11 replies to this topic

[Nucleophile]

This report is the fifth 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/

 

Corona Borealis
COU 610 Theta (15329+3122) mags 4.27/6.29; pa = 199°; sep = 0.85“, (orbital estimate for 2019.3 is a better fit with historical 4th Int. Cat. data vs last precise from 2016)
345x, 460x:  single star
627x:  brightening of diffraction ring that resolves to small dot that is just split 20% of time; at resolution limit and very challenging; re-measure of separation desired

 

Draco
HU 149 (15246+5413) mags 7.48/7.62; pa = 270°; sep = 0.665“, (2016, last precise; solid data)
345x:  moves past elongated to notched (snowman) 30% of time
460x:  at resolved/split border as seeing allows; both stars are light yellow-orange
627x:  resolution aided with orange filter under excellent seeing conditions; a bit above resolution limit

Image below is from 2017.444

 

STF 2054AB (16238+6142) mags 6.15/7.09; pa = 351°; sep = 0.943“, (2017, last precise; solid data)
345x:  easily seen as split 100% of time to two white stars of slightly dissimilar magnitude; above resolution limit
image below is from 2019.455

 

STF 2218 (17403+6341) mags 7.08/8.37; pa = 308°; sep = 1.476“, (2015.5, Gaia DR2; solid data)
345x:  split 100% of time to two whitish stars; averted vision aids visualization of the fainter secondary; above limit

 

STF 2403 (18443+6103) mags 6.25/8.35; pa = 278°; sep = 1.061“,  (last precise, 2011; solid data)
345x:  seen as just split 50% of the time; both stars are yellow with the much smaller secondary sitting a bit past the first diffraction ring; above resolution limit
There may be a number of observations for this one as it is part of the Sissy Haas Uneven Double Project

 

STT 369 (19071+7204) mags 7.82/7.91; pa = 8°; sep = 0.684“, (2015.5, Gaia DR2; solid data)
345x:  just split when seeing allows; both stars are yellowish-orange with secondary a bit smaller
460x:  easier to see as split; above resolution limit

 

MLR 12 (18293+8235) mags 8.90/9.12; pa = 222°; sep = 0.689“, (2008, last precise; data is old)
345x/averted vision:  mostly pointy
460x/averted vision:  much smaller secondary seen as resolved only 20% of the time—very difficult; right at resolution limit; separation re-measure needed

 

STT 312AB Eta (16240+6131) mags 2.80/8.20; pa = 143°; sep = 4.676“,  (2015.5, Gaia DR2; solid data)
345x:  secondary is a tiny speck of light well separated from the primary; held steadily in view on nights of better seeing; above resolution limit

 

Hercules
COU 107 (16169+1948) mags 9.02/9.61; pa = 113°; sep = 0.609“, (2009, speckle; data is old, scant)
345x:  very faint; merely a bit elongated; below resolution limit; important data point to assess faintness factor; re-measure of separation needed

 

STF 2107AB (16518+2840) mags 6.90/8.50; pa = 107°; sep = 1.443“,  (2015.5, Gaia DR2; solid data)
345x:  easily split; both stars are whitish and the secondary is quite a bit smaller than the primary (but not tiny); above resolution limit

 

A 350 (16540+2906) mags 9.47/9.61; pa = 144°; sep = 0.630“, (2019.542, own measure; considered solid because in line with 4th Int. Cat. trend)
345x:  possibly pointy (not resolved); faint!
460x/averted vision:  barely resolved when seeing permits with the secondary appearing just a bit smaller versus the primary; at resolution limit; important data point to set faintness factor

Image below is from 2019.542

 

BU 627A, BC (16492+4559) mags 4.84/8.45; pa = 40°; sep = 2.116“, (orbital estimate for 2019.4; system is opening; value is in line with last precise [2.06”] and Gaia DR2 [2.105”])
345x:  easily split; both stars are white and secondary is quite small; above resolution limit
Inverted image shown below is from 2017.501

 

BU 812 (16071+1654) mags 9.06/9.36; pa = 96°; sep = 0.73“, (2011, last precise; data may be incongruent with historical 4th Int. Cat. values)
345x/averted vision:  image moves past elongated to notched about 40% of time showing two similar magnitude, faint stars; a re-measure of both separation and delta mag is desired; considered a bit above resolution limit

 

A 228 (17063+2631) mags 9.31/9.88; pa = 13°; sep = 0.658“, (2019.553, own measure; system is opening)
345x/averted vision:  image is at the elongated/resolved border; discs are tiny—very faint!
460x/averted vision:  resolved about 50% of the time; a bit above the resolution limit
Note:  listed magnitudes are from Hipparcos, not Tycho
Image below is from 2019.533

 

HDS 2446 (17177+3717) mags 4.62/8.53; pa = 143°; sep = 0.918“, (2010, last precise; solid data)
460x:  split ~100% of time on night of very good seeing; adding an orange filter to the optical train causes the secondary to nearly disappear which explains the exceptional difficulty experienced imaging this object; above resolution limit

 

STF 2315AB (18250+2724) mags 6.57/7.77; pa = 115°; sep = 0.600“, (orbital estimate for 2019.4; solid data)
345x:  merely a bit oblong
460x:  moves past elongated to a snowman shape about 30% of the time—stars clearly of dissimilar magnitude; on border of resolved but never actually seen as resolved; appears to be just below resolution limit
Inverted image shown below is from 2017.512

 

BU 641 (18218+2130) mags 7.03/8.66; pa = 341°; sep = 0.78“, (2015, last precise; solid data)
345x:  moves past pointy to resolved about 10% of the time; secondary is much smaller
460x:  seen as split when seeing allows image to sharpen (~30% of time); above resolution limit

 

STF 2339AB, CD (18338+1744) mags 7.45/8.67; pa = 277°; sep = 1.482“, (2018, last precise; likely solid data)
345x:  easily split to show fine magnitude contrast pair with primary seen as white and secondary as light orange; above resolution limit
460x/averted vision:  secondary [CD] now appears elongated—it has a rho value of 0.492” and is known as WAK 21CD—a very nice bonus!

 

A 238 (18114+2519) mags 8.59/9.55; pa = 74°; sep = 0.632“, (2019.548, own measure)
345x:  persistently pointy
460x/averted vision:  moves past elongated to resolved 20% of time; secondary is tiny; at resolution limit
Image shown below is from 2019.548

 

A 2093 (18054+1624) mags 9.09/9.85; pa = 226°; sep = 0.642“,  (2008, last precise; data is old but considered solid)
460x:  very faint, elongated rod that presents as resolved perhaps 5% of the time; at or slightly below resolution limit

 

TDT 1042 (18461+1328) mags 8.85/9.65; pa = 274°; sep = 0.7“,  (2009, last precise; data is old, not solid)
345x:  merely point; stars are faint
460x:  sharpens to resolved from a rod shape about 10% of time; at resolution limit; re-measure of separation needed

 

STF 2084 Zeta (16413+3136) mags 2.95/5.40; pa = 112°; sep = 1.373“,  (grade 1 orbital estimate for 2019.211)
345x:  light orange secondary just touching bright white primary—beautiful!  Above resolution limit
Image shown below is from 2019.452

 

STF 2203 (17412+4139) mags 7.72/7.81; pa = 293°; sep = 0.757“, (2015.5, Gaia DR2; solid data)
345x:  just split to two white stars—not difficult; above resolution limit

 

Libra
STF 3090AB (15087-0059) mags 9.09/9.34; pa = 287°; sep = 0.627“, (2017, last precise; little corroboration from 4th Int Cat.)
460x:  elongated only; never resolved
627x/averted vision:  never moved past elongated; below resolution limit; not sure why this object is so difficult—a re-measure of separation is desired

 

I1269AB (15249-2322) mags 8.73/8.84; pa = 199°; sep = 0.654“, (2015.5, Gaia DR2; solid data)
345x/averted vision (best conditions):  resolved to two white stars of very similar magnitude about 30% of the time; at or slightly above resolution limit; important data point to establish minimum rho value for calculator

 

BU 225BC (14255-1958) mags 7.16/8.37; pa = 91°; sep = 1.285“, (2015.5, Gaia DR2; solid data)
345x:  split 100% of time showing the primary as white and the secondary as light yellow and smaller; above resolution limit; a beautiful triple with the AB pair designated SHJ 179 or H N 80

 

HJ 4756 (15197-2416) mags 7.90/8.27; pa = 242°; sep = 0.574“, (2015.5, Gaia DR2; solid data)
345x/averted vision:  moves past elongated to notched 50% of time (never resolved)
460x:  resolved 50% of time; discs are very small and appear similar in magnitude; a bit above resolution limit; important data point to establish minimum rho value for calculator

 

A 81 (15089-0635) mags 9.43/9.76; pa = 41°; sep = 0.68“, (2005, last precise; data is old and scant)
345x/averted vision:  rod only; stars are very faint
460x/averted vision:  moves past elongated to resolved at most 5% of the time; below resolution limit; re-measure of separation desired

 

Lyra
HU 1300 (19202+3411) mags 8.92/9.56; pa = 184°; sep = 0.74“, (2015, last precise; data is solid)
345x/averted vision:  mostly a single star, but possibly rod-shaped; faint!
460x:  at most rod-shaped (never resolved); below resolution limit which makes this object an outlier—further investigation warranted

 

A 703 (19072+4451) mags 9.01/9.28; pa = 189°; sep = 0.57“, (2010, last precise; likely solid data)
as yet unobserved; important data point to establish faintness factor for resolution calculator

 

BU 648AB (18570+3254) mags 5.34/7.96; pa = 243°; sep = 1.303“, (grade 2 orbital estimate for 2019.3)
460x:  small brightening apart from the primary that sharpens to a small disc that is seen as split 50% of the time
627x:  split 100% of time; secondary is much smaller, both stars appear white; above resolution limit

 

**Have you observed or imaged any of these double stars?  I would love to hear of your endeavors with these objects.  Are there other, similarly challenging objects in these constellations that I have missed?  Let me know.

Edited by Nucleophile, 13 October 2019 - 09:09 AM.

[Nucleophile]

HU 149

 

   

[Nucleophile]

STF 2054AB

 

   

[Nucleophile]

A 350

 

   

[Nucleophile]

BU 627A,BC

 

   

[Nucleophile]

A 228

 

   

[Nucleophile]

STF 2315AB

 

   

[Nucleophile]

STF 2084 Zeta

 

   

[Nucleophile]

A 238

 

   

[Astroman007]

Excellent and detailed work, Mark. Thank you for sharing your endeavors in double star investigation with us.

[R Botero]

Hi Mark

 

Great follow up to your original set of posts!  Your images are superb also.  I have observed a few of these using my 10” f/20 Mak  (at between 250-300x) under less than ideal conditions from sub-urban London.  Here are my notes:

 

COU 610:  Observed repeatedly since 2013.  I found it more difficult to split than Eta CrB.  PA estimated at 200 in 2013, increasing to 230 in 2017. Blue tint suspected in secondary which was seen as a “fattening” of first diffraction ring of primary.

 

STF 2403:  Last observed in July this year.  My notes were “Large magnitude contrast.  PA275.  Secondary almost sitting on DR of primary.  White-yellow.”

 

STT 312:  From my notes in June 2017:  “Striking magnitude difference.  PA140-150.  Yellow and white blue.  Secondary barely visible in glare of primary.”

 

STF 2107:  Observations since 2013.  Notes include:  “Nice unequal pair.  White primary and cyan secondary.  PA100.  Secondary sitting outside of primary’s DR.  Secondary seems fainter than 8.”

 

HDS 2446:  A negative one.  From June 2017:  “Not split.  Fattening of first DR?  Due SW.”

 

STF 2084:  “Secondary very diffuse sitting on primary’s first DR.  White and white-brown.”

 

STF 2203:  From July 2015:  “Two equal white-blue stars almost touching.  PA295.” 

 

BU 648:  From July 2018: “Tight pair.  Secondary sitting just outside primary’s DR.  Both white-yellow.”  And in June this year:  “Very nice tight pair.  Mirror image of 90 Her. Brighter secondary.  PA225”.

 

Roberto

Edited by R Botero, 14 October 2019 - 03:11 AM.

[mccarthymark]

Excellent as always Mark!

 

Here are some of my observations from your list, plus a few others you might try:

 

Cou 610 AB: 8" 667x: Notched/snowman at best moments.  B definitely fainter and almost blue.  Very faintly split, looks like a blue appendage.  20" diffraction is too messy.

 

STF 2107 AB: !! 12.5” This was a CDSA plot find, didn't expect it to be special.  Yellow and orange pair, very close ~1.5", 1 delta mag.  Very pretty.

 

STF 2315 AB: 12.5” 553x.  Near contact / overlapping disks, 0.5 delta mag.

 

BU 641 AB: 12.5” 553x. !! Extraordinary!  Moderately bright A and much fainter B, <1" separation.  Seeing needs to still.

 

STF 2339 AB-CD: 20”: 533x: White and dull white B. Close but well separated, ~1" [AB-CD seen. AB is Hu 322 1 delta mag 0.2", not noticed]

 

STF 3090 AB: 12.5” Notched to hairline split at the best moments. Faint pair, tough. Seeing not good enough to go above 553x. [AB seen; AC fainter and wider.]

 

BU 648: 8" 333x: 3 delta mag, at first diffraction, needed critical focus and seeing.

 

OTHERS:

 

Met 9: 8" 205x nothing.  8" 410x suspect elongation.  667x see a fleeting, bluish point just outside of first diffraction ring.  A is light yellow orange and bright; 2 delta mag. to B.  A feels elongated / egg shaped.  At 20" and 667x the seeing is too messy though there is a knot in the diffraction where I had noticed the point with 8".  Strong feeling A is elongated.
12h 54m 39.98s +22° 06' 28.8" P.A. 51 sep 1.7 mag 5.70,7.77 Sp F8V+M2-3V dist. 33.85 pc (110.42 l.y.)

 

STF 1967 = Gamma CrB: Definite mis-shape, oval to egg.  8" 667x.
15h 42m 44.57s +26° 17' 44.3" P.A. 104.6 sep 0.22 mag 4.04,5.60 Sp B9V+A3V dist. 44.78 pc (146.07 l.y.)

 

STF 2289: Just split in 20" at 205x, but flaring. 333x had messy diffraction. 8" mask at 333x gave clean disks, split, ~0.7". Dull yellow and yellow-red colors.

18h 10m 08.69s +16° 28' 35.0" P.A. 215.3 sep 1.24 mag 6.65,7.21 Sp A0V+G0III dist. 263.85 pc (860.68 l.y.)

 

STT 359: !! Kissing 8" 333x, hairline split 667x. 20" too diffracted. Near equal white A and bluish white B.
18h 35m 30.40s +23° 36' 19.9" P.A. 3.7 sep 0.75 mag 6.35,6.62 Sp G9III-IV dist. 144.3 pc (470.71 l.y.)

 

A 260 AB: 20" 667x: At 8", small and faint suspected split at 333x: 8" 667x stars are hazy. At 20" 667x got a clean wide split two hard paints of stars.
18h 57m 34.07s +32° 09' 20.2" P.A. 244 sep 0.8 mag 9.17,9.60 Sp A0

 

STF 2422: 8" 333x: Excellent hairline split at 333x with 8” mask. Near equal white stars. Picked them out in a crowded field, suspected elongation right away, split with seeing as I centered it in eyepiece, and from then it was a steady split
18h 57m 07.83s +26° 05' 45.1" P.A. 68 sep 0.8 mag 7.93,8.25 Sp A2IV dist. 156.25 pc (509.69 l.y.)

 

AGC 9 AB = Sulafat: 8” 533x: B star immediately picked out of A's glow like a piece of debris suspended in the explosion, or a planet hanging in the halo.
18h 58m 56.62s +32° 41' 22.4" P.A. 307 sep 13.5 mag 3.24,12.10 Sp B9III dist. 190.11 pc (620.14 l.y.)

 

HO 92 AB 20" 667x: ! Beautifully well split, had an instant of perfect images. White pair near equal.
19h 00m 59.89s +32° 33' 11.6" P.A. 40 sep 1.3 mag 10.59,10.85

 

COU 1156 AB 20" 667x: ! Near qual small and at best moments a clean split, still, just nice points. great star.
19h 00m 34.25s +33° 01' 24.8" P.A. 111 sep 0.7 mag 11.14,11.25

 

STF 2461 AB = 17 Lyr: 20" 667x: ! Huge delta mag. B is obvious in 20", though A's diffraction was horrible. Used 8” mask to clean it up but the B star momentarily disappeared, though I could eventually pull it back out with seeing and critical focus. 4 delta mag.
19h 07m 25.58s +32° 30' 06.2" P.A. 281 sep 3.2 mag 5.26,9.10 Sp F0V dist. 41.58 pc (135.63 l.y.)

Edited by mccarthymark, 14 October 2019 - 11:48 AM.