Friday, January 26, 2018

researched SAO 87428

Strange. I did not identify the elements of SAO 87428 when shot for BGO. And it was not listed in my SkyTools list for BGO completed images... Corrected for this. Did I forget back on 12 Sep '16? Very odd as it was logged in ST3P! Logged but no list entry. Anyhoo.

Then I noticed Minkowski's Footprint wasn't in the BGO completed list either. But that's another story.

As I completed the colour processing, I thought I could then update the doubles life list. There was no colour data recorded. But then I spotted other blog references! I had viewed the system on 2 Jul '16. And then imaged it with the DSLR on the C14 on 29 Aug '16. And both times not bothered to describe the colours! Weirder and weirder. So had a go with the DSLR image and tagged stars with colours. Then studied the most recent image, with the fainter stars.

All the while I was doing this, I wondered what was up with the E star. Was it the bright star opposite G from C? So I jumped into the Washington Double Star database and looked up SLE 647. Whoa! There were 9 entries up to J (no I)! Correction: there are I and N companions! So 12 stars.

plot of SLE 647

SkyTools shows A, B, C, D, G, and H and the positions correspond.

WDS adds E, F, J, and L, all of which I see in the BGO photograph.

E, aka FYM 43 AE, is dim and orange and north-east of D. Is it almost exactly between D and F.

F, aka FYM 43 AF, is the blueish star east-north-east of E. It is slightly brighter than D.

J, aka FYM 43 AJ, is the mystery star opposite G. It is dimmer than D but brighter than F. Pale blue.

L, aka FYM 43 AL, is an extremely dim orange star south-south-west of A. It is barely visible in the BGO image! WDS says it is mag 15.1.

I noticed in the WDS that stars D, G, and H are associated with BKO. Hello Mr Berko. BKO 72.

And then I noticed other BKO 72 and FYM 43 entries. Oh ho!

I plotted BKO D, E, and F separately and they corresponded to the main plot.

I plotted BKO 72 HI. Ha! This is the faint star near H, to the north, clearly visible in my BGO shot! It is a touch dimmer than H. Could it be redder?

Finally I plotted FYM 43 JN. The WDS says it is north (325°) and tight (2.4") and very dim (mag 16). I don't think this is visible in my image.

So. Wow! This started out as a double star system not properly updated in SkyTools and with no colour data on the life list and I ended up logging a bunch of new stars!

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