Table of Contents
-----------------
1. Introduction
2. Address from the New AAVSO Director, Arne Henden
3. VV Pup Mini Campaign In Support for Keck Observations
4. CCD Timing Recommendations and Pitfalls
5. The Recent BZ UMa Outburst Campaign
6. High Precision Photometry Workshop at AAVSO Spring Meeting
7. Infrared Filter Grants Available
8. New Scintillation and Airmass Calculators on AAVSO Web Site
--------------------------------------------------------------------------
1. INTRODUCTION
In the last few months our CCD program has been very active. Campaigns
have been run on CVs, blazars and exoplanet transit objects. In fact,
we've had so many campaigns that we created a web page to keep track
of it all:
http://www.aavso.org/news/campaigns.shtml
The page includes a timeline of all our active campaigns along with
those in the recent past and upcoming campaigns. When planning the next
few days of observation we recommend stopping by that page for new
projects.
We opened the AAVSO Chat Room during the BZ UMa campaign to test its
usefulness as a coordination mechanism. It seemed to be very popular
with people logged in almost all the time during the entire week of the
outburst. While the chat room is open to the public every Thursday, we plan
to open it for longer periods during future campaigns.
The AAVSO Photometry Discussion Group has also been active with
discussion about other types of campaigns and how often we should run
them. The response I gathered from the discussion was: Bring it on! It
seemed that the only limiting factor in observing activity is weather.
So be careful what you ask for, you just may get it. :) Stay tuned for
a very exciting and eventful 2005! And it doesn't hurt that we now have
one of the world's best photometrists ON STAFF! (see below)
Clear skies,
Aaron
--------------------------------------------------------------------------
2. ADDRESS FROM THE NEW AAVSO DIRECTOR, DR. ARNE HENDEN
Obviously, I come from a technical background and welcome the
rapid increase in quality of both telescopes and CCD cameras in the
commercial world. The US$1000 barrier for CCD cameras has been
broken by several vendors, CMOS cameras are just around the bend, and
I forsee the day when cameras are given away like eyepieces with
every telescope purchase. We see amateurs obtaining millimag
precision; others imaging GRB afterglows at 21st magnitude. I think
one of the roles of the AAVSO will be to provide instruction, through
tutorials and workshops, so that amateurs and professionals alike can
learn how to obtain scientifically usable data.
We will always have visual observers in the AAVSO - they are the
life and blood of the organization. The century-long timeseries on
Miras and other variables, the dense coverage on CV outbursts, are
all suited to visual studies. CCD observers expand on this base and
attack other problems - very low amplitude variables, targets where
color information is important, high time resolution, etc. Our goal
in the AAVSO should be to support all observers, no matter what
technique they use to obtain their data, in such a way as to get the
highest possible precision and maximal scientific content.
CCD observing is still in its amateur infancy. We will be running
more pro-am campaigns to show both professionals and amateurs what
can be done with this photometric technique, and will pursue new
directions such as whole-earth 24-hour campaigns, exoplanet transits,
quiescent studies of cataclysmic variables and ground-based support
for high-energy space missions. It is going to be a fun future!
- Dr. Arne Henden
---------------------------------------------------------------------------
3. VV PUP CAMPAIGN IN SUPPORT OF KECK OBSERVATIONS
Dr. Steve Howell, WIYN Observatory & NOAO, has requested
observations of the polar VV Pup to coincide with observations being
done at the Keck Observatory on February 16, 2005 (UT).
Time series observations for as long as possible in BVRI are
requested from 00:00 UT February 15 - 23:00 UT February 17, 2005.
VV Pup is quite faint and also near the quarter Moon during the
observing window. So we recommend the following observing plan:
1) Observe it in one filter instead of alternating between
filters. Set your exposure time to get an SNR > 20. You may need to
stack images to reach this SNR.
2) Small and moderately sized telescopes should observe in Ic
first and in Rc if you don't have an Ic filter or someone else is
currently observing in Ic. This will lessen some of the effects of
the Moon and also lower exposure time (this is a field with heavy
extinction). Those with larger apertures should go for V and B
photometry.
3) Post to the aavso-photometry discussion group and tell us what
filter you are using and the expected start and end time of your
observation run. This way someone else can use a different filter if
they are observing at the same time.
We currently have very few observations of VV Pup. So baseline
observations prior to and immediately after the observing campaign
would be very useful.
The AAVSO Chat Room will be open for this event! Join us during
the campaign at http://www.aavso.org/aavso/chat.shtml .
The VV Pup chart is here:
http://www.aavso.org/cgi-bin/searchcharts3.pl?name=vv%20pup
Our observations of VV Pup are minuscule!! We desperately need
some photometry. Our latest observations of VV Pup:
VV PUP JAN 01.4960 <15.3 SRX Visual
VV PUP DEC 31.8280 17.2 CCD MLF Unfiltered
VV PUP DEC 28.4424 16.305 CCDI CTX ERR: .03
VV PUP DEC 23.4785 18.38 CCDV CTX ERR: .027
SRX - Rod Stubbing, Australia
CTX - Tim Crawford, Oregon, USA
MLF - Berto Monard, South Africa
---------------------------------------------------------------------------
4. CCD TIMING RECOMMENDATIONS & PITFALLS
There are two main sources of error when it comes to CCD image
timing. The first source is the accuracy of your computer clock. We
recommend that you sync your clock with either WWV via a short wave
radio or use one of the US Naval Observatory's NTP Internet servers:
tick.usno.navy.mil
tock.usno.navy.mil
Many deluxe GPS systems can now be purchased with an interface to
your computer which will update your system clock with the GPS
signal.
Regardless of the system you use, please update your clock before
*each* observing run.
Another source of error is in unknown recording of the time into
the FITS header by your camera control software, especially when
stacking images. It has been reported that some software records the
time of the first image, the last image, an average of the images,
etc. What should be reported to the AAVSO is the midpoint of the
observation.
At the URL below I have put online 4 FITS images.
http://www.aavso.org/tmp/fits.zip (~7MB)
Please download the four images and stack them in your software.
Post to the AAVSO Photometry Discussion Group (or e-mail me if not
subscribed) the time that your software recorded in the final image.
Send us:
1. Software Name
2. Software Version (usually found in the "About" menu)
3. Time listed in the FITS header of the stacked image.
In the next issue of CCD Views I'll post a list of the various
software packages and how they handle the timing of stacked images.
We will use that to recommend ways to compensate for the
peculiarities of various photometry packages.
---------------------------------------------------------------------------
5. THE RECENT BZ UMA OUTBURST CAMPAIGN
BZ UMa went into outburst again on January 16, 2005. The AAVSO
commenced a high intensity observing campaign for the duration of
this short outburst (~5 days). AAVSO observers did a fantastic job
building a solid light curve with complete coverage for almost 24
hours when the outburst peaked. The light curve, data and notes on
the outburst can be found here:
http://www.aavso.org/news/bzuma2.shtml
This outburst follows on a campaign the AAVSO conducted on a BZ
UMa outburst in February, 2004 which resulted in an IBVS publication.
A subsequent quiescence campaign was conducted in April with
inconclusive results. We hope the addition of this new, large and
high quality data set will help shed light on this enigmatic system,
which is yet to be classified. We will be working with the data in
the coming weeks and will post updates to the aavso-photometry
discussion group. So far superhumps are still missing but some
interesting features in the decline may give us a few clues.
---------------------------------------------------------------------------
6. HIGH PRECISION PHOTOMETRY WORKSHOP AT AAVSO SPRING MEETING
Arne will be holding a high precision photometry workshop at the
upcoming 3rd High Energy Astrophysics Workshop for Amateur
Astronomers being held alongside the AAVSO 94th Spring Meeting. The
goal of this workshop is to follow up on previous workshops at AAVSO
meetings with a more advanced program focusing on high precision
photometry of faint objects. The additional training is important as
we expand into fainter categories of stars (blazars, quiescent CV
photometry) and stars that need ultra high precision photometry
(exoplanet transits).
Also, during the AAVSO paper session an introduction to IRAF will
be presented which we hope will lay the groundwork for an IRAF
workshop at the AAVSO Annual Meeting in October.
A limited number of travel grants are available for meeting
attendees. Visit the following URL to apply:
http://www.aavso.org/aavso/meetings/hea-app.shtml
P/S: Arne and Brian Warner will be giving a workshop about using
Canopus software for photometry on May 24, 2005 in Big Bear, CA.
This workshop is not affiliated at all with the AAVSO but many AAVSO
observers do use Canopus. For more info visit:
http://www.minorplanetobserver.com/htms/PhotometryWorkshop.htm
---------------------------------------------------------------------------
7. INFRARED FILTER GRANTS AVAILABLE
The AAVSO has received a generous grant from the Curry Foundation
to purchase CCD filters for use by members of the AAVSO International
High Energy Network. We have 15 Iz (SDSS z') and 10 Ic filters
available for semi-permanent loan.
The Iz filters are intended for use in GRB afterglow hunting. The
Ic filters are intended for use in monitoring blazars for the High
Energy Network but can also be used for other variable star projects.
If you would like to receive one of these filters please fill out
the application at the URL below.
http://www.aavso.org/observing/programs/hen/filtergrant.shtml
---------------------------------------------------------------------------
8. NEW SCINTILLATION & AIRMASS CALCULATORS ONLINE
We have put online a tool to automatically do airmass and
scintillation calculations for you. It can be accessed at this URL:
http://www.aavso.org/observing/programs/ccd/airmass.shtml
The results page will give you the airmass of an object and
(optionally) the scintillation. The computation is a rough
approximation but should be good enough for most photometry
calculations. A table of projected airmass and scintillation for the
next ten hours is also displayed. The algorithms used for both
approximations are referenced at the bottom of the results page.
---------------------------------------------------------------------------
CCD Views is published when circumstances warrant via e-mail. An archive
is available at http://www.aavso.org/publications/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. To learn more and
subscribe visit: http://www.aavso.org/publications/email/
Good observing!
Aaron Price, AAVSO Technical Assistant (PAH)
Gary Walker, Chairman of the AAVSO CCD Committee (WGR)
Copyright 2005, 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
----------------------------------------------------------------------------