Bigjoes double star observing tips.

[bigjoe (JOSEPH)]

THIS WAS A LIST I COMPILED WITH THE HELP OF Steve (Tinderboxsky), bombardon(Eugene)and John Bambury(ausastronomer).

Use these tips below when needed, and for cracking my future Monthly Constellation double star lists..or even this months.

1: SEEING - Must be very good for some tough unequal doubles.

2: ALTITUDE - Observe the Double well above the horizon if possible.


3: APERTURE -Depends on variables like Doubles separation, magnitudes , altitude, seeing and their delta etc.

4: POWER - The use of it is necessary at times - Helps darken sky background, and with limiting magnitude ; 200x + may be needed.

5: USE A MASK - Hex , may be necessary.. Also be mindful of diffraction spikes, and thick diffraction rings on some scopes that can obscure the faint secondary.

6: ORIENTATION - Is your diagonal /scope combo displaying an UPRIGHT , EAST/WEST VIEW ? ; If not adjust accordingly ; this is critical to judge what direction the secondary will be...see 19.

7: PRACTISE: On some easy ones first.

8: DRIFTING - For a faint secondary, Is it preceding near the East, or following near the* West when your facing North?

9: WARM CLOTHING , and stool if necessary.

10: PATIENCE - and lots of it - It could take many attempts!

11: LESS GLASS - Use of EPs with fewer elements, 4/5 max, even 3, to increase contrast and detection, may be of help.

12: AVERTED AND DIRECT VISION -
Go back and forth between direct and averted vision, until the companion is held in direct view.

13: ZOOM EP - Use of a good marked zoom EP, to find the optimum power for the seeing and filters if necessary, can be useful.

14: HIGHLY ACCURATE FOCUS with FLAT FIELD, FREE OF CURVATURE - this is a must also , as you may have to re-focus often to find that dim secondary near the edge of the field.

15: VERY STABLE MOUNT - Absolutely no wobbles!

16: VIEWING AT TWILIGHT - Can reduce the glare of a bright primary EG : Sirius A - and this goes for other bright primary doubles as well!

17:STANDARD EYEPIECE..Used to judge star separations in your scope..have one to use, medium 60 ° EPs like Dual EDs, Radians, Delites are good with FLAT FIELD..See 18.

18: KNOW YOUR FIELD-Know what say 10" arc looks like in your STANDARD* eyepiece for example as in Rigel.
Formula for working this is OCULAR FIELD IN MM X 57.3 DIVIDED BY FOCAL LENGTH OF SCOPE IN MM.
EG: EP Has field stop of 3 mm and scope 1719 mm focal length...

Then that is simply ( 3 x 57.3 )÷ 1719 = 1/10 degree true field of view, or 6 mins arc or 360" -So if a double has a separation of 36" it will be one tenth of the field width, so you'll get an idea were the secondary will be!

19: Position angle(PA) Is taken as I've said, from an IMAGINARY LINE on the Celestial Sphere due North , increasing North to East in a clockwise direction - East following (will be on the right if you face North)...
an example is in Sirius B being roughly around 90 degrees or more Position Angle East at this moment in time..
and simply let Sirius B drift into the field of view, by first letting SIRIUS A go past your left (West field) stop, so its GLARE IS MITIGATED .

20: HOOD or COWL; this WILL help if streetlights or other bright light sources are a nuisance -- I rarely observe without one in any case...increases contrast.

21: COLLIMATION.. Crucial that scope is Cooled and well Collimated esp SCTs , though not necessary to use more than 12" aperture, due to the affects of seeing on large obstructed scopes, most nights.

22: USE OF AN OCCULTING BAR EYEPIECE..read JOHN BAMBURYS excellent take on this quoted from his post No. 9 above.

PS: If anyone knows of more tips and suggestions that have not come to my attention please lets me know!

Cheers bigjoe.

[bigjoe (JOSEPH)]

After I initially post next months list, I'll be asking any participants ..to post their reports in the observing report section ...cheers all .
bigjoe.

[bigjoe (JOSEPH)]

Just made some additions to my TIPS list.

bigjoe.

[StuTodd]

Hi Joe and thanks...

That is a great list of "do" and "don't" for doubles. I still have an "ooooh wow" moment when a double comes into the EP.
What are your favourites?

40 Eri, sigma Ori and beta Mon are my faves.

[Bombardon (Eugene)]

A comprehensive list Joe, and the only other preparation I make when I am reasonably positive the night is going to hold is to avoid all media sceens for about 30 mins or you will find the unwanted light is coming from inside your head! Eugene

[bigjoe (JOSEPH)]

Originally Posted by StuTodd

Hi Joe and thanks...

That is a great list of "do" and "don't" for doubles. I still have an "ooooh wow" moment when a double comes into the EP.
What are your favourites?

STU...

40 Eri, sigma Ori and beta Mon are my faves.

Yours and ..
These: Theta Indi,Propus and Wasat in Gemini, Almaak, Izar, Gamma Velorum and Volantis,Cor Caroli,Iota Cancri, Algiebba, Rasalgethi,70 Ophiuchi, 54 Leonis, 32 Eridani,Gamma Delphinus,54 Sagittarii,triple Theta Sagittae,23 Aquilae, Beta and 61 and Mu Cygni,Castor, 95 Herculis,Epsilon Lyrae, Acamar, 41 Aurigae, 52 Tauriii,Gamma Leporis, 31 32 and Rho Orionis,Rigel , Antares,Stf 872,145 Canis, x velorum, Porrima, Tegman, Delta Cygni,94 Aquari, 55 Piscium, 1 , Gamma and Epsilon Arietis, Xi Bootis, 35 Comae, Jabbah, Beta Capricorni, Delta Corvi, Xi Scorpii, 24 Comae, Gamma Ceti, 66 Ceti, Iota Triangulum, 32 Eridani, Tau Leonis.,Upsilon Carinae.. these are ones I remember as OUTSTANDING in no particular order.

bigjoe.

[Tinderboxsky (Steve)]

Wow, Joe, just off the top of your head recall?! That’s impressive.

The other interesting observation of your list is how one’s observing latitude influences the list. I don’t have such recall of my favourite doubles, but certainly I tend to spend more time observing in the -40 to -90 degrees declination. Everything past -47 deg declination is circumpolar for me down here in Hobart!

PS, no clear skies yet to do your Orion list.

Originally Posted by bigjoe

Yours and ..
These: Theta Indi,Propus and Wasat in Gemini, Almaak, Izar, Gamma Velorum and Volantis,Cor Caroli,Iota Cancri, Algiebba, Rasalgethi,70 Ophiuchi, 54 Leonis, 32 Eridani,Gamma Delphinus,54 Sagittarii,triple Theta Sagittae,23 Aquilae, Beta and 61 and Mu Cygni,Castor, 95 Herculis,Epsilon Lyrae, Acamar, 41 Aurigae, 52 Tauriii,Gamma Leporis, 31 32 and Rho Orionis,Rigel , Antares,Stf 872,145 Canis, x velorum, Porrima, Tegman, Delta Cygni,94 Aquari, 55 Piscium, 1 , Gamma and Epsilon Arietis, Xi Bootis, 35 Comae, Jabbah, Beta Capricorni, Delta Corvi, Xi Scorpii, 24 Comae, Gamma Ceti, 66 Ceti, Iota Triangulum, 32 Eridani, Tau Leonis... these are ones I remember as OUTSTANDING in no particular order.

bigjoe.

[bigjoe (JOSEPH)]

After years..you get favourites and can recall them..their that good!

Steve, will try and include some doubles wth a more southerly declination in the next, probably Geminis Southern side.any suggestions ..you can PM them if you wish, as putting something together in a week or so , as this months list started so late.

bigjoe.

[ausastronomer (John Bambury)]

Originally Posted by bigjoe

THIS WAS A LIST I COMPILED WITH THE HELP OF Steve (Tinderboxsky), bombardon(Eugene) some time back.

Use these tips below when needed, and for cracking my future Monthly Constellation double star lists..or even this months.

1: SEEING - Must be very good for some tough unequal doubles.

2: ALTITUDE - Observe the Double well above the horizon if possible.


3: APERTURE -Depends on variables like Doubles separation, magnitudes , altitude, seeing and their delta etc.

4: POWER - The use of it is necessary at times - Helps darken sky background, and with limiting magnitude ; 200x + may be needed.

5: USE A MASK - Hex , may be necessary.. Also be mindful of diffraction spikes, and thick diffraction rings on some scopes that can obscure the faint secondary.

6: ORIENTATION - Is your diagonal /scope combo displaying an UPRIGHT , EAST/WEST VIEW ? ; If not adjust accordingly ; this is critical to judge what direction the secondary will be...see 19.

7: PRACTISE: On some easy ones first.

8: DRIFTING - For a faint secondary, Is it preceding near the East, or following near the* West when your facing North?

9: WARM CLOTHING , and stool if necessary.

10: PATIENCE - and lots of it - It could take many attempts!

11: LESS GLASS - Use of EPs with fewer elements, 4/5 max, even 3, to increase contrast and detection, may be of help.

12: AVERTED AND DIRECT VISION -
Go back and forth between direct and averted vision, until the companion is held in direct view.

13: ZOOM EP - Use of a good marked zoom EP, to find the optimum power for the seeing and filters if necessary, can be useful.

14: HIGHLY ACCURATE FOCUS with FLAT FIELD, FREE OF CURVATURE - this is a must also , as you may have to re-focus often to find that dim secondary near the edge of the field.

15: VERY STABLE MOUNT - Absolutely no wobbles!

16: VIEWING AT TWILIGHT - Can reduce the glare of a bright primary EG : Sirius A - and this goes for other bright primary doubles as well!

17:STANDARD EYEPIECE..Used to judge star separations in your scope..have one to use, medium 60 ° EPs like Dual EDs, Radians, Delites are good with FLAT FIELD..See 18.

18: KNOW YOUR FIELD-Know what say 10" arc looks like in your STANDARD* eyepiece for example as in Rigel.
Formula for working this is OCULAR FIELD IN MM X 57.3 DIVIDED BY FOCAL LENGTH OF SCOPE IN MM.
EG: EP Has field stop of 3 mm and scope 1719 mm focal length...

Then that is simply ( 3 x 57.3 )÷ 1719 = 1/10 degree true field of view, or 6 mins arc or 360" -So if a double has a separation of 36" it will be one tenth of the field width, so you'll get an idea were the secondary will be!

19: Position angle(PA) Is taken as I've said, from an IMAGINARY LINE on the Celestial Sphere due North , increasing North to East in a clockwise direction - East following (will be on the right if you face North)...
an example is in Sirius B being roughly around 90 degrees or more Position Angle East at this moment in time..
and simply let Sirius B drift into the field of view, by first letting SIRIUS A go past your left (West field) stop, so its GLARE IS MITIGATED .

20: HOOD or COWL; this WILL help if streetlights or other bright light sources are a nuisance -- I rarely observe without one in any case...increases contrast.

21: COLLIMATION.. Crucial that scope is Cooled and well Collimated esp SCTs , though not necessary to use more than 12" aperture, due to the affects of seeing on large obstructed scopes, most nights.

PS: If anyone knows of more tips and suggestions that have not come to my attention please lets me know!

Cheers bigjoe.

One of the best tools / tips I have found for observing doubles, particularly those with a bright primary and a dim secondary, is an occulting bar eyepiece. While you can't buy these, they are easily made. Sirius is now a fairly easy split at the moment with a separation of about 11". I was able to split it several times through 1998 to 2000 in an 8" scope with an occulting bar eyepiece, when the separation was ~5". At that time it was an exceedingly difficult split in any amateur telescope and I tried hundreds of times to split it in telescopes up to 20" aperture, without an occulting bar eyepiece and was always unsuccessful.

An occulting bar eyepiece also helps enormously to observe planetary satellites like Phobos and Deimos.

It works by blocking the unwanted light / glare from the primary target which makes it much easier to see the dim secondary target.

You can make one from any simple eyepiece which has the focal plane below the field lens. Orthoscopics are really good as they have the focal plane in the right place and are well suited to this type of observing. If you use the wrong eyepiece the edge of the bar will be fuzzy and out of focus. I have a 6mm UO ortho permanently set up. You just unscrew the barrel and glue in a piece of aluminium foil (cut straight with scissors) or a sliver of timber cut with a Stanley knife just below the field lens. Some people don't use glue through fear of getting it on the lens. I am careful and dab the glue on with a sewing needle. I then put the stop in with tweezers using a loupe. I then take comfort that the stop won't move.

Whilst I only have one eyepiece set up, I sometimes use it in combination with 1.8x and 2.5x barlows.

Cheers
John B

[bigjoe (JOSEPH)]

Originally Posted by ausastronomer

One of the best tools / tips I have found for observing doubles, particularly those with a bright primary and a dim secondary, is an occulting bar eyepiece. While you can't buy these, they are easily made. Sirius is now a fairly easy split at the moment with a separation of about 11". I was able to split it several times through 1998 to 2000 in an 8" scope with an occulting bar eyepiece, when the separation was ~5". At that time it was an exceedingly difficult split in any amateur telescope and I tried hundreds of times to split it in telescopes up to 20" aperture, without an occulting bar eyepiece and was always unsuccessful.

An occulting bar eyepiece also helps enormously to observe planetary satellites like Phobos and Deimos.

It works by blocking the unwanted light / glare from the primary target which makes it much easier to see the dim secondary target.

You can make one from any simple eyepiece which has the focal plane below the field lens. Orthoscopics are really good as they have the focal plane in the right place and are well suited to this type of observing. If you use the wrong eyepiece the edge of the bar will be fuzzy and out of focus. I have a 6mm UO ortho permanently set up. You just unscrew the barrel and glue in a piece of aluminium foil (cut straight with scissors) or a sliver of timber cut with a Stanley knife just below the field lens. Some people don't use glue through fear of getting it on the lens. I am careful and dab the glue on with a sewing needle. I then put the stop in with tweezers using a loupe. I then take comfort that the stop won't move.

Whilst I only have one eyepiece set up, I sometimes use it in combination with 1.8x and 2.5x barlows.

Cheers
John B

Thanks for you timely input and tool tip John.

Was thinking of doing a Section on Masks and Bars ..so this is a very welcome addition, which I will include with reference to you.
Another good reason to have an Ortho handy!

With thanks bigjoe.

[bigjoe (JOSEPH)]

Originally Posted by bigjoe

THIS WAS A LIST I COMPILED WITH THE HELP OF Steve (Tinderboxsky), bombardon(Eugene)and now also John Bambury(ausastronomer).

Use these tips below whenever needed, and for cracking my future Monthly Constellation double star lists..or even this months.

1: SEEING - Must be very good for some tough unequal doubles.

2: ALTITUDE - Observe the Double well above the horizon if possible.


3: APERTURE -Depends on variables like Doubles separation, magnitudes , altitude, seeing and their delta etc.

4: POWER - The use of it is necessary at times - Helps darken sky background, and with limiting magnitude ; 200x + may be needed.

5: USE A MASK - Hex , may be necessary.. Also be mindful of diffraction spikes, and thick diffraction rings on some scopes that can obscure the faint secondary.

6: ORIENTATION - Is your diagonal /scope combo displaying an UPRIGHT , EAST/WEST VIEW ? ; If not adjust accordingly ; this is critical to judge what direction the secondary will be...see 19.

7: PRACTISE: On some easy ones first.

8: DRIFTING - For a faint secondary, Is it preceding near the East, or following near the* West when your facing North?

9: WARM CLOTHING , and stool if necessary.

10: PATIENCE - and lots of it - It could take many attempts!

11: LESS GLASS - Use of EPs with fewer elements, 4/5 max, even 3, to increase contrast and detection, may be of help.

12: AVERTED AND DIRECT VISION -
Go back and forth between direct and averted vision, until the companion is held in direct view.

13: ZOOM EP - Use of a good marked zoom EP, to find the optimum power for the seeing and filters if necessary, can be useful.

14: HIGHLY ACCURATE FOCUS with FLAT FIELD, FREE OF CURVATURE - this is a must also , as you may have to re-focus often to find that dim secondary near the edge of the field.

15: VERY STABLE MOUNT - Absolutely no wobbles!

16: VIEWING AT TWILIGHT - Can reduce the glare of a bright primary EG : Sirius A - and this goes for other bright primary doubles as well!

17:STANDARD EYEPIECE..Used to judge star separations in your scope..have one to use, medium 60 ° EPs like Dual EDs, Radians, Delites are good with FLAT FIELD..See 18.

18: KNOW YOUR FIELD-Know what say 10" arc looks like in your STANDARD* eyepiece for example as in Rigel.
Formula for working this is OCULAR FIELD IN MM X 57.3 DIVIDED BY FOCAL LENGTH OF SCOPE IN MM.
EG: EP Has field stop of 3 mm and scope 1719 mm focal length...

Then that is simply ( 3 x 57.3 )÷ 1719 = 1/10 degree true field of view, or 6 mins arc or 360" -So if a double has a separation of 36" it will be one tenth of the field width, so you'll get an idea were the secondary will be!

19: Position angle(PA) Is taken as I've said, from an IMAGINARY LINE on the Celestial Sphere due North , increasing North to East in a clockwise direction - East following (will be on the right if you face North)...
an example is in Sirius B being roughly around 90 degrees or more Position Angle East at this moment in time..
and simply let Sirius B drift into the field of view, by first letting SIRIUS A go past your left (West field) stop, so its GLARE IS MITIGATED .

20: HOOD or COWL; this WILL help if streetlights or other bright light sources are a nuisance -- I rarely observe without one in any case...increases contrast.

21: COLLIMATION.. Crucial that scope is Cooled and well Collimated esp SCTs , though not necessary to use more than 12" aperture, due to the affects of seeing on large obstructed scopes, most nights.

22: USE OF AN "OCCULTING BAR EYEPIECE"........... read JOHN BAMBURYS excellent take on this quoted from his post No. 9 above.

PS: If anyone knows of more tips and suggestions that have not come to my attention please lets me know!

Cheers bigjoe.

PS:Now...
Includes added tip No.22 from John Bambury.

[Bombardon (Eugene)]

Despite poor seeing last night, using another John Bambury mask, comprising a disc of thin plywood with a 4" offset hole, on my Dob 10" F5 last night and with an ex-Big Joe Orion Zoom at max 7.2 mm I was able to spot the 'Pup' for a split second as Sirius departed the field. I had a one in three transit success rate. I have also used the blocking bar described by John to spot the Mars' Buddies, especially when they are on the opposite sides of Mars during good oppositions. In all cases the drift method is adequate. The key for me was 1st class collimation and patience.Tried Ori 31 and 52 last night but not convinced of splits. A better night might do it. The second reward was the Tangerine Moon as I packed up. [You wont read about this one in the media!] Hello to all southern star splitters who never give up. Eugene

[Tinderboxsky (Steve)]

A great result on the Pup, especially given poor seeing conditions. One definitely needs good seeing to split 31 and 52 Orionis.
I am definitely targeting Mars' moons this coming opposition.

[ausastronomer (John Bambury)]

Originally Posted by Bombardon

Despite poor seeing last night, using another John Bambury mask, comprising a disc of thin plywood with a 4" offset hole, on my Dob 10" F5 last night

Hi Eugene,

As you point out there can also be benefits in using an off axis aperture mask on a Newtonian, this can become very beneficial as the aperture gets larger and the seeing gets worse.

The off axis mask essentially turns your 10"/F5 obstructed Newtonian into a 4"/F12.5 Unobstructed Newtonian. This helps by reducing diffraction as the spider vanes and central obstruction are cut out and the smaller aperture can cope better under turbulent seeing conditions. If the scope has a decent mirror it essentially becomes a high quality 4"/F12 APO refractor. I have at different times in the past used a 7" off axis mask on my 18"/F4.5 Obsession which turn it into an unobstructed 7"/F11.5 scope, or in other words a 7"/F11.5 APO. We also have a 10" Off Axis mask for one of the 25" 3RF Obsessions but we haven't used it in a while as the bigger scopes generally only get pointed at DSO type targets.

Nice work on splitting the Pup under less than ideal conditions.

Cheers,
John B

[Bombardon (Eugene)]

Thank you Steve and John for encouraging me to persist with 'oyster' doubles. I rarely get steady nights at this time of year and am constantly experimenting with eyepieces, masks, a barred eyepiece and a Barlow to reach the difficult ones. I sometimes find that covering up the scope for an hour and trying again later can result in improvements in seeing. However, be careful of this practice as the pleasant sound of rain on the roof can lead to a very fast run to the back yard! Kind regards, Eugene

[Wavytone]

Heres another challenge in the trapezium - F and G are relatively easy in my 9” at mag 10-11, but can you catch H1 and H2 ? You’ll need a 12” or larger as these are fainter than mag 15 and 8” apart.

https://www.cloudynights.com/topic/6.../#entry8435995

[Bombardon (Eugene)]

OK Steve, you have us interested. It will be like scratching around among the crater-lets in Plato! Skies here not so good; however, moon behaving.
Regards, Eugene

[Tinderboxsky (Steve)]

Yes, a real challenge reserved for dark skies and a night of exceptional seeing. At magnitude 15 and fainter, these stars will exhibit relatively low contrast wth the background glow within the Trapezium. I am out - do not have the aperture needed.

Originally Posted by Wavytone

Heres another challenge in the trapezium - F and G are relatively easy in my 9” at mag 10-11, but can you catch H1 and H2 ? You’ll need a 12” or larger as these are fainter than mag 15 and 8” apart.

https://www.cloudynights.com/topic/6.../#entry8435995

[bigjoe (JOSEPH)]

Originally Posted by Wavytone

Heres another challenge in the trapezium - F and G are relatively easy in my 9” at mag 10-11, but can you catch H1 and H2 ? You’ll need a 12” or larger as these are fainter than mag 15 and 8” apart.

https://www.cloudynights.com/topic/6.../#entry8435995

Rules me out Wavy.. only go up to 10" dob; Actually so does the weather..has anyone made a sacrifice to the Cloud Gods yet?
EG:Torch some old Huygens EPs etc.

Still havent been able to re attempt 52 Orionis..wil be listing next Months Constellation soon.
bigjoe.

[ausastronomer (John Bambury)]

Originally Posted by Tinderboxsky

Yes, a real challenge reserved for dark skies and a night of exceptional seeing. At magnitude 15 and fainter, these stars will exhibit relatively low contrast wth the background glow within the Trapezium. I am out - do not have the aperture needed.

Steve,

I have observed H1,H2 on quite a few occasions in one of our 25" Obsessions. I have also observed them on a couple of occasions in Andrew Murrel's 20" Hector and my own 18" Obsession. They are very difficult in any scope under 18".

There's a bit of a trade off here. You need plenty of aperture, the more the better. The rub here is that the bigger the scope the harder they are to cool and keep in thermal equilibrium where you can crank up the power, with sharp stars.

I have found the best time to try them is when Orion is high in the sky just after dark. In the Southern hemisphere this occurs late summer / early autumn. Now is a great time if you have the necessary aperture. You need Orion to have the elevation but you also need to try before the air temperature starts to drop rapidly and take the big scopes out of thermal equilibrium, particularly if you are at any sort of elevation above sea level as the temperature delta is larger from day to night.

Of course the other important factors in addition to the above, are good optics, good eyepieces, good target elevation, good seeing, good transparency, good eyes and a finder chart so you know where to look if you haven't been there before.

Cheers,
John B