Observing report 17/02/2006

[lunator]

On Friday night I managed to get 5+ hours observing in. It was great just being out under the stars for a long period. I had managed to get 1 hour of observing in earlier in the week.

The conditions were very variable with the seeing being good for periods and then poor for a time. There was a variable amount of cloud about.

It had been so long since I had had a decent session so I didn't know where to start.

In the end I decided to try out the stady-pix camera mount and try to video Saturn (now that I have drives).

I took 4 AVI's varying from 30-60 secs at 10fps. the chip size id 640x480. I used the 9mm ortho giving x133 mag.

I have processed 1 of the avi's in registax but I am underwhelmed by the results.

I decided just to watch Saturn for a while and when the seeing was good and the clouds were out of the way she looked fantastic. I could see the cassini division, the Southern Eq. belt and 5 moons. It was great just to sit at the eyepiece and observe.

After observing Saturn for quite a while I had to go back to my favourite aspect of the hobby observing and measuring doubles

I started with Eta Cas and then theta Aur. and found it an easy split so seeing at that time was relatively good. I moved down to Orion and logged Zeta, Sigma, delta & iota. I was going to go after HJ2302 but the high cloud would have made the Mag11 secondary tricky to see.

With the high cloud I decided to measure 2 bright and well known Stars. Alpha Gem. (Castor) & Gamma Leo (Algieba).

Below is how I measured the doubles.

THIS BIT IS FOR DAZ

Observations of 2 Close Bright Doubles

Date:

Standard 17/02/2006 21:00-23.59

Besselian Epoch: 2006.133

Equipment:

Orion Optics 200mm f6 Newtonian Reflector

Vixen 12.5mm illuminated reticle (double cross-hair) Orthoscopic.

Antares Apo Barlow

Stopwatch (Nokia 6822 mobile phone)

Home made external PA dial & pointer

Conditions

Seeing – 5/10 periods of 7/10

Transparency ranged from 4/10-7/10. Some patchy high cloud

Targets

Alpha Gem. (Castor)

Gamma Leo (Algieba)

Objective

To obtain Position Angle and Separation measurements of these stars using the chronometric method.

Method

The method used for the measuring double stars is set out in Chapter 12 (pg145-148) of the ‘Observing and measuring Visual double Stars’ Bob Argyle ed.

This method requires calculating the North Angle (0 degrees) from which the position angle can be measured. Finding a star at 0 degrees declination and near culmination will move due West.

To find an appropriate star I centred Procyon in the eyepiece and set my declination to +5. I moved the declination to 0 degrees and centred on a magnitude 6 star. Turning the motors off I let the star drift to the west and carefully aligned the illuminated wire. I re-centered the star 3 times to ensure the wire was accurately aligned with the star drift and once the star was tracking accurately across the wire I turned the drive on and rotated the PA dial to read 270 degrees aligned with the wire.

Moving the telescope to Alpha Gem (Castor) and centering the star I rotated the cross-hair so it covered the 2 stars and carefully aligning the external pointer took 6 measurements of which the mean was 63 degrees.

I rotated the cross-hairs to a North-South orientation and took 6 stopwatch timings as the stars crossed the wire.

I repeated the process for Gamma Leo and the mean PA to be 127 degrees.

Calculations

The timings for Castor & Gamma Leo are as follows.

Castor Sec. Algieba Sec.

Timing 1 0.35 Timing 1 0.23

Timing 2 0.35 Timing 2 0.23

Timing 3 0.39 Timing 3 0.27

Timing 4 0.39 Timing 4 0.25

Timing 5 0.33 Timing 5 0.27

Timing 6 0.38 Timing 6 0.3

The declinations of the stars are Castor 31:53:19 & Algieba 19:50:30

Converted to decimal Castor 31.89 & Algieba 19.84

Using the formula

P(separation) = 15.0411x t(timings) x cosd(declination)/sin (position angle)

Results

Castor Sec. Sep." Algieba Sec. Sep."

Timing 1 0.35 5 Timing 1 0.23 4

Timing 2 0.35 5 Timing 2 0.23 4

Timing 3 0.39 5.6 Timing 3 0.27 4.8

Timing 4 0.39 5.6 Timing 4 0.25 4.4

Timing 5 0.33 4.7 Timing 5 0.27 4.8

Timing 6 0.38 5.4 Timing 6 0.3 4.8

Mean 5.2 4.5

Castor: PA= 63 Separation = 5.2” (WDS 63” Sep & 4.0” Sep 2003)

Algieba: : PA= 127 Separation = 4.5” (WDS 126” Sep & 4.5” Sep 2003)

I finished the night with an attempt to split zeta Cnc. The wider pair is a very easy 5.9" but the closer pair is 0.9" and I could see the star was elongated but it wasn't close to being split.

All-in-all a productive and enjoyable nights 'work'

Cheers

Ian

[col]

very detailed , sounds like a good night , nicely done report, even i understood some of it

[daz]

Yikes!!

Thanks Ian - some reading and maths to do

[The Warthog]

An enjoyable and productive night! Good for you!

[Naz]

Great report Ian, a lot of detail on your observations & really useful.

nabban

[lunator]

Well Ian, thats one extensive and impressive observation report..... :shock:

Now I know your the 'split king' but can I just add, that I am very proud to say, that I have split Castor, it took a 4mm to do it to....

TT well done. It gives you a real sense of accompliahment.

My 1st split with Castor was using a 4mm eyepiece on my first scope.

Now you've split it with the 4mm you will be able to split it with a lower power eyepiece because your brain knows what to look for.

There are some double star fan who like to see 'how low they can go' on a split.

I will get all the forum splitting doubles.

Cheers

Ian

[lunator]

Caz

I've noticed from your ever-changing sig. that you now have 3 scopes.

You can use one for imaging and the other for doubles splitting.

The best of both worlds.

Cheers

Ian

[lunator]

Well may be only 2

Teach me to type and think at the same time (I am a bloke one thing at a time........................... )

Pollux has several companions but none of them are gravitationally bound to Pollux and they are all fairly distant. The closest on is 13.7 mag so will be tought to spot. The others will be easy to see.

London 2006-2-19 22h56m Center 7h45m19.9s +28°01'03" Width: +01°15'00" Magnitude: 6 Cat: DSL WDS BSC SAC

7h45m18.90s +28°01'34.0" D* BU 580 AB m: 1.14/13.70 1877: 43.0"/275° 1900: 29.7"/280° Sp:K0IIIb n:Np DM:+28 1463

7h45m18.90s +28°01'34.0" D* H 6 42 AC m: 1.20/ 8.90 1781:116.8"/ 66° 1987:243.2"/ 75° Sp: n:N

7h45m18.90s +28°01'34.0" D* BU 580 AE m: 1.20/ 9.70 1877:205.5"/ 90° 1987:274.5"/ 89° Sp: n:

7h45m18.90s +28°01'34.0" D* STFB 5 AF m: 1.33/10.51 1781:160.7"/ 74° 1991:299.6"/ 78° Sp: n:NL

7h45m18.90s +28°01'34.0" D* BU 580 AG m: 1.20/ 1904:170.1"/328° 1987:153.3"/346° Sp: n:

7h45m18.90s +28°01'34.0" * HR 2990 HD 62509 Fl: 78 Ba:Bet const:Gem mV: 1.14 b-v: 1.00 sp: K0IIIb pm:-0.628 -0.046 ;POLLUX;

There are more interesting double than Pollux.

Cheers

Ian

[The Warthog]

I am very proud to say, that I have split Castor, it took a 4mm to do it to....

I have tried and failed. I will someday. Not soon. Glad you got it, though! :sunny: My Sco'ish Mother in law always said "It's no loss what a friend gets..." I think that's what she said. Wi' her accent, it wiz haard tae tell.

[lunator]

Well may be only 2

Teach me to type and think at the same time (I am a bloke one thing at a time........................... )

Pollux has several companions but none of them are gravitationally bound to Pollux and they are all fairly distant. The closest on is 13.7 mag so will be tought to spot. The others will be easy to see.

London 2006-2-19 22h56m Center 7h45m19.9s +28°01'03" Width: +01°15'00" Magnitude: 6 Cat: DSL WDS BSC SAC

7h45m18.90s +28°01'34.0" D* BU 580 AB m: 1.14/13.70 1877: 43.0"/275° 1900: 29.7"/280° Sp:K0IIIb n:Np DM:+28 1463

7h45m18.90s +28°01'34.0" D* H 6 42 AC m: 1.20/ 8.90 1781:116.8"/ 66° 1987:243.2"/ 75° Sp: n:N

7h45m18.90s +28°01'34.0" D* BU 580 AE m: 1.20/ 9.70 1877:205.5"/ 90° 1987:274.5"/ 89° Sp: n:

7h45m18.90s +28°01'34.0" D* STFB 5 AF m: 1.33/10.51 1781:160.7"/ 74° 1991:299.6"/ 78° Sp: n:NL

7h45m18.90s +28°01'34.0" D* BU 580 AG m: 1.20/ 1904:170.1"/328° 1987:153.3"/346° Sp: n:

7h45m18.90s +28°01'34.0" * HR 2990 HD 62509 Fl: 78 Ba:Bet const:Gem mV: 1.14 b-v: 1.00 sp: K0IIIb pm:-0.628 -0.046 ;POLLUX;

There are more interesting double than Pollux.

Cheers

Ian

Caz sorry. I didn't mean to 'blind by numbers'. I have put labels next to each entry.

(Stars location by RA & Declin).(Discoverers Code)(Magnitude)(1st measurement) (Last Measurement)

7h45m18.90s +28°01'34.0" D* BU 580 AB m: 1.14/13.70 1877: 43.0"/275° 1900: 29.7"/280°

Sp:K0IIIb

(spectral type)

The 29.7 is the distance in arc seconds (there are 3600 arc seconds in a degree)

The 280 is the position Angle. North is 0 degrees and you go round through East then South Then West and back to North.

North in the eyepiece of a Reflector is 'down'

Cheers

Ian

[FLO]

Thanks for your report Ian

To be honest, its a bit above me at the moment but its good to know you are out there for when I start splitting/measuring doubles.

[lunator]

I'll be happy to help when you want to start splitting doubles.

I'll soon have everyone on the forum looking at doubles. It will help pass the time whilst the other scope does the imaging

Cheers

Ian

[OXO]

Hi Ian,

Whats the easy splits to begin with mate? i may join in the fun

JD

[lunator]

Hi Ian,

Whats the easy splits to begin with mate? i may join in the fun

JD

James

I'll post up a list of wide 10"+ and bright doubles later tonight.

Cheers

Ian

[OXO]

Thanks Ian, give me something to do whilst imaging

[FLO]

Does Albireo count :mrgreen:

[lunator]

Does Albireo count :mrgreen:

Of course it counts Double

It is the showpiece double. I saw it through a Tec140 Apo and the colour contrast was fantastic.

[lunator]

Hi Ian,

Whats the easy splits to begin with mate? i may join in the fun

JD

James

I'll post up a list of wide 10"+ and bright doubles later tonight.

Cheers

Ian

Sorry I didn't post last night the clouds blew away so I went outside

[The Warthog]

That is pushing that scope way further than it is supposed to go. It's a testament to the quality of the scope that you were able to do it.

[GazOC]

http://www.astroleague.org/al/obsclubs/dblstar/dblstar2.html

I'm currently working (rather haphazzrdly) though this list....

[GazOC]

Theres a PDF version you can print off.

[lunator]

Caz

The astroleague list is a good starting point.

Some of the data on the colser doubles can be a bit out of date. (Porrima/ Gamma Vir is a prime example).

Cheers

Ian

[GazOC]

Thats a small beginners list Caz.....

[lunator]

Hey Ian,

I think I struck gold again last night, I decided to have a go at splitting Regulus, couldn't do it with the 4mm on its own, so I added the 2x barlow, still couldn't do it....>sighs<...but then, I remembered what you told me about pulling the ep further out to get a even higher mag, and BINGO!!!!.... :shock: I could just about make out the 2 stars....

Perhaps on a steadier night, I will be able to see a definite split....

Caz

Regulus is a wide double 175" 1st & 8th magnitude.

It sounds like you saw a closer star.

Cheers

Ian

[Rob]

Thats a cracking report. I really enjoyed reading that. Best post in ages

Lets hope the weather can be a bit more kind over the next few weeks & months.

Thanks for sharing

Rob