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.