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WolframAlpha.com for astroimaging

Since I use a library of darks captured at different temperatures, I have to match my lights to the most appropriate master dark frame.  To find the temperature at which my light frames were captured, I use a website called WolframAlpha.com.  It was created by the inventor of Mathematica software as a site that allows you to data mine from thousands of databases, including two that I’m interested in:  weather stations and astronomy calculations.  WolframAlpha is not a search engine.  It doesn’t scour the web for terms.  It tries to interpret your query and calculate a result.

The site is a lot of (geeky) fun to play with.  It will graph and solve equations, calculate shifts between musical keys, and display financial information, among many other useful things.  But I find that I use it most commonly for astroimaging tasks.

As an example, I had the telescope out capturing images of the Iris Nebula on the night of September 1st.  A few days later, I uploaded the files to my computer and weeded out any problem exposures.  Because I was able to handle a meridian flip before going to sleep, I managed to get nearly continuous exposures from 9pm to 5am.  The transparency was poor, but sometimes you get lucky.  It was a hot day, but cooled off a lot in the evening.  I guessed I might have a pretty big difference in temperature across exposures, and I was right.  Below is the graph that wolframalpha gave me for a query of “temperature” + my ZIP code + “Sep 1, 2010.”  I queried “Sep 2, 2010” to get the temperatures for the whole night.  The weather station is less than 5 miles from my house, so it accurately reflects my conditions.

From the start of imaging at 9pm, until 1am, the temperature falls from 72°F to 66°F.  Then the temperature levels off at 66°F from 1am until sunrise at 5am.  Based on this, I chose to a 71°F master darks I had for the first time period, and a 65°F master for the 1-5am lights.  If I’d had a 68°F master, I might have used that for the whole bunch, but I didn’t happen to have one.

Wolframalpha.com can also provide other useful information about the weather, just by clicking “more” above the temperature graph.  You will probably see the effects of these in your images anyway, but it is nice to know sometimes.  It can show you cloud cover,  relative humidity (when did all that dew start to accumulate on my scope?),  wind speed,  and even incident sunlight:

I also use the site to help choose potential targets the evening before.  I know there are great planetarium programs that will also do this, but I can usually get the information I need here.  If you type in nearly any astronomical object, wolframalpha will not only show you astrophysical information about it, but also where it is in your local sky.  I find this very useful for determining whether it is in my light pollution “no go” zones, and planning for meridian flips.  This is useful for deep sky objects, but note that it can also calculate the exact location of planets and asteroids.  In fact, I used it to get the coordinates for Makemake when I captured the dwarf planet in July:

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