New spreadsheet with automatic calculation of Tc and k'
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I haven't noticed the Teams before and have now joined the DSLR team. I have uploaded my spreadsheet for reduction under "Final Reduction". This is the sheet I have used all along the campaign and it has worked very well. It has an automatic calculation of Tc, k' and Zp using the least-square method between the compairsion stars. After the coefficients is calculated they are applied to the variable star (epsilon in this case). There is also an error calculation done between the compairsion stars so you could see how well your instrumental magnitudes fit. By this you can estimate how good your images is and be confident on how good your end result is. For example I usually got an avereage error of less than +/-0.02 magnitudes with a maximum of +/-0.05 betwen the compairson stars if the sky is good and epsilon has haigh altitude. During the brightest period during may/june it dropped to average +/-0.05 and maximum of +/-0.10. I judge then that the result for epsilon is in the same region.As a calcultate the Tc every time I hade seen how it has changed by altitude. This is what should be expected as all stars go redder as they are near the horizon (think of the sun goes red at sunset). I have got a good correlation between Tc and air mass. At airass 1 (zenith) it was -0.12, at airmass 2 (30º altitude) it dropped to -0.10 and with the huge airmasses up to 7 that was during june the Tc dropped to -0.02.The k' can also vary a great deal. This is mostly due to how clear the sky is. A hazy or moisty sky generally gives a higher k'.If there is any questions of the functions in my spreadsheet just ask!