7 replies to this topic

[Nucleophile]

This report is the second 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/

 

Gemini
STT 149 (06364+2717) mags 7.14/8.97; pa = 277°; sep = 0.733”, orbital estimate for 2019.3 (grade 2 data not a great match to historical 4th Int. Cat. data or last precise)
627x:  at times pointy but that’s it; below resolution limit; yearly separation change is significant (components are closing); requires independent (possibly annual) measure of separation

 

COU 930 (07566+1954) mags 9.10/9.29; pa = 330°; sep = 0.583”, 2008 (data is old)
345x:  single star
460x:  at times slightly elongated, but that’s it; below resolution limit; requires re-measure of separation

 

A 2726 (06293+1233) mags 9.03/9.27; pa = 123°; sep = 0.550” (2015.5, Gaia DR2) vs 0.65”, 2015 (last precise)
345x:  elongated rod which resolves to two discs of slightly dissimilar magnitude 25% of time; appears to be at resolution limit which supports 0.65” value for separation; 4th Int. Cat. data does not help to clarify the situation; requires re-measure of separation to solidify this value

 

A 2464 (07046+1550) mags 9.13/9.78; pa = 40°; sep = 0.73”, 2016 (scant data)
345x:  persistently notched rod
460x:  persistent as snowman shape with slightly dissimilar magnitudes that resolves to two discs 40% of time; just above resolution limit; separation re-measure needed

 

A 2868 (07292+1253) mags 8.59/8.98; pa = 22°; sep = 0.677”, 2015.5 (Gaia DR2, solid data)
552x (Pentax 2.5XO + Paracorr Type 1, setting 1):  definitely pointy but too faint for Airy discs to be seen as distinct points of light; never resolved—just below resolution limit (will revisit next year using powermate/plossl optical train)

 

Bu 1008 Propus (06149+2230) mags 3.52/6.15; pa = 252°; sep = 1.78”, 2017 (solid data)
345x:  just split, secondary is much smaller
460x:  easier to see as split; above resolution limit

 

Leo
STF 1423 (10192+203) mags 9.40/10.03; pa = 300°; sep = 0.600”, 2019.3 (orbital estimate; scant data)
as yet unobserved; requires a re-measure of separation to solidify value

 

STF 1555AB (11363+2747) mags 6.41/6.78; pa = 151°; sep = 0.79”, 2017 vs 0.666”, 2019.3 orbital estimate
460x:  vacillates between snowman shape and resolved with discs of slightly dissimilar magnitude
627x:  pushes past resolved to split 10% of time; observation supports 0.66” value for separation; 4th Int. Cat. supports a value of less than 0.79”; requires re-measure of separation to solidify value

 

STF 1356 (09285+0903) mags 5.69/7.28; pa = 114°; sep = 0.878”, 2019.3 (orbital estimate; solid data)
345x:  just split to two yellow stars of even magnitude; above resolution limit

 

A 2482 (09599+1610) mags 9.26/10.07; pa = 47°; sep = 0.85”, 4th Int. Cat. estimate (data is scant, divergent)
345x:  seen as just split 40% of time; at edge of visibility due to faintness; secondary is much smaller and barely presents as a disc; just above resolution limit; requires re-measure of separation

 

Bu 105AB (09247+2611) mags 4.60/9.70; pa = 209°; sep = 1.960”, 2015.5 (Gaia DR2; solid data)
230x:  fairly challenging; seen as split about 50% of time with secondary as very small dot quite close to the primary; above resolution limit

 

Orion
Bu 885 (05110-0146) mags 8.31/9.01; pa = 198°; sep = 0.601”, 2017 (solid data)
345x:  extremely difficult; at most slightly elongated
460x:  moves past elongated to a snowman shape about 20% of time
627x:  elongated only despite best effort; this object is a bit below the resolution limit

 

Bu 318 (05162-0329) mags 8.81/8.28; pa = 264°; sep = 0.643”, 2017 (solid data)
345x:  single star
460x:  pointy at times
627x:  moves past elongated to resolved using averted vision 25% of time; right at resolution limit

 

A 321 (05568-0304) mags 9.02/10.03; pa = 134°; sep = 0.645”, 1995 (data is old)
345x:  pair is very faint; elongated ~entire time; resolved to two tiny dots <5% of time; at resolution limit; requires re-measure of separation

 

A 2717AB (06152+0631) mags 8.07/8.98; pa = 354°; sep = 0.60”, 4th Int. Cat. estimate (data is old)
345x:  pointy only
460x:  moves past elongated to resolved 50% of time; requires very good seeing because components are faint; just above resolution limit—separation likely greater than 0.60”; requires re-measure of separation

 

STT 517AB (05135+0158) mags 6.79/6.99; pa = 240°; sep = 0.693”, 2017 (solid data)
394x (Pentax 3.5XW, Paracorr Type 1, setting 1):  moves past snowman shape to resolved when seeing allows; above resolution limit

 

DA 4Aa,B (05354-0450) mags 4.61/7.50; pa = 203°; sep = 1.207”, 2015.9 (data is solid)
460x:  seen steadily as just split ~entire time
627x:  secondary visible 100% of time as small white dot easily split from primary; above resolution limit;
I have observed this object (aka 42 Ori) dozens of times over the past 8 years and this was the clearest view I had ever had of the secondary—this result spurred me to change up my preferred double star eyepieces to the currently used tandem of powermate/plossl and also to initiate a detailed study of similarly challenging binaries

 

Bu 190AB (05204-0802) mags 8.12/8.45; pa = 328°; sep = 0.647”, 2015.5 (Gaia DR2, solid data)
627x:  secondary pops into view as resolved 20% of time; at resolution limit

 

STT 119 (05479+0758) mags 8.08/8.93; pa = 355°; sep = 0.706”, 2015.5 (Gaia DR2, needs a confirming measure)
460x:  mostly seen as split to two stars of uneven magnitude; above resolution limit; while the Gaia separation value ‘seems right’, this binary requires a separation re-measure due to conflicting 4th Int. Cat. data

 

STF 652 (05118+0102) mags 6.26/7.44; pa= 180°; sep = 1.667”, 2015.5 (Gaia DR2, solid data)
460x:  brightening of first diffraction ring that sharpens 50% of time to a small secondary seen as split from the primary
627x:  more easily seen as split when seeing allows; above resolution limit; something odd here:  this object is surprisingly difficult, possibly due to the proximity of the secondary to the first diffraction ring (?); will likely re-measure separation to get more info

 

DA 3 (05359-0538) mags 7.33/8.54; pa = 173°; sep = 0.860”, 2015.5 (Gaia DR2, solid data)
345x:  snowman
460x:  just split to two stars of uneven magnitude 30% of time
627x:  more easily seen as split when seeing allows; above resolution limit

 

STF 728 (05308+0557) mags 4.44/5.75; pa = 44°; sep = 1.281”, 2015.5 (Gaia DR2, solid data)
345x:  just split to two white stars of uneven magnitude; above resolution limit

 

HEI 670 (05500+0952) mags 5.97/8.36; pa = 264°; sep = 1.093”, 2011 (solid data)
345x:  brightening of first diffraction ring sharpens to a small secondary seen as just split 20% of time
460x:  more easily seen as split when seeing allows; above resolution limit
Gaia DR2 detects a star at pa = 268° but with a separation of only 0.438”.  Observations seem to confirm separation of 1.09” vs 0.44”—could this be a triple system?  Will image to get more information

 

Bu1052 (05417-0254) mags 6.68/8.22; pa = 183°; sep = 0.649”, 2019.3 orbital estimate (solid data)
345x:  pointy (snowman) shape
460x:  vacillates between elongated and resolved to two discs
627x:  moves past resolved to split 10% of time; above resolution limit; surprisingly easy considering the separation and delta mag; perhaps the binary is in a ‘sweet spot’ for this telescope (?)  Should probably re-measure separation to get more info

 

STF 734AB (05331-0143) mags 6.67/8.22; pa = ; sep = 1.585”, 2015.5 (Gaia DR2, solid data)
345x:  easily split; smaller secondary is perhaps ashen in color

 

Puppis
B 1074 (07451-2855) mags 9.44/9.79; pa = 357°; sep = 0.56”, 1991 (data is old)
as yet unobserved; will need an independent measure

 

STF 1104AB (07294-1500) mags 6.39/7.60; pa = 40°; sep = 1.790”, 2019.3 (orbital estimate; solid data)
345x: easy, wide split to two somewhat dissimilar magnitude white stars

 

Bu 454AB (08159-3056) mags 6.50/8.21; pa = 359°; sep = 1.847”, 2015.5 (Gaia DR2; solid data)
345x:  split 100% of time; considerable magnitude contrast; primary is yellow while the secondary may be light orange

 

STF 1146 (07479-1212) mags 5.73/7.32; pa = 336°; sep = 1.010”, 2019.4 (orbital estimate; solid data)
345x:  easy split; fine magnitude contrast pair with both stars appearing yellowish-white

 

Have you observed any of these objects recently?  Let me know.  Or, perhaps you have a suggestion for a double I should observe—I’m all ears!

Edited by Nucleophile, 12 June 2019 - 08:13 AM.

[mccarthymark]

I love your project and these posts!

 

I have a couple of these:

 

May 2017: 12.5", 553x, seeing 7/10, Transparency 3/5:

STF 1423: Tough! Elongated to hairline split.

STF 1555 / h503: Nice! AB tight hair-split white pair, with fainter & wide separated C in a row to the east.  
STF 1356: Very close but clean split, in each other's diffraction, half delta mag, white.

BU 105: Very faint star mixed up in bright, dancing diffraction, though A's star disk is steady

 

Jan 2017, 12.5", poor seeing, 553x
STF 734: Very close pair, delta mag 1, PA to north.  Seeing is poor, can split it only 10% of the time, one second out of ten.  Other stars west and east and around.  [AB is 6.67, 8.22, 1.7" 357°.  AC is only 8.35, 29.3" 244°, so I may have seen this.  CD is there too, 0.5" and 9.24 -- also doable on a really good night, maybe with the 20-inch.  Should give this one a try.]

[Nucleophile]

I love your project and these posts!

 

I have a couple of these:

STF 1555 / h503: Nice! AB tight hair-split white pair, with fainter & wide separated C in a row to the east.  

Thanks for this info, Mark.  Your observation of STF 1555 matches my estimate of this being in the mid 0.6" range or below.  After an initial hiccup, I was able to get a Gaia DR2 measure on this:  0.612"  As this data is for "2015.5", the pair may be even closer now.

 

I will re-measure this one early next year when it is favorably placed as it is an important data point for my project.

Edited by Nucleophile, 13 June 2019 - 07:58 AM.

[Organic Astrochemist]

Great post and project.

Do you have an easy way to search Gaia DR2 (by interesting search fields) and display the data in a useful and simple means?

Thanks.

[Nucleophile]

Great post and project.

Do you have an easy way to search Gaia DR2 (by interesting search fields) and display the data in a useful and simple means?

Thanks.

Sorry, I don't but you may find this recent JDSO paper of interest in which Gaia data is mined for new pairs.  Perhaps you could contact the author and/or her collaborator (D. Rowe)?

 

http://www.jdso.org/...rot_287_296.pdf

 

Please let me know if you find out how to do this.

[fred1871]

Mark, the author of the paper you linked to, Jocelyn Serot, is male not female - in French, the male name is spelled Jocelyn, the female has an 'e' added, Jocelyne.

[Nucleophile]

duly noted; thanks, Fred

[fred1871]

Okay, having got some other jobs out of the way.... here are notes on some of the doubles you've listed above.

 

To begin, Leo.

STF 1555AB  I'm inclined to read a separation in between your 0.79" and 0.666" - I'm basing this on the long series of speckle measures, and going with the observers I know to be of higher reliability. This pair has obviously been slowly widening in recent decades - McAlister at the end of the 1970s gets around 0.56" with little variation; at the end of the 1980s he and Hartkopf get about 0.635"; in 1995 Hartkopf has 0.68";  in 1999 Mason has 0.70"; and the Scardia group have 0.72" in 2013, agreeing with Prieux in 2014. If the (slow) rate of widening has continued, that suggests perhaps 0.74" by now. I can't see it being less than 0.70", even if the pair has started to close - given the very few years since the measures. The orbit calculated is of long duration, and only Grade 4, so nowhere near definitive. It suggests the start of closing, but I'd prefer a new large-scope speckle measure; but that wouldn't affect my estimate, this binary is slow at present.

 

I have an observation of STF 1555AB from May this year, with 14cm refractor. At 285x a clearly elongated pair. If the separation is 0.74", then that is 0.75-Rayleigh, which would explain a suggestion of notching. 

 

STF 1356 (Omega Leonis)  observed with the Mewlon 210, just separated at 300x.

 

Orion

 

STT 517 AB  Observed with Mewlon 210, notched pair at 345x, just separated in better moments at 480x (didn't try power between).

 

DA 4 (42 Ori)  probably the most difficult pair I've seen separated with the 14cm refractor. It required 400x and above average seeing. The nearly 3 magnitude difference of the stars makes it very tough; and for 14cm the secondary star is impinging on the inner side of the diffraction ring.

 

STT 119  probably the most reliable measure is the 1991 by Hipparcos, at 0.724". Tycho agrees. And Prieux in 2007 gets much the same result, at 0.73". This is not a double that appears to have changed much in separation between discovery (1843) and the present. The Gaia numbers (angle and separation) are very similar to the speckle results. The only conflicting data is the sometimes erratic WSI numbers; I'm inclined to ignore them when they differ from the better speckle operators, just as I ignore Tycho when it differs from Hipparcos, unless there's other evidence to support Tycho.

 

Observation: the 14cm refractor again, at 400x showing a notched pair, a bit unequal in brightness.