studied HD 38

Probed HD 38 aka STT 547 a bit deeper.

Pulled data from the Washington Double Star database for 00057+4549STT 547. Very interesting. Way beyond what is shown in my favourite software.

discoverer	first obs	last obs	P.A.	sep	mag pri	mag sec	spectral
STT 547AB	1876	2016	189	6	8.98	9.15	K6+M0
STT 547AC	1911	2015	263	116.2	8.98	13.71	K6
STT 547AD	1911	2015	230	110.3	8.98	12.51	K6
STT 547AE	1911	2015	344	58.4	8.98	11.75	K6
STT 547AF	1897	2007	254	327.9	8.98	10.19	K6V+M2e
POP 217AP	1994	2015	320	15.4	8.98	13.4	K6
POP 217AQ	1998	2006	130	20	8.98	16	K6
POP 217AX	2004	2006	222	12	8.98		K6
POP 217AY	1998	2005	79	199	8.98	14.8	K6
STT 547BC	1925	2015	266	114.8	9.15	13.71	M0
STT 547BD	1921	2015	232	105.9	9.15	12.51	M0
STT 547BE	1991	2015	346	64	9.15	11.75	M0
STT 547BF	1961	2002	255	326.4	9.15	10.19	M0
STT 547BP	1989	2015	333	19.8	9.15	13.1	M0
POP 217YG	1998	2005	189	10	14.8	15.8

I transcribed the data from SkyTools 3 Professional.

AB	190	5.89
AC	356	54.5
AD	188	82.2
AF	268	84.52

Now, ST3P shows binary data information... The calculated values as of June 2017. AB has a 1551 year period. AF has a 83000 year period! Wow.

I flipped, zoomed, and cropped the image.

North is up; east is right (opposite the full image).

I plotted in my custom Excel workbook the A through F stars using the WDS data. There is good correspondence to my BGO image.

North is up; east is right.

I noted that the labelling between the WDS and ST3P was different. What ST3P called the C star, WDS said was E. What ST3P called star GSC 03246-1561 is C according to the WDS. From the BGO photo, I knew there was an issue with F. The WDS refers to a bright star which ST3P says is J000511.7+454706.

This means that for my log notes, I can claim to have spotted B, C, D, E, and F, according to the WDS. I have to adjust some notes from the initial observations. C is nearly due west of AB. It is extremely faint. It appears to me to be beside another star making it a pair (opposed or at a 90° angle to AB) with nearly the same separation as AB. E is to the north, about half the separation has C. F is far afield to the west.

The WDS shows observations from POP. I plotted the stars POP 217 P, Q, X, and Y. I added the STT 547 F star to maintain the scale in the graph.

P corresponds to the image quite well. It is the medium-bright nearby star to the north-north-west. ST3P calls this GSC 03246-0320. I don't see anything at the Q location. Nor the X spot. Q is listed as mag 16; X has no value. The Y star however lines up with my image with a faint star. In fact, it too seems to be part of a faint double. Their alignment is almost identical to AB, roughly north-south. It is to the east, well away. In ST3P, this is shown as J000600.2+454920 at mag 14.8.

So I think I can safely add the P and Y stars to my life list log.

The WDS catalogue lists C, D, E, F, and P associated with B. I plotted this system. Again I see a very good correlation to my image.

There's another POP 217 entry, this time for the G partner to Y. It is at position angle 189 and is 10 arc-seconds away. I see this in my image. This star is south of Y and fainter. And ST3P shows this too: GSC 03246-1853. I think I can add the G star to my log.

For clarity, I annotated the photograph.

Fascinating.