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Eyepiece Views #2
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THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS
25 Birch Street, Cambridge, MA 02138 USA
Tel. 617-354-0484 Fax 617-354-0665
http://www.aavso.org
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E Y E P I E C E V I E W S
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September, 2001 Vol 1 No 2
Table of Contents
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1. 2nd Issue Introduction & a Plea to Early Morning Observers
2. Comments on LPVs - J.A.M.
3. Seeing Double (Part 1)
4. CV's and Unusual Objects for Fall by Mike Simonsen
5. Recent Chart Updates
6. Binocular Observing
7. The Purkinje Effect on Red Stars
8. Reminders: WZ Sge & Recent Novae
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1. 2ND ISSUE INTRODUCTION AND A PLEA TO EARLY MORNING OBSERVERS
Welcome to the 2nd issue of Eyepiece Views. We hope you found the
first issue useful. Please send us any comments you may have or
suggestions for topics in future issues. Since this is still a new
publication now is the perfect time to have your feedback heard!
We would like to take this opportunity to address non-circumpolar
stars with significant observing gaps. These gaps are especially
troublesome with stars whose period is changing or is not known
exactly. These gaps can be minimized by making observations of a star
as soon as it rises in the predawn hours, throughout the season, and
until it dissapears in the sun's glare at dusk. Mira (OMI CET), is one
of our most popular stars and yet has large gaps in its lightcurves.
Please observe these objects in the predawn hours as soon as you
can. We would like to ask our early morning observers to add stars in
their program which are rising in the predawn hours.
If you have any questions, please post them to the AAVSO Discussion
Group so that others may participate in the discussion.
Thanks and good observing!
Gamze Menali (MGQ)
Aaron Price (PAH)
Mike Simonson (SXN)
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2. COMMENTS ON LPVs - J.A.M.
In the first issue of Eyepiece Views Janet Mattei (JAM) contributed
comments on 15 LPVs which are in urgent need of observation at this time.
We would like to thank the following observers for submitting 286
observations of these LPVs for the months of July and August: TVG, PEX, SRX,
SBX, HZJ, JM, WJD, HHU, SFK, SRB, ABB, BVE, COM, AAX, CMQ, STI, HWD, LTO,
LMK, SVP, EER, DPA, KTZ, HHU, PUJ, SXN, VPJ, WRX, KKI, AAP, MGH, SJZ, GRL,
POX, PAH, ZRE, OSW, FXJ, CNT, SVP, CKN, VFK, GMY, BJS, LTO, DLA, ABB, WLP,
BJS, SGE, TVG, CKB, CBI.
Below is a list of some objects in need of observations for the next
two months.
1802-22 VX Sgr 6.7-13.3
This star is one of the most fascinating variables, a semiregular
variable with the longest period, 732 days. Since 1997, its amplitude
has been decreasing, and particularly since 1998 it has been very
difficult to predict its behavior because its amplitude has decreased
dramatically, varying only from 9.1 to 10.6, which is reminiscent of
its behavior in the early 1960's. A plea to our observers: please
monitor this fascinating star as much as you can until it is lost in
the autumn sky and pick it up as early next season as possible to see
whether it will continue its unusual behavior or return to its
large-amplitude, periodic behavior.
1813+06 BC Oph 8.8-15.6
The maximum brightness of the most recent cycle has been about a
magnitude fainter and the amplitude of the cycle has been smaller than
the previous one. Particularly around maximum, the star may be
suffering from the use of two comparison star sequences, since there
is quite a bit of scatter in the data. Observers are urged to use the
AAVSO chart, which has a good comparison star sequence particularly
around maximum. The next maximum is predicted for September 25.
1922+01 TU Aql 8.9-(15.4
This star can definitely use more observations at all phases. It
has been having alternating bright and faint maxima. The most recent
maximum was about a magnitude brighter than the previous one. The
predicted maximum is for September 12.
2008-22 W Cap <11.7-14.8>
Another LPV in need of more observations at all phases. Due to lack
of observations it has been difficult to predict its maxima and minima
in recent years. It is brightening to its maximum predicted for
October 13.
2011-21 RT Cap 8.9 - 11.7 P
This bright semiregular variable is on the b chart of 2008-22 W Cap.
The data (between magnitude 6.7 and 8.7) in the last decade show a lot
of scatter and so it is very difficult to determine the behavior of
the star. RT Cap is a carbon star, thus it is red, and part of the
scatter in the light curve, on the bright end, may be due to the
Purkinje effect. Observers who observe this star should be
particularly careful in making estimates and should use the quick-look
or out-of-focus method.
2012+07 QZ Aql 10.4-(15.5
Thanks to our observers' efforts, the cycle in 2000 was better
monitored, in comparison to earlier years. The maximum was wide, and
showed small-amplitude variations. Currently it is slowly brightening
to its predicted maximum on October 24.
2013+76 SZ Cep 9.1-15.5
This circumpolar variable can use more observations around maximum.
This star is a good example of observers' possibly using comparison
star magnitudes that are different from the AAVSO D scale chart,
especially around maximum. One can see this particularly at its
maximum of JD 2451504. This star desperately needs a completely new,
better comparison star sequence, but observers are urged to use the
existing magnitude sequence so that when we do have a better sequence
we can transform all of the data to the new sequence. The existing
magnitude sequence is visual. Beware of a nearby 10.4 star to the
east of the variable. Predicted maximum is for September 4.
2049-54 S Ind <8.2-15>
We are counting on our southern-hemisphere observers to provide more
estimates for this star, which is in need of observations at all
phases. The recent maximum in 2000 was about a magnitude brighter
than the previous one. The AAVSO 'd' chart is quite inadequate. We
ask our observers' understanding and patience with the chart, and we
appreciate their efforts.
2056-27 RR Cap <9.3-14.5>
This star can use more observations at all phases. The recent
maximum was about one-and-one-half magnitudes fainter than the
previous one. It is brightening to its maximum predicted for October
22.
2105-16 Z Cap <9.5-14.0>
Partly because of the length of its period (181 days) and the
seaonal-gap effect, the alternate cycles of this variable have been
very poorly monitored. The last cycle in 2000-2001 was well
monitored, thanks to the efforts of our observers. The present cycle
is that alternate cycle, and we urge our observers to continue to
monitor this star closely until it is lost in the western sky and as
soon as possible after it re-appears in the east so that we break the
habit of having the alternate cycles well monitored and have a more
complete light curve. The next maximum is predicted for September 20.
2128-14 Y Cap <11.6-14.8>
This star is badly in need of observations at all phases. It is
slowly fading from its recent maximum.
2142-47 R Gru <8.3-14.6>
Another star for which we are counting on our southern observers for
more observations, particularly as it is brightening from its
predicted minimum of August 28.
2212-30 R PsA <9.2-14.7>
Another star in desperate need of more observations at all phases.
It is slowly brightening towards maximum predicted for November 11.
2228-67 R Ind <8.4-14.3>
Thanks to the efforts of a few observers in the southern hemisphere
- Rod Stubbings, Peter Wedepohl, Tom Cragg, Jaime Garcia - we have
been barely able to predict maxima and minima dates for this star.
We bring this star to the attention of our southern-hemisphere
observers and plead for more observations at all phases. It is slowly
brightening to its maximum predicted for October 10.
2234-62 T Tuc <8.1-13.2>
Another southern variable desperately in need of more observations,
particularly now, around minimum.
2327-46 V Phe <9.2-14.0>
Yet another southern variable in need of observations, particularly
as this star brightens towards maximum predicted for September 12.
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3. SEEING DOUBLE (PART 1)
The following article is the first of two parts written by Mike
Simonsen (SXN). The second part will be published in the next issue of
Eyepiece Views and will include Winter constellations.
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Most amateur astronomers have observed double stars at one time or
another. Many of you have favorites, like Alberio or Epsilon Lyrae.
Splitting a close pair can be a test of your optics, eyes, seeing
conditions, and sometimes, your patience.
Since the majority of stars in our galaxy are members of multiple
systems, it should come as no surprise that some of the variables we
observe also have companions. I'm not referring to the unseen
companions of eclipsing binaries or cataclysmic variables, but rather,
pairs of stars you can actually see.
These variable doubles present their own challenges and rewards in
observing. The following is part of a long list of variables that have
very close companions. These may cause observers some difficulty in
identifying and/or estimating the variable star in the field. In fact,
I have included a few close pairs where BOTH components are variable!
CE LYR 1832+27
This variable sits due west of its 113 comparison/companion.
Strangely enough, my star hop to this variable begins with a close
double in the finder scope.
Z LYR 1856+34
Egad! This one can make you go blind. The 136 and 138 comparisons
are very close to each other and close enough to the variable to cause
confusion. Pile on the fact that you need a magnifying glass to see
the tiny star dots on the e chart, and you have a real puzzler in the
dark with your red flashlight! I recommend using the f chart and high
magnification when it approaches minimum.
UU LYR 1901+27
I don't recall having actually seen this faint Mira yet. It is
located very close, and to the SE of its 137 companion/comparison.
TU AQL 1922+01
I found this one tricky to estimate when it was nearly equal to the
110 comparison/companion. You can't defocus or they run together.
Nicely contrasting colors may be pretty, but they don't help much when
it comes to making the call.
SW AQL 1946+12A
This Mira has a NE companion that can easily be mistaken for the
variable. At maximum, SW Aql only gets to 13.3, so be sure you can see
both stars before making the call.
OW AQL 1946+14A
This Mira is parked right next to a 9th magnitude star. Picking it
out of the glare near minimum can be a test. Steady seeing and high
magnification may be needed.
Z CYG 1958+49
This one isn't too hard to split from its 130 companion/comparison,
but it is in a rather confusing field. The entire sequence is riddled
with comparisons that are themselves double. The 85, 105, 115, 121 and
133 comparisons are all close pairs. Be careful not to use the
combined brightness when making the estimate using these stars.
SY AQL 2002+12
Beware the 14th magnitude impostor due north near minimum. It's very
close. Lots of doubles in this field, including the 73, 95, 104 and
110 comparisons.
FG SGE 2007+20 and ST SGE 2007+20A
Double trouble! FG Sge is often confused for its close neighbor to
the east. What's more, the eastern companion may itself be variable.
As if that weren't enough, on the same chart is another devilishly
close pair, ST Sge and its close buddy. Good seeing and high
magnification are needed when these stars are faint.
On a side note, an article on FG SGE by Ron Royer was published in
1999 in JAAVSO vol. 27, no. 2, p. 146-147. It can be read online at
the URL below:
http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1999JAVSO
..27..146R&db_key=AST&high=3b4f1b442624482
LX CYG 2152+47A
I haven't had the pleasure of seeing this one near minimum. Its 138
companion was a good catch on a steady night when LX itself was 9th
magnitude. This is another chart with lots of booby traps. For faint
comparisons, the 140 near LV Cyg is a double and the 144 and 141 are a
close pair near LY Cyg, which is a close double also! Three variables
in the Milky Way in Cygnus. Two with close companions and close
doubles as comparisons. My advice... take your time.
DV CYG 1917+29, YZ VUL 1940+27 and DG CYG 2039+42
All deserve honorable mention in this region of the sky.
I would like to thank Georg Comello for his input and suggestions
for candidates for this article.
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4. CV'S AND UNUSUAL OBJECTS FOR FALL
By Mike Simonsen (SXN)
Not everyone appreciates the charm and mystery of making hundreds of
negative observations while monitoring CVs that rarely go into
outburst. There really is no way to describe the excitement you feel
when you finally see one of these rare outbursts for the first, maybe
the only, time in your life.
For those of you who might like to add some CVs to your observing
program, but don't fancy making a lot of negative observations, here
is a list of "hyper-active CVs". A quick look at the online light
curve generator (http://www.aavso.org/adata/curvegenerator.shtml) will
show you these stars are always up to something. If you add these CVs
to your fall observing list you will see an outburst or note some
activity before long.
RX AND 0058+40
Although this UGZ has had long periods of standstills one third from
maximum, more often than not it can be seen showing off due east of
M31.
TY PSC 0120+31
NW of M33, this UGSU is fairly active. It has the bonus feature of
being located due north of an unmistakable asterism of four closely
packed stars.
KT PER 0130+50
Another active CV not far from a well-known Messier object, this UGZ
is just a quick star hop from M76. This favorite is fairly active,
sometimes quite bright and pleasantly unpredictable.
TZ PER 0206+57A
Once you've seen this UGZ shining around 12.5 it will be easier to
pick out from its close 13th and 14th magnitude neighbors when not so
bright. At this declination it is nearly circumpolar, so you'll get
lots of practice.
LX AND 0213+40
Although listed as an RVB type star in the GCVS, it is included in
the most recent Downes and Shara catalogue as a UG. At maximum, it
gets into the 13th magnitude range. There are excellent new charts for
this star on the website.
FO PER 0401+50
Usually, this UG bursts into the 13th magnitude range. It has had
bright outbursts into the low 12s. Almost once a month it does
something, so your odds of catching it are pretty good.
FO AQL 1911-00
Although its getting late in the season for this one, it's not too
low in Aql to squeeze in a few more outbursts before this UGSS
disappears into the sun. Outbursts are usually in the mid-13s.
EM CYG 1934+30
Located in a beautiful star field in the Milky Way, EM Cyg can be
followed from minimum to maximum in most 8 and 10 inch scopes.
Frequent outbursts into the 12th magnitude range and typical
standstills for this UGZ.
SS CYG 2138+43
Doesn't everyone in the AAVSO observe this one already? There are
good reasons. It's bright, easy to find and unpredictable.
HX PEG 2335+12
Maybe not as active as some of the other stars on this list, this
UGZ does exhibit the outbursts and standstills of its type. Located in
a sparse field with a fairly bad sequence, this one sometimes makes it
in to the 12s. Hey, I had to throw at least one challenge at you
didn't I?
After experiencing the excitement of seeing these stars blaze forth
and then fade back into quiescence, maybe you'll be ready to stand
vigil on PQ And or EG Cnc or... hmm, sounds like another list.
Clear Skies and Happy Hunting
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5. RECENT VISUAL CHART UPDATES
Below is a list of new charts published in July and August of 2001.
They can be downloaded from /observing/charts/ .
Desig Name Range Type Scales
1148+52 SN 2001dp 14.1 - ? v SN e,er
1234+21 IR Com 13.5-18.0V UGSU b,d,f,br,dr,fr
1448+64 RXJ1450.5+ (Dra) 13.4-17.7V UGSU b,d,f,br,dr,fr
1521+08 QW Ser 12.8-18.0p UGSU b,d,f,br,dr,fr
1530-13 HP Lib 13.0-15.8B AM CVN d,f,dr,fr
1617+19B V589 HER 14.1 -(17.5p UG e,f,er,fr
1750-32 V1178 SCO 10.2p - ? NL? f,fr
1620-04 V699 Oph 13.8-18.5p UG b,d,f,br,dr,fr
1918+04 V1494 AQL 5.0 - V N f,g,fr,gr
2003+17 WZ SGE 7 - 15p UGWZ/DQ b,e,br,er
2059+48 N CYG 01-2 6.6 - v N ab,b,br
We have also added 24 new reversed charts and updated the charts for
DO HER, FZ CYG, V1329 CYG, V1494 AQL, and V2274 CYG (N CYG 01). If
you observe these stars please download and use the updated charts.
For more details and a continually updated list of chart changes
visit /observing/charts/updates.stm .
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6. BINOCULAR VARIABLES FOR NEW OBSERVERS
The observation of variable stars does not require expensive
instruments. For those new to amateur astronomy, binoculars are
frequently a much better investment than a telescope.
Binoculars are both a valuable scientific instrument and easy to
use. They are easy to point and focus, the field of view is larger
than a telescope and it's easier scan the sky and find what you're
looking for. They also provide the convenience of going after stars
whenever you want thanks to the lack of required setup time. If you
want to contribute very valuable data you may want to take a few
minutes after twilight and before dawn to observe. (See the
Introduction to this issue for more information.)
We have a section on our web page for information on a sampling of
stars easy to observe with binoculars at the URL below. We also have
included information on how to use the charts and find the field.
/observing/charts/binocularstars.stm
With binoculars, you can catch Mira at maximum and get the top of
the light curve. You can do the same with V CAS. Also interesting in
binoculars are Z UMA (Semiregular), MU CEP (Semiregular, extremely red
star located on the Delta Cep chart), R SCT (RV Tau star, well within
the range of a standard pair of binoculars.), R CRB, RS OPH (Goes to
max every 15 years or so), CH CYG (Symbiotic).
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7. THE PURKINJE EFFECT ON RED STARS
The Purkinje phenomenon makes red stars seem brighter the longer you
stare at them due to the response of the retina to red light. This
makes estimating red stars even more difficult than it already is.
When observing these stars it is recommended that you use the quick
glance or out-of-focus method. The former involves quickly glancing
between the comp stars and the variable. The latter involves slightly
defocusing your telescope and making an estimate of the defocused
image.
For more information visit the resources below:
- AAVSO Manual for Visual Observing of Variable Stars
http://www.aavso.org/cdata/manual/chapter2.stm
- Mayer, E. "Application of Out-of-Focus Images in Amateur Astronomy".
JAAVSO, Vol. 12, pg. 16; 1983.
http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1983
JAVSO..12...16M
- Isles, J.E. "The Purkinje Effect" Journal of the Royal
Astronomical Society of Canada Newsletter, Vol. 65, p.L6.
Dec, 1971.
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8. REMINDERS: WZ SGE & CURRENT NOVAE
The last two months have been very active. In July, WZ Sge went into
outburst for the first time in a little over 22 years. Right now
recent observations show it between 11-12 mag and steadily fading with
oscillations. If you don't observe it now it may soon get too faint to
see again for another 20+ years! At the URL below we have all sorts of
light curves, charts, spectra, and historical data on WZ Sge.
http://www.aavso.org/wzsge.stm
Also, there have been two novae discovered, one easily placed for
each hemisphere. They both are fading at different and unpredictable
speeds. Below is a table of information on each nova.
2059+48 V2275 CYG (Nova Cygni 2001 No. 2)
Discovery Mag: 8.8ptg (A. Nakamura, Kume, Ehime, Japan)
Current Mag: 11-12 (13 days later)
Data, charts, light curves, spectra, and analysis is
available at: http://www.aavso.org/novacygni.stm
1818-30B V4739 SGR (Nova Sagittarii 2001 No. 2)
Discovery Mag: 7.6 (Alfredo Pereira, Cabo da Roca, Portugal)
Current Mag: 10-11 (3 days later)
Data, charts, light curves, spectra, and analysis is
available at: http://www.aavso.org/novasgr.stm
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EYEPIECE Views is published bimonthly and when circumstances warrant
via e-mail. An archive is available at
http://www.aavso.org/eyepieceviews/ . Please send comments and
suggestions to gamze@aavso.org.
To receive EYEPIECE Views via e-mail send a message to
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e-mail.
The AAVSO has many free online publications including "CCD Views", a
similar newsletter intended for ccd observers. To learn more and
subscribe visit: http://www.aavso.org/mailinglists.stm
Good observing!
Gamze Menali,AAVSO Technical Assistant (MGQ)
Aaron Price, AAVSO Technical Assistant (PAH)
Mike Simonsen, AAVSO Observer (SXN)
Copyright 2001, American Association of Variable Star Observers
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THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS
25 Birch Street, Cambridge, MA 02138 USA
Tel. 617-354-0484 Fax 617-354-0665
http://www.aavso.org
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