Help wanted neglected double HJ2302

[lunator]

Guys

I was wondering if you could help me with a double star observation.

I have been trying to locate the companion to HJ2302 John Hercshel catologue) also know as 71 Orion.

The primary is mag 5.2 so is relatively easy to find.

The secondary is listed as Mag 11.5 and is about 25" away.

Last night I finally caught the secondary. It was South of the Primary but was closer than the 25".

By my estimate it was fainter than Mag 12. I estimated it's brightness by comparing it to 2 faint stars in a 4 star diamond shape just to the east. On my planetarium these are listed 11.8 & 11.9. (TYC 1322-00614-1 & TYC 1322-01009-1)

If any one is able to spot this companion I would be interested to hear what you see.

I am going to measure this star but it will be a challenge due to it's faintness.

Cheers

Ian

[daz]

Next time I'm out, I'll take a look

[Astroman]

I took a look tonight, found the field, but the clouds are rolling in. If it's clear for an hour this week, I'll look again for you. USNO has some different values for magnitudes, but the ones I used are red filters, so may be different than yours. I'll let you know.

[mark RD]

OK got it on my list too

Mark

[lunator]

Got frustrated for the clouds to clear so I decided to take a look at HJ2302 on the Aladin database wher you can get visual images of the whloe sky.

The B component was hidden by the huge disk of the primary but it was just discernable. I managed to get a measurement from the plate and it implied the distance between the A & B components is shrinking. This is not a surprise as primary is a high proper motion star and the pair is probably optical.

I also found that the C & D components appear to be a separate double HLM 4 that was measured once in 1924. I let Bob Argyle of the Webb Society know and I hope he will double check this (please excuse the pun)

To the North west I found a brightish pair of stars that do not appear to be in the WDS. They may just be a chance alignment but I could not find any information on the fainter star to rule then in as a pair or out as a pair.

I have submitted this to the Webb Soc. and I await their response.

All in all a productive night 'viewing'

Cheers

Ian

[lunator]

Got out tonight and managed to view HJ2302.

The companion is definately there and is about 15" away it looks almost due south but I did not have tome to measure it tonight.

Tommorrow night it is my target.

[lunator]

Finally I have beaten the clouds.

Last week I managed to measure the PA of this pair and arrived at the figure of 203 degrees (the last WDS figure is 201.7 by StG - G. Struve!!!)

Then the clouds rolled in and I was unable to make any timing measures.

I had looked at the metoffice chart animation yesterday and it implied a weak ridge of high pressure would be crossing the the South of the UK and so clearer skies were a possibility.

Today when I returned home it was clear and I put the scope out to cool. Put the children to bed, ate dinner etc. whilst it got dark.

The cloud had started to build up again and the wind was gusting strongly but I was determined to get some measurements of HJ2302.

I initially tried with the barlow and 12.5mm reticle eyepiece but the secondary was hardly visible so a 'binned' the barlow and had a crack with just the 12.5mm eyepiece.

I put the illumination as low as I could get it and the secondary was still visible.

The problem I had now was that when there were gaps in the cloud the wind picked up and the stars were jumping all over the place and when the wind dropped the cloud rolled in!!

I decided to wait it out and I knew the drive would keep the star in the FOV even if a couldn't see it.

I stood and watched as the clouds rolled througth the eyepiece FOV (a not very interesting experience) but every so often the clouds would clear and before the wind could pick up I could grab a few timings.

I took the best part of an hour but I managed to get a dozen maesurements.

The mean timing was 1.02 seconds.

(This bit is for Daz again)

As the PA is quite close to 180 degrees so I put the reticle wire at 45 degrees.

To calculate the Separation you use the following equation.

Separation (Rho) = 15.0411x tx cos d/cos theta- sin theta (t is time, d is declination)

HJ2302 has a declination of 19:09.23 which when decimalised is 19.156

P= 15.0411 x 1.02 x cos 19.156/ cos 203 - sin 203

P = 15.35"

Given the method used it is safe to say the star are separated by 15".

Bob Argle sent me all the measurements of this pair and I put them into a spreadsheat and created a scatter graph.

Date P.A. Sep.

1886.21 202.38 31.98

1887.52 200.8 32.05

1896.12 203.6 29.641

1900.76 202.7 29.29

1905.02 201.4 28.584

1907.95 202.5 28.14

1909.16 202.3 27.78

1910.24 202.4 27.57

1912.031 201.8 27.41

1922.431 201.7 25.37

2006.25 203 15

I am very pleased to see the separation is close to the trend line 8) (possible just slightly above)

So tonight it is ME 1 CLOUDS 0

Cheers

Ian

[Naz]

Well done Ian, great to see someone beat this period of gloom. Perseverance pays.

naz

[OXO]

Hello Ian,

Well Done with the Results Ian and great to see you make the most of the clear spell you had.

So tonight it is ME 1 CLOUDS 0

Excellent

James

[daz]

Good report Ian!!!

I'm dying to get to grips with the maths - just need time, time, time.....

[lunator]

Daz

I'll send you an email with all the formulas on it.

Cheers

Ian

[daz]

Cheers mate!