Apache Point Observatory

The observatory consists of a 3.5-meter telescope and three future telescopes which
are under construction.

The APO Site

Located in the Sacramento Mountains in the Lincoln National Forest, APO is 18
miles south of Cloudcroft, NM.

From El Paso, TX take highway 54 north to highway 82 in Alamogordo. From Las
Cruces, take highway 70/82 east to Alamogordo. There, take highway 82 east to
Cloudcroft. In Cloudcroft, turn right onto highway 130 and follow 130 to highway
6563 (toward Sunspot). Turn right onto 6563. After approximately 16 miles, turn left
at the marked spur just before the entrance to the National Solar Observatory. APO is
one mile down this drive.


Directions to Apache Point Observatory

Apache Point was chosen as the site for its altitude and clear weather. At 9200 feet,
the atmosphere above the observatory contains little water vapor or contaminants that
degrade images. Wind flows smoothly over the site, allowing the images formed by
the telescopes to be sharp. The night sky at APO is among the darkest in the United
States because of clean air and the absence of nearby large cities.


The 3.5-meter Telescope

This multipurpose telescope was built to provide astronomers with data to develop
and refine theories of how planets, stars, nebulae, and galaxies form and evolve; and
for the study of exotic objects such as black holes, quasars, the interstellar medium,
and phenomena yet undiscovered.

Light collected by the 3.5-meter diameter concave mirror at the bottom of the
telescope is reflected up to a smaller convex mirror located at the top of the
telescope, and is then reflected down again to a third flat mirror. This last mirror can
be turned to direct the focused light to any of several detectors (electronic cameras,
spectrographs, etc.). The signals collected by the telescope and its instruments are
converted into digital data, which are stored and analyzed using computers.

The telescope boasts several innovations in its construction and how it is used

Lightweight honeycomb boroscilicate mirror 
   The 3.5-meter diameter primary mirror was fabricated with a new
   "spin-casting" technology that enables large mirrors to be made with only
   20% of the weight of a solid glass mirror. The structures that support the
   honeycomb mirror can be made lighter and smaller.

Remote observing 
   With computers and long-distance electronic networks, astronomers can
   operate the telescope from their home institutions, and receive back the
   images and other data from the telescope. The telescope was built with this
   capability in mind allowing greater flexibility and savings over the traditional
   method of the astronomer traveling to the telescope.

Multi-instrumental configuration 
   Up to nine instruments can be simultaneously mounted on the telescope
   permitting rapid changes between different observing programs. With remote
   operation, several astronomers can share the telescope on a given night using
   whichever instrument suits their needs and observing conditions.

Thermal control 
   Local differences in air temperature cause images formed by any telescope to
   blur. The telescope and its box-like enclosure were carefully designed with a
   system of vents and exhaust systems to minimize local warming of the air.


Sloan Digital Sky Survey (SDSS)

With major support under a grant from the Alfred P. Sloan Foundation, construction
has begun on a 2.5-meter diameter telescope of advanced design and with a unique
purpose. The telescope will conduct a survey of a large fraction of the northern night
sky, using a large array of sensitive imaging and spectrographic detectors. A large
amount of digital data will be collected in five separate colors containing images of
hundreds of millions of objects, including some of the faintest detectable galaxies.
From the survey image data, candidate galaxies and quasars will be identified for
follow-up spectroscopic observations. These spectra will yield the distance to more
than one million galaxies, plus over one hundred thousand quasars. An important
objective of the survey is to generate a three-dimensional picture of the local
universe, and we expect other discoveries about the structure and evolution of the
universe.

The principal institutions participating in the SDSS project are:

   The University of Chicago 
   Fermi National Accelerator Laboratory 
   The Institute for Advanced Study 
   Japan Promotion Group 
   Johns Hopkins University 
   Princeton University 
   The US Naval Observatory 

Survey observations are expected to start in 1995 and take several years to complete.
An additional smaller telescope is being built next to the SDSS to provide supporting
calibration data and sky monitoring.


NMSU 1.0-meter Telescope


The 1.0-meter New Mexico State University (NMSU) telescope is for faculty and
staff research and teaching.


Who Are We?

APO is privately owned and operated by the Astrophysical Research Consortium
(ARC), consisting of the University of Chicago, Institute for Advanced Study, Johns
Hopkins University, New Mexico State University, Princeton University, University
of Washington, and Washington State University. ARC is a not-for-profit
organization whose mission is to develop and operate astronomical research facilities
for use by scientists affiliated with the member institutions.