I will be revisiting Bu 720 shortly.
Here is a pic I took in 2016:
EDIT: Last night I tried this one with the 8 inch at high power (627x) and noted it as decidedly elongated with a small difference in magnitude and color vs the primary. I could not detect a 'notch but the seeing was not optimal--I will try again tonight.
Below are my notes from my 2016 post regarding this object. These were written before I knew to look into the 4th Int Cat for historical data. I agree with Fred re: the likely current separation. I will endeavor to measure this one again with my current setup which is superior to the one used to make the image shown above.
Bu 720, 72 Pegasi
magnitudes: 5.7, 6.1
position angle: 105 degrees
separation: 0.575” (orbital elements estimate); 0.505” (last precise measure; 2015)
The separation data are not in good agreement for this object. This is, therefore, a good candidate for quantitative scrutiny.
Visual [15 inch reflector]
At 398x the object vacillated on the border between elongated and just resolved to two golden-orange disks of similar magnitude in the correct position angle; 569x proved sufficient to show the stars as different magnitude and clearly resolved (but not yet split); a final increase in magnitude to 798x showed the pair as split, again with a golden-orange color and a small difference in magnitude. The ease of resolution at modest magnification led me to think the larger separation value [0.575”] was more accurate for Bu 720.
Bu 720 was easily imaged using an exposure of 10 ms [gain = 320]. Four movies were made and separation was measured by three methods using REDUC: cross correlation of the top 5% of frames using S4 filter; simple measure of a Registax composite; and simple measure of a composite generated in REDUC. There was good agreement across these methods, giving a measured separation of 0.61”.
Edited by Nucleophile, 09 October 2019 - 08:46 AM.