The following is my estimate of the nova's brightness today based on visual comparisons with nearby stars (up to 3 degrees away):
- Tues 03 Sept 2013 (8.15pm local; 12:15UTC). Equipment used: 120mm ED refractor and 34mm eyepiece (26.5x).
- The nova was dimmer than star SAO 106156 (mag 6.55); it was dimmer than SAO 88693 (mag 6.43); it was slightly dimmer than SAO 1006143 (mag 6.88); it was brighter than SAO 88715 (mag 7.92); it was similar in brightness to star V399 Vul (variable at mag range 7.01 - 7.17).
- Therefore, I conclude that the nova was at around mag 7.1 then.
(Click here for the actual light curve on the website of the AAVSO: http://www.aavso.org/lcg/plot?auid=000- ... an=&vmean=)
Next, below is a GIF animation of 2 frames, made as follows:
- I took the 1st image/frame on 16 August 2013 at 1706 UTC, which was just a few hours after it reached its peak brightness of around mag 4.3; it was at around mag 4.5 at the time the image was taken. The nova is the star between the two cross hairs. Another star 29 Vulpeculae is marked out as it was similar in brightness (mag 4.80).
- The 2nd image/frame was done this evening, 3 Sept 2013 at 1203 UTC / 8.03pm local). It shows how far the nova had dimmed since 16 Aug! The imaging equipment was the same (Canon EOS 60D with Sigma 17-70 len at around 40mm focal length), but I used an Astrotrac for the 2nd image. Unlike the 1st image where the stars were near the edge of the frame, in the 2nd image the stars were placed nearer the centre of the frame and hence were sharper.
Between mag 4.5 and mag 7.1 is a difference in brightness of 10.97 times (http://www.1728.org/magntudj.htm). I think the GIF animation does bear this out (but compare the nova's brightness on the 2 days relative to the nearby stars).
Click here for the GIF file if it does not show on your screen below:
http://img15.picoodle.com/i593/starfind ... _u8s7b.gif
(PS: Qi Xiang, thanks! Looks like our computations (mine using the on-line calculator) of the nova's absolute intrinsic brightness at peak were indeed correct, as I've found this computation stating a similar absolute magnitude, see:
http://www.astronomerstelegram.org/?read=5313 where it says "this implies an absolute magnitude of Mv ~ -9.3 +/- 0.2")