A (brief) Visit
to Lowell Observatory’s Anderson Mesa and Happy Jack Sites
You may
notice that the main site above Flagstaff that I’ve been concentrating on is
great for history and outreach but not so much for current professional astronomy.
That’s because Lowell’s professional telescopes are all at two dark-sky sites south
of Flagstaff, one at Anderson Mesa, the other at Happy Jack.
There’s not that much to see without some kind of backstage pass,
just the various domes. So this is just a quick fly-by and description of the telescopes if you’re interested,
or are planning on visiting the area and just curious about what you can see.
If I am one day lucky enough to get a tour, I’ll obviously update this into a more major article.
Getting
There
The older
site at Anderson Mesa is accessed from a right turn 12 miles out of Flagstaff
along Lake Mary Road. The road begins at a left-hand turn (going south) just
out of Flagstaff past the I-40 flyover. The road drives through some urban sprawl
before heading out by some largely dry reservoirs. Watch for cyclists along
this stretch.
Happy Jack is
42 miles along the same road out of Flagstaff as Anderson Mesa. Chosen for its
dark skies, I can see why: it really is miles from anywhere in a very remote
spot in the middle of a national forest area.
Even this
sign is scarred by buckshot.
What to
see
Anderson
Mesa Site
It’s not that
easy to find and is just signed-posted ‘NPOI’. The road twists up through pine
forests, past a rough camping area before reaching some domes on top of the
mesa.
The first
observatory you come to on the right is a small one for the US Geological Survey.
It likely houses a 21” F16, but I can’t find details.
A bit further
on is Lowell’s 72" Perkins Telescope in a large dome. The Perkins Telescope is an
older long-focal-length (F17.5) Cassegrain with a truss tube on a massive
single-arm (‘English’) yoke mount and reminds me a bit of McDonald’s 82”. It
was acquired from the Ohio Wesleyan Observatory in the 1960s.
Lowell has partnered
with Boston University as a partial divestment of the Perkins, which nonetheless
has a number of modern instruments, including multi-object spectroscope and
another working in the near infra-red. Of interest if you’re a pro’ with a
project in mind is that it’s apparently inviting proposals for research at the
absolute bargain price of $800 per night.
Past the Perkin’s
dome is a silver one housing the 42” Hall telescope, a fork-mounted F8 truss-tube
Ritchey-Chrétien that Lowell describe as their ‘workhorse’.
It was inaugurated in 1970 and is used for CCD imaging, spectroscopy and
photometry. It got an upgraded lightweight primary mirror in 2004.
Out of sight
is a smaller dome that houses the NURO telescope, a yoke-mounted 31” F15
Cassegrain installed in the sixties for the USGS as part of a lunar imaging
project for Apollo. The 31” is now used by undergraduates 60% of the time. The Lowell
picture shows a piggy-backed orange-tube Celestron
SCT!
Also nearby
is the signposted NPOI – the Navy Precision Optical Interferometer, the world’s
largest optical interferometer - in partnership with the US Naval Observatory
(that has a separate site near Flagstaff). You can’t see much of the NPOI from
the road.
The NPOI is
used to measure exact stellar positions to create a spatial reference system
for GPS calibration, among other things.
Happy
Jack Site
Location of
Lowell’s flagship professional scope, I just drove by to spot the dome from the
road. There’s not much you can see if you’re not invited by Lowell.
What’s
there? The 4.3m Lowell Discover
Telescope that only became fully operational in 2015 (first light was in 2011) and
cost $53 million. The LDT is mainly used as an F6.2 RC, but has other foci too.
The LDT has various instruments, including spectrographs and large imagers in
the visual and near-IR. It also hosts Yale’s exoplanet radial-velocity
instrument. A night on the LDT costs $25,000.
Fun fact: I
got chatting to an astronomer doing outreach work on the 24” Clark and he told
me that they once attached an eyepiece to the LDT and looked at Mars when it
was on the wrong side of the Sun and very small. He said it still showed
amazing detail. If true, this might be the largest telescope ever used visually
on Mars. Given the specs, the minimum likely magnification was ~500x if they
used a custom 100mm eyepiece, double that with a 55mm Plossl (the eyepiece they
mostly use on the Clark).
Lowell
Discovery Telescope dome poking out of the trees near Happy Jack on Highway
209.
Summary
The Anderson
Mesa and (especially) the Happy Jack site probably aren’t worth a dedicated
trip from Flagstaff. However, they are on the first part of a much more scenic
alternative to I-17 if you’re driving down to Phoenix and would be worth a look
then.