|
|
|
|
CCD Views Vol. 3 No. 2
---------------------------------------------------------------------------
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
-------------------------
April, 2002 Vol 3 No 2
Table of Contents
-----------------
1. Introduction: Last Call for Filters
2. V838 Mon Update: Light Echoes and Future Activity
3. CCD Spectrophotometry
4. SN 2002ap Data Request & Update
5. Tips for Finding the Field
6. New CCD Charts
7. CCD Points
---------------------------------------------------------------------------
1. INTRODUCTION: LAST CALL FOR FILTERS
We have noticed that many observers are still making estimates of
variables without using a proper photometric filter. These estimates
are not of much value when combined with other observations in our
database since CCDs respond to light differently when unfiltered. The
AAVSO has a small grant to load filters to observers. If you would
like a V or R filter please fill out and send the form below to
aavso@aavso.org. In one week we will place all the orders collected
over the past 3 months. So act now and get a filter!
Don't forget the upcoming 91st Spring Meeting of the AAVSO and the 2nd
High-Energy Astrophysics Workshop for Amateur Astronomers. Talks on CCD
photometry along with cataclysmic variable and GRB workshops are calling
your name. Find out more at: http://www.aavso.org/meetings/spring02.stm
Also, we will most likely be issuing a special edition of CCD Views
in May with comments from J.A.M. on many long period variables. So
stay tuned!
Aaron Price (PAH) Gary Walker
AAVSO Headquarters CCD Committee Chair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
CCD V & R FILTER REQUEST FORM
Name:
Observer Code:
Full Mailing Address:
Telephone Number:
CCD:
What size filter do you need?:
Which filter(s) do you need? (V, R, or both):
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
---------------------------------------------------------------------------
2. V838 MON UPDATE: LIGHT ECHOES AND FUTURE ACTIVITY
The initial outburst of V838 Mon appears to be acting as a
flashlight illuminating its stellar neighborhood. As the light from
the outburst continues to expand, it is reflecting off material shed
over the past few millenia. This interaction is creating a halo of
brightness around the star that can be seen in a striking U-band image
taken by M. Schwartz of Tenagra Observatory, found at the URL:
http://www.aavso.org/ccdviews/v838monlightecho.shtml
It was suggested by A. Henden et. al. in IAUC 7859 that this "light
echo" is the result of energy from the initial January 1 outburst of
the star interacting with a circumstellar shell of material released
over the past few thousand years. If so, when the bright light from
the February 2nd outburst reaches the material we should see another
light echo, except this one may be quite a bit brighter (due to the
brighter nature of the 2nd outburst).
As the wavelengths increase across the B, V, R, and I photometric
bands the light echo becomes harder to see. This could be a result of
the inherent red color of the star, the fact that dust tends to
reflect blue light more than red, or a combination of the two.
If the 2nd outburst does indeed create a 2nd brighter echo then this
could be a rare opportunity for amateurs to do some multi-colored
photometry on a circumstellar shell. If this happens, the AAVSO will
publish comp stars to use in the B, R, and I bands as well. So keep
your filters handy and stay alert!
---------------------------------------------------------------------------
3. SN 2002AP DATA REQUEST & UPDATE
Now that SN 2002ap is hidden in the glare of the Sun it is time to
turn to data reduction. We are planning to publish SN 2002ap data in
May so for this month we would like to process and finalize the data.
As mentioned in the original announcements, we would like to collect
copies of your FITS images used in your observations. Please FTP them
to the location below:
host: ftp.aavso.org
user: ftp
password: your e-mail address
directory: upload/public/sn2002ap
NOTE: Make sure we can tell your filename from someone else's. One way
is to put your observer code somewhere in the filename. Example
for observer XXX: sn2002ap-XXX-1.fits, sn2002ap-XXX-2.fits ...
Either in the FITS headers (preferably) or in a separate text file,
give us all the information you can about your observations. This
includes name, date and time (UT), geographic location, filter, CCD,
telescope, and anything else pertinent (weather, glare, etc.).
Also, if you have made observations using a chart other than the
final one released on February 8th, please update your observations.
You can find that chart at http://www.aavso.org/charts/PSC/SN2002AP/ .
Simply resubmit the observations with the new estimate and then e-mail
aavso@aavso.org when done and we will remove the older duplicate
observation.
Remember our goal with this project was to collect the very best
data we can. We would like to share this data (both the light curves
and the FITS files) with the professional community to show them what
our capabilities are and see if there is an opportunity for future
supernova collaborations. So please reduce your data carefully and do
the best job possible!
As we process your data we will send you an individual e-mail
confirming receipt of your data and with a progress update. Please
send your data _as soon as possible_ because it will take us
considerable time to work through it all.
For those who are doing photometry in R and I, here are the color
values of the comp stars on the aforementioned chart.
Comp V-R R-I V-Rerr R-Ierr
117 0.616 0.532 0.013 0.011
129 0.390 0.352 0.011 0.009
130 0.443 0.470 0.012 0.009
137 0.363 0.365 0.016 0.009
139 0.496 0.477 0.013 0.015
144 0.411 0.384 0.006 0.017
146 0.338 0.360 0.021 0.012
151 0.371 0.375 0.007 0.023
156 0.479 0.434 0.024 0.026
159 0.435 0.403 0.037 0.073
163 0.429 0.369 0.059 0.123
168 0.289 0.328 0.070 0.018
171 0.433 0.401 -0.012 -0.014
This data is courtesy A. Henden (USNO) and is available in its
entirety at ftp://ftp.nofs.navy.mil/pub/outgoing/aah/sequence/ .
---------------------------------------------------------------------------
4. CCD SPECTROPHOTOMETRY
By Doug West (WJD)
The proliferation of the use of CCD cameras by amateur astronomers
has brought us the ability to image objects much fainter than was
possible just 15 years ago. One of the latest developments is the use
of the CCD camera and a diffraction grating to measure the spectra of
stars. Low resolution spectrophotometry can tell the effective
temperature, spectral type, and gives information about the chemical
composition of the star.
My involvement with CCD spectroscopy started about three years ago
when I developed an amateur-professional relationship with Dr. David
Alexander at Wichita State University. Dr. Alexander is interested in
the study of cool giant type stars, for example, mu Gem and W Cyg. I
was able to contribute to the research with multi-band photometry
(BVRI) and through low resolution spectrophotmetry. In June 2000 I
gave a poster presentation at the American Astronomical Society
(http://www.aavso.org/ccdviews/spectropresentation.ppt). This
presentation has information about what low resolution spectrophotmetry
can tell us about the stars and what is required to get started in CCD
spectroscopy.
There are several web sites that have information about taking the
spectra of stars. Two sites that I have found very useful are
http://www.astroman.fsnet.co.uk/ and
http://users.erols.com/njastro/faas/ .
---------------------------------------------------------------------------
5. TIPS FOR FINDING THE FIELD
By Gary Walker, CCD Committee Chair
Here is a tip that I wanted to pass on to our ccd observers,
particularly those just getting started. Finding the fields has always
been a challenge. I have used high power finders in the past but found
that they also have their problems.
What I have discovered fairly recently, is that with a well aligned
7x50 finder, I am able to put a star on the center of the chip every
time. The trick is to use your usual proceedure to center a star on
your ccd. Now look thru your finder. You will probably find that the
bright star is not in the center of the cross hairs. What I have done
is reset the finder so that the bright star is exactly in the center of
the crosshairs. Now you should be able to put any other star in the
center of your chip.
To give everyone some scale, I use a 7x50 finder which has a 6 degree
field--this is pretty standard. My chip and scope give a 12 arc minute
field, which is typical for ccd photometry. Another requirement is to
mount the camera, and not rotate it after you have set the finder. It
turns out that many cameras do not exactly center their chips, so if you
rotate the camera to pick up a new guide star, the center of the finder
and the center of the chip, may not coincide any more.
As a result, I have chosen to fix the camera, with ra going left and
right and dec going up and down on the display. I never move the
camera. I align the finder scope so that a star centered in it will be
on the center of the chip. This is done in two steps. First I point
the scope using the finder cross hairs, then I look on the monitor using
the focus function, and move the scope until the star is right in the
center. I usually have less that 2 arc minutes of error. The second
step is to go back and align the finder exactly. I usually have to
realign the finder only once a season. It stays pretty well. This
means that your finder may not be exactly aligned when you use your
eyepieces, but I find this an acceptable trade off. This also assumes
that you have solved the mirror flop with focusing problem that affects
most moving primary mirror optical systems. I am also fortunate enough
to have a permanent setup, so the finder does not get tweaked during
transit.
So if you have been ignoring your finder, as I have for many years,
and you have a field near 12 arc minutes on your ccd, this technique may
make centering a field much simpler.
---------------------------------------------------------------------------
6. NEW CCD CHARTS
We recently put on-line 239 new charts for 84 variable stars. Of
these, 35 of the stars were already in the AAVSO observing program and
we made new and expanded scales available. The other 49 stars have been
in the AAVSO program but did not have published AAVSO charts until now.
Most of the stars are faint with e and f-scale charts. The e-scale
charts were based on the USNOA2 and Tycho-2 catalogs and the f-scale
charts use DSS images. For most of the f-scale charts we have been able
to include CCD tables with comparison star magnitudes typically to 0.02
magnitude accuracy and B-V color data.
More information on these new charts including a list of the stars
can be found at this new web page: /observing/charts/hs.shtml .
The selection of comparison stars in each field are made and
contributed by Bruce Sumner and the CCD V and B photometry are from
Arne Henden. The AAVSO thanks Arne and Bruce for their valuable
contribution to this project.
The charts were created by Mike Simonsen and Aaron Price in most
cases using the computer program developed at AAVSO headquarters by
George Hawkins. Please send any comments on or about the charts to
charts@aavso.org.
---------------------------------------------------------------------------
7. CCD POINTS
Wow. In the last issue we had 36 individual CCD observers, now we
have 53! This field is really beginning to take off. For those of you
who are new, feel free to send questions to aavso@aavso.org or
post to the AAVSO Discussion Group. And keep up the great work!
I know I promised a running total in this issue but I lied. Time
constraints reared its ugly head. We'll shoot for the next issue.
As always, remember that CCD Points are for *fun only* and serve
no official AAVSO purpose and are not recorded anywhere other than CCD
Views. In fact, I spend more time checking the locations of observers
in the list than I do checking the point totals! :)
Pts Obs Who Where
2061 929 OAR OKSANEN, ARTO FINLAND, MUURAME
1024 231 DRG DIETHELM, ROGER SWITZERLAND, RODERSDORF
492 131 GKA GRAHAM, KEITH A. IL, MANHATTEN
455 153 WJD WEST, JERRY DOUG KS, MULVANE
405 350 NLX NELSON, PETER AUSTRALIA, ELLINBANK
403 142 WGR WALKER, GARY MA, SHERBORN
357 141 COO COOK, LEWIS M. CA, CONCORD
306 121 ZRE ZISSELL, RONALD E. MA, SOUTH HADLEY
303 77 SFK SCHEDER, FRANK L. MD, LEONARDTOWN
186 99 MTK MICHALIK, TOM VA, LYNCHBURG
163 21 NMI NICHOLAS, MIKE AZ, GLENDALE
160 60 AWJ AQUINO, WILLIAM JOHN NY, WHEATFIELD
159 49 GBL GARY, BRUCE L. CA, SANTA BARBARA
153 22 ARJ ARNOLD, JAMES TX, DAINGERFIELD
150 188 AMI AHO, MIKA FINLAND, KORPILAHTI
141 53 KDM KLINGLESMITH, DANIEL A. NM, SOCORRO
135 123 KMP KOPPELMAN, MICHAEL MN, GOLDEN VALLEY
134 22 PCH PULLEN, CHARLES CA, WILTON
128 154 SDB STARKEY, DONN RAY IN, AUBURN
126 RIX RICHARDS, THOMAS J. AUSTRALIA, ELTHAM, VI
115 47 SYZ SANCHEZ, CRISTINA SPAIN, GIJON-ASTURIAS
113 465 RCW ROBERTSON, CHARLES W. KS, GODDARD
75 HDU HURDIS, DAVE RI, NARRAGANSETT
62 RGY RUBRIGHT, GARY PA, LANCASTER
60 RZD RODRIGUEZ, DIEGO SPAIN, VILLALBA, MADR
49 MMN MARTIGNONI, MASSIMILIANO ITALY, MILAN
46 SHB SHERROD, CLAY AR, NORTH LITTLE ROCK
44 VWA VAN WERVEN, ARNO FL, PLANTATION
42 WJL WILLIAMS, JAMES L. CA, STOCKTON
36 BVJ BARENTINE, JOHN NM, SUNSPOT
35 HOU01HOETTE, VIVIAN WI (YERKES)
33 GTN GANDET, THOM AZ, TUCSON
33 PAH PRICE, AARON MA, WATERTOWN
33 RSE ROBINSON, STEPHEN E. MD, ROCKVILLE
22 UMB01TITTLEY, ERIC MD (UNIV MARYLAND)
22 RVM RIGO VIDAL, MIQUEL SPAIN, MALLORCA
21 GFB GOFF, WILLIAM CA, SUTTER CREEK
21 OCN O'CONNOR, STEPHEN D. CANADA, MONTREAL, QUE
21 RVM RIGO VIDAL, MIQUEL SPAIN, MALLORCA
20 SBS BREWSTER, STEPHEN CA (ORIG. SINGER-BREW
20 MLF MONARD,LIBERT A.G.(BERTO)SOUTH AFRICA, PRETORIA
19 KZX KERESZTY, ZSOLT HUNGARY, MISKOLC
18 KDA KAISER, DANIEL H. IN, COLUMBUS
14 CRI CASAS, RICARD SPAIN, BARCELONA
18 KDA KAISER, DANIEL H. IN, COLUMBUS
14 CRI CASAS, RICARD SPAIN, BARCELONA
12 TPE TIKKANEN, PETRI FINLAND, JYVASKYLA
12 BJS BEDIENT, JAMES R. HI, HONOLULU
12 GAJ GARCIA, JAMIE RUEBEN ARGENTINA, B.A. LI
12 MTT MATTEI, JANET AKYUZ MA, LITTLETON
10 MHE MAIER, HARALD GERMANY, MUNICH
10 AMI AHO, MIKA FINLAND, KORPILAHTI
Observations less than 20 are withheld from view in order to protect
our super-duper-secret point formula.
---------------------------------------------------------------------------
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 2002, 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
----------------------------------------------------------------------------
|
