Question for observers

[Tim]

In the middle of NGC281, the Pacman nebula, there is a very tight cluster of four stars HP4121 A-D.

Is it possible to seperate and view these visually? I cna just about split them into three with a camera, but its tricky and seeing dependant.

Thanks

TJ (I dont come down here very often, it's a lot darker than im used to )

[Sam]

I'll swing the 16" that way next time it's clear and let you know!

[Doc]

I have never tried Tim.

I'm sure that they are a Quadrouple star and go by the names...

Bu1 A is mag 8.58

Bu1 B is mag 9.33

Seperation 1.4

Bu1 C is mag 9.21

Bu1 D is mag 9.82

Seperation 7.8

Will try next time. The 1.4 seperation might be a bit tough.

[GazOC]

I never tried it but from Micks figures at least theres no overpowering star in the system. I'll give it a go next time out.

[lunator]

Looking at the data I would say the AB pair would be a tricky unless the seeing is very steady.

I will have a try at these at some point.

Cheers

Ian

[Tim]

Thanks chaps.

[Talitha]

Got it. The C and D components were easily seen but the E component was washed out by the moonlight. At 222x the A/B components looked circular. At 404x they elongated into an oval with the correct PA, but there was no hint of a separation. I kicked it up to stupidpower (560x) just for grins and giggles, but it didn't improve anything. The pair was still an oval and even in fleeting moments of better seeing, they never stretched out into a peanut shape.

[Doc]

Fantastic work Carol. I didn't know about the fifth companion.

[Talitha]

Thanks Mick, i didn't know about the E component either, till it turned up in the SkyTools program. It's a mag 12.1 star with a PA of 333 degrees from the primary, separation is 16.10" (1987).

ST lists the designation as "BU 1E" (??) and also lists some alternate designations:

ADS 719E

CCDM 00528+5638E

J005248.3+563753

[Talitha]

Just a note..

The seeing was pretty steady tonight and i was able to detect the E star (under a blazing Full Moon, can you believe it?) but still couldn't separate A/B or stretch it out into a peanut. It looked the same as yesterday.. an oval.

[jarbi]

Talitha,

Thanks for the challenging observation idea, I will try it with my 16" LB the next time.

cheers,

Janos

[lunator]

I have some additional info.

The last maeasurement of this pair in 2005 was 1.1. PA 80.

The 1.4 figure relates to the 1992. PA 81

This variation in measurement could well be down to the 'human' factor.

My guess is that the pair are closer to 1" in separation than 1.5" making it only splitable in the best conditions.

The other consideration is that the pair are at the sort of magnitude where in a smallish scope the cones of the eyes won't be activated and relying on the rods will make the split impossible.

I will still have a try when the seeing is steady here.

Cheers

Ian