[Aavso-photometry] Shortest period Variables..

[Wolfgang Renz]

Hi Steve

For such short periods (below 1.5 h, down to 7 min for V988 Cas) one
doesn't really need a prediction to catch a ToM in twice the period
(if the LC shows a double wave, even within just a single period). Just
set up and start to image as early as possible to not miss the first ToM
of the night due to an unnecessary delay (like spending time to calculate
the HJD of the first ToM of the night ;-).

Many of these short period rotatorts and pulsators (especially the multi-
periodic ones) do not have a HJD0 (usually called Epoch or E0 given
in HJD) in the GCVS or VSX. But one might find one in some cases if
one reads the literature. But for multi-periodic pulsators without a do-
minating period (= a period having a much higher amplitude than the
other periods) it won't help much anyway. To derive a ToM for these
doesn't make much sense if its not just for fun. These require a multi-
site, multi-longitude campaign to detect up to some dozens of periods
by a continous as possible monitoring.
.
The HJD0 it not given in the Search Results list of VSX, but if a var
has one, its given in the 'Epoch' row of the Detail Sheet of the var.
One can search VSX also for HJD0 in the 'Epoch' row at:
http://www.aavso.org/vsx/index.php?view=search.top&ql=2
but this usually doesn't make much sense as the HJD0 can vary over
the entire JD range for different vars and its value can be updated
whenever a better one is available. Here one must obey that one
must not input the HJD but the HJD-2400000.
One can also use this in the URL by specifying "&ephi=..." and
"&eplo=...". E.g. to catch AM CVn (Epoch: 08 Mar 1978 = HJD
2443575.7212) one can write:
<http://www.aavso.org/vsx/index.php?view=results.get&perhi=0.0001&perlo=0.08&maxhi=-2&maxlo=15&ephi=43575&eplo=43576&order=5>

There is a partially outdated VSX HTTP GET URL spec in VSX Bugzilla
available. See attachment:
http://www.aavso.org/bugzilla/attachment.cgi?id=5&action=view
of Bug #318:
http://www.aavso.org/bugzilla/show_bug.cgi?id=318

Christopher, could you please make an updated version available to all ?
See see the 2007 "NEW" enhancement request Bug #375:
http://www.aavso.org/bugzilla/show_bug.cgi?id=375

Clear skies
 Wolfgang

-- 
Wolfgang Renz, Karlsruhe, Germany
Rz.BAV = WRe.vsnet = RWG.AAVSO



----- Original Message ----- 
From: "Steven Orlando" <sorlando at sorlando.com>
To: "Wolfgang Renz" <w_renz at onlinehome.de>
Cc: <aavso-photometry at mira.aavso.org>
Sent: Thursday, August 28, 2008 1:52 AM
Subject: Re: [Aavso-photometry] Shortest period Variables..


> How can you search for HJD0 once you have a star with a period and
> mag that you think you want to observe?
> 
> Steve
> 
> 
> 
> ----- Original Message ----- 
> From: "Wolfgang Renz" <w_renz at onlinehome.de>
> To: "Derek C Breit" <breit_ideas at hotmail.com>
> Cc: "AAVSO-PHOTOMETRY" <aavso-photometry at mira.aavso.org>
> Sent: Wednesday, August 27, 2008 6:52 PM
> Subject: Re: [Aavso-photometry] Shortest period Variables..
> 
>> Hi Derek
>>
>> Why don't you use the extended search possibility of VSX ?
>> http://www.aavso.org/vsx/index.php?view=search.top&ql=2
>>
>> Set a min 'Period' a bit larger than 0 to exclude stars without
>> a period (e.g. "0.0001") and the max 'Period' to e.g. "0.06" for
>> vars with periods below ~ 1.5 h.
>> Set max 'Max mag.' to e.g. "2" and min 'Max mag.' to e.g. "10"
>> according to the range you can and want to observe with sufficient
>> accuracy. But remember that giving values for 'Max mag.' will
>> exclude vars without a set 'Max mag.'.
>>
>> Set the 'Order by' to "Dec." to inspect circumpolar vars:
>> <http://www.aavso.org/vsx/index.php?view=results.get&perhi=0.0001&perlo=0.06&maxhi=2&maxlo=10&order=4>
>> Set the 'Order by' to "R.A." to inspect non-circumpolar vars
>> in the RA range from 14h to 22h for current evening targets:
>> <http://www.aavso.org/vsx/index.php?view=results.get&perhi=0.0001&perlo=0.06&maxhi=2&maxlo=10&order=3>
>> Set the 'Order by' to "Period" to see the shortest ones:
>> <http://www.aavso.org/vsx/index.php?view=results.get&perhi=0.0001&perlo=0.06&maxhi=2&maxlo=10&order=7>
>> ...
>>
>> Clear skies
>> Wolfgang
>>
>> -- 
>> Wolfgang Renz, Karlsruhe, Germany
>> Rz.BAV = WRe.vsnet = RWG.AAVSO
>>
>>
>>
>> ----- Original Message ----- 
>> From: "Derek C Breit" <breit_ideas at hotmail.com>
>> To: <aavso-photometry at mira.aavso.org>
>> Sent: Wednesday, August 27, 2008 11:10 PM
>> Subject: [Aavso-photometry] Shortest period Variables..
>>
>>
>>> Can someone point me to a listing of currently visible (in California
>>> evenings) variables of the shortest periods???
>>>
>>> Derek
>>> http://www.poyntsource.com/New/index.htm
>>
>>
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