Exposure adjustment

My first ever photo of Mercury
It was a nice clear evening, about 45 minutes after sunset. I could see Mercury with the naked eyes just above the horizon. I used a tip from someone, suggesting I stretched my hand with my thumb or little finger pointing at Venus and towards 5 pm. I did that and there it was Mercury, a small bright dot just above the horizon.
Settings I used :
Exposure 1/13 sec
F 5.3
ISO 3200
Focal length 44mm
Below is a composite picture of a magnified of Venus and Mercury at 300mm