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8 Inch Reflector Investigations. Part IV: Bootes, Canes Venatici, Coma Berenices, Ursa Minor, and Virgo

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#1 Nucleophile

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Posted 03 July 2019 - 08:21 PM

This report is the fourth installment of a series of observational investigations I have made using an 8 inch f/5.9 reflecting telescope. 

 

Check out this link for goals and methods used in this study:

https://www.cloudyni...-and-monoceros/

 

Bootes
BU 224 (14135+1234) mags 8.94/9.35; pa = 95°; sep = 0.65“, 2015 (last precise; not solid, opening)
345x:  single star
460x:  pointy but never resolved; well below resolution limit; magnitude data is from Hipparcos (1991, 515nm); needs a re-msre of delta mag and separation

 

STT 287 (14515+4456) mags 8.40/8.62; pa = 5°; sep = 0.575“, 2017 (last precise vs 0.659” orbital estimate for 2019.3; data incongruent)
345x:  seen as elongated 30% of time
460x/averted vision/extended viewing:  elongated only, never resolved; below resolution limit; needs a re-msre of separation

 

STF 1866 (14417+0932) mags 8.48/8.65; pa = 205°; sep = 0.733“, 2015.5 (Gaia DR2, solid data)
345x:  on the border of resolved and split to two even magnitude light yellow stars; above resolution limit

 

STF 1863 (14380+5135) mags 7.71/7.80; pa = 60°; sep = 0.654“, 2017, (last precise, solid data)
460x/orange filter/averted vision/extended viewing:  moves past elongated to resolved 20% of time
627x/orange filter: just resolved 50% of time; just a bit above resolution limit; important data point (equal mag pair) to set minimum value of rho

 

STF 1867 (14407+3117) mags 8.36/8.83; pa = 355°; sep =0.674“, 2017 (data needs confirmation)
460x:  just split 50% of time to two white stars of slightly dissimilar magnitude; need re-msre of separation

 

A 148 (14220+5107) mags 8.32/8.96; pa = 190°; sep = 0.535“, 2019.3 (4th Int. Catalog estimate vs 0.58” last precise in 2015; data not solid)
627x:  a bit elongated but never resolved; well below resolution limit; need re-msre of separation

 

KUI 66 (14148+1006) mags 5.44/8.43; pa = 111°; sep = 0.99“, (my own measure in 2017 with ASI 178MC camera; data tentatively considered solid as it is a match with 4th Int. Cat. estimate)
627x/orange filter:  much smaller secondary seen as a resolved dot very near first diffraction ring 30% of time; just above resolution limit; important, large delta mag data point so re-msre with ASI 290MM camera neededSee image below.

 

AGC 6 (14339+2949) mags 9.81/10.30; pa = 133°; sep = 0.752“, 2015.5 (Gaia DR2, solid data)
345x/extended viewing:  seen as elongated rod, never resolved; very faint and difficult; below resolution limit; important data point to set ‘faintness factor’

 

STT 298AB (15360+3948) mags 7.16/8.44; pa = 187°; sep = 1.208“, 2019.4 (orbital estimate, solid data)
345x:  easily split to two small light yellow stars of similar magnitude; very pretty; above resolution limit

 

A 1110AB (14497+0759) mags 7.69/7.93; pa = 245°; sep = 0.692“, 2015.5 (Gaia DR2, solid data)
345x:  oscillates between resolved and split; both stars are yellow with secondary seen as smaller and *delta mag is likely >0.24
460x:  seen as split 100% of time with secondary possessing a hint of orange; above resolution limit; Gaia DR2 gives a delta mag of 0.67 which does not agree with Tycho value of 0.24—will attempt a measure of delta mag to rectify

 

Canes Venatici
STF 1606 (12108+3953) mags 7.44/7.93; pa = 145°; sep = 0.611“, 2019.3 (orbital estimate vs 0.627”, last precise in 2017; data not solid)
460x:  elongated but never resolved
627x:  moves past notched rod to resolved 20% of time; at or just above resolution limit; observation supports tighter value of rho [0.611”]; this is an important data point; will re-msre (possibly annually) to firm up value

 

STT 251 (12291+3123) mags 8.35/9.27; pa = 61°; sep = 0.781“, 2017 (last precise; data not solid)
345x:  just resolved 30% of time with secondary much smaller
460x:  just split 50% of time; a bit above resolution limit; faint secondary plays role in difficulty; re-msre of separation needed

 

STF 1768AB (13375+3618) mags 4.98/6.95; pa = 95°; sep = 1.656“, 2019.3 (orbital estimate; solid data)
345x:  well split, primary is white and secondary is light yellow and considerably smaller—a fine sight!  Above resolution limit

 

Coma Berenices
STF 1639AB (12244+2535) mags 6.74/7.83; pa = 324°; sep = 1.855“, 2019.3 (orbital estimate; solid data)
345x:  well split, primary is white and secondary is light yellow; very pretty mag contrast pair; above resolution limit

 

STF 1687 (12533+2115) mags 5.15/7.08; pa = 200°; sep = 1.18“, 2018 (last precise; solid data)
345x:  a bit past just split 100% time with secondary noticeably smaller; both stars are yellow; above resolution limit

 

COU 397 (12575+2457) mags 9.06/9.71; pa = 63°; sep = 0.70“, 2015 (last precise; solid data)
345x:  single star; faint!
460x/averted vision:  slightly elongated but never resolved; below resolution limit; important data point to establish ‘faintness factor’

 

A 567 (13328+2421) mags 6.21/9.71; pa = 256°; sep = 1.450“, 2015.5 (Gaia DR2, solid data)
345x:  secondary seen as split 50% time and appears as very small, very faint dot a bit past first diffraction ring of primary; above resolution limit

 

Ursa Minor
STF 1989 (15396+7959) mags 7.32/8.15; pa = 23°; sep = 0.67“, 2013 (last precise vs 0.603”, orbital estimate for 2019.4; data not solid)
345x:  moves past elongated to exhibit a snowman shape
460x:  resolved about 40% time with secondary a bit smaller; above resolution limit (observation supports separation closer to 0.67” value; re-msre of separation needed)

 

BU 799AB (13048+7302) mags 6.60/8.45; pa = 265°; sep = 1.39“, 2017 (last precise; solid data)
345x:  easily split; both stars are white and secondary is considerably smaller—very pretty; above resolution limit.

 

A 1136 (16135+7147) mags 9.22/9.47; pa = 9°; sep = 0.727“, 2007 (last precise, data is old)
345x:  barely split; both stars are very small and white, and secondary is just a bit smaller; helps to establish ‘faintness factor’; above resolution limit; a re-msre of separation is needed

 

Virgo
BU 797AB (12345+0558) mags 9.10/9.39; pa = 146°; sep = 0.61“, 2010 (last precise, data is a bit old but considered solid)
345x/averted vision/extended viewing:  slightly pointy
460x:  elongated and on the border of resolved, but never did resolve despite an extended view
627x:  moved past elongated to resolved about 5% of time; at or slightly below resolution limit; a very important data point that warranted 45 mins of study under very good seeing conditions

 

RST 4484 (11447-0431) mags 8.46/8.39; pa = 64°; sep = 0.738“, 2017 (last precise; data not solid)
345x:  just split to two ~even magnitude yellowish-white stars—beautiful!  Above resolution limit; re-msre of separation needed

 

BU 935AB (13459-1226) mags 5.66/8.47; pa = 304°; sep = 1.03“, 2001 (last precise; data is old)
460x:  brightening of first diffraction ring sharpens to much smaller secondary 30% of time; both stars are yellow; above resolution limit; a new measure of separation is needed for this important mag contrast binary

 

**Have you observed or imaged any of these objects recently?  Let me know.  Do you have a suggestion for a double I should observe within one of these constellations?  I would like to hear about it.**


Edited by Nucleophile, 03 July 2019 - 08:22 PM.

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#2 Nucleophile

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Posted 03 July 2019 - 08:24 PM

Here is an image of KUI 66 I obtained in 2017 using an ASI178MC camera operating in mono mode.

 

     KUI66_JDSO.jpg


Edited by Nucleophile, 03 July 2019 - 08:24 PM.


#3 mccarthymark

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Posted 03 July 2019 - 11:40 PM

Cool, another crop!  Here's some of mine for comparison:

 

STT 287, 552x 12.5”.  Wow!  Hair-split, ~0.7", near equal or half a delta mag.  

 

STF 1867, 552x 12:5”.  0.5 delta mag, hair to figure 8 split, white. Not especially good seeing

 

Kui 66: 12.5” Unresolved faint haze at 553x, but adding the apodizing mask I had a glimpse of the B star 15% of the time, very small and faint, ~3" and 4-5 delta mag.  Both orange.  Definitely there. 

 

STT 289: 8" 205x: Noticed a very much fainter star emerge with averted vision then could hold direct.  Very fine, well split.  8" 410x: Tried to bring out the B star with higher magnification, but oddly it disappeared.  Curious.  20" 410x: B star easily seen though the disks are bloated, seeing not good.

 

STT 298. 12.5” 552x  Wow!  Almost didn't look at this one since it was split in the 80mm finder.  One component is a close equal pair, ~2".

 

STT 251. 12.5” 553x: Decidedly not round disk -- there's also a brightening in the diffraction -- but not really split.

 

STF 1768: 8" 205x: Very tight pair, a little more than hairline split, ~2 delta mag.  8" 333x: white and dull blue, ~1", split, Nice!

 

STF 1768. 12.5: 553x: Very pretty pale yellow and orange, 2-3 delta mag, ~2"

 

STF 1639: 8” 205x White and slightly blue pair; close, around 3" [overestimated the split, it was so clean!]

 

STF 1687: 12.5” 553x = 35 Com: Bright orange & fainter B, showpiece, ~1.5"

 

A 567: 12.5” 553x: very faint B, very close, ~1" when seeing stills, 3-4 delta magnitude. Surprised it is not so difficult. B looks like it doesn't have any light of its own and is illuminated by A.

 

BU 935 = 86 Vir: 12.5” Pretty orange star but @ 553x poor seeing won’t allow split of 3 delta mag, 1.2" B.


Edited by mccarthymark, 04 July 2019 - 01:36 AM.

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#4 Nucleophile

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Posted 04 July 2019 - 08:17 AM

Excellent info, Mark.

 

my notes on your notes:

 

a.  STT 287, inclined to think it is tight--like 0.6"  I will def msre next year.

b.  the much studied KUI 66, nice use of mask to glimpse the companion!  I used an orange filter and very high power on an excellent night

c.  STT 289--I will add this large delta mag object to my list (thanks!)

 

d.  STT 298AB  something is askew here with the delta mag as both of us describe the mags as being similar--I didn't catch this first time around but have made a note for next year to try and get a msre of delta mag for this one; I looked back into my log notebook and also noted:  "tiny headlights; beautiful!"  Additional note based on the 4th Int Cat.:  the same year as the Tycho mag values [as listed in the WDS] are those from Hipparcos (albeit at a slightly shorter wavelength = 511nm) which found  the magnitudes to be 7.59 and 7.78--a much closer match to what we observed.  This is humorous:  WDS notes say the 'D' component at 167" is actually a galaxy (possibly a quasar)!  How's that for 'optical illusions' lol.gif  At mag 14, I will be chasing that one for sure with the 15" scope.

 

e.  STT 251 was surprisingly difficult for both of us...

f.  BU 935  you may wish to give this one another shot on a night of very good seeing; it is difficult


Edited by Nucleophile, 04 July 2019 - 10:16 AM.


#5 Nucleophile

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Posted 05 July 2019 - 05:46 PM

Here is a composite image of A 1110AB taken in 2017 with the ASI 178MC camera.  The image supports a delta mag of >0.24

My measured value differs quite a bit from that of Gaia DR2 (0.692") for this object.

 

    A1110AB_JDSO.jpg


Edited by Nucleophile, 05 July 2019 - 05:46 PM.


#6 fred1871

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Posted 05 July 2019 - 11:35 PM

Too many doubles to comment immediately on all of them. I'll offer some notes on a few, and have a look at some of the doubles in your other lists as well. However not everything leads to further thoughts....smile.gif 

 

I'll start with A 1110AB because that's your most recent one, photo and measures issues.

 

I had a look at the list of speckle measures from the first such, 1983 and onwards. Ignoring the WSI measures, ball-park, but erratic at the high-accuracy level, somewhat inconsistent, I've noticed with a number of doubles that the WSI numbers can be less than firm.

 

The pattern is slow decrease of PA from the early 1980s (McAlister) to 2011 (Scardia). At the same time, gradual widening of the pair, near 0.62" in 1983 to 0.68" in 2011. The 2014 measure (Prieur) suggests numbers closer to Hartkopf in 1995, which would make the Scardia series (2005, 2007, 2011) too reduced in angle and too wide in separation, by small amounts. There are, incidentally, systematic differences (as well as random ones) with differing techniques used in speckle measuring; these show up in comparing measures across various groups of measurers. And some of the amateur speckle folk with smaller scopes are not getting the accuracy the approach promises; some of them I'd suggest could be better using lucky imaging.

 

Coming to the Gaia measure, it could be that as with a lot of Gaia data it will be revised slightly in the DR4 release some years hence. For now, the Gaia numbers give continued widening and a PA at 245 that's less reduced (numerically speaking) than the Scardia and Prieur (2014) measures.

 

Your measure suggests a continued decrease of PA number, rather more than the trend line would suggest, and a separation slightly closer than the trend line suggests, closer to Prieur than to Scardia or Gaia. The solution to this would be a new measure with speckle on a 4-metre scope; I might suggest that to the measuring guys, to see if they're interested. We know that some of the Gaia data is less than solid: and back in the Hipparcos/Tycho period there was quite a lot of cross-checking via big-scope speckle. A repeat wouldn't hurt. grin.gif 

 

And, of course, we expect that the widening will come to an end at some time. This one was discovered by Aitken when much closer than in recent decades, and isn't likely to get an orbit calculated soon, given the small angle traversed since 1905, and continuing widening. It's not a nearby object, the Gaia parallax suggesting 180 parsecs, so the separation in projection at 0.67" is 120 AU. Not a quick orbit if it goes at least that wide.

 

A final note: I have only one observation of A 1110, back in 2013 with my 14cm refractor; optimistic I know, but I was interested in the various appearances of elongation relative to Rayleigh for a particular aperture. Unsurprisingly, no separated stars, but clear elongation at 400x. That's 0.7-Rayleigh, so a fairly predictable result, based on Taylor's elongation series in Argyle's book, and Couteau's series in his double star book. Taylor notes obvious notching at 0.8-Rayleigh, and sometimes visible notching at 0.7-R, but the seeing on that occasion didn't provide that visual effect. 


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#7 fred1871

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Posted 08 July 2019 - 09:52 AM

Okay, a few thoughts on Kui 66/15 Boo. I'm not sure why you used an orange filter for visual observation; mostly they're for the purpose of reducing seeing problems in lucky imaging, as the longer wavelength allows less damage from seeing to the image and CCDs typically have high red sensitivity, unlike our eyes. 

 

Your measure looks good. The 2015 measure in the Interferometer Catalog looks definitely too small, given the trend line and dates involved.

 

Observing this one: I have notes from various attempts on it, further back in time with my 14cm refractor, later with Mewlon 210. The notes are interesting because this is a tough double for the 14cm refractor, pretty much a Rayleigh split, and with the 3-magnitude brightness difference to  make things not-so-easy. Depending on seeing, of course.  The refractor showed on the least steady night a hint of a tiny companion adjoining the primary at 285x and 400x, flickering in and out of visibility. On the best of the 5 nights (spread over a 4 year period) the companion was clearly seen at 400x, after showing less well at 285x.

 

Several nights over a couple of years with the Mewlon 210 showed the companion each time, flickering into view at 480x on the least good night. On the best night, at 300x clear resolution of a quite unequal pair, the companion on the outer part of the diffraction ring. Reducing the power to 240x, a very tight barely separated pair, the companion of similar brightness to the diffraction ring but clearly a star.

 

My experience with many close and quite unequal pairs has shown me that seeing makes a big difference, sometimes the difference between visibility and invisibility of a pair, with the same scope and powers. And often enough there is, with the marginal objects, a right power that shows the pair and wrong powers (sometimes too high, as well as too low) that won't show them.


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#8 Nucleophile

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Posted 08 July 2019 - 06:55 PM

Hi Fred,

 

Thanks as always for your insightful comments.  Yes, the mag contrast pairs require added skill and patience.  It is somewhat trial and error (as you mention with respect to optimal magnification.)  In this vein, I have found on some pairs, the orange filter increases the contrast just enough to compensate for less than great seeing.  When I list the orange filter in my notes it is because this is the best condition of several tried.  Of course, I routinely use this filter when imaging/measuring using the 15" reflector/ASI 290MM CMOS camera system.

 

-Mark M

 

PS  Your Mewlon sounds like a fine instrument; I once considered getting one of these--and I may yet in the years to come!


Edited by Nucleophile, 08 July 2019 - 07:12 PM.


#9 fred1871

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Posted 10 July 2019 - 09:29 AM

Regarding the Mewlon 210 - very good definition in the centre of the field, but not a versatile scope, as the off-axis coma quickly limits definition when going wider than planets or doubles. Coma seems to me similar to an f/4.0 to f/4.5 Newtonian, and I'm sensitive to coma so I notice it. Takahashi unfortunately don't make a coma corrector/field flattener for the Mewlon 210 and 180; they do for the 250 and 300, and these are nowadays integrated systems.

 

I've commented on this in another thread on CN regarding the Mewlon 180 (Cats and Casses....).


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#10 Ptarmigan

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Posted 11 July 2019 - 09:16 PM

Interesting double star reports. cool.gif waytogo.gif

 

I like the title 8 Inch Reflector Investigations.



#11 Nucleophile

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Posted 11 July 2019 - 10:45 PM

Interesting double star reports. cool.gif waytogo.gif

 

I like the title 8 Inch Reflector Investigations.

The next installment (in the works) is proving very interesting because of some unexpected mysteries that have cropped up.



#12 Ptarmigan

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Posted 12 July 2019 - 09:29 PM

The next installment (in the works) is proving very interesting because of some unexpected mysteries that have cropped up.

I will be awaiting that. I like looking at double stars.


Edited by Ptarmigan, 12 July 2019 - 09:52 PM.



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