Deep-Sky Notes. Deep-Sky Note cards are printed on heavy 3x5-inch card stock (same size as our AstroCards) and fit any standard card file box. The are a handy way of keeping a record or sketch of all your observations. Recording observations improves your observing skills and also gives you a permanent record. May be placed on top of our card lighter while writing or drawing. Observations may be filed by NGC No., R.A., or constellation.