[Aavso-photometry] RE: [AAVSO-DIS] RE: AAVSO special notice 5 object

[arne]

The submission method as described by Aaron is fine for now.  Note that
this is a way in which you can submit *any* differential photometry, by
either using a reasonable guess for the comp star magnitude, or else
just setting it equal to zero and submitting the raw differential data.
I don't recommend the latter since our staff looks at the data and having
differential data (say, +/- 1 mag) show up on the same screen as the
regular magnitudes (say 12-14mag) throws off the display scaling.

If you don't know the magnitude of the comp star from some true calibration,
use USNO-A/B/Tycho/etc.  Be *sure* to report the magnitude used for the
comp star along with its identification.  Do *not* do ensemble photometry
under these circumstances, as there is no way we can subsequently correct
the data.  If you need to do ensemble photometry, then make a request to
the AAVSO for the magnitudes of your comp stars, and wait to submit until
we can get accurate magnitudes for you (may be days to months).
Arne

Aaron Price wrote:
> (Note I've removed aavso-discussion from the CC: list since this involves 
> photometry.)
> 
>  This is a good question about a grey area.  Current AAVSO policy is to
> submit absolute magnitudes, not differential. If you don't have a
> magnitude of the comp star in the same filter as your observations then
> what you basically have is a differential estimate with an offset. So we
> recommend that you not submit that data until you can find an appropriate
> comparison star value.  When possible, we find the photometry and will
> post it and/or update the chart. But that is sometimes not possible,
> especially for faint stars in the southern hemisphere. That is something
> for which I don't have an answer for. Perhaps Arne does. I do know it is
> something we plan to address with our upgrade of WebObs and the
> observation pipeline in the next year.
> 
>  Note on your other comment, put the magnitude in the "comp star" field
> and then the GSC ID# in the Comments Explained field. And then use Comment 
> Code "G" (for Guide Star magnitudes).
> 
> Aaron
> 
> 
> 
>>The next question is what to do with my B, R, and I data.  If I use the same GSC
>>as a reference star and use its nominal GSC magnitude, that is patently wrong
>>and likely going to confuse users of the data if I can't also report the
>>magnitude I assumed for the reference star.  These questions have been raised
>>before of course.  Any updates on the progress of resolving the issue?
>>
>>Thanks!
>>Walt
>>
>>
>>
>>
>>
>>-----Original Message-----
>>From: aavso-discussion-bounces at mira.aavso.org
>>[mailto:aavso-discussion-bounces at mira.aavso.org]On Behalf Of
>>arne at aavso.org
>>Sent: Sunday, February 12, 2006 12:05 PM
>>To: Tom Krajci
>>Cc: aavso-photometry at mira.aavso.org; aavso-discussion at mira.aavso.org
>>Subject: Re: [AAVSO-DIS] RE: AAVSO special notice 5 object
>>
>>
>>Hi Tom!  Seiichiro Kiyota indicates that this object
>>is very red (B-V = 1.49), so that is why your unfiltered
>>differential photometry will have a large offset from Walter's.
>>For most novae, it is better to use a standard filter.
>>At 11th magnitude, you shouldn't have any problem using
>>a V filter for example.  Classification waits on a
>>decent spectra.  It is in a tough spot for a single site
>>to follow, so observations from everyone at all of our
>>longitudes will be essential to follow its light curve.
>>Arne
>>
>>On Sun, Feb 12, 2006 at 10:12:53AM -0700, Tom Krajci wrote:
>>
>>>>From: "Walt Cooney" <waltc at cox.net>
>>>
>>>>I imaged the area of the ASAS object reported in AAVSO Special Notice 5
>>>
>>>this
>>>
>>>>morning and can confirm the new object.   It is approximately 0.8
>>>
>>>magnitudes
>>>
>>>>brighter in V than the nearby star GSC 6826:280.  I am taking a time series
>>>
>>>in V
>>>
>>>>now.
>>>
>>>I have submitted about 90 minutes of time series data from this morning via
>>>WebObs...call it up in Quick Look by the designation 1727-24.  My unfiltered
>>>data shows it to be about 0.4 mag brighter than GSC 6826-0280.  No signs of
>>>modulation/humping.
>>>
>>>Tom Krajci
>>>Cloudcroft, New Mexico
>>>http://overton2.tamu.edu/aset/krajci/
>>>
>>>
>>>
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>>
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> 
>