![]() Sythetic SQM: A value derived from the all-sky measurements using an algorithm designed to mimic the response of the Unihedron Sky Quality Meter, in magnitudes per square arc-second (mag arcsec-2), aimed at the zenith.Classes are whole numbers 1-9, with 1 the very best and 9 the poorest. Bortle Class: A semi-quantitative measure of the sky quality observed visually, as developed by astronomer John Bortle.A number lower (brighter) than 6.3 usually indicates significantly degraded sky quality. 7.4 is excellent, just about the faintest attainable, although some observers have confirmed seeing stars as faint as magnitude 8.2 with the naked eye. 7.0 is achievable under good seeing conditions and with proper dark adaptation of the eye. 6.6 is considered near pristine under average conditions. This observation varies somewhat from observer to observer, but all observers are instructed to practice the same methods. NELM: Naked eye limiting magnitude, or the faintest stars than can be observed visually without optical aid (naked eye) near the zenith, or darkest part of the sky.The number reported is the extinction coefficient in astronomical magnitudes in the V band per airmass. This value is computed for each data set from measurements of 50-150 standard stars on the images over the entire sky. A star viewed at the exact zenith is by definition view through one airmass. Airmass depends on its zenith angle and the relationship is not linear. Extinction is a measure of the opacity of the air, the units are astronomical magnitudes per airmass. Extinction Coeff: A report of calculated all-sky atmospheric extinction for each data set.Wind Speed (mph): Average wind speed at the start of image acquisition as measured by a portable weather meter held at eye level.R.H.(%): Relative humidity at start of image acquisition as measured by a portable weather meter.Air Temp (C): Air temperature at start of image acquisition as measured by a portable weather meter in degrees Celsius.Observers: The name(s) of the observer(s).Most of the data reported was imaged with cameras utilizing the KAF 1001E sensor exceptions include "Apogee" and "MaxCam" which used a smaller sensor and many more images to cover the sky (see Duriscoe, Luginbuhl, and Moore 2007). The camera name is usually the manufacturer, such as SBIG (Santa Barbara Instruments Group), followed by a number separating multiple cameras used with the same manufacturer. Camera: Short description of the camera used.Time (LMT Hours): The time at the middle of the imaging sequence in Local Mean Time (LMT) using a 24 hour clock 23.5 hours is 11:30 PM.Date(LMT): The date at the middle of the imaging sequence in Local Mean Time (LMT) note that LMT is not adjusted for daylight savings time.Elevation (m): Elevation above mean sea level in meters, taken with GPS receiver, typical vertical positional accuracy 15 meters.Latitude: Latitude in decimal degrees (north is positive), Datum WGS 84, taken with GPS receiver, typical horizontal positional accuracy 5 meters.Longitude: Longitude in decimal degrees (west is negative), Datum WGS 84, taken with GPS receiver, typical horizontal positional accuracy 5 meters.Site Name: Place name or description of the location of the observing site.Park: The name of the park or land manager where the data was collected.If you see them frequently, be sure to share that information with your doctor.Data Set Attributes and Visual Indicators ![]() Seeing stars in your eyes could also indicate a few other health problems, including diabetes complications (via Healthline), high blood pressure that isn't well-controlled, an infection, blood clots in the retinal blood vessels, or an ocular tumor (via Verywell Health). The older you get, the higher the risk of damage to your retina, one of the leading causes of the visual phenomenon, also known as photopsia. Another time seeing stars might indicate a more severe condition is if you see them randomly.Īge plays a factor in how big a deal it is to see flashes of light. ![]() The bright flashes could also be a symptom of a severe head injury like a concussion or a retinal tear or detachment (via Healthline). Migraine headaches, for example, can lead to seeing stars. While most flashes of light are often relatively benevolent, sometimes they warrant a call to your doctor if they appear frequently. You may see stars, or phosphenes, after a hard sneeze, which Health noted usually doesn't indicate a serious problem. ![]()
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