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CVs and Unusual Objects for Fall
At this time of year, the western and eastern horizons at dusk and dawn
are
dominated by constellations representing hunters and heroes. This
"season of the hunter" is my favorite time of year to
observe. Mild
temperatures, longer nights, better seeing, and generally clear skies get
me to the telescope early, and
I stay as long as I can.
These bright constellations, lying on either side of the summer Milky
Way, contain
a number of interesting cataclysmic variables and unusual
objects. So, whether you prefer hunting for CVs in the evening
or the
morning, here is something for everyone.
Bootes seems to hang above the eastern horizon far longer
than expected.
As the days grow shorter, he is given a nightly reprieve from vanishing
into the sun's glare.
1344+08
CR Boo- (AM CVn) This is an odd binary system consisting of two
white dwarfs, one accreting mass from the other. Outbursts
occur, as with
"normal" dwarf novae, and are usually in the 13th magnitude range.
1439+22A UZ Boo- (UGSU) With outbursts
occurring in 1978 and 1994, this is
one that you will have to wait for patiently. This star is comparable to
other dwarf
novae with large amplitude outbursts and long cycle times. In
outburst it may get as bright as 11.5, so it will be hard
to miss!
1454+41 TT Boo- (UGSU) At +40.6 degrees north declination, this is the last
of my program CVs in Bootes
to fall into the sun each year. The outburst
cycle is around 200 days or so, and it gets into the mid-12's in outburst.
My
star-hop to this variable begins at an 8th magnitude star attended by a
string of fainter stars running almost due north
of it. As it happens, this
grouping makes an excellent indicator of the sky conditions for the
evening.
Hercules
no longer gets the full ride across the zenith, but starts out
high enough that faint observations can still be made in
darkness.
1626+21 V592 Her- (UGWZ?) Another one you will have to be patient for. Last
seen in outburst in 1998,
this dwarf nova was discovered in 1968. Only one
other outburst has been detected, and that was recorded photographically,
in
1986. It shows large amplitude outbursts into the 12th magnitude range
with, obviously, long cycle times.
1640+25
AH Her- (UGZ) One of the most hyperactive of the UGZ type stars,
and easy to keep track of in a moderate sized scope. This
one seems to have
gone into a small outburst from standstill in late August. Keep an eye on
this one. You never know
what it will do next.
1802+31 V1008 Her- (UG) Formerly known as Var61 Her, this little studied UG
outbursts into
the 14th magnitude range, roughly once every 300 days or so.
There are new charts with a CCD(V) sequence that make this
one easier to
find and observe.
1830+24A CH Her- (UG) This CV seems to exhibit bright outbursts in the 14th
magnitude
range and fainter outbursts in the 15th magnitude range at very
irregular intervals.
In the morning, Perseus rises
in the northeast, chasing Cassiopeia around
the pole. If I were to re-make the constellations, the Pleaides would be
part
of Perseus, instead of Taurus.
0130+50 KT Per- (UGZ) One of my 'top ten' favorite CVs, this is a fun one
to follow.
It is fairly active, so about half the time I observe it, it is
in outburst, fading or in standstill. It can get as bright
as 10.6 in
outburst, and fades to around 16th magnitude in quiescence, so bigger
scopes can follow the action in its
entirety. The star-hop to get there
takes me right past M76, the Little Dumbbell.
0203+56A UV Per- (UGSU) This is
another CV with fairly long cycles and
large amplitude outbursts that may get as bright as 11.7! This is a field
that
I sometimes take in just for the sheer beauty of the stars and
asterisms that abound in the vicinity of the variable. Even
the view in the
finder scope is impressive.
0206+57A TZ Per- (UGZ) Just a short hop north from UV Per, in the same
finder
scope asterism, is another of the more hyperactive UGZs. TZ Per
seems to be up to something all the time. It has a close
14th magnitude
companion that can fool uninitiated observers, so be careful in identifying
the variable. With a range
of 12.3 -15.6, this is another one that can be
followed all the time with a 12" or bigger scope.
0228+55 DY Per-
(R CrB) This star is just recovering from a dramatic fading
episode. Usually hovering precariously around 11th magnitude,
this star
began to fade in January last year. It seems to have bottomed out around
14th magnitude, and has now recovered
to almost 12th magnitude. This is a
strangely enigmatic R CrB type star, which may one day prove to be a
missing link
or member of a subset of R CrB types.
0401+50 FO Per- (UGZ) Leaving the cluster-laden regions around UV, TZ and
KT
Per behind, I head north to another old favorite, FO Perseii. This is
another UGZ that is quite active. I don't recall
seeing it exhibit
standstills, like most UGZs, but frequent outbursts in the 13th magnitude
range make it a worthwhile
stop if you want to actually see a CV in
outburst from night to night.
When the great hunter, Orion, finally clears
the trees before dawn here in
Michigan, the foliage on the trees begins to turn. A sense of urgency sets
in, to take
advantage of the mild weather and clear skies, because I know
winter can't be too far away.
0507-05 CN Ori- (UGZ)
Almost due east of M42, this is another UGZ that
lacks the obvious typical Z Cam type standstills. It is quite active and
fairly
bright in outburst, getting up to 11.9 or so. Passing by M42 on the
nightly run can be a distraction or a blessing, depending
on your frame of
reference.
0524-03 V1159 Ori- (UGSU ER)- Located about mid-way between M42 and Eta
Orionis,
this star is one of the most active UGSU types, with an outburst
cycle of around four days! Unfortunately, this star lies
in one of those
mysterious hazy patches in the sky that make it a bit difficult to observe.
There are a number of these
hazy regions in Orion, Taurus and Monoceris
that I think are nebulous, and make observations more difficult than usual.
0611+15
CZ Ori- (UGSS)- Sometimes you get lucky and find CN, V1159 and CZ
Ori all in outburst on the same night! This UGSS is also
quite active and
reaches 11.2 in outburst on occasion. This chart is a "twofer", with V344
Ori (UG: 14.2- 17.5p)
WNW on the same chart.
For those of you that monitor these and other CVs in the wee hours of the
night, my
hat is off to you for being the "hunters" of amateur astronomy.
And to the researchers and professional astronomers, who
rely on your
notification of outbursts of targets of opportunity, you are the 'heroes'
of variable star observing.
Clear
Skies and Happy Hunting!
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