|
|
|
|
CCD Views: October 2001
---------------------------------------------------------------------------
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
---------------------------------------------------------------------------
C C D V I E W S
-------------------------
October, 2001 Vol 2 No 3
Table of Contents
-----------------
1. Introduction: Invitation to Precision CCD Photometry Workshop
2. New Schedule of Cataclysmic Variable Monitoring For XMM-Newton
Observations
3. New Method of Uploading Large Numbers of CCD Observations
4. Observing Faint CVs at Quiescence w/Comments by J.A.M.
5. V1548 Aql (N Aql 01) CCD Multi-Color Lightcurve
6. Faint LPV Comments by J.A.M.
7. Letter: Free Photometry Textbook in PDF Format
8. New Web Page: Magnitude Zero Points
9. CCD Observer Totals for August - September, 2001
---------------------------------------------------------------------------
1. INTRODUCTION: INVITATION TO PRECISION CCD PHOTOMETRY WORKSHOP
We'd like to take this moment to invite you to a special Precision CCD
Photometry workshop to be held on Friday, Nov. 2, 2001 during the 90th
AAVSO Annual Meeting in Somerville, MA. Arne Henden, who will lead the
workshop, will address concepts of differential photometry, special
techniques for AAVSO program stars (eclipsing binaries, GRBs, CVs, etc.),
and other CCD-related topics. More information on the Workshop and the
Annual Meeting visit http://www.aavso.org/meetings/ .
In addition we regret the delay in getting this issue out while we
prepared for the Annual Meeting.
Aaron Price (PAH) Gary Walker (WGR)
Technical Assistant, AAVSO CCD Committee Chair
---------------------------------------------------------------------------
2. NEW SCHEDULE OF CATACLYSMIC VARIABLE MONITORING FOR XMM-NEWTON
OBSERVATIONS
Astronomers at University of California, Santa Barbara, will be
observing several cataclysmic variables in the coming weeks in X-ray
and near-ultraviolet wavelengths with the X-Ray Multi-Mirror Telescope
(XMM-Newton) orbiting observatory. As mentioned in Alert Notice #290
& News Flash #850, they have requested our assistance in monitoring
these objects before, during, and after the satellite observations in
order to provide optical data for correlation.
Observers, particularly CCD observers, are urged to monitor closely
as many as possible of the targets listed below over the next several
weeks so that there will be good knowledge of the activity state
(outburst, quiescence, high or low state, etc.) of each target at the
time of the satellite observations.
** Please note that many of the observations have been rescheduled
due to a revised observing timetable received from our colleagues.
Target Type Range Date of Observation
0409-71 VW Hyi UGSU 8.5-13.8V October 19
0812-48 IX Vel UX (Novalike) 9.1-10.0v Postponed
0745+15 PQ Gem DQ (Intermed. Polar 14.1-14.5V Postponed
0749+22 U Gem UGSS 9.1-15.2V Postponed
0831+48 EI UMa UG 13.4-14.9P Postponed
Periodic monitoring has still been requested for the postponed
observations. New dates will be published in the News Flash, CCD
Views, and on our web site when we get them.
Charts are available at /observing/charts/ .
---------------------------------------------------------------------------
3. NEW METHOD OF UPLOADING LARGE NUMBERS OF CCD OBSERVATIONS
We have added a new feature to the AAVSO web site which makes it
easier to submit large volumes of CCD observations. Visit the URL
below for more information on how to use the new system.
http://www.aavso.org/cdata/webobsccd.shtml
Basically, you upload your CCD observations in one of two formats (a
default generic format or the format that AIP4WIN creates) using a web
browser. You then fill out a form giving us the star information we
need (comp star, chart info, etc.). Then the program will convert your
file to the Official AAVSO Format and place it in our database.
We hope you will find this new method of uploading CCD observations
very quick and easy. We would like to ask our CCD observers to please
feel free to upload any backlog of CCD observations you have from the
past. It is never too late to send in data!
---------------------------------------------------------------------------
4. OBSERVING FAINT CV'S AT QUIESCENSE
One area where CCD observing alone can increase our knowledge of
variable stars is by studying cataclysmic variables (CVs) at
quiescense. This is the time in between outbursts where they are
faint and relatively quiet as seen from Earth.
In 1996 a paper was published by L.N. Sproats, S.B. Howell, and K.O.
Mason titled "Infrared colours, distance determination and absolute
magnitudes of a sample of faint cataclysmic variables." In this paper
they called for further observations of a select list of faint CVs
believed to be in the galactic halo. This request was made to help
"redress a bias" in our knowledge of CVs by only studying optically
bright ones, which happen to be either close by or extra luminous.
Below is a quote from their paper:
"Another question posed by these intrinsically faint systems, and
one which can be addressed by further observations, is to what extent
their low luminosity reflects conditions in the quiescent state
alone, or if the overall accretion rate of the system is low. To
assess this we need information about the luminosity generated during
outbursts, i.e statistics on outburst amplitudes, durations, and
recurrance times. Because these systems are (by definition) very
faint during quiescence, however, they have not been well monitored
and information on the outburst duration and recurrance times, in
particular, is incomplete... There is clear need for improved
observational data before this question can be conclusively laid to
rest."
The AAVSO currently has observing charts for 23 of the 34 stars in
their program. Below is a list of those 23 stars along with comments
by J.A.M. If possible, please add these stars to your observing
program. For the some of the really faint ones this will be quite a
challenge. Good long term data is needed on all of them. Are you up
to it?
Unless otherwise noted, the magnitude ranges are from "A Catalog and
Atlas of Cataclysmic Variables Living Editions" by Ronald Downes, et.
al. available at http://icarus.stsci.edu/~downes/cvcat/ .
0006-12 WW Cet 9.3V-15.7V
This star is fairly well monitored by visual observers. CCD
observations are welcome to provide better coverage.
0111-18 WX Cet 9.5V-18.5V
Needs positive observations badly at quiescence.
0139+37 AR And 11.0V-17.6V
Outburst maxima are covered fairly adequately by visual observers.
CCD observations are badly needed at quiescence.
0203+56A UV Per 11.7V-17.9V
Ron Zissell has been monitoring the quiescence of this star and so
at last we had some positive observations at quiescence. However,
recently even Ron has not been following UV Per, so CCD observations
are badly needed to determine the quiescence level of this star.
0223+39 PQ And 10.1v-19V
We have _NO_ positive observations of this star in the AAVSO
International Database; all the observations are fainter-thans.
Positive CCD observations are badly needed.
0309+42 QY Per 14.2-(20P (GCVS)
Except for a very few observations by Ron Royer and Ron Zissell, we
have no positive observations during quiescence. CCD observations are
badly needed.
0324+58 AF Cam 13.4V-17.3V
In recent years, Steve O'Connor and particularly Roger Diethelm,
have been monitoring the quiescence level of this star. We need more
observers contributing positive observations during quiescence.
0406-15 XZ Eri 14.6p-18.7p
Another CV with no positive observations at quiescence. CCD
observations are badly needed.
0418-13 AH Eri 13.5V-18.5V
Ron Royer and Steve O'Connor and, recently, Robert James, have been
contributing some observations at quiescence. More positive CCD
observations are badly needed.
0905+51 DI UMa 15.2V-18.0V
Visual observers have been contributing to the outburst phase of
this star, and Roger Diethelm has been contributing CCD observations
at quiescence, but we need observations from more CCD observers for
this star.
0956+34 RU LMi 13.8-19.5P (GCVS)
Another star that Roger Diethelm has been monitoring at quiescence.
We need closer coverage by more CCD observers to determine the
quiescence level.
1049+30 SX LMi 13V-17.4V
Another star for which outbursts have been covered fairly well by
visual observers. However, the quiescent phase needs observations
badly. Recently, Ron Zissell and Aaron Price have been contributing
CCD observations; we need better coverage through the participation
of more observers.
1132+02 RZ Leo 11.5V-19.2V
Steve O'Connor and Aaron Price have been contributing a few CCD
observations at quiescence, but this phase has mostly fainter-thans by
visual observers. We need positive observations from CCD observers.
1133+03 T Leo 10.0V-15.9V
Visual observers are monitoring both the outburst and quiescence
phases, and recently Roger Diethelm has been monitoring it with CCD.
More positive CCD observations are needed to determine well the
quiescence level of this SU UMa-type cataclysmic variable.
1147+49 BC UMa 10.9B-18.3B
Thanks to observations from Ron Zissell and recently, a few from
Roger Diethelm, we have some idea of the quiescence level of this
star. However, more CCD observations are very much needed to
determine well the quiescence level. Zissell reported quiescence to be
around 18-19 in V.
1227+14 AL Com 12.8V-20.8V
Except for a few CCD observations by Ron Zissell, the quiescence
level of this very interesting star has no positive observations.
CCD observations are badly needed to determine well the quiescence
level. Observers are cautioned to make sure that the identification
of AL Com is correct.
1251+27 GO Com 13.1-20P (GCVS)
Ron Zissell and Roger Diethelm have been monitoring this star at
quiescence, and visual observers during outburst. More CCD
observations are badly needed to determine the quiescence level.
1841+37 AY Lyr 12.3V-18.0V
The outburst is well monitored by visual observers and in recent
years particularly Ron Zissell and Roger Diethelm have been monitoring
the quiescence level. More positive CCD observations are needed for
better coverage of quiescence.
1920-10 DH Aql 12.5p-18.3V
Another CV in which the outbursts are fairly well monitored by
visual observers but the quiescence level has only fainter-than
observations. Positive CCD observations are badly needed for this
star.
1951-09 UU Aql 11.0V-17.0V
Thanks to the observations of Jan Manek, Marco Fiaschi, Ron Zissell,
Gary Walker, Frank Scheder, and particularly Steve O'Connor, in recent
years we have a handful of CCD observations of this star at
quiescence, while the outbursts have been well monitored by visual
observers. We need CCD observations to have better continuous
coverage of this star at quiescence.
2106-09 VY Aqr 8.0B-17.5B
Our visual observers Robert Modic, Roland Lebert, Francois Pineau,
and Michel Verdenet have been contributing a few visual observations,
and recently Steve O'Connor has been contributing some CCD
observations at around 16-17mag in V, but apart from these
observations, the quiescence level is made up of fainter-than
observations from visual observers. Positive CCD observations are
badly needed for this star. VY Aqr is overdue for an outburst - we
have not had an outburst since 1993! Please monitor it as closely as
you can during this season, both to determine the quiescence level and
to catch the next outburst.
2110+13 EF Peg 10.7V-18.5V
We have a few positive CCD observations from Ron Zissell, Roger
Diethelm, and Robert James, and a few visual observations from Dick
Stanton, but otherwise all of the observations are fainter-thans
during quiescence. The star's rare outbursts are well monitored by
visual observers. Better coverage and positive CCD observations are
badly needed at quiescence.
2125-03 VZ Aqr 11.3p-17.2p
Another CV in which the outbursts are well monitored by visual
observers, but except for recent CCD observations from Steve O'Connor,
quiescence is marked mainly by fainter-thans from visual observers.
Positive CCD observations are badly needed.
2325+43 DX And 11.0-16P (GCVS)
Another CV for which both the outbursts and quiescence are fairly
well monitored by visual observers. The minimum level reported by
visual observers around 14.5 is a bit brighter than those reported by
our CCD observers Roger Diethelm, Robert James, and Frank Schedere. We
need participation of more CCD observers. Please report the
comparison stars you are using to reduce your data for this and all
the other variable stars.
* * * * * * *
The complete paper is online at the URL below:
http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1996MNRAS.282.1211S&db_key=AST&high=3b4f1b442615845
Sproats, L. N.; Howell, S. B.; Mason, K. O. Monthly Notices of the
Royal Astronomical Society, Volume 282, Issue 4, pp. 1211-1222.
---------------------------------------------------------------------------
5. V1548 AQL (N AQL 01) CCD MULTI-COLOR LIGHTCURVE
Doug West (WJD) has been compiling a fantastic light curve for all
AAVSO CCD observations of V1445 AQL. It covers V,R, and I observations
from March to September, 2001. You can view the light curve at the URL
below:
http://www.aavso.org/ccdviews/v1548.shtml
---------------------------------------------------------------------------
6. FAINT LPV COMMENTS BY J.A.M.
The stars listed below are either at or around minimum at this time
and need the attention of our CCD observers. For quite a number of
the stars, the charts do not have faint enough comparison stars to
enable good visual estimates around minimum. However, our CCD
observers may be of great help in filling the gaps with their
observations.
It is very important for our CCD observers who are monitoring Mira
variables to use a V filter. Because these stars are quite red, the
magnitudes of observations made with unfiltered CCD are often very
much brighter than the stars actually are, and as such are very
misleading, especially when there are no other CCDV or visual
observations available for comparison. Several of the stars listed
below show these too-bright observations in their light curves. I
strongly urge observers using CCDs to obtain a V filter so that their
observations are compatible with visual observations and with CCDV
observations from other observers.
0044-35 X Scl <10.6-(14.2>
This Mira variable has been in need of observations badly since
1999, when the late Danie Overbeek stopped observing it. Because we
have received so few observations in the last two years it has been
very difficult to determine its behavior and to predict its maxima and
minima. I leave it in the hands of observers who can reach
declination -35 degrees to make the observations we badly need.
Presently it is fading to minimum, predicted for mid-December.
0120+20 RX Psc 9.5-(14.7
Due to observing gaps, there are large gaps in the light curve of
this star over the past several cycles, particularly around minimum.
The last maximum was a bit brighter than the previous three; presently
the star is fading towards minimum, predicted for the beginning of
November. We have 'd' and 'e' scale preliminary charts available for
monitoring this star this season.
0202+27 Z Tri 9.4-15.2
Observations are badly needed as this star slowly fades towards
minimum, predicted for late October. There are 'd' and 'e' scale
preliminary charts on which the sequence does not go faint enough to
cover the variable at minimum. We need our CCD observers' help to
provide better coverage throughout the forthcoming minimum.
0259+19 RT Ari 9.8-(15.0
The observations of this Mira have been sporadic, with some cycles
fairly well monitored around maximum, while minima have been poorly
monitored. We have 'd' and 'e' scale preliminary charts, but the
sequence does not go faint enough to cover the whole range of
variability of this star. Presently RT Ari is fading towards minimum,
predicted for the end of November. I leave this star in the hands of
our CCD observers to monitor it as it fades to minimum and through
minimum so we can obtain good coverage during this observing season.
0452+56 TX Cam 8.1-(15.3
The cycles following the bright cycle of 1996, when this star
reached magnitude 8.7, have been progressively fainter; the maxima of
the last two cycles have been around 11.4 and 11.2, respectively.
Together with the level of maximum, the level of minimum also appears
to be getting fainter, however, do not have enough observations to
determine what the level of minimum has been. Our thanks to our
observers who have alreaded provided some data this season as the star
faded to minimum, predicted for the end of August. Please continue
your efforts and monitor this star through minimum and as it slowly
brightens towards maximum, predicted for mid-2002. TX Cam is one of
the few Miras with a very long period, 557 days.
1626+23 DO Her 10.3-(16.0
The minima of DO Her have been poorly monitored for several cycles,
making it difficult to make good predictions of minimum dates and
determine brightnesses of minimum. Minimum is predicted for
mid-October. There are 'd' and 'e' scale standard charts available,
but the sequence is not adequate, particularly at the fainter end.
Whatever our CCD observers can do would be very much appreciated.
1708-33 RW Sco <9.6>-15.0
More observations are needed at every phase for this Mira variable,
particularly around minimum, predicted for mid-October. From the
little data we have, it looks as though the amplitude of the cycles
since 1996 has decreased quite a bit. However, to verify this, we
need more observations. There is a 'd' scale standard chart with not a
very adequate comparison star sequence that does not go faint enough,
but our CCD observers may be able to make observations so we may pin
down the minimum magnitude level and the amplitude.
1805+18 XZ Her 10.2-(15.5
We do not have any positive observations during minimum for the most
recent several cycles. This star is badly in need of positive
observations for the minimum predicted for this month. There are 'd'
and 'e' scale preliminary charts.
1814+06 AY Oph 10.4-(15.5
There is quite a bit of scatter around maximum of the most recent
cycle in 2001. The reason for this scatter may possibly be
non-homogeneity of the charts being used to observe AY Oph. We have
an 'e' scale preliminary chart on which the sequence does not go faint
enough. Again, we ask the help of our CCD observers in monitoring
this star around minimum, predicted for early October.
1850+32 RX Lyr <11.9-(15.5>
The last two maxima of this Mira have been rather faint, 12.2 and
12.5, respectively, and there is quite a bit of scatter in the data
around maximum. There are no positive observations during minimum for
the past several cycles, although we have quite a number of
fainter-than observations. CCD observers can really contribute during
its current minimum, predicted for late October. There are 'd' and 'e'
scale standard charts and an 'f' scale preliminary chart. An extra
bonus in observing this star is that the Ring Nebula is very close by,
in fact, for most observers it is in the same field of view (to the
northwest of RX Lyr).
1913-21 Z Sgr <8.6-16.0>
The last three maxima of this star have been progressively fainter,
following the normal one in 1997 in which the maximum was about 8.7,
at 10.3, 10.9, and 11.0, respectively. Several minima have been in
need of positive observations. Presently, the star is fading towards
minimum, predicted for mid-December. There are 'b' and 'd' scale
standard charts, but the comparison star sequence does not go faint
enough to cover the minimum adequately. Thus, the help of CCD
observers is badly needed in determining the brightness of minimum at
this time.
1913-31 SW Sgr <10.0-(13.4>
This Mira variable has been poorly monitored since the late Danie
Overbeek stopped observing it in late 1999. More observations are
needed at every phase. We have a very inadequate 'd' scale standard
chart that does not go faint enough to cover the star's minimum. We
ask our CCD observers to do whatever is possible to provide better
coverage for this star, particularly around minimum.
2104+05 RR Equ 9.2-15.6
The current maximum, at mean magnitude about 10.8, is about one
magnitude fainter than the previous one. The minimum of this star has
not been well monitored for several cycles. The star is fading
towards minimum, predicted for early November. There is a 'd' scale
preliminary chart.
2351-50 R Phe <8.0-14.1>
More observations are needed badly throughout the current cycle,
particularly as the star fades towards minimum, predicted for
mid-November. We have a very inadequate 'd' scale standard chart on
which the comparison stars do not go faint enough to cover the star at
minimum. We depend on our CCD observers to help obtain more positive
observations at this time as the star fades towards minimum.
2352-65 R Tuc <9.8-15.1>
This southern variable is in dire need of more observations at all
phases of variability. It has been extremely difficult to predict its
dates of maxima and minima in recent years. Presently it is slowly
fading towards minimum, predicted for mid-November. We have a 'd'
scale standard chart that does not go faint enough to cover the
variable at minimum. We bring R Tuc to the attention of our southern
hemisphere observers, and ask you please to obtain more of the
positive observations that are so badly needed.
Thanks to the following observers for submitting 46 CCD observations
on six of the twelve LPVs listed in the last issue of CCD Views: WRX
(18), JM (11), PAH (7), SFK (4), MDA (2), OFA (2), MDW (1), WGR (1).
Keep the observations coming!
---------------------------------------------------------------------------
7. NEW WEB PAGE: MAGNITUDE ZERO POINTS
In JAAVSO Volume 26, Number 2 (1998) Ron Zissell published an
article titled "Evolution of the 'Real' Visual Magnitude System". Included
that article is an excellent reference and discussion for those
interested in understanding zero points. The article can be viewed
online at the URLs below:
Zero point discussion in HTML:
http://www.aavso.org/committees/zeropoint.shtml
Complete article in PDF format:
http://www.aavso.org/journal/v26n2/zissell.pdf
Complete scanned article via ADS:
http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1998JAVSO..26..151Z
---------------------------------------------------------------------------
8. LETTER: FREE PHOTOMETRY TEXTBOOK IN PDF FORMAT
Dr. William Romanishin, Department of Physics and Astronomy at
the University of Oklahoma, has contacted us about an excellent resource
he has placed online for those interested in photometry. Everyone we know
who has used this textbook has raved about it. His e-mail is below:
"I am developing a textbook for doing photometry with CCDs. I use this
in a course I teach for astro majors here at the University of Oklahoma.
I am making the book available free of charge to anyone who wants it (in
.pdf format). To find the pdf file, go to http://observatory.ou.edu and
follow the link at the bottom of the page.
Any questions, just email me - wjr@mail.nhn.ou.edu
Bill Romanishin"
---------------------------------------------------------------------------
9. CCD OBSERVING TOTALS FOR AUGUST - SEPTEMBER, 2001
Total Observer Location
5628 SDB STARKEY, DONN RAY IN, AUBURN
3211 COO COOK, LEWIS M. CA, CONCORD
1807 OAR OKSANEN, ARTO FINLAND, MUURAME
1502 PCH PULLEN, CHARLES CA, WILTON
690 HTY HAGER, TIMOTHY CT, NEW MILFORD
665 MMF MOILANEN, MARKO FINLAND,
588 JM JAMES, ROBERT A. NM, LAS CRUCES
537 GKA GRAHAM, KEITH A. IL, MANHATTEN
501 ZRE ZISSELL, RONALD E. MA, SOUTH HADLEY
343 HHT HYVONEN, HARRI T. FINLAND, JYVASKYLA
297 DRG DIETHELM, ROGER SWITZERLAND, RODERSDORF
240 WJD WEST, JERRY DOUG KS, MULVANE
139 WGR WALKER, GARY MA, SHERBORN
135 GOH GOLBASI, ORHAN TURKEY, TUBITAK OBSERVAT
97 OFA O'FEARGHAIL, AENGUS IRELAND, DUNSHAUGHLIN
97 OCN O'CONNOR, STEPHEN D. CANADA, NORTH MONTREAL
90 PAH PRICE, AARON MA, WATERTOWN
54 MTK MICHALIK, TOM VA, LYNCHBURG
34 MDW MACDONALD II, WALTER J. CANADA, OSHAWA ONT.
33 HDU HURDIS, DAVE RI, NARRAGANSETT
31 WRX WILLIAMS, ROGER MI, KALAMAZOO
29 PCH PULLEN, CHARLES CA, WILTON
19 SFK SCHEDER, FRANK L. MD, LEONARDTOWN
7 MDA MORTON, ART WA, EDMONDS
6 RR ROYER, RONALD E. CA, LAKEWOOD
5 FGI FAVERO, GIANCARLO ITALY, PADOVA
3 RIX RICHARDS, THOMAS J. AUSTRALIA, ELTHAM, VICTORIA
2 TOA TOTH, ALEXANDER HUNGARY, BUDAPEST
2 MHE MAIER, HARALD GERMANY, MUNICH
2 LIW LILLER, WILLIAM CHILE, VINA DEL MAR
1 MTM MATTEI, MICHAEL MA, LITTLETON
1 CRI CASAS, RICARD SPAIN, BARCELONA
CCDPOINTS ARE COMING...
As you can tell, CCD totals are now dominated by those who perform
high speed photometry. However, some stars do not require such large
volumes of observations. We did not want to make observers of those
stars feel left out. So in the next issue of CCDViews we will be using
a system of awarding points to CCD observers based on a large
number of factors which will be kept super secret! In fact, we will
give a HOA t-shirt to the first person who can correctly reproduce
this formula! So keep observing and look forward to the December
edition of CCDViews.
---------------------------------------------------------------------------
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
---------------------------------------------------------------------------
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
----------------------------------------------------------------------------
|
