VelaClock 1.3 for iPhone and iPod touch from the Vela Design Group is for professional and amateur astronomers, air and naval crews, navigators or movie makers photographers who need to know everything about time around the world, UTC, sunrise, sunset, moonrise, moonset and other quantities associated with time.

The design of VelaClock makes sense. A scrolling region at the top of the display scrolls up and down to show up to 50 different cities, the local time, and the three stages of twilight: civil, nautical and astronomical. The bottom pane scrolls sideways to reveal three different groups of time data.

A small triangular marker along each city's time line shows the local time with respect to day, night or twilight. The white line in the center of the time line shows the time of moonrise and moonset. The user can just touch one of the cities, it turns a darker shade of blue, and text information for that city is displayed in the pane below: sunrise, sunset, moonrise, moonset, the duration of daylight, and the times of the various twilights.

Settings

Touching the white italics "i" moves the user into the setting mode where its possible to not only add various locations but also set a "home" city. This takes into account the fact that the current location may not always be the home location.

A thoughtful touch is the ability to set the coordinates of the home city to the same as the current location with the touch of a button. In addition, Coordinated Universal Time (UTC) is also included in the default list. That avoids errors because simply selecting London for a proxy UTC is an unsuitable choice -- London goes on daylight saving time in the summer.

The cities are selected by just entering the first few characters, and the app finds them fast. Cities can be sorted by local time, name or by dragging the names into a custom list.

One piece of data I liked is one the first of the bottom panes: the time remaining until sunset in hours and minutes. Also included is the azimuth of sunrise and sunset. This kind of information could come in especially handy for movie makers.

Accuracy

I checked the times of sunrise and sunset against tables from the U.S. Naval Observatory for Denver and the match was very close, within a minute, which is acceptable. Note that sunset and sunrise times are always "astronomical" which assumes an unobstructed horizon. In Denver, we have mountains to the west which will cause the actual sunset time to be a few minutes earlier, depending on the location.

A representative from Vela Design Group said that they tested the time for various locations against U.S. Naval Observatory tables to insure the accuracy of their algorithms.

Issues

One minor issue with the UI is the failure to clearly show which location/city has been selected. In my first use of the app, I didn't notice how the selected city turns a slightly darker shade of blue, and that led to a display of an erroneous sunset/sunrise time for Denver. The representative from Vela Design Group said that this will fixed in a future version -- to make the selected city more prominent.

There were no other issues, and I found the app to be friendly, well thought out and easy to use.

It's About Time

As an amateur astronomer and sky watcher, I had been looking for a great iPhone app to quickly display the current phase of the moon and times of sunrise and sunset. This app performs that function very well, and it's modestly priced. From my communications with the developer, it appears that they will be continuing to improve the app, especially the UI, so the US$3.99 investment is worthwhile.

VelaClock 1.3 from Vela Design Group requires OS X iPhone 2.0 or later. It also works with iPod touch. There is also a corresponding Mac OS X widget.