J(H)AC's SQM Measurement Guidelines
This webpage may be printed out by anyone, but is
intended for use by those in our Jackson (Hole) Astronomy Club, using our (2)
SQMs. To be consistent with readings posted on this website, this form
provides a checklist for what we desire/require, to maintain that
consistency. Readings should be accomplished only on moonless
nights. (A Garmin GPS 38 unit is available for location ID from the
club, courtesy Dan and Sharon Smitherman.) Please use your own batteries
in the unit as it only requires 4 AA types. (Turn D ring on bottom of
GPS to open.) With SQM, a 9V is included. Slide compartment door
on back of SQM to access 9V battery, place battery in & remove when
done. (Keep in the ziploc bag.) Remove when done, so that they
don't drain away with lack of use, or eventually corrode terminals in the
unit. Take a second and third reading within several minutes of the first to
HOW TO OPERATE SQM &
1. 9V battery installed
2. Point the unit vertically, sensor pointed directly up toward zenith
3. Press button firmly, release, and wait.
4. A reading will appear, probably within about 15-30 seconds.
5. Notate this reading and as this is so easy, take 2 more over the
next couple of minutes.
6. Take avg. reading to report for your location
7. A copy of the above info is on our website.
8. If you press the button again, you'll get consecutive readings of
temperature in C & F, of the unit. If it has been inside, it will
read that temperature until it adapts to outdoor temp. Temp will not
affect the readings.
9. You can read other nearby light sources for info or amusement, by
aiming it toward those sources & pressing the red button.
Measure with no moon, on a clear night w/very good to excellent seeing
Info needed, print this guideline or notate on separate sheet:
Local time of night
Name of reader
Location description: eg. Hoback Jct., Yellowstone
– Norris Geyser Basin, GTNP – atop Signal Mtn., Driggs – 2 miles east
of town, Village – Base of Bridger Lift, Jackson – 120 W. Simpson, etc.
Also: GPS if available, nearby ground lighting
(airport, street lights, neighbor yard light, ball park, etc.) Provide in
format of Degrees, minutes, seconds, NOT Decimal degrees.
Zenith info: tail of Big Dipper, center of Cygnus
in Milky Way present, Capella, M31, Vega, etc.
Other info: ie. Avg. of 3 readings. You can, and are
encouraged, to take the SQM on a trip & take readings to
be logged upon your return. Just let the
custodian know in advance.
Call Walt with info (733.2173) or give them to him when you return the
Or, call Walt to provide readings
verbally & to find out whom to pass the SQM to next.
It is the reader’s responsibility to return the SQM to Walt, not
for Walt to chase after the unit to retrieve it.
is at 505 Ponderosa Dr., at the corner of S. Ponderosa Lp. & Spring
Gulch Rd. across from the airport.
one else is currently on the wait list, the unit should be returned to
Walt within 2 wks. or by the NEXT meeting. Your readings will be logged onto the club website’s
for this info,
for access by anyone who wishes to see