Night Sky Quality Monitoring Report

Canyonlands NP, Utah

Grandview Point, June 2, 2003

To effectively manage any resource, we need to know what we have and what we've lost. "Light Pollution", the brightness in the nighttime sky due to artificial light, can be seen from almost every park. The NPS has developed a system for measuring sky brightness to quantify the source and severity of light pollution. This system, developed with the assistance from professional astronomers and the International Dark-sky Association, utilizes a research-grade digital camera to capture the entire sky with a series of images. Data clearly shows that even remote national parks are not immune from stray artificial light. Sky brightness is measured in astronomical magnitudes in the V-band, abbreviated as "mags". The V-band measures mostly green light, omitting purple through ultraviolet and orange through infrared. The magnitude scale is a logarithmic scale. A difference of 5 magnitudes corresponds to a 100x difference in brightness. Lower values (smaller or more negative) are brighter. Further information on astronomical magnitudes can be found on this Sky and Telescope webpage. Data images are shown in false color, with yellow, red, and white corresponding to brighter sky and blue, purple and black corresponding to darker sky.

A more detailed explanation is available.

Category	Details	Image
Park	CANY	Narrative: Very dark with excellent views in all directions. Even with its overlook of hundreds of square miles, the glare of only 2 or 3 permanent lights are seen. Moab only significant light dome, also see Monticello, La Sal Junction, Price, and Hanksville, but barely. Benchmark in slickrock makes excellent relocatable site. Seeing poor, transparency very good, windy, clouds near horizon 10% interfere with light dome measure of Moab. One of the darkest sites yet visited.
Site Name	Grandview Point
Longitude	-109.85825
Latitude	38.310417
Elevation (m)	1914
Date (UT)	June 2, 2003
Time Start (UT)	5:06:44
Data Quality	Excellent
Equipment	Apogee, 35mm f/2, Bessel V
Observers	D. Duriscoe, C. Duriscoe, A. Richman
Air Temp (°F)	–
Rel Humid (%)	–
Wind Sp (mph)	–
CCD Temp (°C)	-25
Exp (seconds)	8
Bortle Class	3
ZLM	6.8

SKY BRIGHTNESS DATA

Data Set Number	Time (UT)	Extinction Coefficient (mag/air-mass)	Std Err Y Extinction Stars (mags)	Zenith (mag/sq arc-sec)	Whole Sky (mags)	Sky Above 20° Altitude (mags)	Brightest (mag/sq arc-sec)	Darkest (mag/sq arc-sec)	Links to Sky Maps
1-Start End	5:06:44 5:35:44	0.171	0.036		-7.24	-6.60	20.63	22.08	PAN HEMI

LIGHT DOME DATA

City	Distance (km)	Azimuth	1st Data Set Brightness (mags)	Image
Moab, UT	40	43.0	-0.05
Monticello, UT	67	136.6
Hanksville, UT	75	275.6
Price, UT	165	330.6
Green River, UT	77	344.9
Total			-0.05