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CCD Views: August 2001
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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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C C D V I E W S
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August, 2001 Vol 2 No 2
Table of Contents
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1. Welcome to the 2nd Issue of CCD Views
2. Comments from J.A.M.: WZ SGE Outburst, LPVs
3. Letter: I Band Photometry & Comp Stars
4. 76th GCVS Name-List
5. Survey of Some Suspected Variable Comp Stars in Cygnus
6. Report on Last Issue's Faint LPV List
7. New CCD Charts
8. Web Page: Newbie Guide to CCD Observing of Variable Stars
9. CCD Observer Totals for June - July, 2001
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1. WELCOME TO THE 2ND ISSUE OF CCD VIEWS
It is hard to believe that two months have passed by since the
first issue of the new electronic version of CCD Views. We received
many positive comments and appreciate all feedback, good and bad. If
you have any suggestions, topic ideas, or would like to contribute
something yourself please e-mail us at aavso@aavso.org. We will
continue to tweak and adjust this new publication based upon feedback
from you.
This summer has been an exciting summer for CCD observers. We
were unable to fit everything into this issue that we wanted. Don't be
surprised to see an extra issue sent out within the next month
covering projects we were unable to place in this issue including
feedback on the SU UMA campaign and an interesting light curve of
V1548 AQL (N AQL 01).
Thanks and good observing!
Aaron Price, Technical Assistant Gary Walker
AAVSO Headquarters Chairman, CCD Committee
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2. COMMENTS FROM J.A.M.: WZ SGE OUTBURST & LPVs:
The rare outburst of WZ Sge that started on July 23 continues
with prominent superhumps in the light curve. Our webmaster Kate
Davis has created a special web page on WZ Sge on our website at URL:
http://www.aavso.org/wzsge.stm
The webpage is updated daily as we get your observations in the Quick
Look file. The webpage is linked to various useful sites, such as
that of G. Masi who has obtained impressive photometry of the
superhumps.
Our member Lew Cook has also obtained CCDB photometry of the superhumps
which can be seen in the WZ Sge webpage.
AAVSO observer J. D. West has obtained a very nice spectrum of WZ Sge
which is also posted, along with a description. Doug has also analyzed
the AAVSO observations in the Quick Look file and he wrote:
"Using the AAVSO "Quick Look" file visual and CCDV observations from
July 23.8 to 27.2 UT for WZ Sge a period analysis was conducted. The
final analysis file consisted of 383 observations (6 observations were
thrown out), most of observations which were visual. The programs AVE
and EXCEL were used to perform the analysis. The results of the
analysis (linear fit) indicate that WZ Sge is decreasing in brightness
by 0.212 magnitudes per day. The two shortest period peaks in the
periodograms were at 0.047 and 0.059 days. The period of 0.059 day is
very close to the period of variation of 0.057 day reported in
vsnet-alert 6115".
WZ Sge is scheduled to be observed with several satellites such as
FUSE, HST, and Chandra X-ray Satellite as well as with several ground
based telescopes at professional observatories worldwide in the coming
weeks and months.
Please continue to monitor WZ Sge _very_ closely and submit your
observations to the AAVSO as soon as possible. CCD observations
of the superhumps made at every 3 to 5 minutes, for as long as
possible throughout the night is of particular importance to study the
development of the superhumps. Please observe in V and also in B, R,
and I if you have the appropriate filters.
WZ Sge was originally classified as a Recurrent Nova, but subsequently
after its 1978 outburst it was reclassified into its own category of
cataclysmic variables. During the 1978 outburst the star faded from
8.0 to 10.8 in one month, while the superhumps continued during this
time. Then within four days the star faded to magnitude 12.5 and then
recovered before it continued to fade slowly to minimum in three
months. It would be interesting to see if there will be the "dip" in
the light curve after a month. When we plot the observations of this
outburst on to the light curve of 1978 outburst, the two outburst
look very similar.
Charts along with a table of precision photometry of the comparison
stars of WZ Sge are available at the AAVSO webpage on WZ Sge.
We would like to thank DRG, WJD, COO, KDA, and OAR for their quick
reactions and already submitting thousands of CCD observations. More
is still needed!
LPVs IN NEED OF OBSERVATIONS AND YOUR ATTENTION:
1345-36 RX Cen <9.4>-(15.0
This star has been poorly observed the past two years, particularly
during minimum. The AAVSO 'd' Standard chart does not go faint
enough for visual observers to observe at minimum, but with CCDs
it may be possible to make minima observations. Minimum is predicted
for August 24.
1434-17 V Lib <9.7-14.7>
Needs more observations as it fades to and reaches minimum,
predicted for mid-September. Use AAVSO 'e' scale Standard chart and
beware of the very close 14.9 comparison star directly to the east
of the variable.
1611-22A R Sco <10.4-15.0>
Needs observations at all phases, particularly as it fades to
and reaches minimum, predicted for September 15. Use AAVSO 'd' scale
Standard chart, which has adequate faint magnitudes.
1708-33 RW Sco <9.6>-15.0
Needs observations badly at all phases. Minimum is predicted for
October 15. The AAVSO 'd' scale Standard chart does not go faint
enough; do the best you can to obtain positive observations during
minimum.
1757+18 WZ Her 10.8-(15.0
Needs observations as it fades to minimum and around minimum,
predicted for the beginning of September. Needs better sequence,
particularly for fainter magnitudes. Use the AAVSO 'e' scale
Preliminary chart; beware of the close 14.8 comparison star to
the north of the variable.
1913-19 S Sgr <10.2-14.8>
Needs more observations as it fades to minimum and around minimum.
Beware of the 14.4 comparison star closeby to the south of the
variable on the AAVSO 'd' scale Standard chart.
1953-08 RS Aql <9.7-15.2>
The amplitude has decreased and the light curve has become very
different from its mean curve. Monitor the variable closely to
determine its behavior. Presently it is slowly brightening from its
recent minimum in June.
2007+06 TV Aql 9.5-(15.0
Needs observations, particularly as it fades to minimum and around
minimum, predicted for the beginning of September. While you are in
this field, check out the 13.8 comparison star (southeast of the
variable, 2007+06B 138 VAR? E) that is reported to be a
possible variable. Use the AAVSO 'e' scale Preliminary chart.
2101-21 X Cap <11.1-14.8>
Needs observations as it fades to minimum and around minimum,
predicted for early September.
2106+12 AN Peg 10.0-(15.5
Needs observations around minimum now and as it brightens to maximum.
No observations have been recorded for the past several minima;
positive observations will help us nail down how deel the faint
the minima are.
2142-47 R Gru <8.3-14.6>
We have received very few observations over the past two cycles. It
is in dire need of observations! Our southern-hemisphere observers,
we are depending on you to cover this star more closely and
particularly around its minimum predicted for around the end of
August. The AAVSO 'd' scale standard chart does not go faint enough;
do the best you can to obtain some positive observations.
2331+09 FF Peg 9.8-15.8
The minima of this star have been missed for many cycles. Minimum
is predicted for mid-August. The AAVSO 'd' scale Preliminary chart is
inadequate and does not have faint comparison stars; do the best you
can to obtain some positive observations so we may determine how faint
the minima go. Beware of the 13.1 comparison star closeby southwest
of the variable.
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3. LETTER: I BAND PHOTOMETRY & COMP STARS
Doug West had a couple of questions about I band photometry and the
number of comp stars to use while reducing data.
"...when I am doing I band photometry should I use the AAVSO charts
which are V band for comparison or Hipparcos stars?"
When doing I band photometry with a non-CCD AAVSO chart you will
need to transform the V magnitudes to I. You can do this by consulting
the photometric database that was used to make the sequence. This is
listed at the bottom of the chart. If you cannot access the database
then you can use Tycho or Hipparcos data. Just be very careful that
you are using the right data for the right star. Also, it is *vital*
that you use the "K" comment code when submitting the observation put
the photometric database used in the "Comments" field. Here is an
example:
1755+23 WY HER 2450000.0000 14.0 K CCDV 142,150,110 TST HIPPARCOS
"Another thought/question, is it better for the CCD'ers to use one,
two, or three comparison stars. My reduction software (MIRA) allows
the use of multiple comparison stars and give their residuals, this
gives a more accurate measurement. However, it would make it harder
for someone to back out color corrections."
In general, the more comp stars the better. For .1 mag accuracy one
or two comp stars may be sufficient. However, for anything higher use
as many as you can. If your software only allows one comp star, then
perform photometric reduction with a number of different comp stars
and average the results together.
If you would like to discuss these specific questions further,
please direct the comments to the AAVSO Discussion Group so everyone
can benefit from the discussion.
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4. 76th GCVS NAME-LIST
Many of you observing esoteric objects may be interested to know
that the GCVS has issued the 76th Name-List which includes 1,406 new
variables (for a total of 37,391 named variable stars!). Many of the
new variables are objects that had difficult names to type such as
RXJ1450.5+640.
For the list and more information read IBVS #5135 at this URL:
http://www.konkoly.hu/cgi-bin/IBVS?5135
Remember to always submit your observations using names listed in
the AAVSO Validation File, which is updated monthly at the URL below:
http://www.aavso.org/validation.stm
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5. SURVEY OF SOME SUSPECTED VARIABLE COMP STARS IN CYGNUS
One of the downsides to having so many variable stars in the sky is
that it is difficult to pick comparison stars that are constant.
Richard Huziak has recently been keeping track
of a few variables in Cygnus that have comparison stars or nearby stars
that may vary as well. Many of these "suspect" stars are of low
amplitude, making them perfect CCD targets. Please consider adding
these suspected variables to your observing program and submitting the
observations to the AAVSO. [Note from HQ: Sporadic observations of suspect
comparison and field stars are of very low value. If you want to observe
these stars - or the many others like them noted in the AAVSO Validation
File - please make regular observations of them, at least every time you
observe the variables in whose fields they appear, and keep them in your
observing program from year to year.]
Here are the stars along with some comments courtesy of Mr. Huziak.
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100 comp E (of U Cyg) - 2016+47C. [first reported to AAVSO as suspect by
P. Abbott in December 1985] I've been following this star for about 4 years,
and the data may indicate outbursts of about 0.5 mag every 1200 days.
Normally, this star is at about 10.7 mag - not the 10.0 listed on the chart,
and seems to rise to as bright as 10.5 during outbursts.
103 var? E (of RT Cyg) - 1940+48B. [first reported to AAVSO as suspect by
T. Akiyoshi in May 1972] This star seems to show periodic fadings of about
0.6 mag every 2400 days, though may have smaller irregular dips more often.
The star is 'normally' at 10.3.
var NW (of WX Cyg) - 2014+37E. [first reported to AAVSO as suspect by
E. Ofek in July 1993] This star was reported faint (11.6) at around JD
2450350, seems to have been at about 11.1 to 11.3 for several years, and now
has faded as low as 11.7. This may be an irregular variable.
131 comp S (of EY Cyg) - 1950+32E. [first reported to AAVSO as suspect by
R. Huziak in September 1999] This star is certainly not at 13.1 as the chart
indicates and has been hovering around 13.6 - 14.0 for the last few years,
possibly showing a semi-regular variation of about 400 days.
120 comp W (of SS Cyg) - 2138+43G. [first reported to AAVSO as suspect by
D. Iadevaia in August 1981] This star seems to vary between 12.0 and 12.6,
and may have a period of about 400 days. It is immediately W of SS.
Since all of these stars make "convenient" comparison stars for
their "parent" variable stars nearby, it would be nice to definitively
know if these stars are variable. They could then be marked as such.
Obviously a variable comparison star will scatter the estimates!
For those of you not familiar with how suspected variables work,
they are listed in the Validation File as 'letter' variants of the
closest confirmed variable star's designation. Thus, for the first
example on the list, 100 comp E means the 10.0 comparison star East,
with the designation 2016+47C. And 2016+47 is U Cygni, so the
suspected variable is the 10.0 comp star E of U Cyg. Note that the
"var NW" of WX Cyg is the star marked 'var' on the WX chart. The 131
comp S of EY Cyg is more to the SE than S (but AAVSO ran out of
space in the Name field). Good observing!
- Richard Huziak (HUZ)
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6. REPORT ON LAST ISSUE's FAINT LPV LIST
In the last issue of CCD Views Janet Mattei (J.A.M.) published a
list of 21 faint LPVs in need of more observations because of unusual
activity or poor coverage. Thanks to JM, SFK, RZD, GKA, DRG, PAH,
WJD, OCN, ZRE, WRX, OSW, and SMI we received 154 CCD observations for
these stars. If you have room in your program, please observe these
objects every two weeks.
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7. NEW CCD CHARTS
Three new CCD observing charts were issued in July for the following
stars. Visual B, D, F, and corresponding reversed charts are also
available.
Star Type Range Filters
1234+21 IR COM UGSU 13.5 - 18V V
1448+64 RX J1450 DRA UGSU 11.3-14.5V B,V,R,I
1620-04 V699 OPH UG 13.8 - 18.5p B,V,R
For more information visit /observing/charts/new071801.stm
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8. NEWBIE GUIDE TO CCD OBSERVING OF VARIABLE STARS
We have placed on the AAVSO web site a new page title "Getting
Started With CCD Variable Star Observing". Observing variable stars
with a CCD can be quite daunting to someone just starting out with a
CCD camera and a casual interest in variable stars. This guide is
intended to help introduce relatively new CCD owners to the world of
variable star photometry.
This is a good URL to hand out to others interested in what we do:
http://www.aavso.org/committees/ccdnew.shtml
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9. CCD OBSERVATION TOTALS FOR JUNE 1 - JULY 31, 2001
Below is a total of all CCD observations received per observer
during the past two months.
Ttl Observer Location
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1300 COO COOK, LEWIS M. CA, CONCORD
516 DRG DIETHELM, ROGER SWITZERLAND, RODERSDORF
373 KDA KAISER, DANIEL H. IN, COLUMBUS
233 JM JAMES, ROBERT A. NM, LAS CRUCES
154 PAH PRICE, AARON MA, WALTHAM
95 ZRE ZISSELL, RONALD E. MA, SOUTH HADLEY
92 WJD WEST, JERRY DOUG KS, MULVANE
58 OCN O'CONNOR, STEPHEN D. CANADA, MONTREAL, QUE.
51 WGR WALKER, GARY MA, SHERBORN
38 MTK MICHALIK, TOM VA, LYNCHBURG
31 SFK SCHEDER, FRANK L. MD, LEONARDTOWN
31 HDU HURDIS, DAVE RI, NARRAGANSETT
24 OCN O'CONNOR, STEPHEN D. CANADA, MONTREAL, QUE.
18 WMG WEICHINGER, MICHAEL AUSTRIA, VIENNA
13 LIW LILLER, WILLIAM CHILE, VINA DEL MAR
9 GKA GRAHAM, KEITH A. IL, MANHATTEN
9 RR ROYER, RONALD E. CA, LAKEWOOD
8 SMI SMITH, ALAN L. ENGLAND, HORSHAM
5 PEF PROSPERI, ENRICO ITALY, LARCIANO
4 WRX WILLIAMS, ROGER MI, KALAMAZOO
3 FMQ FIASCHI, MARCO ITALY, PADOVA
2 OSW OSBORN, WAYNE MI, MOUNT PLEASANT
2 CRI CASAS, RICARD SPAIN, BARCELONA
1 SPK SCHMEER, PATRICK GERMANY, BISCHMISHEIM
Thanks for the observations!
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CCD Views is published bimonthly and when circumstances warrant
via e-mail. An archive is available at http://www.aavso.org/ccdviews/ .
Please send comments and suggestions to aaronp@aavso.org.
To receive CCD Views via e-mail send a message to
majordomo@aavso.org with "subscribe ccdviews" in the body of the
e-mail. To unsubscribe, place "unsubscribe ccdviews" in the e-mail.
The AAVSO has many free online publications including "Eyepiece
Views", a similar newsletter intended for visual observers. To learn
more and subscribe visit: http://www.aavso.org/mailinglists.stm
Good observing!
Aaron Price, AAVSO Technical Assistant (PAH)
Gary Walker, Chairman of the AAVSO CCD Committee (WGR)
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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