Hi all,
My son and I have been putting together a light curve for Nova Delphinus, as a grade 6 science project. Rather than doing visual estimates, we have been taking an image using my 50D dSLR and 70-200mm telephoto lens using an exposure that is short enough to avoid saturating the star images (typically 1 sec at f/4 and 800 iso). After converting the RAW files to monochrome using Lightroom3, we have then taken the average of the 4 brightest pixels in the image of the nova and a reference star (HIP100754, just below the nova and mag 5.7), and subtracted the background level from a region without stars. We have then expressed the brightness of the nova as a percentage relative to the reference star. This means that we are using a linear scale, rather then the commonly used logarithmic scale for stellar magnitudes.
We missed the brightest phase of the nova on August 16th, but have made an observation each night from the 18th. Here's the results so far. You can see that its brightness has roughly halved during this period. As expected for these events, the initial drop in brightness was quite rapid, but it seems to have levelled out a bit over the last couple of days. We plan to keep the observations going for at least two more weeks, just in case the nova flares up again
.
Cheers,
Stephen