[vsnet-chat 5522] (fwd) Re: RU Peg- the tip of the iceberg

[Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>]

From: Robert J Stine <bobstine@earthlink.net>
Subject: Re: [AAVSO-DIS] RU Peg- the tip of the iceberg
Date: Thu, 19 Sep 2002 21:30:37 -0700

Greetings All,

Though I'm a relative new and inexperienced member of AAVSO, I feel compelled to
weigh in on this one.

Rejoining AAVSO in 2000, after a 37 year hiatus, was as though I had gone
through a time warp.  I was thrilled to find that charts could now be downloaded
from the web and observations could be likewise uploaded.  Coupling that with
the fact that I was able to buy, off the shelf, a large aperture digital
telescope (unimaginable in my youth)  that lets me locate stars in my light
polluted and very horizon-restricted locale meant that I was in the VSO
business, right from my own backyard!  I began building an observing program
that now includes 500 variables, mostly LPVs from the Bulletin.  And I've spent
a lot of time (by my humble standards) at the eypiece using the charts.

Some of those charts are great and some are awful.

So here's this new guy's opinion: we need to fix the awful charts and get them
distributed.  If they are already fixed, but are sitting on a shelf somewhere,
then they need to be dislodged and distributed.  And we need to do it *NOW*.

The great charts have three characteristics that I've noticed.  The first is
that they have "star dot" sizes that appear proportional to what I see in the
eyepiece.  Bright stars have nice big dots.  Fainter stars have little dots.
And, likewise, all the dots in between appear like the stars they represent.
The second characteristic is that the comparison stars seem to make sense to my
eye.  If one comp is 10.2 and the other is 10.7, then, by golly, the 10.7 looks
fainter than the 10.2!  Period.  And that's how it should be because I'm using
an unfiltered carbon unit eyeball, not an electronic detector or film.  The
third characteristic of the great charts is that they appear to have been made
by an automated method within the last ten years.  The great charts are a joy to
use and they greatly facilitate locating and estimating the variable.

The awful charts are the antithesis of the great charts.  The worst of them have
dots that all appear the be the same size, irrespective of brightness, and the
magnitude numbers confuse and clutter the field.  the clutter and confusion is
exacerbated by the inclusion of coordinate grid lines plow through the star
field like Peterbilts and squash stars like road kill.  Sorting all that out in
the dark with a red flashlight is unpleasant and frustrating.  And often the
10.7 comp appears brighter than the 10.2 in an awful chart!  And, yes, these
charts are often the older charts.  The awful charts are awful to use.
Sometimes they even make me - well, let's just say, to keep this epistle "G"
rated - *irritated*.

Between "great" and "awful" are all kinds of charts with some good and some bad,
such as great looking star dots but terrible comp star sequences.

I don't want to use awful charts any longer than I have to.  It's true: they
beat nothin'.  But not by much.

Ya know, I've spent literally hundreds of hours these past two years reversing
charts, some of them 70 years old, so that I can VSO with my SCT.   I don't care
if a chart is old, just as long as it's good.  If there are better charts out
there, then I want them, and I want them NOW!  I'd much rather be at the eypiece
than the keyboard.  And when I am at the eyepiece, I want my estimates to be as
accurate as they can be and I want the accuracy-limiting factor to be my
eyeballs, not erroneous comp stars.  It just frosts me when I think of the time
I've spent hunced over the eyepiece trying to decide between a tenth of a
magnitude, when it's possible that the comp stars I was using might be in error
by many times that amount!

Now I don't know anything about the issue of the sanctity of the AAVSO
database.  But it seems to me that data in any database can be no better than
the standards used to generate the data.  Comp stars are our standards.  If we
are retaining erroneous comp star sequences for the sake of continuity and
consistency, will we not then just end up with consistently erroneous data?  And
what good is that?

Bob Stine (SRB)





Mike Simonsen wrote:

> August 22, 2002 the AAVSO released a number of new and improved charts. This
> was announced on the website and in the new email list, charts-announce.
> Observers were emphatically urged to update to these charts.
>
> The first one on the list was RU Peg, which has just been reported, albeit
> uncertainly, to be in outburst.
>
> Following HQ's advise, I began to download the new charts. After printing
> the first one, RU Peg, I noticed immediately that something was wrong with
> the sequence. I had been personally involved in creating a new sequence for
> this star with Arne Henden and Bruce Sumner in September and October of
> 2001.
>
> Several of the comp stars in the SE quadrant of this new chart are
> erroneous. They are, in fact, equivalent to rough estimates I supplied in a
> message to Arne describing why this section of the sky probably held stars
> that would fill annoying gaps in the sequence. Dr. Henden obliged with
> additional photometry in this area, which did address the gaps in the
> sequence.
>
> I notified headquarters and Dr. Henden on August 28, 2002 of the errors on
> the newly released chart, and supplied them with the correct sequence
> information documented by Bruce Sumner.
>
> Thus far, headquarters' response has been to remove A. Henden's name from
> the sequence field, but to keep the wrong sequence on the chart!?
> The "official policy" is not to revise any sequence without specific
> approval from the director.
>
> It has been several weeks now, and several emails, since they decided the
> sequence was wrong and removed Arne's name from it to appease the world's
> leading photometrist.
>
> I find it hard to believe that Marc Beismans and Charles Scovil have not
> already made revised charts (standard and reversed) with the correct
> information, once they were notified of the errors.
>
> I have corresponded with the observer who made the "uncertain" observations
> of RU Peg in outburst, and he has confirmed the fact that the sequence was
> the problem with his making a positive/certain estimate visually.
>
> There is no good argument for not having already fixed this mess.
>
> This is an unacceptable situation for a scientific organization.
>
> Unfortunately, it is endemic of a pervasive problem in the AAVSO; the
> reticence to update, upgrade or change charts or sequences because of the
> negative impact it would have on the AAVSO database; and the limited time
> and resources available to the one person who can ultimately approve the
> changes.
>
> For those of you who wish to make accurate visual or CCD measures of this
> star (RU Peg), a CCD(V) sequence in text form is available at:
> http://ftp.nofs.navy.mil/pub/outgoing/aah/sequence/sumner/
>
> Mike Simonsen
>
> _______________________________________________
> aavso-discussion mailing list
> aavso-discussion@mailman.McMaster.CA
> http://mailman.McMaster.CA/mailman/listinfo/aavso-discussion



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