Wilfried
Knapp
Double Star
Astronomer
Vienna/Austria
|
|
Viewing celestial
objects with a telescope on clear nights is an anachronistic but fascinating
passion. The photons you see are ancient, so you are effectively looking into
the past. Since I live in a big city in Central Europe with heavy light
pollution, I concentrate on objects that are clearly visible even in such a
gray sky - mainly double stars and open star clusters. This fascination is
complemented by the fact that the tools and equipment available to amateurs
today are incredibly more powerful and easier to use than anything available
to professional astronomers a few decades ago: a multitude of online star
catalogs and image libraries, e.g. CDS VizieR and Aladin, remote telescopes
for imaging, software for plate solving, astrometry and photometry, for
planning of observation sessions and creating star maps and so on. With these
tools, the amateur astronomer can sometimes even achieve scientifically
interesting results. About
visual resolution of double stars with "small" telescopes Session
Plans
for Double Star observation sessions for northern
skies List of papers published so
far: |
|
List of Reports |
Co-Author |
Journal |
Vol/No |
Pages |
Year |
|
Photometric and
astrometric measurements 2022 CCD
images taken in 2022 with remote telescopes are used to report photometric
and astrometric measurements |
|
DSSC |
31 |
21-28 |
2023 |
|
Unconfirmed Tycho double stars versus Gaia DR3 – I This
report takes a closer look at a subset of 2,149 unconfirmed Tycho Double Stars
with angular separation >1.45 arcseconds based on the assumption that Gaia
DR3 should resolve any such object with ease |
Ross Gould |
DSSC |
31 |
29-37 |
2023 |
|
Unconfirmed
Tycho double stars versus Gaia DR3 – II As
follow up to our paper ‘Unconfirmed Tycho Double Stars versus Gaia DR3 - I’,
this report takes a closer look at the remaining subset of 8,625 unconfirmed
TDS/TDT objects with angular separation below 1.45 arcseconds based on the
assumption that Gaia DR3 should most likely resolve such close double stars |
Ross Gould |
DSSC |
31 |
38-49 |
2023 |
|
Wide
Pairs in the Sixth Catalog of Orbits of Visual Binary Stars – II New
measurements for seven wide pairs from the Sixth Catalog of Orbits of Visual
Binaries give reason to assess the accuracy of the existing orbits. In most
cases, the result is the suggestion of a new orbit or, in some cases, of an
alternative rectilinear solution |
|
JDSO |
18/2 |
160-195 |
2022 |
|
CCD
images taken in 2021 with a remote telescope covering the southern skies are
used to report photometric
and astrometric measurements |
|
DSSC |
30 |
16-23 |
2022 |
|
Neglected Orbits in the Sixth Catalog of Orbits of
Visual Binary Stars The
Sixth Catalog of Orbits of Visual Binary Stars lists as of March 2020 around
3,200 orbits, of which 342 were published 20 to 29 years ago and additional
94 even 30 or more years ago. This seems a bit odd because orbital element
values of visual binaries are moving targets – a few additional measurements
in the observation history lead often to at least minor but significant and
in some cases even to major changes. This report checks the orbits published
30 or more years ago in detail to find an explanation why these orbits
remained unchanged for such a long time. Re-calculated orbits are presented
for the binaries with an observation history that extends significantly
beyond the publication date of the currently listed orbits provided the
changed values of the orbit elements offer a better match with the
observation history and a better match of the dynamical mass with system mass
data from other sources |
|
JDSO |
17/4 |
296-408 |
2021 |
|
The
WDS catalog contains currently (January 2021) about 154,000 objects. About
50,000 of these come with a magnitude for the primary with single digit
precision indicating rather an estimation than a precise measurement and over
16,000 objects are listed with magnitudes in the blue or red band (WDS note
codes B/K/R/I) thus in need of a measurement in the V band. After eliminating
all objects not suited for resolution with the tools currently available to
me (too close, too faint or too bright) about 26,000 objects remained as targets
of interest for this project. The selection criterion for the objects for a
specific imaging session is then at a given point of time simply the
currently highest given altitude to eliminate atmospheric effects as far as
possible – so this is then a more or less random selection out of the
mentioned 26,000 objects. This report covers about 100 such objects
(including several KPP objects also in need of photometry) with images taken
2020 with V -filter to allow for visual magnitude measurement by differential
photometry. Several WDS objects that happen to be near the selected targets
in the captured images are additionally listed and some objects are listed
twice when they are covered by a second imaging session |
|
DSSC |
29 |
49-60 |
2021 |
|
Double Star Photometry – June 2019 The
WDS catalog currently (March 2020) contains about 150,800 objects. About
50,000 of these come with a magnitude for the primary with single digit
precision indicating an estimation rather than a precise measurement and over
16,000 objects are listed with magnitudes in the blue or red band (WDS note
codes B/K/R/I) and thus in need of a measurement in the V band. After
eliminating all objects not suited for resolution with the tools currently
available to me (angular separation too small, too faint, too bright), about
26,000 objects remained as targets of interest for this project. The
selection criterion for the objects for a specific report is then at a given
point of time simply the currently highest given altitude to eliminate
atmospheric effects as far as possible – so this is then a more or less
random selection out of the mentioned 26,000 objects. This report covers
about 70 such objects (including some KPP objects also in need of photometry)
with images taken June 2019 with V-filter to allow for visual magnitude
measurement by differential photometry. This paper lists also a few WDSS
objects as several newly detected likely physical pairs reported in Knapp
2019 were meanwhile included in the WDSS catalog. All objects were
additionally checked for potential gravitational relationship using GAIA DR2
data for a Monte Carlo simulation of the spatial distance between the
components of a pair and StarHorse median mass values for calculating tidal
radii for these components |
|
JDSO |
16/4 |
352-361 |
2020 |
|
Star
Systems in the Solar Neighborhood up to 10 Parsecs Distance The
stars and star systems in the solar neighborhood are for obvious reasons the
most likely best investigated stellar objects besides the Sun. Very fast
proper motion catches the attention of astronomers and the small distances to
the Sun allow for precise measurements so the wealth of data for most of
these objects is impressive. This report lists 94 star systems (doubles or
multiples most likely bound by gravitation) in up to 10 parsecs distance from
the Sun as well over 60 questionable objects which are for different reasons
considered rather not star systems (at least not within 10 parsecs) but might
be if with a small likelihood. A few of the listed star systems are newly
detected and for several systems first or updated preliminary orbits are
suggested. A good part of the listed nearby star systems are included in the
GAIA DR2 catalog with parallax and proper motion data for at least some of
the components – this offers the opportunity to counter-check the so far
reported data with the most precise star catalog data currently available. A
side result of this counter-check is the confirmation of the expectation that
the GAIA DR2 single star model is not well suited to deliver fully reliable
parallax and proper motion data for binary or multiple star systems |
|
JDSO |
16/3 |
229-288 |
2020 |
|
A
recent paper (El-Badry et al. 2019, in the
following EB19) reports the discovery of a sharp excess of equal mass “twin”
binaries based on the data from an earlier paper (El-Badry
and Rix 2018, in the following EB18) reporting the construction of a very
pure catalog of ~55,000 wide binaries based on Gaia DR2 catalog data. This
report counter-checks both propositions using basically the identical Gaia
DR2 catalog data, but with different assessment methods and different quality
requirements especially regarding the relative parallax data error and using
Gaia DR2 StarHorse catalog data for star masses with the result that both
papers seem somewhat questionable in their use of existing data and also in
their conclusions. This report contradicts the EB18 “very pure” claim with
the assessment that >50% of the reported binary pairs are, with more
stringent data selection and evaluation criteria, most likely optical pairs
and not binaries. The culprit for this disappointing record is the allowance
for Gaia DR2 objects with an unreasonably large parallax error as well as the
questionable method for calculating the likely spatial distance between the
components of the assumed physical pairs. The in EB19 reported discovery of a
specific equal mass “twin” binary population seems to be a consequence of a
questionable method for estimating star masses and can besides the caveats
regarding the EB18 data for this reason not be confirmed. A moderate excess
of very similar to equal mass pairs seems simply a consequence of the
frequency of star masses in the selected star population – the most frequent
masses have for obvious reasons a larger chance to be combined in a pair than
other masses |
|
JDSO |
16/2 |
190-205 |
2020 |
|
Double star photometry - May 2019 The
WDS catalog contains at June 2019 about 148,500 objects. About 50,000 of these
come with a magnitude for the primary with single digit precision indicating
rather an estimation than a precise measurement and over 16,000 objects are
listed with magnitudes in the blue or red band (WDS note codes B/K/R/I) thus
in need of a measurement in the V band. After eliminating all objects not
suited for resolution with the tools currently available to me (too small
angular separation, too faint, too bright) about 26,000 objects remained as
targets of interest for this project. The selection criterion for the objects
for a specific report is then at a given point of time simply the currently
highest given altitude to eliminate atmospheric effects as far as possible
so this is then a more or less random selection out of the mentioned 26,000
objects. This report covers about 40 such objects (including some KPP objects
also in need of photometry) with images taken May 2019 with V -Filter to
allow for visual magnitude measurement by differential photometry. This paper
lists also a few WDSS objects as several newly detected likely physical pairs
reported in Knapp3 were meanwhile included in the WDSS catalog. All objects
were additionally checked for potential gravitational relationship using GAIA
DR2 data for a Monte Carlo simulation of the spatial distance between the
components of a pair |
|
DSSC |
28 |
64-71 |
2020 |
|
Double Star Photometry – March 2019 The
WDS catalog contains per June 2019 about 148,500 objects. About 50,000 of
these come with a magnitude for the primary with single digit precision
indicating rather an estimation than a precise measurement and over 16,000
objects are listed with magnitudes in the blue or red band (WDS note codes
B/K/R/I) thus in need of a measurement in the V band. After eliminating all
objects not suited for resolution with the tools currently available to me
(too small separation, too faint, too bright) about 26,000 objects remained
as targets of interest for this project. The selection criterion for the
objects for a specific report is then at a given point of time simply the
currently highest given altitude to eliminate atmospheric effects as far as
possible – so this is then a more or less random selection out of the
mentioned 26,000 objects. This report covers the first 37 such objects from
images taken end of March 2019 with V-filter to allow for visual magnitude
measurement by differential photometry. All objects were additionally checked
for potential gravitational relationship using GAIA DR2 parallaxes |
|
JDSO |
16/1 |
17-22 |
2020 |
|
Double Star Photometry – April 2019 The
WDS catalog contains per June 2019 about 148,500 objects. About 50,000 of
these come with a magnitude for the primary with single digit precision indicating
rather an estimation than a precise measurement and over 16,000 objects are
listed with magnitudes in the blue or red band (WDS note codes B/K/R/I) thus
in need of a measurement in the V band. After eliminating all objects not
suited for resolution with the tools currently available to me (too small
angular separation, too faint, too bright) about 26,000 objects remained as
targets of interest for this project. The selection criterion for the objects
for a specific report is then at a given point of time simply the currently
highest given altitude to eliminate atmospheric effects as far as possible –
so this is then a more or less random selection out of the mentioned 26,000
objects. This report covers 46 such objects from images taken end of April
2019 with V-filter to allow for visual magnitude measurement by differential
photometry. All objects were additionally checked for potential gravitational
relationship using GAIA DR2 parallaxes |
|
JDSO |
16/1 |
23-29 |
2020 |
|
Counter-Check of Reported Common Origin Pairs All
stars are born in molecular clouds most likely together with other stars
nearby in the same cloud but most such systems are separated over time by the
tidal forces of the galaxy. Kamdar et al. 2019 report the detection of 111
pairs of co-moving stars with similar metallicity assumed to be born together
but separated later on. This report counter-checks this proposition by
cross-matching the listed objects with the GAIA DR2 catalog and using the
found data to calculate the spatial distance between the components as well
as spatial velocity speed and direction. The results confirm with some
caveats the data given in the Kamdar et al. 2019 paper but do not necessarily
confirm the conclusion that all reported pairs have to be indeed of common
origin. Finally all WDS pairs listed as common proper motion pairs (note code
“V”) but with spatial separation likely too large for gravitational
relationship are checked for common origin |
|
JDSO |
16/1 |
48-64 |
2020 |
|
Discovery of a Wide Binary in the Solar Neighborhood During
the work on a report with the topic of star systems in the solar neighborhood
up to 10 parsecs a so far unknown wide binary was discovered at a distance of
~8.1 parsecs from the Sun. This comes rather as a surprise as stars in the
solar neighborhood are most likely the best investigated stellar objects |
|
JDSO |
16/1 |
84-86 |
2020 |
|
Counter-Check
of WDS Farihi Objects with GAIA DR2 The
topic of this report is the recovery of 68 WDS FAR objects in GAIA DR2 with
the intention to counter-check proposed potential gravitational relationship
and assumed minimum distances between the components of these pairs |
|
JDSO |
15/4 |
530-535 |
2019 |
|
Jonckheere
Double Star Photometry – Part XIV If any double star discoverer is in urgent need of photometry then it is Jonckheere. There are over 3000 Jonckheere objects listed in the WDS catalog and a good part of them with magnitudes obviously far too bright. This report covers the Jonckheere objects in the constellations Pup, Pyx and partly Mon. One image per object was taken with V-filter to allow for visual magnitude measurement by differential photometry. All objects were additionally checked for potential gravitational relationship |
|
JDSO |
15/4 |
544-553 |
2019 |
|
Recovery
of Proposed Young Star Binaries in GAIA DR2 A
recent paper (Bowler et al. 2019) reports the identification of 221 young
star binaries in the solar neighborhood. A common proper motion assessment
scheme was used for the purpose to declare a pair as likely binary based on
the comparison of multi-epoch images if available. For the remainder of the
reported pairs without multi-epoch images available the authors assumed that
the vast majority are likely physical binaries due to the low density of
comparably bright stars nearby. This report counterchecks this proposition
using GAIA DR2 parallax data allowing to check the likelihood for
gravitational relationship by calculating the spatial distance between the
components of the proposed binaries. Only 49% of the 221 proposed young star
binaries could be successfully cross-matched with GAIA DR2 and only 25% got
confirmed as likely binaries but most of these are already known doubles
listed in the WDS catalog while the confirmation rate drops dramatically for
pairs considered as newly detected. The overall low recovery rate suggests an
issue with the GAIA DR2 object coverage in the solar neighborhood |
|
JDSO |
15/4 |
559-574 |
2019 |
|
Jonckheere Double Star Photometry – Part XIII: Peg If
any double star discoverer is in urgent need of photometry then it is
Jonckheere. There are over 3000 Jonckheere objects listed in the WDS catalog
and a good part of them with magnitudes obviously far too bright. This report
covers the Jonckheere objects in the constellation Pegasus. At least one image
per object was taken with V-filter to allow for visual magnitude measurement
by differential photometry. All objects were additionally checked for
potential gravitational relationship and 11 qualify indeed as potential
physical pairs |
J. Nanson |
JDSO |
15/3 |
322-326 |
2019 |
|
Recovery of “Very” Neglected WDS Objects in Gaia DR2 The
USNO WDS catalog website lists also 3 sets of neglected objects selected by
different criteria (mainly “Not observed in 20 years”) to point out double
stars in need of new observations. To concentrate on “very” neglected double
stars not observed in 60 years all objects with a last observation date
before the year 1958 were selected directly from the WDS catalog and 3,149
such objects remained after elimination of all pairs with data not suitable
for cross-matching with GAIA DR2. After a drill down process in several steps
1,473 pairs were successfully matched with GAIA DR2 objects – a recovery rate
of about 47 percent. For the rest most not recovered objects are either bogus
(or lost due to wrong J2000 positions) or simply not resolved in DR2 mostly
with separations below 1 arc second |
|
JDSO |
15/3 |
327-331 |
2019 |
|
The “True” Movement of Double Stars in Space Common
movement of any kind (proper motion, transverse velocity, radial velocity,
total or spatial velocity) of double star components is neither a sufficient
nor a necessary criterion to consider a double star as likely physical. This
proposition is substantiated by analysis of the movement of double star
components in space and confirmed by counter-checking with double stars
listed in the 6th Catalog of Orbits of Visual Binary Stars. An earlier
suggested assessment scheme for potential gravitational relationship (PGR)
based on the likely distance between the components of a double star is
discussed more in detail |
|
JDSO |
15/3 |
464-488 |
2019 |
|
Cross-Match of WDS KOI objects with GAIA DR2 The
WDS catalog contains in total 2,640 pairs with the designation KOI. So far
(per end of August 2018) only 835 such objects have been confirmed by at
least a second observation. Out of these 835 confirmed KOI objects 594 or
~71% were recovered as GAIA DR2 pairs. This
statistic has been broken down to separation classes to check the performance
of GAIA DR2 for resolving doubles in more detail. Additionally 1,043 KOI
objects with so far only one observation have been confirmed by GAIA DR2
raising the percentage of confirmed KOI objects from ~32% to ~62%. Finally
the matched KOI objects were checked for being potential binaries by means of
common parallax. Regarding GAIA Performance: With an update of the WDS data
base in September 2018 with GAIA DR1 matches the number of confirmed KOI
objects increased from 835 to 1,167 so the added value of GAIA DR2 compared
to DR1 is not only the availability of proper motion and parallax data beyond
TGAS but also in a significant larger number of confirmed objects |
J. Nanson |
JDSO |
15/2 |
242-247 |
2019 |
|
Recovery of KPP objects in Gaia DR2 As
per end of December 2018 the WDS catalog contains 2,695 KPP objects with most
of them being V-coded means considered most probably physical based on common
proper motion of the components. The detection of most of these objects is
based on checking catalogs like LSPM or UCAC5 for stars with high proper
motion and looking then for pairs with most probably common proper motion.
After dealing with some issues of data quality like precise J2000 positions
or missing proper motion data in GAIA DR2 for a small number of objects 100%
of the KPP objects could be recovered with 1 object left as probably bogus.
The CPM assessment was then repeated with GAIA DR2 proper motion data and got
confirmed for 69% of the objects. Assessment for potential gravitational
relationship based on GAIA DR2 data was positive for 22% of the KPP objects |
|
DSSC |
27 |
73-80 |
2019 |
|
Physical pairs found in Gaia DR2 The
wealth of precise parallax data in the GAIA DR2 catalogue is simply too
attractive to be ignored even if in some cases caution is appropriate. To be
on the safe side only objects with a parallax value larger than 5 and an
error range smaller than 0.5% were selected and checked for pairs up to 60
arcseconds separation. For all such pairs the distance between the components
was calculated using the parallax data and the angular separation. After
elimination of all already known WDS and WDSS objects over 4,000 new pairs were
found to be most probably gravitationally bound doubles |
|
DSSC |
27 |
55-72 |
2019 |
|
Recovery of SKF objects in Gaia DR2 As
Brian Skiff declared his DSSC 25 contribution (Ski 2017) as the last one of this
kind it seems of interest to recover the so far WDS listed SKF objects in
GAIA DR2 and assess them for being potential physical pairs by means of GAIA
DR2 parallax data. In a first cross−match process nearly 96% of the SKF
doubles could be successfully matched with GAIA DR2 objects and about 25% of
them are most probably bound by gravitation. In a final manual drill down
process the number of GAIA unconfirmed SKF objects could be reduced to less
than 1% with only a few objects left as potentially bogus or listed with
erroneous WDS data |
|
DSSC |
27 |
33-54 |
2019 |
|
High
Proper Motion Stars in the Southern Sky (HPMS3) catalog Star catalog VizieR J/other/JDSO/15.21 |
J. Nanson |
CDS |
2019 |
||
|
A Catalog of High Proper Motion Stars in the Northern Sky
(HPMSNS Catalog) As
follow up to our report on high proper motion stars in the southern sky
(Knapp and Nanson 2019 - HPMS3 catalog) we present here our attempt to
counter-check and extend the LSPM north catalog (Lepine and Shara 2005)
covering the high proper motion stars in the northern sky. The GAIA DR2
catalog contains in total 78,279 high (>150mas/yr) proper motion objects
in the northern sky compared to 61,977 LSPM objects which means an increase
of 26%. A cross-match of LSPM and HPMSNS objects suggests a “loss” of several
thousand LSPM objects – a closer look made clear that this is mostly caused
by LSPM objects with GAIA DR2 proper motion values smaller than 150mas/yr
missing for this reason the cut. Several thousand HPMSNS objects come in
pairs up to 60 arc seconds separation. A good part of these pairs are already
listed in the WDS catalog, the rest are newly discovered pairs most of them
with common proper motion. Several hundred of the newly discovered CPM pairs
have parallax data similar enough to be considered as potentially
gravitationally bound while the rest travel most probably by chance in the
same direction with similar speed. The CPM pairs potentially bound by
gravitation are listed in a separate table as newly discovered binaries and
other catalogs were checked to give an observation history. This list
includes several pairs with potential gravitational relationships but proper
motion different enough to be considered not quite common up to quite
different – we consider these pairs also as potential binaries assuming that
fast orbits add extra motion to the proper motion of the pairs as system |
J. Nanson |
JDSO |
15/1 |
42-58 |
2019 |
|
A Catalog of High Proper Motion Stars in the Southern Sky
(HPMS3 Catalog) The
LSPM catalog (Lepine and Shara 2005) covers the high (>150mas/yr) proper
motion stars in the northern sky. This report presents in tribute to the work
of Lepine and Shara the second half of such objects – high (>150mas/yr)
proper motion stars in the southern sky selected from the Gaia DR2 catalog,
in total over 90,000 such objects. Several thousand objects come in pairs up
to 60 arc seconds separation. A part of these pairs are already listed in the
WDS catalog and given with the corresponding WDS ID, the rest are newly
discovered pairs most of them with common proper motion. Several hundred CPM
pairs have parallax data similar enough to be considered as potentially
gravitationally bound so the other CPM pairs are most probably random pairs
travelling in the same direction with the same speed. The CPM pairs
potentially bound by gravitation are listed in a separate table as newly
discovered binaries and other catalogs were checked to give an observation
history. A new class of pairs are those with potential gravitational
relationship but proper motion different enough to be considered not quite
common up to quite different – this might be a serious hint that fast orbits
might overlap proper motion to the degree of rendering the criteria common
proper motion as irrelevant for the assessment as binary double star if there
are good reasons to suspect an orbit |
J. Nanson |
JDSO |
15/1 |
21-41 |
2019 |
|
KOI Objects in the WDS Catalog The
very presence of Kepler Objects of Interest in the WDS catalog seems curious
enough to have a closer look at a random sample of such objects. This report
counterchecks about 50 double stars with reference to the Kepler mission for
being potentially physical pairs |
J. Nanson |
JDSO |
15/1 |
130-161 |
2019 |
|
Cross-Match of WDS TDS/TDT Objects
with Gaia DR2 The WDS catalog contains in total 14,169 Tycho
Double Stars (based on Fabricius et al. 2002) with the designation TDS/TDT.
So far (per August 2018) only 1,366 such objects got confirmed by at least a
second observation. Out of these 1,366 confirmed TDS objects 1,079 were
recovered as Gaia DR2 pairs. This statistic has been broken down to
separation classes to check the performance of Gaia DR2 for resolving close
doubles more in detail. Additionally 1,034 TDS objects with so far only one
observation got confirmed by Gaia DR2 raising the percentage of confirmed TDS
objects from less than 10 to ~17%. Finally the matched TDS objects were
checked for being potentially binaries by means of common parallax |
|
JDSO |
15/1 |
178-183 |
2019 |
|
Jonckheere
Double Star Photometry – Part XII: Mon I If
any double star discoverer is in urgent need of photometry then it is
Jonckheere. There are over 3000 Jonckheere objects listed in the WDS catalog
and a good part of them with magnitudes obviously far too bright. This report
covers about half of the Jonckheere objects in the constellation Monoceros.
At least one image per object was taken with V-filter to allow for visual
magnitude measurement by differential photometry. All objects were
additionally checked for common proper motion and about 10 qualify indeed as
potential physical pairs |
J. Nanson |
JDSO |
14/4 |
609-647 |
2018 |
|
CPM
pairs from LSPM so far not WDS listed – Part V The LSPM catalog (Lepine and Shara 2005) is a rich source for CPM pairs. We thought that after our four recent “CPM pairs from LSPM” reports – now largely exhausted – to make sure we had once again a closer look and found against our expectations that indeed nearly 200 additional potential CPM pairs so far (per March 2018) not listed in the WDS catalog. This report covers about 90 of these objects |
J. Nanson |
JDSO |
14/4 |
667-692 |
2018 |
|
Measurements of WDS Objects Found in Images Taken for Detecting
CPM Pairs in the LSPM Catalog - II During our research for CPM objects in the LSPM catalog so far not included in the WDS catalog part IV (Knapp and Nanson 2018) we found again a surprisingly large number of WDS objects in the field of view of several images taken for this project. To use the existing image material in the best possible way we decided to take measurements of these objects and to look at other existing catalog data allowing a check for potential common proper motion. This report presents the findings of this research |
J. Nanson |
JDSO |
14/3 |
404-414 |
2018 |
|
Counter-Check of Janes Double Stars
for being Physical Pairs This report counter-checks 93 objects
reported by Kenneth A. Janes in Nov. 2016 as wide binaries in the Kepler field
for the probability of being physical pairs using UCAC5 proper motion data.
Additionally these objects are counter-checked against the WDS catalog for
being newly detected or already listed as double stars. All objects are
listed in a table format giving all parameters necessary for being included
into the WDS catalog if newly detected. Finally a newly detected common
proper motion pair was found by chance during the work on this report |
|
JDSO |
14/3 |
415-426 |
2018 |
|
Assessment of 26,840 WDS Objects for
being Common Proper Motion Pairs The WDS catalog contains (as of August 2017)
more than 100,000 objects which are currently not considered to be physical.
For 26,840 of these objects both components were identified in the UCAC5
catalog and checked with UCAC5 proper motion data using a common proper
motion (CPM) assessment scheme according to Knapp and Nanson 2017 with
extensions. A surprisingly large number of these pairs seem to be physical.
Additionally, GAIA DR1 positions are given for all components, and precise
separation and position angle based on GAIA DR1 coordinates were calculated
for all of the 26,840 pairs Download spreadsheet: WDSvsUCAC5_II.xlsx
|
T. Bryant |
JDSO |
14/3 |
427-431 |
2018 |
|
Jonckheere Double Star Photometry – Part XI: Lepus and
Vulpecula If
any double star discoverer is in urgent need of photometry then it is Jonckheere.
There are over 3000 Jonckheere objects listed in the WDS catalog and a good
part of them with magnitudes obviously far too bright. This report covers the
Jonckheere objects in the constellations Lep and Vul. At least one image per
object was taken with V-filter to allow for visual magnitude measurement by
differential photometry. All objects were additionally checked for common
proper motion. Five qualify indeed as most probably CPM pairs with an
additional five as potential CPM pairs |
J. Nanson |
JDSO |
14/3 |
443-472 |
2018 |
|
A New Concept for Counter-Checking of Assumed Binaries The
CPM assessment scheme presented a year ago (Knapp & Nanson 2017) proved to
be a very useful concept for counter-checking of assumed CPM pairs using the
most reliable catalog data for either star positions or proper motion
available. Suggestions to make the proposed letter based scheme easier to
understand led in consequence to an extension of the letter based scheme and
a concept for transforming this scheme into an estimated probability for a
pair being physical. The obvious usability of this concept for checking any
double star for being a potential common proper motion pair made it necessary
to make some modifications to allow for undecidable cases due to
insignificant proper motion values Download
spreadsheet: CPM_and_Plx_CHK_V6_Double_Line
|
|
JDSO |
14/3 |
487-491 |
2018 |
|
Estimating Visual Magnitudes for Wide
Double Stars The WDS catalog data error contamination rate
is especially high for the visual magnitudes of fainter secondaries rather
often given as rough estimations instead of precise measurements. This report
presents a formula for calculating a rather precise Vmag estimation from GAIA
DR1 Gmag and 2MASS J/H/K-mag data Download spreadsheets: |
J. Nanson |
JDSO |
14/3 |
496-502 |
2018 |
|
Estimating
Visual Magnitudes for Wide Double Stars with Missing or Suspect WDS Values The
WDS catalog often gives visual magnitudes of fainter objects rather as rough
estimations instead of precise measurements or magnitudes of the blue or red
band depending on availability and in some cases the given magnitude for the
secondary is simply blank. This report suggests for a good part of such
objects a rather precise Vmag estimation calculated from GAIA DR1 Gmag and
2MASS J/H/K-mag data. As side result a cross-match of the WDS catalog with
GAIA DR1 is presented to provide recent precise measurements for about 80,000
WDS objects. During the research for this report several errors were found in
the WDS as well as the GAIA DR1 catalog |
J. Nanson |
JDSO |
14/3 |
503-520 |
2018 |
|
495 Common Proper Motion Pairs so far not WDS Listed This report covers 495 common proper motion
pairs so far (per end of February 2018) not WDS listed. The pairs come with a
separation less than 5 arcseconds and are considered to be probably physical.
For each pair an observation history covering 2MASS, UCAC4, UCAC5 and GAIA
DR1 is given. Visual magnitudes are estimated using GAIA DR1 Gmags and 2MASS
J/H/K-mags Download spreadsheets: |
|
JDSO |
14/3 |
546-551 |
2018 |
|
Reliability of UCAC5 Proper Motion Data for Common Proper Motion
Assessment of Double Stars Proper motion data should be as reliable as
possible to be of use for common proper motion assessment of double stars.
The UCAC5 catalog was created to deliver just that. Intensive use of this
catalog for this purpose (see Knapp and Bryant 2018) raised some doubts about
the overall UCAC5 proper motion data quality and led to a detailed
examination of this proposition with some surprising and interesting results
which we present in this report |
T. Bryant |
JDSO |
14/3 |
577-586 |
2018 |
|
2126 Common Proper Motion Pairs so far not WDS Listed This report covers 2126 common proper motion
pairs so far (per April 2018) not WDS listed. The pairs come with a
separation between 5 and 25 arcseconds and are considered to be probably physical
based on identical proper motion speed and direction within the given error
range. For each pair an observation history covering 2MASS, UCAC4, UCAC5 and
GAIA DR1 is given. Several other catalogs like for example USNO A2, SDSS1,
PS1 etc. were also checked and provide an observation history if only for a
part of the listed objects. Estimated visual magnitudes are calculated for
each object using GAIA DR1 G-band and 2MASS J/H/K-band magnitude data Download spreadsheets: |
|
JDSO |
14/3 |
587-599 |
2018 |
|
CPM
Pairs from LSPM so Far Not WDS Listed – Part IV The
LSPM catalog (Lepine and Shara 2005) is a rich source for CPM pairs we
thought already exhausted – but as we found during research for our report “A
New Concept for Counter-Checking of Assumed CPM Pairs” (Knapp and Nanson
2017), there are still many potential CPM pairs indicated in LSPM not listed
in the WDS catalog. After our first three reports on about 100 such objects
(Knapp and Nanson 2017 - CPM pairs from LSPM so far not WDS listed – Part
I/II/III), this report with 30 additional potential common proper motion
pairs is presented here |
J. Nanson |
JDSO |
14/2 |
367-388 |
2018 |
|
Counter-Check of CBL Double Stars for
being Physical Pairs This report counter-checks a random sample of
CBL objects for the probability of being physical pairs using TGAS proper
motion and parallax data finding most of them common proper motion pairs
indeed but only in one case with some probability for gravitational
relationship |
|
JDSO |
14/2 |
357-361 |
2018 |
|
Jonckheere Double Star Photometry – Part
X: Hercules If any double star discoverer is in urgent
need of photometry then it is Jonckheere. There are over 3000 Jonckheere
objects listed in the WDS catalog and a good part of them with magnitudes
obviously far too bright. This report covers 28 of the in total 82 Jonckheere
objects in the constellation Hercules selected by a quick WDS data check for
being potentially listed with questionable magnitudes. At least one image per
object was taken with V-filter to allow for visual magnitude measurement by
differential photometry. All objects were additionally checked for common
proper motion and two qualify indeed as potential CPM pairs. |
|
JDSO |
14/2 |
344-352 |
2018 |
|
Counter-Check of 4,937 WDS Objects for
Being Physical Double Stars The WDS catalog contains (as of August 2017)
more than 20,000 V-coded objects which are considered to be physical pairs
because of their common proper motion (CPM) or other attributes. For 4,937 of
these objects both components were identified in the UCAC5 catalog and
counter-checked with UCAC5 proper motion data using a CPM assessment scheme
according to Knapp and Nanson 2017. A surprisingly large number of these
pairs seem to be optical rather than physical. Additionally GAIA DR1
positions are given for all components, and precise separation and position
angle based on GAIA DR1 coordinates were calculated for all of the 4,937 pair Download spreadsheet: WDSvsUCAC5 |
T. Bryant |
JDSO |
14/2 |
389-394 |
2018 |
|
2017 measurements of some wide and faint
double stars This
report presents astrometry and photometry results from images taken during
the year 2017 for about 50 WDS objects considered to be in need of precise measurements
for different reasons like for example questionable magnitude for the
secondary or unexpected results in visual observing sessions |
|
DSSC |
26 |
49-58 |
2018 |
|
As
announced in our report “Measurements of WDS Objects found in images taken
for detecting CPM pairs in the LSPM catalog” we present here a report on
Kruger 60. This multiple is listed in WDS with such a large number of
components that we thought it deserves a separate report |
J. Nanson |
JDSO |
14/1 |
3-21 |
2018 |
|
Physical Double Stars in
GAMBLES The GAMBLES (Gaia Assorted Mass Binaries Long Excluded from SLoWPoKES) project combines the data from TGAS (Tycho-Gaia Astrometric Solution) with the SloWPoKES (Sloan Low-mass Wide Pairs of Kinematically Equivalent Stars) approach to identify binaries. This report takes a critical look at this effort |
|
JDSO |
14/1 |
43-53 |
2018 |
|
Jonckheere Double Star Photometry
– Part VIII: Sextans If any double star discoverer is in urgent
need of photometry then it is Jonckheere. There are over 3000 Jonckheere
objects listed in the WDS catalog and a good part of them with magnitudes
obviously far too bright. This report covers the Jonckheere objects in the
constellation Sextans. One image per object was taken with V-filter to allow
for visual magnitude measurement by differential photometry. All objects were
additionally checked for common proper motion and a good part of the objects
qualify indeed as potential CPM pairs |
|
JDSO |
14/1 |
59-65 |
2018 |
|
Visual observation of double stars is an
anachronistic passion especially attractive for amateurs looking for sky
objects suitable for visual observation even in light polluted areas. Session
planning then requires a basic idea which objects might be suitable for a
given equipment—this question is a long term issue for visual double star
observers and obviously not easy to answer, especially for unequal bright
components. Based on a reasonably large database with limited aperture
observations (done with variable aperture equipment iris diaphragm or
aperture masks) a heuristic approach is used to derive a statistically well
founded Rule of Thumb formula Download Rule of Thumb spreadsheet: RoT.xlsx Download data base for RoT: LimitObservations.xlsx |
|
JDSO |
14/1 |
99-121 |
2018 |
|
Jonckheere Double Star
Photometry – Part IX: Sagitta If any double star discoverer is in urgent
need of photometry then it is Jonckheere. There are over 3000 Jonckheere
objects listed in the WDS catalog and a good part with magnitudes obviously
far too bright. This report covers a part of the Jonckheere objects in the
constellation Sagitta including a check if physical by means of UCAC5 proper
motion data. In most cases only one image per object is taken for
differential photometry as even a single image based measurement is better
than the currently often given mere estimation. As by-product a new CPM
candidate pair was discovered and as appendix the UCAC5 proper motion data
quality was counter-checked with GAIA DR1 (TGAS) |
|
JDSO |
14/1 |
147-160 |
2018 |
|
Physical
Double Stars in the SLoWPoKES Catalogs The
ongoing research on binaries is lately supported by very comprehensive and
precise new catalogs like SLoWPoKES (Sloan Low-mass Wide Pairs of
Kinematically Equivalent Stars). This report counter-checks the claim that
all objects in this catalog should be physical double stars by testing a
small, randomly selected sample of objects for potential common proper motion |
|
JDSO |
13/4 |
615-625 |
2017 |
|
TGAS
is a subset of GAIA DR1 objects comprising those stars in the Hipparcos and
Tycho-2 catalogs for which proper motion as well as parallax data are
available. Good reason to have a look if this data is of use for checking if
existing WDS catalog objects are to be considered physical or not |
|
JDSO |
13/4 |
580-584 |
2017 |
|
Measurements
of WDS Objects Found in Images Taken for Detecting CPM Pairs in the LSPM
Catalog During our research for CPM objects in the LSPM catalog so far not included in the WDS catalog part II (Knapp and Nanson 2017) we found by chance a surprisingly large number of WDS objects in the field of view of several images taken for this project. To use the existing image material in the best possible way we decided to take measurements of these objects and to look at other existing catalog data allowing a check for potential common proper motion. This report presents the findings of this research |
J. Nanson |
JDSO |
13/4 |
553-567 |
2017 |
|
CPM
pairs from LSPM so far not WDS listed – Part III The
LSPM catalog (Lepine and Shara 2005) is a rich source for CPM pairs we
thought already exhausted – but as we found during research for our report “A
new concept for counter-checking of assumed CPM pairs” (Knapp and Nanson
2017) there are still many potential CPM pairs indicated in LSPM which as of
the end of 2016 are not listed in the WDS catalog. After our first two
reports on in total about 70 such objects (Knapp and Nanson 2017) the next
paper with about 25 additional potential common proper motion pairs is
presented here |
J. Nanson |
JDSO |
13/4 |
538-552 |
2017 |
|
Jonckheere
Double Star Photometry - Part VII: Aquarius If
any double star discoverer is in urgent need of photometry then it is
Jonckheere. There are over 3000 Jonckheere objects listed in the WDS catalog
and a good part of them with magnitudes obviously far too bright. This report
covers the Jonckheere objects in the constellation Aquarius. One image per
object was taken with V-filter to allow for visual magnitude measurement by
differential photometry. All objects were additionally checked for common
proper motion by comparing 2MASS to GAIA DR1 positions and a rather
surprisingly large part of the objects qualify indeed as potential CPM pairs.
For a few objects also WDS position errors were found |
|
JDSO |
13/4 |
475-484 |
2017 |
|
CPM
Pairs from LSPM so far not WDS Listed – Part II The
LSPM catalog (Lepine and Shara 2005) is a rich source for CPM pairs we
thought already exhausted – but as we found during research for our report “A
new concept for counter-checking of assumed CPM pairs” (Knapp and Nanson
2017) there are still many potential CPM pairs indicated in LSPM which as of
the end of 2016 are not listed in the WDS catalog. After our first part on
about 40 such objects (Knapp and Nanson 2017) the next report with about 30
additional common proper motion pairs is presented here |
J. Nanson |
JDSO |
13/4 |
447-464 |
2017 |
|
STT Doubles with Large ΔM –
Objects Nearby Following
our series of reports on STT doubles with large ΔM, we are submitting
measurements of WDS objects which were by chance found nearby in the images
taken of the STT doubles. In these cases we did not suspect any issues with
the current WDS catalog data, but wanted to make use of existing image
material as any double star visited is worth a current measurement |
J. Nanson |
JDSO |
13/3 |
299-314 |
2017 |
|
Jonckheere Double Star
Photometry – Part V: Cancer If
any double star discoverer is in urgent need of photometry then it is Jonckheere.
There are over 3000 Jonckheere objects listed in the WDS catalog and a good
part of them have magnitudes which are obviously far too bright. This report
covers the Jonckheere objects in the constellation Cancer. Only one image per
object was taken as despite the risk of random effects even a single
measurement is better than the currently usually given estimation, although
the J-objects in this constellation seem with some exceptions better covered
with observations as usual for Jonckheere doubles |
|
JDSO |
13/3 |
363-372 |
2017 |
|
Jonckheere Double Star Photometry –
Part VI: Auriga If
any double star discoverer is in urgent need of photometry then it is
Jonckheere. There are over 3000 Jonckheere objects listed in the WDS catalog
and a good part of them has magnitudes which are obviously far too bright.
This report covers the Jonckheere objects in the constellation Auriga. Only
one image per object was taken as despite the risk of random effects even a
single instance visual magnitude measurement is better than the currently
usually given estimation although the J-objects in this constellation seem
with some exceptions better covered with observations as usual for Jonckheere
doubles |
|
JDSO |
13/3 |
419-432 |
2017 |
|
As
already reported (Knapp and Gould 2016), most Tycho Double Star objects in the
WDS catalog are unconfirmed. From the huge number of in total nearly 1000
TDS/TDT objects in the Cygnus constellation, all unconfirmed pairs (per
beginning of 2016) listed with 2" separation were visually observed and
measured based on CCD images |
|
JDSO |
13/2 |
133-139 |
2017 |
|
CPM Pairs from LSPM so far
not WDS Listed The
LSPM catalog (Lepine and Shara 2005) is a rich source for CPM pairs we thought
already exhausted – but as we found during research for our report “A new
concept for counter-checking of assumed CPM pairs” (Knapp and Nanson 2016)
there are still many potential CPM pairs indicated in LSPM which as of the
beginning of 2016 are not listed in the WDS catalog. A first part of about 40
such objects is presented here |
J. Nanson |
JDSO |
13/2 |
140-161 |
2017 |
|
STT Doubles with Large
ΔM – Part VIII: Tau Per Ori Cam Mon Cnc Peg The
results of visual double star observing sessions suggested a pattern for STT
doubles with large ΔM of being harder to resolve than would be expected
based on the WDS catalog data. It was felt this might be a problem with
expectations on one hand, and on the other might be an indication of a need
for new precise measurements, so we decided to take a closer look at a
selected sample of STT doubles and do some research. Again like for the other
STT objects covered so far several of the components show parameters quite
different from the current WDS data |
J. Nanson |
JDSO |
13/2 |
174-188 |
2017 |
|
Jonckheere Double Star Photometry –
Part IV: Cetus If
any double star discoverer is in urgent need of photometry then it is
Jonckheere. There are over 3000 Jonckheere objects listed in the WDS catalog
and a good part of them have magnitudes which are obviously far too bright.
This report covers the Jonckheere objects in the constellation Cet. Only one
image per object was taken as despite the risk of random effects even a
single measurement is better than the currently usually given estimation
although the J-objects in this southern constellation are better covered with
observations as usual for Jonckheere doubles |
|
JDSO |
13/2 |
257-263 |
2017 |
|
Some 2016 measurements of wide and faint
double stars The
number of my 2016 visual double star observation sessions remained modest due
to ongoing cloudy weather conditions. Yet the number of objects with questionable
WDS data (mostly suspect magnitudes for the secondary) found in these
sessions or during session planning is rather high. Additionally several
objects were suggested in private communications to be WDS listed with
suspect data or to be of interest for other reasons. Images of these objects
were taken with remote telescopes and then used for astrometry and photometry
measurements to counter-check such impressions. This report presents the
results of these measurements confirming in most cases the need for updating
the current WDS catalog data but demonstrate in some cases also simply that
visual impressions can be very misleading |
|
DSSC |
25 |
21-50 |
2017 |
|
Counter-Checking Tycho Double Stars with
the SDSS DR9 Catalog As
already reported (Knapp and Gould 2016), most Tycho Double Star objects in
the WDS catalog are unconfirmed. Small separation and faint components make
these objects hard to resolve either by visual observation or by imaging in
the V-band and only few public domain star catalogs offer resolution for
stars with less than 2-3 arcseconds. One exception is the SDSS DR9 catalog
based on images with a resolution of 0.396 arcseconds per pixel. This report
shows that SDSS DR9 is of good use for counter-checking double stars down to
a separation of 1.5 arcseconds or even less |
|
JDSO |
13/1 |
87-89 |
2017 |
|
STT Doubles with Large
ΔM – Part VII: And Pisces Auriga The
results of visual double star observing sessions suggested a pattern for STT
doubles with large DM of being harder to resolve than
would be expected based on the WDS catalog data. It was felt this might be a
problem with expectations on one hand, and on the other might be an
indication of a need for new precise measurements, so we decided to take a
closer look at a selected sample of STT doubles and do some research. Similar
to the other objects covered so far several of the components show parameters
quite different from the current WDS data |
J. Nanson |
JDSO |
13/1 |
75-86 |
2017 |
|
A New Concept for
Counter-Checking of Assumed CPM Pairs The inflation of “newly discovered” CPM pairs makes it necessary to develop an approach for a solid concept for counter-checking assumed CPM pairs with the target to identify false positives. Such a concept is presented in this report |
J. Nanson |
JDSO |
13/1 |
31-51 |
2017 |
|
Measurements of Faint and Wide Doubles
in Boötes and Corona Borealis Images
of several double stars in Boötes and Corona Borealis published on the
“Double Star Imaging Project” Yahoo Group page suggest magnitude issues
compared with the corresponding WDS catalog data per Jan 2016. Taking
additional images with V-filter enabled photometry and astrometry for these
pairs as a counter-check |
C. Thuemen |
JDSO |
13/1 |
25-30 |
2017 |
|
Another Kind of Data Mining - Looking
for Anomalies Comparing
the data of different star catalogs with the WDS catalog data is a highly
suitable method to find WDS entries that need to be further checked. This
approach is similar to the WDS Neglected Doubles lists but it also adds the
magnitude discrepancies between the WDS and the other catalogs |
|
JDSO |
13/1 |
10-12 |
2017 |
|
Measurements
of Some VizieR I/330 Objects Data
Mining is a contemporary form of double star detection – software running
over a star catalog with proper motion data producing long lists of newly
detected pairs, most of them rather wide and faint and thus of little
interest for the visual observer. For evaluation of such an approach I
measured a random sample (selected by altitude suitable for imaging) of
objects from the VizieR I/330 “Binary star discoveries in the URAT1 catalog”
(Nicholson, 2015). Without exception the astrometry results were rather close
to the I/330 catalog values proving the reliability of the provided data but
in total several questions arose regarding the validity of Nicholson study |
|
JDSO |
12/6 |
589-594 |
2016 |
|
Measurements
of some Tycho Double Stars – Follow Up Canis Minor and Columba As
follow up to our report “Visual Observation and Measurements of some Tycho
Double Stars” we decided to have a look at some more wider TDS objects in
other constellations but to replace the hapless visual observation task by
counterchecking with existing Sky Survey images |
R. Gould |
JDSO |
12/6 |
547-455 |
2016 |
|
Measurements
of Wide Tycho Double Stars in Orion About
25 TDS objects in Orion with separation of 1.5" or larger remained at
the beginning of 2016 in the WDS catalog without confirmation while 10 are
listed as confirmed. Several of the so far unconfirmed objects have now been
successfully observed while most of the remaining objects are to be suspected
as being bogus as the evidence suggests single stars. The number of confirmed
TDS objects of this separation range in Orion is greater than in the other constellations
we have studied so far |
M. McPhee |
JDSO |
12/6 |
541-546 |
2016 |
|
STT
Doubles with Large ΔM – Part VI: Cygnus Multiples The
results of visual double star observing sessions suggested a pattern for STT
doubles with large ΔM of being harder to resolve than would be expected
based on the WDS catalog data. It was felt this might be a problem with
expectations on one hand, and on the other might be an indication of a need
for new precise measurements, so we decided to take a closer look at a
selected sample of STT doubles and do some research. Of these objects we
found three rather complex multiples in Cygnus of special interest so we
decided to write a separate report to have more room to include the non STT
components as well. Again like for the other objects covered so far several
of the components show parameters quite different from the current WDS data |
J. Nanson |
JDSO |
12/6 |
519-534 |
2016 |
|
Measurements
of Some SKF Objects Data
Mining is a contemporary form of double star detection. As all existing star
catalogs are to some degree in error the question arises how good the data
quality of such objects might be. For evaluation I measured a random sample
(selected by altitude suitable for imaging) of SKF objects. With few
exceptions the measurement results were rather close to the current WDS
catalog data |
|
JDSO |
12/6 |
507-510 |
2016 |
|
Some 2015 Measurements of Wide and Faint
Double Stars Compared with Visual Observations A
backlog of astrometry and photometry measurements made in 2015 for comparison
with visual observations is reported here with the intention of providing
recent precise measurements for the given objects |
|
JDSO |
12/5 |
420-426 |
2016 |
|
Visual Observation and Measurements of
Some Tycho Double Stars No
humble human visual observer would dare to challenge a robotic telescope – yet
many Tycho based results are highly questionable to utterly wrong as is shown
on several examples |
R. Gould |
JDSO |
12/5 |
427-436 |
2016 |
|
Mind the Gap – Jonckheere Double
Stars Not Listed in the WDS We
describe our efforts to determine the cross-referenced identifications of a
large group of Robert Jonckheere’s double stars which failed to turn up in a
search of the WDS catalog sorted by discoverer ID |
J. Nanson |
JDSO |
12/5 |
450-467 |
2016 |
|
STT Doubles with Large
ΔM – Part V: Aquila, Delphinus, Cygnus, Aquarius The
results of visual double star observing sessions suggested a pattern for STT
doubles with large DM of being harder to resolve than would
be expected based on the WDS catalog data. It was felt this might be a
problem with expectations on one hand, and on the other might be an
indication of a need for new precise measurements, so we decided to take a
closer look at a selected sample of STT doubles and do some research. We
found that, as in the other constellations covered so far (Gem, Leo, UMa etc.), at least several of the selected objects in Aql, Del, Cyg and Aqr show
parameters quite different from the current WDS data |
J. Nanson |
JDSO |
12/5 |
474-487 |
2016 |
|
STT
Doubles with Large ΔM – Part IV: Ophiuchus and Hercules The
results of visual double star observing sessions suggested a pattern for STT
doubles with large DM of being harder to resolve than
would be expected based on the WDS catalog data. It was felt this might be a
problem with expectations on one hand, and on the other might be an
indication of a need for new precise measurements, so we decided to take a
closer look at a selected sample of STT doubles and do some research. We
found that like in the other constellations covered so far (Gem, Leo, UMa, etc.) at least several of the selected objects in
Ophiuchus and Hercules show parameters quite different from the current WDS
data |
J. Nanson |
JDSO |
12/4 |
361-373 |
2016 |
|
Jonckheere Double Star Photometry – Part III: Lyra,
Equuleus, and Eridanus If
any double star discoverer is in urgent need of photometry then it is Jonckheere.
There are over 3000 Jonckheere objects listed in the WDS catalog and a good
part of them have magnitudes which are obviously far too bright. To keep the
workload manageable only one image per object is taken and photometry is done
with a software allowing a simple point and click procedure – even a single
measurement is better than the currently usually given estimation |
|
JDSO |
12/4 |
351-360 |
2016 |
|
Photometry of Faint and Wide Doubles in Vulpecula Images
of several double stars in Vulpecula published on the “Double Star Imaging
Project” Yahoo Group page suggest magnitude issues compared with the
corresponding WDS catalog data per April 2015. Taking additional images with
V-filter enabled photometry for these pairs, providing confirming results |
C. Thuemen |
JDSO |
12/4 |
347-350 |
2016 |
|
Jonckheere
Double Star Photometry – Part II: Delphinus If
any double star discoverer is in urgent need of photometry then it is
Jonckheere. There are over 3000 Jonckheere objects listed in the WDS catalog
and a good part of them have magnitudes which are obviously far too bright.
To keep the workload manageable only one image per object is taken and
photometry is done with a software allowing a simple point and click
procedure – even a single measurement is better than the currently usually
given estimation |
|
JDSO |
12/4 |
327-337 |
2016 |
|
Measurements of BU109 in Cetus - Follow Up As
was detailed in a paper published in Vol. 11 No.3, July 1, 2015 in the
Journal of Double Star Observations, the data within WDS 2014.96 for BU 109
in Cetus was suspect. Since our discussions with the WDS in late 2014 and
prior to the publication of this paper, updates were made for BU 109 based on
the existing available data. In the July 2015 paper, we discussed that
further research by way of new imagery allowing more detailed photometry and
astrometry would be initiated. This current paper is the results of the new
photometry and astrometry |
J. Nanson C. Thuemen |
JDSO |
12/2 |
107-110 |
2016 |
|
STT Doubles with Large ΔM – Part II: Leo and UMa The
results of visual double star observing sessions suggested a pattern for STT
doubles with large DM being harder to resolve than would be expected based on the WDS
catalog data. It was felt this might be a problem with expectations on one
hand, and on the other might be an indication of a need for new precise
measurements, so we decided to take a closer look at a selected sample of STT
doubles and do some research. We found that also in Leo and Uma at least
several of the selected objects show parameters quite different from the
current WDS data |
J. Nanson S. Smith |
JDSO |
12/2 |
111-127 |
2016 |
|
STT Doubles with Large ΔM – Part III: Vir, Ser, Com, CrB and Boo The
results of visual double star observing sessions suggested a pattern for STT
doubles with large delta_M of being harder to
resolve than would be expected based on the WDS catalog data. It was felt
this might be a problem with expectations on one hand, and on the other might
be an indication of a need for new precise measurements, so we decided to
take a closer look at a selected sample of STT doubles and do some research.
We found that like in Gem, Leo, and Uma also in Vir,
Ser, Com, CrB, and Boo at
least several of the selected objects show parameters quite different from
the current WDS data |
J. Nanson |
JDSO |
12/2 |
128-142 |
2016 |
|
Jonckheere Double Star Photometry – Part I: Cyg If
any double star discoverer is in urgent need of photometry then it is Jonckheere.
There are over 3000 Jonckheere objects listed in the WDS catalog and a good
part of them have magnitudes which are obviously far too bright. To keep the
workload manageable only one image per object is taken and photometry is done
with a software allowing a simple point and click procedure – even a single
measurement is better than the current estimate |
J. Nanson |
JDSO |
12/2 |
168-179 |
2016 |
|
Eps Lyr – Visual
Observation and Measurements The
famous double-double star object Epsilon Lyrae
includes also some lesser known faint components. Visual observation results
made the current WDS data on these faint components somewhat questionable. A
follow up with photometry and astrometry delivered recent precise
measurements confirming the need for an update |
|
JDSO |
12/2 |
180-183 |
2016 |
|
Photometry of Faint and Wide Doubles in Sagitta Images
of several double stars in Sagitta published on the “Double Star Imaging
Project” Yahoo Group page suggest magnitude issues compared with the
corresponding WDS catalog data per April 2015. Taking additional images with
V-filter enabled photometry for these pairs, provided confirming results |
C. Thuemen |
JDSO |
12/2 |
184-187 |
2016 |
|
Photometry on
Some Wide and Faint Double Stars Some
doubles with suspect magnitude data for the secondary were found during session
planning. For several of them, images were made with remote telescopes and
used for photometry to get precise measurements |
|
JDSO |
11/4 |
384-386 |
2015 |
|
STT Doubles
with Large Delta M – Part I: Gem The
results of visual double star observing sessions suggested a pattern for STT
doubles with large DM of being harder to resolve than
would be expected based on the WDS catalog data. It was felt this might be a
problem with expectations on one hand, and on the other might be an
indication of a need for new precise measurements, so we decided to take a
closer look at a selected sample of STT doubles and do some research. We
found that indeed most of the selected objects show parameters quite
different from the current WDS data |
J. Nanson S. Smith |
JDSO |
11/4 |
390-401 |
2015 |
|
Photometry of
Faint Wide Doubles in Hydra Images
of several double stars in Hydra published on the “Double Star Imaging
Project” Yahoo Group page suggest magnitude issues compared with the
corresponding WDS catalog data per end of 2014. Taking additional images with
V and B filters enabled photometry for these pairs, suggesting significant
corrections to the old data in WDS |
C. Thuemen R. Gould |
JDSO |
11/4 |
418-423 |
2015 |
|
Measurements
of BU109 in Cetus Images
of BU109 in Cetus raised questions about magnitudes and positions of components
as listed in the WDS catalog, the most valuable resource for double star
observers. Further research suggested changes for magnitudes and positions
and questioned whether the most recent listed precise measurements are always
the most precise measurements. |
J. Nanson C. Thuemen |
JDSO |
11/3 |
154-157 |
2015 |
|
Photometry and
Measurement of Faint and Wide Doubles in Eridanus Images
of several double stars in Eridanus published on the “Double Star Imaging
Project” Yahoo Group page suggest magnitude issues compared with the
corresponding WDS catalog data per 2014.12. Taking additional images with
V-filter enabled photometry for these pairs with confirming results |
C. Thuemen |
JDSO |
11/3 |
139-142 |
2015 |
|
Wide and Faint
Double Star Photometry and Measurement with Online Tools Using
Landolt standard stars as reference, it is shown that generally available
online tools can with moderate efforts deliver reliable photometric results,
and with the example of ROE 76 in Perseus it is also shown that measuring of
wide double stars is quite possible. By chance ROE 76 also offered the
possibility to do some astrometry with online tools |
|
JDSO |
11/3 |
125-129 |
2015 |
DSSC: Double Star Section
Circulars - The Webb Deep-Sky Society
JDSO: Journal of Double Star
Observations
CDS: Centre de Données astronomiques de Strasbourg, VizieR star catalog