High Resolution.jpg

Russell W. Porter developed the Art Deco architecture of the Observatory's buildings, including the dome of the 200-inch Hale Telescope. Porter was also responsible for much of the technical design of the Hale Telescope and Schmidt Cameras, producing a series of cross-section engineering drawings. Porter worked on the designs in collaboration with many engineers and Caltech committee members.{{Cite web|url=https://www.space.com/26310-palomar-observatory.html|title=Palomar Observatory: Facts & Discoveries|last=June 2014|first=Elizabeth Howell 20|website=Space.com|date=20 June 2014|language=en|access-date=2020-04-06}}{{Cite web|url=https://www.britannica.com/topic/Palomar-Observatory|title=Palomar Observatory {{!}} observatory, California, United States|website=Encyclopedia Britannica|language=en|access-date=2020-04-06}}{{Cite web|url=https://sandiegohistory.org/journal/1998/october/palomar/|title=Palomar, After 50 Years|website=San Diego History Center {{!}} San Diego, CA {{!}} Our City, Our Story|language=en-US|access-date=2020-04-06}}

Max Mason directed the construction and Theodore von Karman was involved in the engineering.

• Ira Sprague Bowen, 1948–1964
• Horace Welcome Babcock, 1964–1978
• Maarten Schmidt, 1978–1980
• Gerry Neugebauer, 1980–1994
• James Westphal, 1994–1997
• Wallace Leslie William Sargent, 1997–2000
• Richard Ellis, 2000–2006
• Shrinivas Kulkarni, 2006–2018
• Jonas Zmuidzinas, 2018–

Much of the surrounding region of Southern California has adopted shielded lighting to reduce the light pollution that would potentially affect the observatory.[http://www.darksky.org/mc/page.do?sitePageId=55060&orgId=idsa International Dark-Sky Association] {{webarchive|url=https://web.archive.org/web/20080101110647/http://www.darksky.org/mc/page.do?sitePageId=55060&orgId=idsa |date=2008-01-01 }} (IDA): [http://data.nextrionet.com/site/idsa/is020.pdf "Sky Glow Effect on Existing Large Telescopes"] {{Webarchive|url=https://web.archive.org/web/20110714180114/http://data.nextrionet.com/site/idsa/is020.pdf |date=2011-07-14 }}, IDA Info #20.

File:Palomar Observatory.jpg

File:Palomar Observatory 2012 09.jpg

• The {{Convert|200|in|m|adj=mid}} Hale Telescope was first proposed in 1928 and has been operational since 1949. It was the largest telescope in the world for 26 years.{{cite web |title=Caltech Astronomy – The 200-inch Hale Telescope |url=http://www.astro.caltech.edu/palomar/about/telescopes/hale.html |publisher=Caltech Astronomy |access-date=2014-12-09}}{{Citation needed|date=April 2023}}
• A {{Convert|60|in|m|adj=mid}} reflecting telescope is located in the Oscar Mayer Building, and operates fully robotically. The telescope became operational in 1970, and was built to increase sky access for Palomar astronomers. Among its notable accomplishments is the discovery of the first brown dwarf.{{cite web |title=Caltech Astronomy – The 60-inch Telescope |url=http://www.astro.caltech.edu/palomar/about/telescopes/60-inch.html |publisher=Caltech Astronomy |access-date=2014-12-09}} The 60-inch telescope currently{{When|date=May 2024}} hosts the SED Machine integral field spectrograph instrument used as part of ZTF transient followup and classification.{{cite web |title=Welcome to SED Machine's documentation! |url=https://www.astro.caltech.edu/sedm/ |access-date=2020-07-29 |website=sites.astro.caltech.edu}}{{cite journal|last1=Blagorodnova|first1=Nadejda|date=March 2018|doi=10.1088/1538-3873/aaa53f|title=The SED Machine: A Robotic Spectrograph for Fast Transient Classification|journal=Publications of the Astronomical Society of the Pacific|volume=130|issue=985|page=035003|url=https://ui.adsabs.harvard.edu/abs/2018PASP..130c5003B/abstract|arxiv=1710.02917|bibcode=2018PASP..130c5003B|s2cid=54892690}}
• The {{Convert|48|in|m|adj=mid}} Samuel Oschin telescope development began in 1938, and the telescope saw first light in 1948. It was initially called the 48-inch Schmidt, and was dedicated to Samuel Oschin in 1986.{{cite web |title=Caltech Astronomy – Samuel Oschin Telescope |url=http://www.astro.caltech.edu/palomar/about/telescopes/oschin.html |publisher=Caltech Astronomy |access-date=2014-12-09}} Among many notable accomplishments, Oschin observations led to the discovery of the important dwarf planets Eris and Sedna.{{cite web |title=Caltech Astronomy – Discoveries from Palomar Observatory's 48-inch Samuel Oschin Telescope |url=http://www.astro.caltech.edu/palomar/about/telescopes/oschin.html#science |publisher=Caltech Astronomy |access-date=2014-12-09}} Eris's discovery initiated discussions in the international astronomy community that led to Pluto being re-classified as a dwarf planet in 2006. The Oschin presently operates fully robotically and hosts the 570-million-pixel ZTF Camera {{Cite book |last1=Dekany |first1=Richard |last2=Smith |first2=Roger M. |last3=Belicki |first3=Justin |last4=Delacroix |first4=Alexandre |last5=Duggan |first5=Gina |last6=Feeney |first6=Michael |last7=Hale |first7=David |last8=Kaye |first8=Stephen |last9=Milburn |first9=Jennifer |last10=Murphy |first10=Patrick |last11=Porter |first11=Michael |last12=Reiley |first12=Dan |last13=Riddle |first13=Reed |last14=Rodriguez |first14=Hector |last15=Bellm |first15=Eric |chapter=The Zwicky Transient Facility Camera |editor-first1=Christopher J. |editor-first2=Luc |editor-first3=Hideki |editor-last1=Evans |editor-last2=Simard |editor-last3=Takami |date=2016 |title=Ground-based and Airborne Instrumentation for Astronomy VI |chapter-url=https://authors.library.caltech.edu/74385/1/99085M.pdf |journal=Proceedings of SPIE |volume=9908 |pages=99085M |doi=10.1117/12.2234558|bibcode=2016SPIE.9908E..5MD |s2cid=38035871 }}—the discovery engine for the ZTF project.
• The {{Convert|40|in|m|adj=mid}} WINTER (The Wide-field Infrared Transient Explorer) 1x1-degree reflecting robotic telescope has been operational since 2021. It is dedicated to the seeing-limited time domain survey of the infrared (IR) sky, with a particular emphasis on identifying r-process material in binary neutron star (BNS) merger remnants detected by LIGO. The instrument observes in Y, J, and a short-H (Hs) band tuned to the long-wave cutoff of the InGaAs sensors, covering a wavelength range from 0.9 to 1.7 microns.{{cite book |title=Ground-based and Airborne Instrumentation for Astronomy VIII |chapter-url=https://ui.adsabs.harvard.edu/abs/2020SPIE11447E..67F/abstract |bibcode=2020SPIE11447E..67F |access-date=2021-10-18|last1=Frostig |first1=Danielle |last2=Baker |first2=John W. |last3=Brown |first3=Joshua |last4=Burruss |first4=Rick |last5=Clark |first5=Kristin |last6=Fżrész |first6=Gábor |last7=Ganciu |first7=Nicolae |last8=Hinrichsen |first8=Erik |last9=Karambelkar |first9=Viraj R. |last10=Kasliwal |first10=Mansi M. |last11=Lourie |first11=Nathan P. |last12=Malonis |first12=Andrew |last13=Simcoe |first13=Robert A. |last14=Zolkower |first14=Jeffry |chapter=Design requirements for the Wide-field Infrared Transient Explorer (WINTER) |editor1-first=Christopher J |editor1-last=Evans |editor2-first=Julia J |editor2-last=Bryant |editor3-first=Kentaro |editor3-last=Motohara |year=2020 |volume=11447 |page=113 |doi=10.1117/12.2562842 |arxiv=2105.01219 |hdl=1721.1/142211 |isbn=9781510636811 |s2cid=230542025 }}

• An {{Convert|18|inch|cm|adj=mid}} Schmidt camera became the first operational telescope at the Palomar in 1936. In the 1930s, Fritz Zwicky and Walter Baade advocated adding survey telescopes at Palomar, and the 18-inch was developed to demonstrate the Schmidt concept. Zwicky used the 18-inch to discover over 100 supernovae in other galaxies. Comet Shoemaker-Levy 9 was discovered with this instrument in 1993. It has since been decommissioned and is on display at the small museum/visitor center.{{cite web |title=Caltech Astronomy – The 18-inch Schmidt Telescope |url=http://www.astro.caltech.edu/palomar/about/telescopes/decommissioned.html#p18 |publisher=Caltech Astronomy |access-date=2014-12-09}}{{Cite web |title=Greenway Visitor Center |url=https://sites.astro.caltech.edu/palomar/visitor/visitorcenter.html |website=sites.astro.caltech.edu}}
• The Palomar Testbed Interferometer (PTI) was a multi-telescope instrument that made high-angular-resolution measurements of the apparent sizes and relative positions of stars. The apparent sizes and in some cases shapes of bright stars were measured with PTI, as well as the apparent orbits of multiple stellar systems. PTI operated from 1995 to 2008.{{cite web |title=Caltech Astronomy – Palomar Testbed Interferometer (PTI) |url=http://www.astro.caltech.edu/palomar/about/telescopes/decommissioned.html#pti |publisher=Caltech Astronomy |access-date=2014-12-09}}
• The Palomar Planet Search Telescope (PPST), also known as Sleuth, was a {{Convert|10|cm|in|abbr=|adj=mid}} robotic telescope that operated from 2003 until 2008. It was dedicated to the search for planets around other stars using the transit method. It operated in conjunction with telescopes at Lowell Observatory and in the Canary Islands as part of the Trans-Atlantic Exoplanet Survey (TrES).{{cite web |title=Caltech Astronomy – Sleuth: The Palomar Planet Finder |date=30 October 2009 |url=http://palomarskies.blogspot.de/2009/10/goodbye-to-sleuth.html |publisher=Palomar Skies |access-date=2014-12-09}}

File:18 Inch Schmidt Camera at Palomar Observatory.jpg

Palomar Observatory remains an active research facility, operating multiple telescopes every clear night, and supporting a large international community of astronomers who study a broad range of research topics.

The Hale Telescope remains in active research use and operates with a diverse instrument suite of optical and near-infrared spectrometers and imaging cameras at multiple foci. The Hale also operates with a multi-stage, high-order adaptive optics system to provide diffraction-limited imaging in the near-infrared. Key historical science results with the Hale include cosmological measurement of the Hubble flow, the discovery of quasars as the precursor of Active Galactic Nuclei, and studies of stellar populations and stellar nucleosynthesis.

The Oschin and 60-inch telescopes operate robotically and together support a major transient astronomy program, the Zwicky Transient Facility.

The Oschin was created to facilitate astronomical reconnaissance, and has been used in many notable astronomical surveys—among them are:

The initial Palomar Observatory Sky Survey (POSS or POSS-I), sponsored by the National Geographic Institute, was completed in 1958. The first plates were exposed in November 1948 and the last in April 1958. This survey was performed using 14-inch² (6-degree²) blue-sensitive (Kodak 103a-O) and red-sensitive (Kodak 103a-E) photographic plates on the Oschin Telescope. The survey covered the sky from a declination of +90° (celestial north pole) to −27° and all right ascensions and had a sensitivity to +22 magnitudes (about 1 million times fainter than the limit of human vision). A southern extension extending the sky coverage of the POSS to −33° declination was shot in 1957–1958. The final POSS I dataset consisted of 937 plate pairs.

The Digitized Sky Survey (DSS) produced images which were based on the photographic data developed in the course of POSS-I.Minnesota Automated Plate Scanner (MAPS): [http://aps.umn.edu/ MAPS catalogue]; Mollise, Rod. (2006). {{Google books|Z0mvZk0s_TMC|The Urban Astronomer's Guide: a Walking tour of the Cosmos for City Sky Watchers |page=238}}

J.B. Whiteoak, an Australian radio astronomer, used the same instrument to extend POSS-I data south to −42° declination. Whiteoak's observations used the same field centers as the corresponding northern declination zones. Unlike POSS-I, the Whiteoak extension consisted only of red-sensitive (Kodak 103a-E) photographic plates.

{{Redirect|Second Palomar Observatory Sky Survey|POSS I|Palomar Sky Survey}}

The Second Palomar Observatory Sky Survey (POSS II, sometimes Second Palomar Sky Survey) was performed in the 1980s and 1990s and made use of better, faster films and an upgraded telescope. The Oschin Schmidt was upgraded with an achromatic corrector and provisions for autoguiding. Images were recorded in three wavelengths: blue (IIIaJ. 480 nm), red (IIIaF, 650 nm), and near-infrared (IVN, 850 nm) plates. Observers on POSS II included C. Brewer, D. Griffiths, W. McKinley, J. Dave Mendenhall, K. Rykoski, Jeffrey L. Phinney, and Jean Mueller (who discovered over 100 supernovae by comparing the POSS I and POSS II plates). Mueller also discovered several comets and minor planets during the course of POSS II, and the bright Comet Wilson 1986 was discovered by then-graduate-student C. Wilson early in the survey.Caltech: [http://www.astro.caltech.edu/~wws/poss2.html The Second Palomar Observatory Sky Survey (POSS II)] {{webarchive|url=https://web.archive.org/web/20090516193335/http://www.astro.caltech.edu/~wws/poss2.html |date=2009-05-16 }}

Until the completion of the Two Micron All Sky Survey (2MASS), POSS II was the most extensive wide-field sky survey. When completed, the Sloan Digital Sky Survey will surpass POSS I and POSS II in depth, although the POSS covers almost 2.5 times more area on the sky.

POSS II also exists in digitized form (that is, the photographic plates were scanned) as part of the Digitized Sky Survey (DSS).NASA/Space Telescope Science Institute (STScI).: [http://archive.stsci.edu/dss/ Multimission Archive at STScI (MAST)]

The multi-year POSS projects were followed by the Palomar Quasar Equatorial Survey Team (QUEST) Variability survey.Caltech press release: [http://pr.caltech.edu/media/Press_Releases/PR12417.html "New Sky Survey Begins at Palomar Observatory."] {{Webarchive|url=https://web.archive.org/web/20040405033327/http://pr.caltech.edu/media/Press_Releases/PR12417.html |date=2004-04-05 }} July 29, 2003. This survey yielded results that were used by several projects, including the Near-Earth Asteroid Tracking project. Another program that used the QUEST results discovered 90377 Sedna on 14 November 2003, and around 40 Kuiper belt objects. Other programs that share the camera are Shri Kulkarni's search for gamma-ray bursts (this takes advantage of the automated telescope's ability to react as soon as a burst is seen and take a series of snapshots of the fading burst), Richard Ellis's search for supernovae to test whether the universe's expansion is accelerating or not, and S. George Djorgovski's quasar search.

The camera for the Palomar QUEST Survey was a mosaic of 112 charge-coupled devices (CCDs) covering the whole (4° × 4°) field of view of the Schmidt telescope. At the time it was built, it was the largest CCD mosaic used in an astronomical camera. This instrument was used to produce The Big Picture, the largest astronomical photograph ever produced.Caltech: [http://bigpicture.caltech.edu/ "The Big Picture"] {{webarchive|url=https://web.archive.org/web/20070204102050/http://bigpicture.caltech.edu/ |date=2007-02-04 }} The Big Picture is on display at Griffith Observatory.

Current research programs on the 200-inch Hale Telescope cover the range of the observable universe, including studies on near-Earth asteroids, outer Solar System planets, Kuiper Belt objects, star formation, exoplanets,JPL: [http://www.jpl.nasa.gov/news/news.cfm?release=2009-090 "Planet-Hunting Method Succeeds at Last."] {{Webarchive|url=https://web.archive.org/web/20220201162200/https://www.jpl.nasa.gov/news/news.cfm?release=2009-090 |date=2022-02-01 }} May 28, 2009. black holes and x-ray binaries, supernovae and other transient source followup, and quasars/Active Galactic Nuclei.Caltech: [http://www.palomar.caltech.edu:8000/instruments/p200_calendar.tcl Hale Telescope Observing Runs] {{webarchive|url=https://archive.today/20121212205940/http://www.palomar.caltech.edu:8000/instruments/p200_calendar.tcl |date=2012-12-12 }}

The 48-inch Samuel Oschin Schmidt Telescope operates robotically, and supports a new transient astronomy sky survey, the Zwicky Transient Facility (ZTF).

The 60-inch telescope operates robotically, and supports ZTF by providing rapid, low-dispersion optical spectra for initial transient classification using the for-purpose Spectral Energy Distribution Machine (SEDM){{Cite journal|url=https://iopscience.iop.org/article/10.1088/1538-3873/aaa53f/pdf|doi=10.1088/1538-3873/aaa53f|title=The SED Machine: A Robotic Spectrograph for Fast Transient Classification|year=2018|last1=Blagorodnova|first1=Nadejda|last2=Neill|first2=James D.|last3=Walters|first3=Richard|last4=Kulkarni|first4=Shrinivas R.|last5=Fremling|first5=Christoffer|last6=Ben-Ami|first6=Sagi|last7=Dekany|first7=Richard G.|last8=Fucik|first8=Jason R.|last9=Konidaris|first9=Nick|last10=Nash|first10=Reston|last11=Ngeow|first11=Chow-Choong|last12=Ofek|first12=Eran O.|last13=Sullivan|first13=Donal O'|last14=Quimby|first14=Robert|last15=Ritter|first15=Andreas|last16=Vyhmeister|first16=Karl E.|journal=Publications of the Astronomical Society of the Pacific|volume=130|issue=985|page=035003|arxiv=1710.02917|bibcode=2018PASP..130c5003B|s2cid=54892690}} integral field spectrograph.

File:Greenway Visitor Center.jpg]]

Palomar Observatory is an active research facility. However, selected observatory areas are open to the public during the day. Visitors can take self-guided tours of the 200-inch telescope daily from 9 a.m. to 3 p.m. The observatory is open 7 days a week, year round, except for December 24 and 25 and during times of inclement weather. Guided tours of the 200-inch Hale Telescope dome and observing area are available Saturdays and Sundays from April through October. Behind-the-scenes tours for the public are offered through the community support group, Palomar Observatory Docents.{{Cite web |title=Docents |url=https://sites.astro.caltech.edu/palomar/community/docents.html |website=sites.astro.caltech.edu}}

Palomar Observatory also has an on-site museum—the Greenway Visitor Center, containing observatory and astronomy-relevant exhibits, a gift shop,{{cite web |title=Palomar Observatory Gift and Book Store |url=https://store.palomar.caltech.edu/ |website=store.palomar.caltech.edu}} and hosts periodic public events.{{Cite web |title=Greenway Talk Series |url=https://sites.astro.caltech.edu/palomar/visitor/visitorcenter/talks/ |website=sites.astro.caltech.edu}}

For those unable to travel to the observatory, Palomar provides an extensive virtual tour that provides virtual access to all the major research telescopes on-site and the Greenway Center and has extensive embedded multimedia to provide additional context.{{Cite web |title=Virtual Tour |url=https://sites.astro.caltech.edu/palomar/visitor/virtualtour.html |website=sites.astro.caltech.edu}} Similarly the observatory actively maintains an extensive website{{Cite web |title=Welcome to Palomar Observatory |url=https://sites.astro.caltech.edu/palomar/homepage.html |website=sites.astro.caltech.edu}} and YouTube channel{{Cite web|url=https://www.youtube.com/channel/UC9YssB4C-EIWZ6yXH_uuytw|title = Palomar Observatory – YouTube|website = YouTube}} to support public engagement.

The observatory is located off State Route 76 in northern San Diego County, California, two hours' drive from downtown San Diego and three hours' drive from central Los Angeles (UCLA, LAX airport).{{Cite web |title=Driving Directions to Palomar Observatory |url=https://sites.astro.caltech.edu/palomar/visitor/driving.html |website=sites.astro.caltech.edu}} Those staying at the nearby Palomar Campground can visit Palomar Observatory by hiking {{convert|2.2|mi|km}} up Observatory Trail.{{cite web | title=Observatory Trail in Cleveland National Forest | url=https://www.hikespeak.com/trails/observatory-trail-palomar-mountain/ | website=hikespeak.com | publisher=Hikespeak | access-date=March 28, 2017}} Notably, Ben Burt, sound designer for the original Star Wars, recorded various sounds at the Palomar Observatory, including motors and the shutters on the dome, to add background sounds for the Death Star.

Palomar has a hot-summer Mediterranean climate (Köppen Csa).

{{Weather box

| collapsed =

| location = Palomar Observatory (1991–2020 normals, extremes 1938–present)

| single line = Y

|Jan record high F = 82

|Feb record high F = 77

|Mar record high F = 82

|Apr record high F = 83

|May record high F = 91

|Jun record high F = 104

|Jul record high F = 100

|Aug record high F = 100

|Sep record high F = 100

|Oct record high F = 97

|Nov record high F = 80

|Dec record high F = 80

| Jan avg record high F = 63.4

| Feb avg record high F = 63.9

| Mar avg record high F = 69.5

| Apr avg record high F = 76.1

| May avg record high F = 82.0

| Jun avg record high F = 88.7

| Jul avg record high F = 92.9

| Aug avg record high F = 92.0

| Sep avg record high F = 88.3

| Oct avg record high F = 81.0

| Nov avg record high F = 71.5

| Dec avg record high F = 64.8

|year avg record high F = 94.3

|Jan high F = 51.4

|Feb high F = 51.0

|Mar high F = 56.0

|Apr high F = 61.3

|May high F = 69.3

|Jun high F = 78.5

|Jul high F = 84.3

|Aug high F = 84.4

|Sep high F = 79.3

|Oct high F = 69.1

|Nov high F = 58.2

|Dec high F = 50.7

|year high F= 66.1

|Jan low F = 37.1

|Feb low F = 36.1

|Mar low F = 38.7

|Apr low F = 41.8

|May low F = 48.4

|Jun low F = 57.0

|Jul low F = 63.9

|Aug low F = 64.5

|Sep low F = 59.5

|Oct low F = 50.8

|Nov low F = 42.5

|Dec low F = 36.6

|year low F= 48.1

| Jan avg record low F = 24.4

| Feb avg record low F = 24.0

| Mar avg record low F = 25.4

| Apr avg record low F = 28.1

| May avg record low F = 33.4

| Jun avg record low F = 41.2

| Jul avg record low F = 55.3

| Aug avg record low F = 55.1

| Sep avg record low F = 45.5

| Oct avg record low F = 36.8

| Nov avg record low F = 29.0

| Dec avg record low F = 23.9

|year avg record low F = 19.8

|Jan record low F = 8

|Feb record low F = 12

|Mar record low F = 16

|Apr record low F = 19

|May record low F = 24

|Jun record low F = 28

|Jul record low F = 36

|Aug record low F = 36

|Sep record low F = 30

|Oct record low F = 18

|Nov record low F = 17

|Dec record low F = 8

|precipitation colour = green

|Jan precipitation inch = 5.93

|Feb precipitation inch = 7.34

|Mar precipitation inch = 4.61

|Apr precipitation inch = 2.00

|May precipitation inch = 0.89

|Jun precipitation inch = 0.17

|Jul precipitation inch = 0.29

|Aug precipitation inch = 0.68

|Sep precipitation inch = 0.48

|Oct precipitation inch = 1.21

|Nov precipitation inch = 2.25

|Dec precipitation inch = 4.56

|year precipitation inch= 30.41

|Jul snow inch = 0.0

|Aug snow inch = 0.0

|Sep snow inch = 0.0

|Oct snow inch = 0.0

|Nov snow inch = 0.4

|Dec snow inch = 2.4

|Jan snow inch = 6.2

|Feb snow inch = 10.6

|Mar snow inch = 3.1

|Apr snow inch = 3.5

|May snow inch = 0.0

|Jun snow inch = 0.0

|year snow inch= 26.2

|unit precipitation days = 0.01 in

|Jan precipitation days = 6.5

|Feb precipitation days = 7.3

|Mar precipitation days = 5.9

|Apr precipitation days = 3.9

|May precipitation days = 2.3

|Jun precipitation days = 0.4

|Jul precipitation days = 1.1

|Aug precipitation days = 1.3

|Sep precipitation days = 1.3

|Oct precipitation days = 2.0

|Nov precipitation days = 3.2

|Dec precipitation days = 5.8

|year precipitation days=

|unit snow days = 0.1 in

| Jul snow days = 0.0

| Aug snow days = 0.0

| Sep snow days = 0.0

| Oct snow days = 0.0

| Nov snow days = 0.3

| Dec snow days = 1.5

| Jan snow days = 1.2

| Feb snow days = 2.1

| Mar snow days = 0.9

| Apr snow days = 1.1

| May snow days = 0.0

| Jun snow days = 0.0

|year snow days =

| source 1 = NOAA{{cite web |url = https://www.weather.gov/wrh/Climate?wfo=sgx |title = NOWData – NOAA Online Weather Data |publisher = National Oceanic and Atmospheric Administration |access-date = August 13, 2022}}

}}

• 1983 — Calvino, Italo. Mr. Palomar. Torino: G. Einaudi. {{ISBN|9788806056797}}; [https://www.worldcat.org/oclc/461880054 OCLC 461880054] {{in lang|it}}
• 1987 — Preston, Richard. First Light. New York: Atlantic Monthly Press. {{ISBN|9780871132000}}; [https://www.worldcat.org/oclc/16004290 OCLC 16004290]
• 1994 — Florence, Ronald. The Perfect Machine. New York: HarperCollins. {{ISBN|9780060182052}}; [https://www.worldcat.org/oclc/611549937 OCLC 611549937]
• 2010 — Brown, Michael E. How I Killed Pluto and Why It Had It Coming. Spiegel & Grau. {{ISBN|0-385-53108-7}}; [https://www.worldcat.org/oclc/495271396 OCLC 495271396]
• 2020 — Schweizer, Linda. Cosmic Odyssey. MIT Press {{ISBN|978-0-262-04429-5}}

{{Portal|Astronomy|California}}

• List of astronomical observatories
• Mount Laguna Observatory
• National Geographic Society – Palomar Observatory Sky Survey

{{Reflist}}

• {{cite book | first =David Livingston | last =Crawford | date = 1966| title =The Construction of large telescopes | publisher =Academic Press | location = London & New York |oclc=1093049}}
• {{cite book | first = Rod | last = Mollise | date = 2006 | title = The Urban Astronomer's Guide: a Walking Tour of the Cosmos for City Sky Watchers | url =https://books.google.com/books?id=Z0mvZk0s_TMC&pg=PA238 | publisher =Springer | location =Berlin| isbn = 978-1846282171|oclc=299995003}}
• {{cite book | first = T.V. | last = Watterson | date = 1941 | title =Palomar Observatory | publisher = Frye & Smith | location =San Diego, California|oclc=6327013}}

{{commons category|Palomar Observatory|position=left}}

• [https://sites.astro.caltech.edu/palomar/homepage.html Caltech Astronomy: Palomar Observatory – official observatory website]
• [http://palomarskies.blogspot.com/ Palomar Skies], news and history written by former Palomar public affairs coordinator Scott Kardel
• [https://web.archive.org/web/20031231045038/http://lyra.colorado.edu/sbo/sboinfo/readingroom/poss.html The SBO Palomar Sky Survey Prints]
• [http://cleardarksky.com/c/PalomarObkey.html Palomar Observatory Clear Sky Clock] Forecast of observing conditions.
• [https://www.youtube.com/c/PalomarObservatoryPalomarMountain Palomar Observatory YouTube Channel]
• [https://sites.astro.caltech.edu/palomar/visitor/virtualtour.html Palomar Observatory Virtual Tour]

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{{California Institute of Technology}}

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Category:Astronomical observatories in California

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Category:Palomar Mountains

Category:Buildings and structures in San Diego County, California

Category:Natural history of the Peninsular Ranges