Introduction

Project LAVA (Low Amplitude Visual Analysis) started in the context of this Visual Observing forum topic:

in which Matthew Templeton made the following comments:

"I've...worked up a spreadsheet showing variables with no appreciable visual amplitude..."

"...a good community project: run Fourier transforms of all such visual light curves and flag those where the only detectable periods are around one month or one year."

"...a list of stars...to investigate, where the cut was made entirely based on a...query "stdev(magnitude) <= 0.3". I should caution (a) 0.3 is very arbitrary, and (b) there are some things I know are visibly variable despite having low amplitude. As an example of (b), do a Fourier transform of the visual data of SY Mus -- the signal around 620 days is far above the background noise despite having a semiamplitude of only 0.2 visual magnitudes...I see a bunch of other objects that I know for a fact are variable, so this might actually be a good test of both the data and the analysis."

"The two criteria I described above are arbitrary, so I encourage you and anyone else interested to do something more rigorous. And regarding the methods, I think using multiple methods does have a place. Fourier and ANOVA are nice when there is a strictly periodic signal present, but something like autocorrelation or self-correlation can pick up things that aren't so strict (like an RV Tauri)."

"...a list of stars that would be interesting to analyze. This is NOT a list of stars to be dropped!"

A forum topic has been created for Project LAVA.

Objective

Analyse the stars in the "Objects Under Study" list to determine which ones show detectable periods other than those caused by regular observing gaps, or from seasonal/terrestrial variations in viewing conditions (e.g. Ceraski effect).

Objects Under Study

The Julian Day range

Start with a JD range of 2452700 to 2456380, with a focus on the visual observations. Where there is insufficient data (e.g. less than 100 observations), the range should be extended, e.g. by requesting all data from the AID.

Analysis

Using light curve inspection and tools such as VStar, Peranso, Period04.

LAVA: Low Amplitude Visual Analysis (last edited 2013-07-12 15:41:40 by admin)